Quick Chainring Wear - Ideas?
 

I have a Trek 5200 that's little less than a year old. I wipe down the chain and/or clean with a relube every week. The bike has a 10-speed cassette so I realize that the chain will wear a bit more quickly than my previous bikes. Here's a brief history:

- At 1000 miles, chain replaced by LBS -- cassette/chainrings, OK
- At 2000 miles, chain replaced by LBS, cassette worn and replaced as well, however my 52/39 chainrings are worn and need to be replaced as well.


Does this sound quick to anyone else regarding chainring wear/replacement?

I'm not at all surprised by the chain at 1000 miles and 2000 miles from the cassette isn't too bad I suppose -- but I'm really wondering why the chainrings went so quickly. On my previous two road bikes, I never had a chainring replacement.

The LBS is kind of at a loss as well -- their best guess is that the 5200 shipped with Bontrager chainrings/crank (all the other components are Ultegra) and they're now a little suspicious of the Bontrager chainrings.

Any ideas?

Thanks.

Rules of my LBS owner:

Mileage isn't a consideration in replacement.
Replace 'chain only' before stretch reaches 1/8" over 12 links (12 links or 24 half links should measure 12" center of pin to center of pin when new).
Chain stretch 1/8" or more over 12", replace entire drive train or replace nothing.

Theory is that once the chain has stretched 1/8" or more it begins to wear on the cassette / rings. Replacing only one or two components allows the remaining worn component(s) to transfer the wear to the new components accelerating wear on the entire drive train.

Hope this helps. I've found these guidelines to be the most economical.

You're going through drivetrain parts way too quickly, especially for a road bike. I agree with threadend, use the guideline of chain wear as your guide. When the chain is worn to the point that it's 1/16" longer than twelve inches over a span of twelve links, replace it. Doing this should make the cassette and especially the chainrings last a very long time; much, much longer than what you're talking about. I have no idea what your LBS is basing their opinion on as far as the worn cassette and chainrings, but no way should you be replacing either of those parts at only 2000 miles..........maybe when they replaced the chain at 1000 miles, they installed the wrong chain (perhaps a nine speed chain?) and it has worn the parts prematurely, I don't know. Something definitely ain't right-

This may sound crazy, but I look at this in a completely differant manner. For the average rider (who doesn't stress the drivetrain nearly like the pros), the cost of replacing the chain every 1000 miles may be an economically bad decision. Now, why would I say this?

Well, one example is my commuter and my wifes bike.

My commuter (Veloce grou) has about 3,000mi of harsh commuting and winter/rainy riding on it now, and the chain has stretched a bit, but the whole sytem still runs as smooth and shifts as well as when I first installed it. Better in fact. And, the cogs and chainrings don't appear to have any significant wear or "dolphin" shape to them. At the current rate of wear, I would estimate my drivetrain will run well up to 10,000mi or more.

My wifes bike (Centaur group) has over 4,000mi on it now, and the drivetrain still looks new with frequent lubing with a PTFE based spray lube (Liquid Wrench w/PTFE). That's all I use for maintenance on both our bikes.

My point is this....

If you get 10,000mi or more of good quality service out of a drivetrain, then why replace anything on a regular basis, like the chain every 1,000mi?

Think about it. A chain will run you about $40-$50 (or there abouts with taxes, shipping, etc). If you change your chain every 1,000mi, then you will have invested $400 in chains alone after 10,000mi of use. Now, along that way, one would replace the cassette and chainrings at least once to keep up, even though chains have been replaced. So, you have effectively replaced your entire drivetrain, along with 8 or 9 extra chains regardless. So, you've essentially paid an extra $400 for chains when you didn't really need to.

I have found, the best way to do business (money, and labor wise), is to simply run your chain and chainrings for as long as they can. All of the components will wear and run smoothly together for thousands of miles. Constant lubing and cleaning is also key. After about 10,000mi of service, just replace the whole drivetrain at once (if needed), and you are completely good for another 10,000mi.
Some drivetrains can go for 15,000-20,000 miles before needing replacement, even if you use the original chain. Hard to believe, but true. When the whole drivetrain finally poops out, it'll cost about $130-$200 (depending on the group) to replace the cassette, rings, and chain.

