Bicycle Advice - how long should chains/cogs last for ?
May 6, 2013 3:44 PM   Subscribe

I have a five year old bike - an Avanti Blade. In those five years it's averaged 2 hours / week of riding. I'm being told I need to replace not only the chain but the front and back cogs but I have questions .... !

I like riding but I'm not a super keen/super fast rider.

I'm being quoted a price to replace "the drive chain" (apparently the cogs and the chain) which is approximately 50% of the price of the bike when new. I'm being told that if i don't do this work within six months "everything will start to slip".

I'm not very happy about this - I don't recall having to do this on previous bikes.
  • I'm not sure how real the problem is - what is a reasonable life-span for these parts (I seem to have got 500 hours use out of these parts which doesn't seem very long to me) ?
  • Does replacing them make good economic sense or should I just replace the bike ?
  • Is there something I could do in future to increase the lifespan of these parts ?
BTW where I live I don't have a lot of options for shopping around and the prices probably are going to be higher than elsewhere - just thought I'd throw that in to give some context for pricing etc.
posted by southof40 to Sports, Hobbies, & Recreation (15 answers total) 1 user marked this as a favorite
The short answer is that you shouldn't have to replace all those parts.

The long answer? Replacing the chain once it's showing wear will basically prevent it from deforming the cassette and crank chainrings. Park Tool makes a simple chain wear indicator that can usually be had for about US$10, though based on the bike you have, you're in NZ? You can check wear on the cassette and crank chainrings by just looking at them. Provided they aren't chipped or deforming (they'll start to look more like hooks and less like teeth as one edge rounds out from the chain) you are not likely to need to replace them.

There are lots of technical things that will affect all of the above, but replacing your chain will probably fix any/all issues you may be having. Chains don't have a set life. I've been putting 800ish miles/year on my current commuter bike and am still using the same chain four years later. I check it occasionally, but haven't had any stretch issues thus far.

Keep your chain clean of debris and lubricated with a light oil. Any other drive-train maintenance should be in case of shifting issues but you can probably get by without doing anything else.

tl;dr -- Clean and lubricate the chain. Check it for wear. Replace chain before anything else.
posted by komlord at 3:58 PM on May 6, 2013

The chain alone's pretty cheap, and will likely show some benefit to replacement (you can check for chain wear yourself pretty easily). It's also not something that should incur significant labor costs, and is fairly simple to DIY.

As for the rest of your gears, that's more significant work and it could be a good cleaning and lube will do you up nicely. Are any of the cogs bent or damaged? You can investigate that sort of wear yourself pretty easily, too. Sheldon Brown on chains may be more info than you want, but it's got some decent photos illustrating what to look for there.

Good luck! Every bike requires a certain amount of maintenance, and it sounds like you've been riding regularly, so it's not like you can avoid it entirely.
posted by asperity at 3:59 PM on May 6, 2013

I think it may be "the drivetrain," not the "drive chain." And the wear on these parts is generally influenced by a lot of things like the surfaces you ride over, the weather you ride in, lubrication, etc. I think the warning that "everything will start to slip" likely refers to the chain slipping over the cogs or chainrings if the drivetrain is particularly worn. This can happen, but I don't see much sense in replacing your drivetrain before it starts to happen, especially at such a high cost, unless you're racing or are often in a position where some drivetrain slippage could be dangerous (e.g. you're mountain biking along steep ridges or something; unlikely on your blade).

To increase the lifespan of the parts, clean your chain and lube it with a lubricant matched to your riding conditions (some are designed for wet weather, some for dry, etc.) regularly. How regular depends on how often you're riding and in what conditions.

Zinn's book suggests that you should get 1500 or so miles from a chain with lousy lubrication and conditions, and up to 5000 miles under ideal conditions, and almost infinite life from chainrings and cogs according to this post.
posted by craven_morhead at 4:01 PM on May 6, 2013

Generally chains are the consumables, not the cogs. If the cogs are in good visual condition i.e. not missing teeth etc, just leave them as they are. I'm restoring a bike from the 1960s atm and the front and back cogs were all fine, FWIW. You can certainly change the chain yourself, they're pennies of ebay and there are plenty of youtube videos that make doing so really easy.
posted by prentiz at 4:02 PM on May 6, 2013

Say you ride around at 12 mph average pace. Your 500 hour estimate is 6000 miles (!), which is well into the chain-replacement time frame. If you haven't been oiling your chain regularly, have been operating the chain in nasty weather, or have been using a misadjusted derailleurs, you can expect lower life out of the chain. On the other hand, chains for 8 (rear) gear bikes tend to last longer than 9/10 (rear) gear bikes. I only expect 2000-ish miles out of a bike chain.

