E-bike Conversions 101
May 2, 2021 6:55 PM   Subscribe

Actually, maybe more like e-bike conversions 001, since I'm pretty early in my research, but I'd appreciate some help in sorting out possible plans for my bike, and converting it to pedal-assist.

What I ride right now: a Trek commuter(?) bike that my dad bought sometime in the mid-90's and gave to me (after a decade+ in the garage) in 2014*. I really, really love this bike and would like to keep riding it. It's a workhorse, but is also weighs like 35 lbs and is...kind of unwieldy? It's legitimately the biggest bike I've ever seen. (Dad's 6'4", I'm 5'10" and like a tall frame.) I don't mind that I'm slow -- I really cannot overemphasize how much I don't care how fast I ride, and actually am extremely happy pootling along around 14 mph at most -- but I think the weight and overall difficulty is starting to get to me. Mostly I do longish rides on paved trails and bike-camping rides, let's say ~30 miles max, although I'd really like to go longer. Probably not more than ~75 miles in a day. I'm also hoping to start gravel riding soon.

So! I love my slow bike! It is great for touring/bike camping! The downside is, I hate riding up hills. Hate it hate it hate it. Am not good at it. Dun care. I am filled with impotent rage every time I have to haul this thing and my ass and, at times, a load of camping gear up a hill, personally fighting gravity and wheezing the entire way. Living in the PNW, you can guess how well this works out for me.

So my potential solution: convert it to a pedal-assist e-bike. I don't really want a throttle e-bike (see above in re: my lack of need for speed), I honestly just want a big ol' push when I'm going up a hill. I even really like pushing myself and doing all the work on flats and downhills, and feeling sweaty and strong!

So here's my dream set-up, can you tell me how much of a reality it is? And if it is in touch with reality, can you recommend a conversion kit?

- pedal assist, and a reasonably generous one at that -- I don't mind pedaling but I don't want to work as hard as I am currently.
- A system I can easily turn on and off so that I'm only using it on hills (or yeah if I'm really exhausted on the home stretch, I have no pride left.)
- a range that makes sense for this -- I'm guessing if I can turn the pedal-assist off and I'm doing, say, a 40-mile ride but only 5 miles of that is uphill, I'm fine with a 20-mile range.
- a smallish battery so that I still have room for two water bottle cages on the frame, and can mount rear panniers/camping gear pretty easily. Can post a picture of my current set-up if anyone's curious/wants to see. I'd love to be able to use this bike for grocery or farmer's market runs too.
- I'm not super-worried about weight, but I weigh at least 200 lbs, probably more like 220. Dad, who is not a small man, definitely weighed more when he was riding than I do now, so as long as the battery isn't crazy heavy, I think I should be ok?
- I have the best local bike shop in the whole world and will probably work with them no matter what I wind up doing, so no worries if it's hard to install, because I will almost certainly be paying someone good at bikes to install it.

My rough plan is to convert the Trek into a touring bike used almost only for camping, and maybe a couple up to 20- or 30-mile rides for fun, and buy a second, lighter bike for much longer road/trail riding and maybe gravel riding, and hope the lightness makes for easier hills. Does this make sense?

Also! If reading this list just made you feel exhausted inside, I can be talked into buying an e-bike and cutting out the conversion thing altogether. (I can be talked into buying a lot of bikes.) For example, I really love the looks and weight and specs of this, and it seems to do exactly what I want. Is it worth just getting that as my new touring and hauling groceries and I guess long-distance riding, and keeping the Trek for shorter, flattish rides?

Also, fwiw, we don't need to take the shortage of bikes or supplies into account -- this is something I have to save up for, and I am not in a huge hurry anyway, but researching high-value purchases is one of my favorite things to do. So you can assume a mostly-restored global supply chain, I think.

*Just because I like to carry a grudge and wish to share it with you all, my sister got his old LeMond. I don't even like road bikes, but I think I'm justified in some saltiness here.
posted by kalimac to Sports, Hobbies, & Recreation (15 answers total) 2 users marked this as a favorite
 
Just to be clear here, you've ruled out a new Trek or similar without the assist?

You can pay a lot less than your suggestion for a decent hybrid commuter (hybrid here being 'with off-road aspirations', for the car centric among us, and 'a lot less' being say $500 at the cheap end of things) and aluminium frames seem to be pretty standard at this point, making it so very much lighter.
posted by How much is that froggie in the window at 7:03 PM on May 2


Response by poster: Oh, good question -- I haven't ruled it out exactly. I'd consider just getting a lighter bike for most things -- I mean, every bike is lighter than my bike, it's not hard -- but I'm worried that once it's loaded down with camping gear or my groceries, I'll still be reasonably miserable going up hills. So I'd have a nice, light hybrid commuter for really long road or gravel rides, and the converted Trek for rides where I'm potentially hauling stuff.

So I think yet another solution might be to get the lighter bike and see if it really makes a huge difference getting it + stuff up hills :) Just having the lighter, faster bike might take care of some of the psychological stuff around climbing hills too, perhaps.

(Sorry to threadsit! I'm going to go do not-computer stuff now, but this seemed worth answering! It also gets to the heart of my question which is I can see like ten potential things for me to do, and I appreciate advice on which ones are better than others.)
posted by kalimac at 7:13 PM on May 2


Best answer: Personally I think converting a rim-brake bike to pedal assist is a bad idea. Rim brakes will not provide enough stopping power and you’ll burn through your rims quickly.
posted by computech_apolloniajames at 7:27 PM on May 2 [3 favorites]


Best answer: 40 year PNW cyclist (in Portland now, but grew up in Seattle, used to ride from work downtown to my GF's on Queen Anne then back to my place on Cap Hill multiple times weekly) and recent (seven months ago) e-bike purchaser here. I totally feel you on the hill thing, and I can say that buying my e-bike has completely changed the way I feel about cycling overall. I'm a big person for a cyclist (6'2" and about 260), and hills used to destroy me. With the e-bike, I no longer dread hills, and I actually seek them out.

To your specific points:

- pedal assist, and a reasonably generous one at that -- I don't mind pedaling but I don't want to work as hard as I am currently.
Yep, that's what e-bikes offer. The way it was explained to me when I bought mine (a Specialized) was that its three assist levels are "you plus 20%, you plus 40%, and you plus 75%", and I have found that to be pretty spot on. I still work to get up hills, but the work I do feels to me like the work small skinny cycling people do and not big ol' dudes like myself. I still feel it in my legs, I still sweat, but I can now ride at more than a walking pace, and at the top of a hill, I still have energy.

