Switching bike forks back and forth: doable?
October 3, 2013 7:50 PM   Subscribe

I have a commuter bike with no suspension and light tread tires. i have taken it on light mountain bike trails, and it handles well, but the jarring caused by a lack of suspension is killing me. i was wondering how practical/possible it would be to buy a second suspension fork and knobby(er) tire and switch the forks depending on whether i want to ride on concrete or a trail.

My bike is a 2009 Giant Seek 3 commuter bike, with 700x32c tires and a standard (that is, no suspension) fork. when i purchased it the dealer told me it would work fine on roads and packed dirt trails, which was my intended use.

I have on occasion, however, used it on light mountain biking trails, and besides the odd sandy corner, it has fared quite well (I'm actually faster than the mountain bikers, as no energy is being absorbed by a suspension or knobby tires. though gaining too much speed on straightaways can be risky with the possibility of impediments or sudden turns).

When i do this however, the jarring is unbelievably unpleasant. i'd like to occasionally ride trails but i don't want to buy a new bike. so i am wondering how practical it would be to swap the forks at will.
A complicating factor is the fact that the bike has disc brakes. I am guessing that the swapped fork/tire would have to be fitted quite well if i wanted the front brake to work (yes i know i would have to get a second disc break installed on the second fork), and i imagine reconnecting the brake wire might be more of a pain than swapping the fork. alternatively, would riding with only a rear break be seriously advised against as a safety issue?
posted by camdan to Sports, Hobbies, & Recreation (15 answers total) 1 user marked this as a favorite
Suspension forks are longer than non-suspension forks. A bike's geometry is usually designed around the fork type, with some companies going so far as designing specialty parts to allow non-suspension forks be used with suspension geometry frames and not change the geometry.

I don't know much about the bike you have, but 700x32c seems to suggest you are running 'road bike' or 'cyclocross' tires/wheels which wont fit the run of the mill 26" mountain bike fork.

My recommendation would be to keep the Giant, and invest in a trail bike.
posted by SirStan at 7:58 PM on October 3, 2013 [1 favorite]

Best answer: Changing out a fork is a pain in the ass. Doing it every time you want to do something different on your bike is making a lot of work for yourself and asking for problems.

SirStan's got a good recommendation, but you have a couple other options.

You can run wider tires at much lower air pressure, which will smooth out your ride quite a bit. So, you could just put wider "29er" tires on your current rims -- the only limitations are rim width (see Sheldon's chart for guidance on how wide a tire will fit a particular width rim) and the width of your fork and rear triangle. Or, you could get a 29er wheelset w/wide tires to mount when you go mountain biking. That sounds like it'd be a pain, but it'd take maybe a couple minutes and there's much less to go wrong vs. swapping out a fork.
posted by cog_nate at 8:27 PM on October 3, 2013 [1 favorite]

Best answer: Yep, change the tires, not the fork. Get a 29er wheel set to make it even easier on yourself. People ride hardtail frames with non-suspension forks all the time; it's lighter and more efficient.

Are you wearing gloves and riding "light" on the bike? Make sure you're putting enough of your weight on the pedals-- your legs are natural shock absorbers.

Don't ride trails without a front brake. Rear brake is for slowing, front is for stopping.
posted by supercres at 8:33 PM on October 3, 2013

Best answer: Switching out forks is a big job. Do you not want to have a suspension fork when you're riding on the road? Lots of them have lockouts, which would accomplish the same thing.
posted by M.C. Lo-Carb! at 8:33 PM on October 3, 2013

Best answer: You could put a different fork on there, like an 80mm 29er fork, but that's going to change the geometry of the ride like SirStan said. Swapping the caliper from one fork to the next every time would be a major pain in the ass, a lot more work than just swapping the fork. Even if you buy a second caliper you're going to have to run a cable and housing and adjust the brake every time. Adjusting Hayes MX4 brakes sucks.

I wouldn't ride with just a rear brake.

You're going to have to adjust the headset every time you swap the fork. Not hard, but you need to know what you're doing.

I wouldn't do this. I'd start looking for a second bike or I'd put an 80mm fork on there and call it done. Swapping forks back and forth is possible, but my guess is that you're going to do it once, maybe twice, before you decide that it's just not worth the hassle and you're never going to touch it again.