Chains are cheap (think $15-$50 parts, similar for labor). However, the thing about worn chains is that worn chains significantly reduce the life of the gear cassette cluster on your bike. Cassettes are not cheap. I suspect the costs quoted include a gear cassette replacement due to the cogs wearing due to using a worn chain.

Moral of the story: replace chains when they are worn so that you don't have to replace chains and cassettes.
posted by saeculorum at 4:04 PM on May 6, 2013 [1 favorite]

Another comment: Replacement parts costs don't track well with bike value and labor definitely doesn't track with bike value. Most bike shops don't like to keep low end parts in stock because they don't have much profit. So, it's likely they are replacing bike parts with "nicer" parts (ie, more expensive) because that's what they have in stock. For labor, replacing a cassette on a carbon fiber race bike is just as hard as on a commuter hybrid.
posted by saeculorum at 4:09 PM on May 6, 2013

Often it's advisable to change the cassettes when you change your chain. It depends a lot on how often you shift, and the percentage of the time that you spend in a given gear, and how aggressively you ride. Road bikes tend to outlast mountain bikes, and weather shortens the lifespan of everything. If your cassettes DO need to be replaced and you only replace the chain, you will not be a happy cyclist.
posted by maleru at 4:22 PM on May 6, 2013

I'm gonna guess you took it in for a tune up, and maybe it doesn't shift so awesome? Just have them fix the riding stuff, maybe replace the chain if it's demonstrably worn, but that you'll worry about the other stuff yourself. If the drivetrain does start to "slip" in 6mos, it's not going to involve replacing more parts than they're telling you now. I'm all for supporting your local bike shop, but this is how you can resist their upsell.
posted by rhizome at 4:24 PM on May 6, 2013

It's totally plausible that it's time to replace your whole drive train, especially if you haven't been taking good care of it.

That said, if you're a casual rider you could just ride it out until the chain slipping becomes unbearable then replace whatever needs replacing (or buy a new bike).

But yeah, you definitely need to expect to have to replace you chain a cogs, and to a lesser extent your chainring every so often if you ride regularly.
posted by no regrets, coyote at 5:06 PM on May 6, 2013 [1 favorite]

I work in a bike shop. A lot of customers bring in bikes very similar to the Avanti Blade. By the way, do you have the Blade 1.0, 2.0, or 3.0?

Chains wear out. A five-year old chain that gets about two hours of use a week is probably well past the point where it needs to be replaced. If you don't trust your mechanic, ask them to show you precisely how they arrived at this decision. When I recommend a chain needs to be replaced, I always have a chain checker in my pocket, because invariably a customer will ask "How do you know?" and I can show them on the spot "Boom, your chain is at 75%, see?". Sometimes chains are so worn they don't even register on the scale. We use three different chain checkers in my shop. The Park CC2 is my favorite, but other techs in my shop like this one by ProGold. The Park CC3.2 is cheap but sucks (it's a go/no go gauge).

So, your five-year old chain needs to be replaced. The chain and cogs in the back (aka casette or freewheel) wear together. If you replace your chain at about 50% wear, you usually don't have to replace the cogs in the back. Visual inspection isn't always effective. In my shop, we first replace the chain, check shifting performance, and replace the cogs if things aren't working as they should. So what your mechanic is telling you, that you need to replace your chain and the gears in the back, is probably solid advice.

This is costing 50% of the bike? In my shop, in the United States, the chain we would put on a bike like yours would cost about $16 (for the Blade 1.0) to about $30 (for the Blade 3.0) plus about $9 for labor, a cassette would be anywhere from $20 (for the Blade 1.0) to about $35 (for the Blade 3.0) for a 10-speed Tiagra cassette. Again around $9 in labor. So, between about $54 to $83 for parts and labor. That's for a new chain and a new cassette, installed. That doesn't include the gears on the front (chain rings).