- A system I can easily turn on and off so that I'm only using it on hills (or yeah if I'm really exhausted on the home stretch, I have no pride left.)
My Specialized is exactly this. There's one button to turn it on/off and one button to adjust the assist level, right on the top tube in my eyeline as I look down while riding. Super easy, and I think most e-bikes have a similar setup.

- a range that makes sense for this -- I'm guessing if I can turn the pedal-assist off and I'm doing, say, a 40-mile ride but only 5 miles of that is uphill, I'm fine with a 20-mile range.
Range will vary a lot depending on your weight and the load you're carrying - my e-bike (a road bike) is advertised as having about an 80 mile range, but I'm big enough that on my normal city route here, which incorporates mostly rolling terrain and a couple decently steep but short climbs, I get about 45-50 miles (or in bike terms, I go from 95% battery to about 10%). If I'm doing purely hills, I won't get more than about 25-30 miles out of a full charge, because of the strain of hauling my extra mass up a hill. So a fully camping-loaded bike like you describe will get significantly less than the advertised range of any bike on a full charge.

- a smallish battery so that I still have room for two water bottle cages on the frame, and can mount rear panniers/camping gear pretty easily. Can post a picture of my current set-up if anyone's curious/wants to see. I'd love to be able to use this bike for grocery or farmer's market runs too.
See above - you don't want a smallish battery, because if your primary use of the bike will be to fully load it and go camp somewhere, your battery may not last the trip. This is why I would suggest buying a purpose-built e-bike and not a conversion; if you're willing to save for a while as you say, you could get one like mine, where the battery is actually built into the down tube and the motor is essentially the bottom bracket. That frees up the whole frame for cages, gear, etc.

- I'm not super-worried about weight, but I weigh at least 200 lbs, probably more like 220. Dad, who is not a small man, definitely weighed more when he was riding than I do now, so as long as the battery isn't crazy heavy, I think I should be ok?
The motor assist means you absolutely don't need to worry about the weight of the bike itself - a 35 lb e-bike isn't functionally different from a 24 lb conventional bike, because the power assist makes up for the weight penalty and then some. But this is where the load factor I was talking about comes into play - the heavier the load you put on the bike, the less range you'll have, because the motor will be working harder to push all that stuff through the air.

- I have the best local bike shop in the whole world and will probably work with them no matter what I wind up doing, so no worries if it's hard to install, because I will almost certainly be paying someone good at bikes to install it.
I did a bunch of research about building from a kit v. buying an e-bike, and honestly, for me it got to the point where buying one built for purpose made a lot more sense - it is cheaper to build one, for sure, but it's also a lot more...finicky to build and maintain one, and as computech_appoloniajames says, you'll almost certainly have to beef up your brakes significantly in order to provide enough stopping power for a motorized bike.

The bike you linked to would be really good for what you say you want an e-bike for - I've never ridden that specific one, but I'd be willing to bet that little lump above the Cannondale logo is the on/off/assist level function I was talking about above. The other advantage of bikes like that is that they handle like traditional bikes when the power's off, because the added weight of the battery/motor is down low, in the bottom bracket. You won't notice a huge difference between it and a traditional bike on flats or small inclines riding that bike with no power assist (but big hills will be really hard without it!).

I'd be happy to answer more specific questions if you want to memail me, but I would absolutely recommend going the built route rather than the convert route.
posted by pdb at 8:43 PM on May 2 [4 favorites]


Best answer: I'm what might be charitably described as a Clydesdale rider (male, 6', 260 lbs). I converted a discarded Timberline 1.0 29er to a PAS hub-drive e-bike, and it's now my daily ride for a 20 mile round trip commute that includes plenty of hills.

250W is street legal where I live, but 500W and now 1000W kits are sold as "off road" kits (here's mine) and they're conveniently indistinguishable from a street legal kit. If you're a larger rider, you want one of those. I got 500W, and it's fine, but 1000W would be better.

I got the cheapo secondhand bike because it came with disc brakes. Pretty much everything I read said that an e-bike will chew through rim brakes in no time at all, and given how often I change disc brake pads, I can believe it.

It's easy to turn pedal assist on and off. First, there's a power button that completely disables the motor. I wouldn't recommend riding like this, because the motor creates a fair bit of drag in an unpowered state. Better to leave it on and choose a low level of assist using the control panel. The extra weight of the motor and battery alone means you'll need some pedal assist just to make it feel like an unassisted bike. Mine comes with 9 levels of assist; 4 is fine for cruising, I drop it back to 3 for steep parts where I don't have a decent run up, and I sometimes take it to 6 on long flats, especially if there's a head wind.

I'm not sure what you mean by a "small" battery. My battery is 48V / 13Ah, and while that's technically enough for my hilly-ish 20 mile round trip, I charge the battery when I get to work so it's full for the ride home. My recommendation is to get the biggest battery you can afford. Between your weight, the bike's weight, the motor and battery, and your gear, you're going to need it. I can't imagine fitting a water bottle on any bike with any size of battery that's mounted to the centre of the frame.

Most PAS kits come with a thumb throttle. It's super handy for taking off from a stop - small press down to get you going, start pedaling, release the throttle, PAS takes over.

Get good tyres with puncture protection and consider double thickness tubes. Extra weight and speed saw my puncture rate climb markedly. If it's the front wheel, that's easy. If it's the rear, it means disconnecting the electrics, taking off the torque arm (definitely get one of these), then removing and reattaching a much heavier wheel. Not too bad at home but a sumbitch on the side of the road.

If you do get a hub motor preinstalled in a rim, get a bike shop to give the spokes a once over after you've been riding for a week or so.

Installing a hub wheel kit is easy. Unscrew your bottle and mount the battery controller. Remove the back wheel, drop in the new rim with the hub motor, connect the motor cable to the battery controller. Ideally, install a torque arm before you tighten up the rim. Click the PAS sensors over your pedal on one side. Run your brake and PAS controller cables up to your handle bars. You want magnetic sensors that will detect when you're braking and automatically cut power to the motor. Plug in the screen and the PAS switch. Zip tie the cables in place. Happy to send you pics of my set up if it helps.