Unless you are into racing where you need a high level of reliability and perfect function with no possibility of failure as a requirement, replacing chains every 1,000mi of service is simply not needed. At least that has been my experience.

Keep in mind, I am specifically referring to my road bikes, not MTB's. MTB's no doubt, go through a higher level of abuse, and high torque on the cranks and drivetrains on a more regular basis due to there environment. So, replacing a drivetrain would most likely occur more often.

This has just been my personal experience.

I have a similar situation occuring with one of my mountain bikes. I've repeatedly read about changing the chain at the sign of wear etc. I've tried everything but really not much helps.

I have learned a couple things though:

1. Replacing a chain early isn't always practical. Sometimes it is a better option to just run the crap out of them and then replace the chain/cassette at the same time. It all depends on the expense of your chain, chain rings and/or cassette. If you are running Dura Ace stuff, you better change religiously. If you are running inexpensive SRAM, then maybe it doesn't matter.

2. Something that never gets mentioned is gear ratios as a cause of chain wear. I have learned that running for long periods of time on the smaller cogs of your cassette drastically accelerates wear on EVERYTHING. Mainly it starts with wearing the chain earlier than necessary, and that wears the cassette and ring.

It all depends on how you ride and how your bike is geared. If you spend a GREAT deal of time in a couple different combos you will wear down the teeth on those cogs and that will zap your chain. The hosed chain will then zap your chain rings.

This is really the only explanation i can come up with as to why I have been tearing through drivetrain parts like mad since I put on a new crankset last August. The new crankset had a smaller middle ring which made me run on the outer cogs of the cassette most of the time. They are smaller so they wear quicker. Since then I've put on 3 chains and 2 cassettes. Now my middle ring is hosed and i just ordered a new one a minute ago.

Only this time I ordered the RIGHT one. It is 2 teeth larger and will enable me to run the chain on larger cogs like I used to. Back when i had a 34 tooth middle ring before I really had no issues. Hard to imagine that 2 teeth can make that big of a difference, but for my riding it does.

The bigger issue with mountain bikes is DIRT. Dirt destroys a drivetrain and lube quickly.

^^^ Hence the word "environment". Yup, dirt is bad, bad, bad on the drivetrain.

One problem with not replacing the chain is that different sprockets get different amounts of use. The commonly used ones wear to match the streatched chain but less fequently used ones might not.

Another option is to use several chains and rotate them. Gives you plenty of time to clean and lube the dirty chain you take off and you don't have to bother with measuring chains.

I agree that paying for $100 worth of chains to protect a $35 cassette is poor economics. On my main road bike, i change the chain and cassette together annually which is about 6,000 miles. At that point, the chain has stretched just over 1/16" in 12" and the cassette has three or four worn cogs. I'm not the strongest rider in town but I ride a LOT of hills and ride in all kinds of weather. I do clean and lube the chain frequently but I don't replace it at what I consider ridiculously short intervals.

I would replace "1/8"" with "1/16th"".

Al

Seems like this thread has veered off course a little.....the OP has a bike that's not a year old, has only 2000 miles on it, and his LBS is saying he needs another new chain and now a new cassette and chainrings. I think either the LBS is trying to take advantage of a customer, or there's something wrong that needs to be determined; he's being told to replace these parts way too quickly in my opinion. Has nothing to do with whether he subscribes to the philosophy of replacing chains often, or just running the whole drivetrain together without changing anything until the whole thing wears out together. His bike simply isn't old enough or well used enough that it should need a new cassette and new chainrings, at least based on my experience. And the fact that he will soon be on his third chain (original, first replacement, now second replacement), in only 2000 miles, seems suspect.

Good catch, thanks Al1943. well biked also caught my error and corrected it almost immediately, thanks.