Chain rings generally don't wear as quickly as the chain and cassette do. On some bikes it's more economical to just get an entirely new crankset (the chain rings and the crank arms). On other bikes it's better to just replace the chain rings separately. Quality chain rings are not cheap, they start around $50, and you're going to need three of them. On the 1.0 I'd just get a new crankset. The 3.0 has a Tiagra crankset, which is decent, and I'd probably stick with that and just replace the chainrings as needed. However, when you say "replace the drive train" I don't know if you mean swap out the cranks as well.

Labor cost to replace cranks in my shop is around $15 I think. Parts, well, cheap cranks are ~$45-$60, Tiagra cranks are around $100.

What are they quoting you? Does it include the cranks as well, or just the chain and cassette?
posted by spikeleemajortomdickandharryconnickjrmints at 5:58 PM on May 6, 2013 [6 favorites]

I'm a bike mechanic and own a shop in the US. What spikelee said is EXACTLY what I would say. I don't know why you think it's 50% of the cost of the bike, unless it's a Walmart-type special? Again, I'm in the US, but my shops' prices are exactly in line with spikelee's, above. Usually a drivetrain on a 7 speed is $55ish, 8 speed is like $70ish, we can throw a tiagra 9-speed on for under $100, and it goes up from there. Not sure what your bike cost new. Chains and cogs are meant to be replaced. I'm surprised your front rings are that worn. I almost never see front rings actually worn down to need replacement...

what prentiz said about the cogs not needing to be replaced, just chain, isn't really the same with ramped cassettes/freewheels of today. you could end up putting a chain on, it skips worse, and then you have to just do the whole thing again.
don't throw away good money in an attempt to cheap out on it.
posted by kpht at 6:07 PM on May 6, 2013 [2 favorites]

Backing what everyone else is saying and adding; bike parts are expensive compared to whole bikes, just like car parts. If you built a car from parts it would be crazy expensive.
posted by bongo_x at 8:12 PM on May 6, 2013 [1 favorite]

Assuming that South of the 40th Parallel means you're in either NZ or Tasmania (I'm guessing not the tip of Chile & Argentina) then the cost of bike parts in your LBS is hit hard by greedy distributors inflating the wholesale prices the LBSs need to pay, which is probably what's driving up the cost to 50% of the whole bike.

If you source the parts online & install the things yourself you should be able to do it for about a third to a half what the LBS is quoting. It's not massively complicated, but you might need a special tool or two - eg a chain whip & perhaps a castellated key to loosen the nut that holds the cassette in place, plus a chain break tool to get the old chain off, and maybe to install the new chain (although some have handy links you can click together without a tool).

It's really a long way from rocket science, and you've got (the spirit of) Sheldon Brown online to talk you through it. Maybe read up on how to do it, then decide if DIY is for you.
posted by UbuRoivas at 8:16 PM on May 6, 2013

I just replaced the chain, rear cassette, and chainrings on my bike. The thing was slipping to the point that it was unrideable except in the absolute highest gear. But this is also a bike I have been riding for 20 years, on the original chain. Cost me $250 USD including a tune-up, new front derailleur, and brake pads. For me, it was totally worth the expense - I like my bike and it is in good enough shape that I may well get another 20 years out of it. For you, it depends: how much do you like the bike?
posted by caution live frogs at 6:43 AM on May 7, 2013

I ride a few thousand miles every year, half of that in bad weather, so I usually end up replacing the drivetrain every year or so (a bit different now that I have a dedicated winter bike). In theory, I might be able to do this less if I monitored the chain and replaced it earlier but that never seems to happen.

In any case, if you are already at the point of having to replace everything then I'd say go ahead and keep riding the bike until the performance becomes unacceptable. Basically, your shifting will start to get less smooth, then you might have to shift up and down to land in certain gears and eventually you just won't be able to get into certain gears. At whatever point you get tired of dealing with this, bring it in and get everything replaced. It will feel like a new bike again!

It might be six months, it might be longer. Either way if you consider the cost over five years of ownership it stings less. I wouldn't buy a new bike unless you are just looking for an excuse to buy a new bike anyway.
posted by mikepop at 6:43 AM on May 7, 2013 [1 favorite]

« Older Recommendations for a Denver Dentist?   |   Guidance for a male with HPV Newer »
This thread is closed to new comments.