My ride to work starts around 1830 feet, drops to 1710 feet, climbs up to 1980 with a drop to 1860 in the middle, then falls back to 1830. (The ride home is less enjoyable, particularly the last leg from 1710 to 1830 on a winding path, and without an e-bike, I just wouldn't do it.) My speed averages around 20mph on the flatter parts, and drops to 12.5 to 15.5 mph on the hills. Overall the 10 miles takes me about 40 minutes, but that's with plenty of time stopped at traffic lights. Despite being a much larger, much less fit rider on a heavier bike, I don't have much trouble keeping pace with the lycra / carbon fibre road bike crowd, particularly on hills where I often overtake (to much glaring).

One of the great features of an e-bike is you don't have to change gears nearly as often. I have a 24 speed bike; I leave it on the second smallest gear at the back, and just change the front from the largest gear for flats to the second for hill climbing - that's it.

I'm definitely getting a work out, and I'm sweating at the other end, but more "quick mop up with a towel" than "must have shower now" sweating.
posted by some little punk in a rocket at 8:54 PM on May 2 [4 favorites]


Best answer: I converted my Marin mtb to an ebike with a bbshd mid-drive motor (1000 watt). The reason for this much power was not about speed but to get up steep hills with a fully loaded bike, on my commute.
I found many store-bought ebikes have weak motors (250w-500w) that don’t climb well and people just get bored with. In any case, do a search for your particular bike model including ‘bbshd’, and check the compatibility. Lunacycle is where I bought my kit. I feel it was a great decision to build rather than buy as I loved my Marin before the conversion, and def even more after. It was fun to build, and now it’s the perfect ebike for me.
If buying store-bought, I’d suggest test riding up the steepest hill you can find. Happy ebiking!
posted by artdrectr at 10:35 PM on May 2


MetaFilter: what might be charitably described as a Clydesdale.

(I am 6'1" and about 190, and only in reading this thread am I realizing that my size might be a reason why bicycling has always seemed so much harder for me than it looks when a peloton of those wiry, thin 40-y.o. dudes in my town zoom past on the state highway.)
posted by wenestvedt at 5:49 AM on May 3


Not to ... not answer the question, but cheaper, lighter, and potentially easier than an e-bike might be to look into making your gearing easier. A lot of bikes with two chainrings in the front come standard with a small ring that is too large for loaded uphill riding of the sort that you're talking about. You might find that for like $100 in take-off parts from a bike shop you could put a smaller small ring on the crank and have a much easier time of it going up hills because it will enable you to stay in your desired cadence.

If your bike has 3 rings in the front then the smallest ring is already performing that function and that is probably not the issue. Also, your front and/or rear derailleurs may limit how small a ring you can put in front so this is not a surefire solution, but it is what I would look into before dropping coin on an e-assist, personally.
posted by gauche at 6:09 AM on May 3


Best answer: Loving all the good boots-on-the-ground advice here. I researched this a few years ago and came to the conclusion that conversion kits felt good from a non-"N+1" perspective, but weren't quite checking all the boxes I had. That might have changed.

I would add that it's worth going to a trusted ebike specialty shop just to get another lens for your decision. I've particularly appreciated G&O Cycle owner's advice when I was researching this a few years ago. They are in Seattle, not overly attached to outcome (i.e. getting your sale), and have been doing this a while and have tried a lot of the ideas mentioned above. They're pretty active on Twitter if you're not local. Dandelion Bikes is another good shop, I believe one of the previous co-founders to G&O.
posted by SoundInhabitant at 6:11 AM on May 3


Best answer: Hi Kalimac!

You've met me and my ebike conversion, and for your notes it's the Bafang BBSHD 1000 watt mid drive conversion kit with a 52V battery, a throttle and the Color 500C display/controller. (More on the display and controller in a moment.)

And as you saw when we met I'm a HUGE FAN and rabid fanatic about my e-bike conversion. I went through the same process where I was very hesitant to convert my beloved gravel/touring bike over to an ebike, and I was looking around at getting a second bike to convert over to leave my every day bike alone.

But then I realized I was basically trying to find and build a second version of my exact bike complete with all of the add-ons I have like my cargo racks, my handlebars and cockpit accessories and so on and it was entirely out of my budget - even if I could find the right frame and parts. Which I couldn't because there's a global shortage in bikes and bike parts right now due to the pandemic and everyone building new bikes for commuting, fun and exercise.

I purchased my kit last summer from the bafangusadirect.com site and had no problems with them except for the time it took for delivery, which they note on their site that they're still facing significant delays in shipping due to demand. It did take about a week longer than expected for delivery but it wasn't a ridiculously long wait.

I also went with the larger 52V battery upgrade instead of the stock 48V battery, which means the nominal wattage of my motor is more like 1200-1250 watts (ish) with a peak power of something like 2000-2200 watts.

I have ridden 250-500 Watt hub drive conversions and they definitely did not have enough power to haul my fat butt around up steep hills, especially not with a full load of groceries in two panniers or any decent amount of cargo for camping or other adventures.

I have my battery mounted on my seat tube with the battery mounting tray taking up the seat tube water bottle mounts. This also blocked the downtube water bottle cage mounting bolts, but I solved this by using an add-on water bottle cage holder that just straps on to the frame and moving it forward about two inches up from the stock bolts and it works fine. A slightly smaller battery would probably allow me to use the stock bottle cage mounting bolts in the same configuration, but I didn't want to compromise on battery size or life.

I also have and use another strap-on bottle cage holder that can be moved around my frame as needed depending on what I'm doing and my bike luggage configuration, because for bike touring I have front panniers I sometimes put on it as well. I usually put this one on my fork if I want two bottle cages. Or I just use my panniers to hold extra water bottles.

So, lets talk about controllers/displays. The controllers and displays on the ebike systems are an important choice that is often overlooked, and I would strongly recommend doing some homework about these display/controller computers because they have different levels of functionality and usefulness. I went with the 500C display because of the information and settings it offers, as well as the easier one-cable installation.

Some of these displays have separate units for the controlling buttons and displays, which on one hand offers more flexible mounting options, but this can also clutter and crowd your cockpit because they need to take up more than one mounting zone on your handlebars. The buttons control stuff like what power assist level you're running and other functions that interface with the drive controller built into the mid-drive motor unit.

