I have a trek 7.1 that I bought last March (2014) and have been told that the pads, front wheel, chain and cassette need replacing. Is this normal for 4 to 5 days a week usage for commuting (5 to six miles total) then the odd longer cycle? The wheel was my fault as I damaged it by not replacing the pads.

Should this stuff be covered by warranty considering it's less then a year? I have been told it's wear and tear which isn't covered but I don't think it's reasonable I should have to make these repairs so early on (minus the wheel obviously). Just wondered if I should try and get this done under warranty or if it's a lost cause.

  • 1
    I figure a chain is good for around 2000 miles. A cassette for about 5000. Brake pads depend very much on how you ride -- can last 1000 or 10,000. And it probably is possible to abuse the shifters in a way that will cause premature chain and cassette wear, though you'd really have to work at it. Your commuting would be about 1000, so you could have racked up close to 2000 total. (And some folks will insist that you must replace the cassette when you replace the chain, though it's not necessary if the chain is replaced in a timely fashion.) Jan 20, 2015 at 12:32
  • (The shop should have a "stretch gauge" for the chain, and a wear gauge for the cassette -- if they're not using those (and the chain and cassette are not visibly worn) then go somewhere else. You can buy an inexpensive chain stretch gauge and check the chain yourself from time to time.) Jan 20, 2015 at 12:35
  • (Though as someone reminded me below, if you failed to keep the chain properly lubed it could wear out prematurely -- and take the cassette with it. With your use you should have been lubing the chain roughly weekly.) Jan 20, 2015 at 12:55
  • Technique could have a big impact on wear. Using poor gear combinations and crossing the chain would exacerbate wear. Pads are just about how often you use the brakes. Wheel, pads, chain and cassette replacement would be much cheaper if you buy the parts and tools online. These are all easy jobs with a quick google. The hardest thing is calculating chain length which you can just measure against your old chain.
    – DWGKNZ
    Jan 21, 2015 at 3:31
  • When you figure chain length, don't measure the length of the old chain, count the number of links. Jan 26, 2015 at 12:38

3 Answers 3


Many things on bicycles are consumable and anything that moves or rubs is going to have to be replaced, it's just a matter of when.

It's unusual for a cassette to wear out completely within a year although if it's been ridden on a stretched chain or without regular cleaning and lubing it'll wear out much faster.

In my experience chains are normally the first things to wear out, presumably because they almost constantly in motion and rubbing against the cogs while you ride plus picking up all kinds of stuff that flies off of the wheels. I normally replace my chains every year regardless of the state that they are in simply because of the low cost of a replacement chain and the relatively high amount of damage that running a worn chain can cause.

You can tell if the cassette (or the chainrings) need replacing by checking the teeth. If the teeth looked ramped you should switch out the part. See Image:

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If the teeth don't look worn but are black with dirt you can clean them with a de-greaser you may find it easier to clean the cassette if you remove it although this requires a cassette removal tool otherwise you can leave it on and clean it with a brush and ordinary dish soap, just rinse afterwards, dry it and remember to lube the inside of the chain again after cleaning it being careful not to overdo it as that will just cause muck and grit to stick to it while riding.

To check the wear on your brake pads look at them from the side and check for grooves. New brake pads come with groves which allow water to escape from under them much like the tread on a tyre. If your brake pad has no visible groves on the face that touches the rim, they should be replaced.

  • It's very easy to leave a chain on too long once its worn and wear out the cassette (or at least some sprockets on it). For commuting when you just get on and go, sometimes heavily laden, it's not all that easy to remember to check everything all the time, and before you know it parts are wearing out.
    – Chris H
    Jan 20, 2015 at 12:21
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    Nothing wrong with WD-40 as a cleaner. Jan 20, 2015 at 12:37
  • @DanielRHicks WD-40 is fine for cleaning tiles on your kitchen floor and will clean up a bike chain nicely but it will cause dust and dirt to stick to the chain and will not lubricate the chain, doing more harm than good. To lube a chain you should use a bicycle specific lube like.
    – nettux
    Jan 20, 2015 at 12:47
  • Clearly, a chain should be lubed with chain lube. That's a separate issue (though, come to think of it, failure to properly lube could be the cause of the OP's premature wear). Jan 20, 2015 at 12:53
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    @nettux443, in my understanding, lubing the chain is aimed at lubing the internal pin/roller pairs. Failing that, the pins wear out the rollers and the chain stretches. However, I am not aware of a mechanism that lubing the cassette reduces cassette or chain wear (I would expect it to only accelerate gunk accumulation). This is actually quite an interresting question!
    – Vorac
    Jan 21, 2015 at 11:44

Chain wear is objectively measured. Ask the shop to show you the chain wear measurement. It's a simple device that shows how much the chain has stretched. But if the chain is really worn with such small mileage, then something else may be wrong. Even if it has never been cleaned or lubed, I doubt that it could be worn out already.


No warranty for these items:

  • pads wear. If you use them in wet and sandy conditions they wear faster.
  • front wheel damage is your fault
  • chain grows and wears, especially if you don't shift properly
  • cassette wears, especially if you don't shift properly

Having said that, I don't think that you need to change your chain and cassette. Unless you do racing you can get away with the same chain and cassette for 2-3 years.

  • Thanks for the feedback. The bike shop told me the chain and cassette where past their critical point.
    – David
    Jan 20, 2015 at 11:41
  • Shops will sometimes exaggerate these things to make you spend money. Ask them what is the worst case scenario that could happen with a "worn" chain and cassette. Probably nothing that matters to you.
    – cherouvim
    Jan 20, 2015 at 11:46
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    It would be fairly easy to rack up 2000 miles (and a worn-out chain) in a year or two. The need to replace the cassette, however, is questionable. Jan 20, 2015 at 12:36
  • I don't agree with your last statement. It would be easy to wear your chain sufficiently to destroy the cassette and chainrings in much less than 2-3 years.
    – Mac
    Jan 20, 2015 at 21:32
  • @David I'd trust the shop on that advice. I've had friends who haven't taken this advice and then ended up spending $500+ on cassette and chainrings.
    – Mac
    Jan 20, 2015 at 21:33

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