See how big of a tire you can get in the rear, then try to match it with the front. Bigger tires, like others have said above, can give you a little passive suspension. If anything, I'd put a fork on there that would allow wider tires, like a Surly Ogre fork, which is disc compatible and can easily run tires as wide as you'd dream. Looks like the bike comes stock with 32c tires; try 38c before you swap a fork, and run them on the low side of the pressure rating.
posted by spikeleemajortomdickandharryconnickjrmints at 8:38 PM on October 3, 2013 [1 favorite]

Response by poster: i think you've answered my question, i will try a fatter/lower pressure tire first. my tires now are rated for 90-100 PSI, which i understand is way high, that might be a lot of the jarring problem right there.

if the ride is still too jarring for me i'll do a permanent switch to a suspension fork with lockouts so i can get the stiff road ride when i want it.
posted by camdan at 8:48 PM on October 3, 2013

If you're actually running your tyres at 90+ PSI, that will give you wonderfully low rolling resistance on made roads and a shitty bumpy ride on anything else.

Simply lowering the pressure in a standard road tyre and using it on a mountain biking trail is just asking for a pinch flat.

Horses for courses.
posted by flabdablet at 9:41 PM on October 3, 2013

Response by poster: flabablet: yes thanks for the advice, when i first purchased the bike i was getting pinched flats before the dealer told me about the high PSI. so i certainly will not be making that mistake intentionally ;)
posted by camdan at 11:09 PM on October 3, 2013

How much room is there between the tire and the top of the front fork? Searching for pictures of the bike, it looks like there isn't that much, which would make it hard to fit fat knobby tires.

So if you want to use this bike as a trail bike, you might just have to learn to ride lighter and avoid big drops. Plenty of people do the same with cyclocross bikes with the same size tires. Definitely use lower pressure offroad.
posted by akgerber at 5:41 AM on October 4, 2013

Best answer: akgerber's picture makes me skeptical that a 29er tire would fit in there, but you should be able to get cyclocross tires in there. Combined with a lower psi, it will help some in traction, but not a lot in shock absorption.

I'd lean towards finding a used mountain bike as bike number 2 if that would fit with your lifestyle.
posted by advicepig at 6:41 AM on October 4, 2013

Response by poster: advicepig, i rarely am on trails, i'm usually on concrete. so i feel getting a second bike wouldn't really be justified.

i think my strategy now is to troll ebay and craigslist for a used 29er wheel. if knobby tires won't work with the fork i'll get a fatter, lower psi cyclocross tire, or a new fork that allows it, supension or not.
posted by camdan at 9:12 AM on October 4, 2013

Best answer: How technical are the trails we're talking about? One thing to consider is that your frame really isn't meant for big hits, not to mention the geometry is just going to be.....well.......unpredictable.

I'm all for this. I love frankenbikes, and I love tweaking whatever you can on a bike to get it to do what you need it to do. If you have the clearance for a wider tire and go for it on that stock fork, things are going to still feel a lot different than a hard tail MTB. Things are going to feel weird even with suspension on your Giant. It's a commuter bike. It's really not meant in any way for technical trails.

HOWEVER......why not? Find out just what about this bike sucks the most on the trail and you'll know what you want out of your next bike.

BEWARE: that stock fork was not engineered with trail riding in mind. I would give this bike frequent close inspections.

One of the bikes I'm riding right now is a women's medium MTB frame with a rigid Surly Troll fork swapped on it and drop bars with bar-end shifters. It's somewhat comfortable in the rocky stuff because a) it's got 2.2" knobbies running tubeless, at about 21psi and b) the geometry of the stupid thing lets me really shift weight fore/aft to get over the bigger things when I need to. Even with drop bars, you can throw the bike around pretty easily.

So go for it. Try bigger tires. Maybe think about swapping forks, but a frame that's geared a little more towards the trail is going to be the best foundation to start from. Either way, please update this if you do anything and let us know how it goes.
posted by spikeleemajortomdickandharryconnickjrmints at 10:21 AM on October 4, 2013

Response by poster: spikeleemajortomdickandharryconnickjrmints i'm not talking about very technical trails, i don't know trail ratings but everything i've ever gone on i would call easy. i haven't thought about frame stability before but i will keep that in mind.

my spidey senses are telling me that i'll probably have to get a new fork anyway if i want a beefier tire to work, i'll cross that bridge after i get the new tire.

i'm going to take my time looking for a wheel but once it's all set up i will give you a progress update
posted by camdan at 11:55 AM on October 4, 2013

Response by poster: i am also going to take supercres' advice and make sure that i am riding "light" on the bike and i'll get some gloves. i think i tend to overgrip for support, i'll have to make a conscious effort not to.
posted by camdan at 12:07 PM on October 4, 2013

Response by poster: i went in to the local bike shop to discuss my plans. he showed me a 700c with some tread on a fatter tire, 40psi that should work. so i'm bringing in my bike tomorrow to make sure there is no clearance issues with my stock fork and then he will order the parts.
posted by camdan at 3:24 PM on October 4, 2013

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