There are also some much more advanced computer/controller units available that have a lot more options and information, like more finely controllable and tunable pedal assist levels, checking battery life and health and even Bluetooth connectivity and app support for things like tracking power level outputs, range and much more.

These computer/controller units are also rated for voltage levels, and some of the older ones can't handle more than 48V and are incompatible with 52V batteries even if the drive itself can handle it.

Next, let's talk hub drive vs mid drive systems. Bafang offers both kinds of systems, and I prefer mid drive over hub drives hands down.

There are some major differences between the two kinds of systems.

The main benefit to hub drives is they tend to be smaller and lighter with a slightly easier DIY installation process. The installation is really only slightly easier because you still have to do cable management and stuff, and now you have to do it from either the front or rear wheel axle dropouts.

The way the wires feed into hub drives through the axle is at significant risk of wear and tear and damage. The axles of hub drives themselves can also spin if they're not locked down super tight, and if the whole axle spins under load the first thing to go is the power and Hall effect sensing cables when they get twisted up under load and torn off, which is a difficult or expensive repair.

One benefit to hub drives is that you can also keep your existing drive train including the front chainrings and derailleurs - but in practice in the real world on my mid drive and 8 speed rear end I honestly don't even miss my front gears at all because of how I can adjust my pedal assist power levels to work with my rear gears. It's super easy to increment the power level of the power assist for climbing hills to match whatever gears I need for easier riding.

There are major downsides to hub drive systems. The cheapest bolt on ebike conversion kits use front wheel hub drives, and applying power to the front wheel feels super unnatural and has problems with effective power transfer due to the weight loading on the front wheel being less than the rear wheel. It feels SUPER WEIRD and dodgy when the power is applied during turning and can seriously throw off your balance on the bike like someone yanked on your handlebars in the middle of a turn.

Hub drive motors deliver less power per watt to the ground as well due to the traction issues and less torque available at the wheel since they're applying all of that torque at the hub, so they're not as efficient about battery use as a mid drive system that drives through the chain and drivetrain.

Then there is the biggest drawback of all for hub drive systems, which is the wheels. Sure, most bike shops at this point are totally capable of doing custom spoke lacing and builds for any hub size, but if you bend or break a rim you can't just go get a set of new off the shelf wheels since your drive motor is built into the wheels.

This was important to me for bike touring. I really don't want to be on a bike tour and end up getting stuck somewhere waiting for a local bike shop to rebuild my wheel on my hub motor, or having to mail a broken hub motor built wheel home or other known bike touring related issues. With a mid drive system I can use any given wheel that fits my frame, and the mid drive doesn't really care if it's a totally different wheel or if I'm making do with a 26" wheel even though I normally run a 700c wheel, etc.

If you want options like stronger touring-grade rims this means it's a custom build, otherwise you are stuck with the stock rims and wheel builds that come with the hub drive motors, and the stock quality of these rims and spokes aren't great. Upgrading to a tubeless wheel system also offers similar conversion costs and problems requiring a custom wheel build to lace your hub motor into the new rim.

If I want to change up my rims or switch to tubeless or something it's just as easy to do on my ebike as it is on any other bike. With a mid-drive system my bike basically stayed exactly the same as it was before the installation and conversion, except now my drivetrain is 1x8 instead of a 3x8 drivetrain with a front triple chain ring and front derailleur, and now there's a lot more wires and stuff bolted to it.

Mid drives really are the best way to ebike if you want to keep your existing bike the way it is, except now it's powered.

There's also the issue with those spokes being under a rotational torque load that they're not really designed for. Even lower powered 250 watt hub drives put out more torque than most humans are capable of delivering through a normal bike drive train, and the spokes on these wheels get a lot of extra stress and so you really need to keep your spokes tight and in good shape.

Another major drawback to hub drive systems is that it makes fixing a flat on the road a lot more challenging. As far as I know you can't really use quick release skewers on a hub drive motor, which means you need to carry a wrench and tools to undo the locking nuts and lockrings on a hubdrive, then be super careful of the wiring harness as you remove and reinsert the wheel for fixing a flat, which can also mean you may need to cut off any zip ties holding your wiring harness together on your bike and then reinstall them every time you change a wheel or fix a flat.

The one clear advantage that hub drive systems may have come in the form of either going for the much more expensive and advanced two wheel drive systems people are experimenting with, mainly for off road fat tire e-bikes or more advanced hub motor setups that have fancier options like internally geared systems and modern belt drives - but you can also run belt drives on mid-drive motors, and using a mid drive with a belt drive system and an internally geared hub is an increasingly popular option for a grease free, maintenance free drivetrain.

That's probably enough general background info, so lets dive into some of your direct questions:

- pedal assist, and a reasonably generous one at that -- I don't mind pedaling but I don't want to work as hard as I am currently.


So, there are multiple types of pedal assist out there, and at this point most of them don't have torque sensing.

The more expensive Bosch mid drives do have torque sensing and will modulate power based on how hard you're actually pedaling.

The Bafang and related systems do not have torque sensors. It just uses a Hall Effect sensor in the motor that detects how many magnet poles in the motor have moved before it turns on PAS. I can adjust how many poles in my computer/controller, and I have mine set to 3 poles, which is about one third to a half of a pedal revolution before it kicks in.

It was a little weird to get used to but at this point it's just second nature and i know how and when the power is going to kick in.

The power it applies isn't set by how hard I'm pedaling but the level I set my PAS to in the controller. If I have it set to level 1, as soon as the Hall Effect sensor detects movement, the motor turns on to full power at that level whether it's 1 or full power at 9. There's no modulation or feathering of the power, and if I am not mindful and I try to set off from a low gear at power level 9 it's kind of like popping the clutch on a motorcycle, and if I'm not ready for it and leaning into it doing an unplanned wheelie is totally a thing.

- A system I can easily turn on and off so that I'm only using it on hills (or yeah if I'm really exhausted on the home stretch, I have no pride left.)

Something else to remember is that basically every ebike I've ever seen is that once the power is off or the battery is dead - you now have an extra heavy bike that has increased drag and resistance, and this is especially true of hub drive motors. Without power my bike goes from something that's effortless to ride up hills even at the lowest pedal assist power settings to feeling like I'm pushing uphill with a flat tire.

I was not expecting this part. I have yet to take my bike on any sort of ride over a few hundred feet without any power. I would definitely not want to ride more than a mile or two without it unless I wanted the exercise.

So far I have never run out of battery on a ride and I don't want to, but in the worst case scenario it's easier than walking many miles home and I could at least pedal and slog home on a dead battery.

- a range that makes sense for this -- I'm guessing if I can turn the pedal-assist off and I'm doing, say, a 40-mile ride but only 5 miles of that is uphill, I'm fine with a 20-mile range.

I went with the largest 52V battery I could get at the time from the bafangusadirect.com site and I'm very glad I did. 20-30+ mile rides without pedaling at all and just using the throttle are totally possible. If I'm economical with the throttle and power levels, I keep the speeds lower and I pedal more 100 mile ranges are easily possible.

Just like a car with a combustion engine, your actual mileage and range for a full charge is highly variable based on driving/riding style. Hammer on the speed and power means less range and mileage per charge.

Take it easy and apply "hypermiler" style conservative riding and the range increases dramatically, just like with a car.

- a smallish battery so that I still have room for two water bottle cages on the frame, and can mount rear panniers/camping gear pretty easily. Can post a picture of my current set-up if anyone's curious/wants to see. I'd love to be able to use this bike for grocery or farmer's market runs too.

I strongly recommend not skimping on the battery and making room for it in your setup. I went with the frame mounting option for my battery to keep the center of gravity lower and keep my rear rack free for panniers.

I also put it on my seat tube instead of my downtube for better weight distribution and balance. Since it's right below my bodies center of gravity I barely know it's even there as far as bike handling and balance is concerned.

I can't even imagine what it would feel like to have this heavy battery mounted on the rear cargo rack up high and behind me. It would probably make doing accidental wheelies even more of a thing.

- I'm not super-worried about weight, but I weigh at least 200 lbs, probably more like 220. Dad, who is not a small man, definitely weighed more when he was riding than I do now, so as long as the battery isn't crazy heavy, I think I should be ok?

My mid drive motor and battery together weigh about 25-30 pounds, not including the wiring harness and computer/display. Off the top of my head I think the BBSHD mid drive motor unit is about 13 pounds, and the battery I'm using is about the same weight.

I have hauled 80-100+ pounds of groceries or gear in my panniers with this setup and I barely even notice it. Climbing hills is much slower under a heavy load but I have enough power and battery that I can easily do a fully loaded ride up steep hills with no pedaling at all and just using the throttle and a lower hill friendly gear.

Something else to remember about batteries is voltage sag. As you deplete your battery, it offers less and less power and torque at the motor, and it's noticeable.

With a larger battery my voltage levels stay higher for longer even under heavy loads, meaning more power and range per unit of weight, with larger reserves and range.

I generally do not deplete my battery more than 50%. At full charge my 52V battery charges to a bit over 58V, and if I let the battery drop below about 40-45V that means there is something like less than 1/3rd to 1/2 of the actual battery range or capacity left, and at that point the battery starts to deplete much faster with much less power available and things start to slow down in a hurry.


- I have the best local bike shop in the whole world and will probably work with them no matter what I wind up doing, so no worries if it's hard to install, because I will almost certainly be paying someone good at bikes to install it.

Installing the BBSHD was actually impressively easy. You just need the tools to remove your bottom bracket, and to install the mid-drive unit it just slides right into the empty space and replaces the whole bottom bracket. There's a special spanner/lock ring tool you use to lock it in place and clamp it on the bottom bracket shell of your frame. It doesn't use the internal BB threads and is just a friction/press fit to the outside of your BB shell.

The most difficult part of the installation for me was figuring out how I wanted to route my cable harness and deal with that, and where to mount my battery tray mount.

When I did my conversion and installation it took me a grand total of like 4-5 hours, and most of that was just figuring out the sparse instructions and guides and cross referencing some YouTube videos about how to install and configure the BBSHD.

If I did the same setup today it might take me less than two hours and I wouldn't even need the instructions or guides.

I will say I'm more comfortable and skilled than most bicycle owners and I do almost all of my own work. I think the only thing I haven't done in bike building and repair is building and lacing my own rims, which isn't something most people do because it's a huge pain in the ass and you really do need a proper wheel truing stand and a dishing tool to do it right, especially with modern wheels that are often offset and heavily dished to make room for larger cassettes or disc brake ready hubs.

So my potential solution: convert it to a pedal-assist e-bike. I don't really want a throttle e-bike (see above in re: my lack of need for speed), I honestly just want a big ol' push when I'm going up a hill. I even really like pushing myself and doing all the work on flats and downhills, and feeling sweaty and strong!

Ok, I may have scared you off talking about how fast my ebike setup is when we met, but my bike is kind of unusual in that I was already a fast rider, and since it's basically a skinny-tire road/sport/gravel kind of hybrid bike that's super efficient, especially considering my ebike setup is the sort of power and battery size usually used for fat tire comfort and all terrain e-bikes.

Yes, my ebike is stupid fast especially when it's not hauling groceries.

Also I love my throttle. It serves multiple functions beyond just having the option to not have to pedal at all. It's super useful for adding a boost of power when climbing hills. The bafang controllers are set up so that the while the throttle levels are defined by your chosen pedal assist level, as in that max throttle value only puts out roughly the same value as that pedal assist level, but slightly more.

What that means is if I'm riding up a hill at, say, level 3 PAS and I'm starting to bonk, my options are either to adjust the PAS to a higher level OR I can hit the throttle lever while pedaling, and it gives a slight boost to the current PAS level. This is super super handy for hill climbing and ease of use.

One of the things I didn't talk about is how good my bike also is at low speeds, and how it works with off road and gravel riding. With my setup and using a throttle it also has a ton of low speed torque for climbing rough terrain, and it's a total joy for super low speed off road riding on twisty single track trails covered in tree roots and rocks.

Since my bike has no suspension at all I have found this to be very useful in situations where I would normally be trying to pedal on rough terrain, and instead I can stand up on my pedals to spring my body weight off the bike and use the throttle instead of pedaling and treat it like a silent motorcycle even at very low speeds, especially since the throttle is more variable and easy to control compared to the pedal assist levels.

On the other side of things and still getting exercise and pedaling hard, I also find myself turning the power way down and pedaling more. I can still get a ton of exercise, as much as I want. When it's colder out I tend to pedal more to warm up and get a workout. If I get too hot or sweaty for my tastes I just turn up the power a bit more or take a break from pedaling and use the throttle. I have a lot of freedom and flexibility to adjust my riding between lazy commuting and grocery runs to getting a proper workout.

This has been super helpful for my relatively long commute to work, especially after a shift if I'm tired and worn out.

It's also really nice in situations like cruising up a hill when I want to grab my water bottle and have a drink while rolling. I can just let the throttle take over for a few seconds and keep cruising while I have a drink, where as before power I'd generally have to crank harder to build up some momentum for coasting and grabbing my water bottle.

Here are some other notes about ebikes, things I didn't expect going into this:

You really want brake levers with cutoff sensors. Most ebikes have these. The sensors in the brake levers cut all power to the motor as soon as you barely pull on them, and this is a major safety feature for a number of reasons, like preventing a runaway bike or stuck throttle or other issues.

It's also super important to have them for controlling the power and pedal assist. I have found that having power suddenly applied in a slow speed turn to be problematic, just like riding a motorcycle. If your pedal assist level is turned up and the pedal assist kicks in during a low speed turn it will surprise the hell out of you and may cause crashes or lurching into nearby trees or worse - innocent bystanders or pedestrians.

With the brake lever sensors and power cutoff either brake lever can act just like the clutch lever on a motorcycle, except instead of one clutch lever you have two of them, and they are also your brake levers which is super handy once you get used to it. When I start off riding I do so by feathering my brake levers and keeping the power cut off until I get rolling, then I release them once I'm underway to let the pedal assist kick in.

They also make stand alone brake lever sensors that you apply to your existing brake levers using high strength adhesive tapes, but I haven't used these yet and went with the stock flat bar levers with built in sensors, and so far I'm happy with them. With how hard I ride I bet I'd be having problems with the stick-on sensors coming off by now. But they exist as an option if you have some brake levers you prefer to use.

Alternatively this is another way a throttle lever comes in handy. I often mount my bike and use the throttle to get moving, then switch over to pedaling and letting go of the throttle. The throttle and pedal assist both work together on the same system, and on the Bafang setups the throttle overrides the pedal assist.

The system is not totally seamless though, and it can be a little glitchy depending on your PAS level settings, because on the Bafang the pedal assist isn't modulated, it basically applies whatever full value of your PAS level which can conflict with a light throttle touch as opposed to maximum throttle. (This is hard to explain in text.)

Another add on item I got with my kit was the gear sensor option. This helps prevent chain and cassette wear and tear by momentarily cutting off the motor power when I change gears, just like how you're supposed to unload your pedal strength during gear shifts.

However I will note that I now have trained myself to use the brake levers and just lightly feather them enough to trigger the sensors to cut power during gear shifts, but sometimes I forget to do that and I'm glad the gear sensor is there to cut power for me between gear shifts.

Also, the Bafang system relies on a wheel magnet for the speedometer and as a safety check and it can be fussy. If this sensor isn't working and detected while under power, the computer/controller will display an error code, and after about 5 minutes the whole system will shut down for safety. So if the magnet and sensor aren't aligned properly, not only does the speedometer and odometer stop working, the whole ebike stops working and you have to power off and restart it to get it working again.

In the beginning of my ebike riding I had trouble keeping this magnet and sensor aligned and have had to adjust it in the middle of rides a bunch of times, but now that I know about the problem it hasn't happened much unless I do something like try to put my bike in someone's truck or car and I bump it and move it out of alignment.

They make an add on part that defeats this safety interlock by replacing the sensor with a small timer chip that just sends steady state pulses but this breaks the speedo/odometer function and makes it useless for tracking range and mileage.

Another thing I did not expect nor plan for when converting to an ebike was how much faster some bike parts would be worn out and used up, especially the chain and brake pads.

Granted I'm a really hard or heavy load rider. I'm heavy. My bike and cargo is heavy. I like to go fast.

But even with light and conservative riding a mid drive ebike is putting much more power and load into the chain and drivetrain than most humans can accomplish, so the chain and drive trains on ebikes is much higher than most chains and cassettes are designed to handle, so chain stretch and wear happens much sooner than it would normally even on a per mile basis and all other things being equal.

I also ride a lot more than I did before, so my total monthly mileage on my bike has possibly tripled over what I was doing before converting my bike to an ebike.

I ride a whole lot more than I did before even just for fun, and I was already using my bike as my primary mode of transportation. Now with the ebike I don't even think twice about taking off for a fun ride just to go get lunch somewhere or sit on a beach or something.

Drive train maintenance is now even more important than it was before due to these factors. I should also probably clean my chain more often but in practice I just wipe it down if it's really muddy and keep it nice and lubed up with Triflow, which matches my low effort bike maintenance before converting it to an ebike.

Likewise I'm also going through brake pads a lot faster than I did before. The ebike is heavier and goes faster, and this would be true even with a lower powered system. It takes more braking force to stop in the same space from the same speed since the bike is about twice as heavy as it was before the conversion.

Another pro tip I want to share is the use of dielectric grease on any/all connections, plugs and electrical fittings. You can get little packets of this grease at an auto parts store for a few bucks. It keeps water out of the connections and prevents corrosion. I dabbed a little bit on all of the connectors and also all over the connection tabs in the battery and battery tray.

Also, note that most of the battery trays I've seen are NOT weather sealed. They have open spaces and gaps in the tray that let mud and water right inside. I went and sealed all of these gaps with carefully cut strips of Gorilla Tape applied to surfaces I cleaned very well with alcohol, and then I burnished all the tape down really good with a spudger tool, and then used plenty of the dielectric grease on the battery contacts.

I also invested in some heat shrink tubing in a couple of different sizes and used this to seal the main power connectors, battery tray connectors and other plugs to add an extra layer of protection to everything for wet weather riding.

Technically the Bafang batteries and the whole system is not supposed to be weatherproof, and there are higher quality batteries out there that are properly weatherproofed. My 500C computer/controller is rated to like IPX 7 or so for weather proofing, but I have read on various ebike forums that riding a stock bafang system in the rain can be hazardous.

But so far my setup has been flawless in all sorts of weather, including snow and heavy rain and mud and i haven't had a single problem. I've ridden it in extremely heavy rain and mud without any issues.

Another thing to keep in mind about battery health and life is that you get a lot less range and capacity in cold weather, especially near freezing temperatures.

You do not want to put a cold battery pack on the charger as it can severely damage a lithium ion battery to the point of it being permanently damaged and a major fire risk. Make sure batteries are brought inside and up to room temperature before charging.

It is fine to use the battery in even below freezing temps, and I think the bottom safety range for using a battery is something like 20-30 below freezing. Granted, this gives you much less range but the battery won't hate it as long as it isn't being charged at low temps.

When I went riding in the snow this past winter in freezing or near freezing temps I used some of those disposable chemical hand warmers and taped them right to the battery case, and then covered the whole thing with my aluminum sheet windscreen from my camp stove. Covering it in some aluminum foil would also work for this, to help keep the heat from the hand warmers in and keeping the battery warm.

This trick improved the battery range in cold weather a great deal and made a huge difference, especially since I was slogging around in snow with all of the increased rolling resistance this created on my snowy rides.

Another point to consider is your charger. The stock/cheapest chargers are only 2 amps, which means it takes a lot longer to charge a large battery. I went with the 3 amp version, and I kind of wish i went with a 5 amp or larger charger for even faster charging.

In practice and reality with the way I ride and never depleting my battery more than about 50% it generally takes about 2-4 hours for a full recharge. I've had a few charge cycles that took more like 6 hours when I've really run the battery down.

Last, another thing I wish I knew when I started was the existence of GRIN Technologies: https://ebikes.ca/ as well as Luna Cycles.

GRIN has a bunch of aftermarket parts and accessories, as well as more advanced battery systems, controller systems and more. I've been looking at their site and parts a lot because of my vague plans to do a solar kit capable of charging my ebike off grid on camping or bike tour trips. I have some vague ideas about being able to go on off grid self supported tours where I can taking working vacations and do remote work from the middle of nowhere, and I kind of want to be able to set up my ebike to not only charge itself with portable folding solar panels but also keep my computer and phone charged for remote work and not having to plug in anywhere at all for an e-bike supported bike tour.

I basically want to modify my existing battery to have options like USB C and maybe even an AC inverter to make it function like a solar generator/battery set on wheels. It has more than enough power to drive an AC inverter or a high wattage USB C charging circuit, but I need special charge and power controllers for that.

I also wish I knew about Luna Cycles earlier because they have a bunch of Bafang compatible parts like better mid drive chain rings and heavier duty parts, controllers, etc. You can rebuild and take apart the entire Bafang mid drive system and do stuff like replace the motor controller, the clutch/locking pawls in the drivetrain inside the motor system, or even upgrade the stock nylon pinion gear to a much more durable steel pinion gear.



Anyway, go for it! Ebikes are awesome, and you're going to love it, especially climbing hills!

Feel free to ask more questions!
posted by loquacious at 8:26 AM on May 3 [1 favorite]


I looked into converting my 2007 trek commuter bike to pedal assist. I can't remember all the variables but it looked like it would cost the same as purchasing an entry level e-bike.

[So once I have a little extra cash I am going to do that. So probably never. ]
posted by Morpeth at 11:05 AM on May 3


Best answer: I looked into converting my 2007 trek commuter bike to pedal assist. I can't remember all the variables but it looked like it would cost the same as purchasing an entry level e-bike.

i came to a different conclusion and answer. While there are some decent ebikes in the $1000-1500 range I found that they skimped on both the bike and the ebike parts of the equation. The bike quality and components just aren't great and often use off-brand or bottom shelf components for the drive train, derailleurs, seat, rims, tires and more.

Complete Bafang/Lunacycle mid drive kits in the 750 watt range that include a battery can be had for as little as about $700-900ish if you catch one of their regular sales and they'll mount on just about any bike as long as you get the right size for your bottom bracket shell.

My admittedly overpowered and nearly maxed out BBSHD kit was something like $1450 with tax and shipping and all of that, and so far after about a year of riding and over 1500 logged miles I haven't had to replace any ebike parts at all, just my regular bike parts.

If I tried to buy a complete and off the shelf high performance "pedalec" gravel bike with the specs I have now both for the bike and the ebike system the closest options I've seen are in the $3000-5000 range because ebike builders charge a huge premium for quality components and frames.

An easy example: Rad Power Bikes is known for fairly good quality yet affordable complete ebikes and the closest thing they have that even vaguely looks like my converted bike is the Rad Mission model listed at $1099, which is an earnest price for what it actually comes with, but it's about a one fourth of the bike that I have in all aspects be it the bike frame, components or the ebike specs.

The Rad Mission is a internally geared single speed 500W hub drive with about half the battery capacity of what I'm running. The brake and other bike components are bottom of the line entry level components, and it looks like it would have trouble mounting any decent cargo racks or have enough heel clearance to carry full sized panniers.

Max weight capacity of the Rad Mission is 275 as well, which doesn't leave a lot of room for luggage for groceries or touring loads for heavy riders.

To compare I've probably had 400-450 pounds on my bike when I add up my own weight, a heavy grocery run plus my racks and luggage and it takes it like a champ. I can hit 20-25 MPH going up a steep hill with that load and some mild pedaling - and this does not include the 30+ pounds of the ebike kit and oversized battery.

And the Rad Mission is their lightest bike, but is actually heavier than my mid range aluminum bike if I took off the luggage and racks and stripped it down to a similar state of just the basic bike and the ebike kit. My bike's dry weight comes out to less than 50 pounds, has more range, torque, power and gears and has even better components from drive train to brakes and so on.

It is a pretty good value for the price but in the bike world the frame and components are just a step or two up from what cyclists call "Bike Shaped Objects" as found in a department store or something.

And if I wanted to clone my bike and build a completely new one from scratch from the frame on up to all of the touring/commuter add ons that I have I could probably do it for less than $2500-3000.

And if I went with a used frame and found a lot of used parts I could probably do it for well under $2000. I could probably go buy a used gravel bike with similar specs to my bike for somewhere between $300-500 or even less, with the main cost being the BBSHD conversion kit.

If I dialed back the specs a bit and went with a smaller batter and a 750 Watt mid drive I could probably pare that price down to about 1250 or so, and it would still be roughly about twice the ebike of the Rad Mission, and might even come in under 40 pounds total dry weight without racks or luggage in a similar commuter/hybrid style pedalec setup.

In the end I have been very, very happy with converting my existing bike over to an ebike. I ended up with a bike I already loved that fits me perfectly and already had all of the extras I wanted. If I went with something like the Rad Mission I simply wouldn't have enough power or range to haul my heavy 260+ pound self up hills, much less haul groceries and ass at the same time.

In the end I strongly recommend going this route - find a used bike that fits you that you actually like, one that matches your riding style, your terrain and comfort needs, and then add on a conversion kit whether it's a more affordable hub drive or a higher performance mid drive.

Once you have a good base bike you can tailor the conversion kit to meet your needs, price and specs.

Take care of that bike and you can upgrade the ebike side of things as needed either one part at a time or a whole new kit. Try to do the same with a Rad Power Bike or other affordable complete ebike system and you'll find that it might not even be possible because DIY parts like the ones found at Lunacycle or Bafang won't fit or work with their systems.

You also can't really upgrade the drive train to something with gears or pick and choose your own drivetrain components. It doesn't even have a derailleur hanger or bracket.

On any given normal mid-range bike you can pick and choose from so many components and parts that fit that it would take a thick catalog to list them all, and that's also true for the Bafang/Luna Cycle conversion kits. There's a huge market of both OEM and 3rd party upgrades and parts available for those ebike kits. There are dozens of different controllers and computers and the whole system is highly hackable.

They're also just now starting to release firmware hacking tools for the motor controllers as well, while the Bosch and big names like Trek have completely locked systems and require authorized service techs to work on them and so on.

This problem with upgradeability is especially true of higher end ebikes like the Bosch drive systems used by Trek, Specialized or other high end bike makers since they build the bike around the drive and battery system. Frames with built in battery compartments in the frame or downtube are cool looking and all of that, but you're limited to that exact size of battery, so upgrading to a higher capacity or voltage battery can start getting super expensive (if you can do it at all) because that means they have to use more expensive, higher capacity cells to fit more watt-hours into the same space.

Sorry if I'm typing too much and dominating this thread. I've done a ton of homework about this and I'm very enthusiastic about ebikes! I talk to a lot of other ebike owners locally and I probably have the fastest, raddest ebike on my local trails and I love it!

Also my knees don't hate me and I don't hate hills any more!
posted by loquacious at 7:43 PM on May 3


Response by poster: ahhhhh, as per usual, Metafilter is amazing when it comes to knowledge and discussion and ahhhh I am genuinely overwhelmed with everyone's generosity in sharing their time, experiences and advice.

Also I am 100% referring to myself as a Clydesdale rider from now on, what a delightful name. (Also people get weird when I call myself fat, which I am, but anyway.)

I have loved reading everyone's input, and after reading and thinking and pondering, I'm going to go with buying a dedicated ebike, and keeping my old Trek around for shorter, flatter rides, and as a bike that travels a skoosh more easily. I have gotten over my need for a small battery, and am definitely looking at larger bikes that can take me + camping gear and still go a decent ways; the one I linked to is simply too small and not really as powerful as I'm hoping for. I've started looking around and will hopefully start at least test-riding soon :) I'll update here when I finally buy a bike, in hopes that it'll be helpful to future readers. I am very excited to keep my old workhorse, and also frankly to get a shiny new bicycle that doesn't date to the Clinton administration.

(Also I have gone cycling with loquacious who was awesome enough to show me around some local trails, and can confirm their set-up is AWESOME, and probably tipped me over into thinking more seriously about getting an e-bike.)

Finally, I'm truly happy to hear from everyone whose relationship to hills has vastly improved. It's become a pretty limiting factor on where I'm comfortable riding (the Burke-Gilman isn't that interesting), and I'm really excited to actually range farther, especially on the gravel trails in W Washington, and probably become a better rider. So thank you!
posted by kalimac at 10:20 AM on May 4 [1 favorite]


Clydesdale riders rule!

Yeah, don't skimp on the battery. The weight and size difference isn't really that much when you go from a small to medium sized battery to a much larger one, and the cost increment per watt hour isn't that much, either.

Larger batteries will also generally have a longer lifespan over the same discharge and charging cycles because you're not depleting them completely as often as you would with a smaller battery and the larger battery will be under less stress, especially with higher peak loads hauling a larger rider around, and this is especially important if you're planning on using it as a grocery getter or hauling camping gear.

If you change your mind about going with an off the shelf bike - I would totally be into helping you do a conversion. You could pick up a second used or new bike that fits you that you like and then we could pick out a Bafang system that also fits your needs and your bike. I already have all the tools we would need except for maybe the right bottom bracket tool for whatever bike. (I do have a bottom bracket tool, but it may or may not fit depending on the BB system of any given bike in question.)

I can easily do a mid drive conversion in less than a day, if not just a couple of hours. I even have a bunch of zip ties and heat shrink sitting around to do the waterproofing stuff I was talking about.
posted by loquacious at 12:21 PM on May 4


Best answer: Personally I think converting a rim-brake bike to pedal assist is a bad idea. Rim brakes will not provide enough stopping power and you’ll burn through your rims quickly.

I haven't found this to be a problem. I do go through brake pads much faster but rim wear from braking hasn't been an issue, and I was super hard on my brakes with all of the bike touring and off roading I would doeven before I converted it to an ebike.

If there was any ebike that this would be a problem on it would be mine because it's basically a torture laboratory for rim brakes with all the high speed wet, muddy, sandy and otherwise dirty riding that I do.

Seriously, you guys should see my bike after a muddy, rainy ride. I've had to scrape off several actual pounds of dried on mud and gravel. Like a fairly large flowerpot sized pile of dirt and rocks and stuff. My bike non-figuratively can end up like 5+ pounds heavier after a muddy ride when it's still wet mud and it's all over my bike frame and packed up inside the fenders. Sometimes I get so muddy I have to scrape it off the spokes and hubs because it's starting to bridge the spokes and turn my wheels into disc wheels made out of adobe.

Granted I do make sure to buy good salmon koolstop pads and set them up with proper alignment and toe-in, and replace them often because fresh brake pads are really nice.

Another caveat is I probably destroy rims and wheelsets more often than most people and the sidewalls never get a chance to wear out from braking. As a Clydesdale myself wheelsets are basically consumable parts.
posted by loquacious at 2:35 PM on May 4


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