Bicycle Mechanics - Changing Chainrings together with Chain and Freehubs/Freewheels - General Rule?

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kmcrawford111
02-19-09, 11:28 AM
I recently changed a chain and freehub and I got to thinking - when should I change the chainrings? I have read here that the chainrings will outlast the freehubs/wheels, but by how much? I would think it would be best, for wearing purposes, to change the chainrings at the same as changing the chain and freehub/wheel, so is there some general rule as the following:

"Change the chainring every xth time you change a chain and freehub/freewheel"

It would seem following this rule would be a good practice. So if such a practice exists, what is the value of "x"? Does it depend on the type of bike and the type of riding?

Many thanks.


Mr. Underbridge
02-19-09, 11:36 AM
It'll depend on the material the chainrings are made out of for sure. Steel will last longer than lighter things.

dabac
02-19-09, 11:39 AM
I recently changed a chain and freehub and I got to thinking - when should I change the chainrings? ..is there some general rule as the following:

"Change the chainring every xth time you change a chain and freehub/freewheel"

Well, it would depend very much on personal experiences, but I seem to get abt 3 sets of chain/cassettes before I need to replace the chain wheels.


.. what is the value of "x"? Does it depend on the type of bike and the type of riding? It does, but it also depends on how long you run the chains/cassettes before you replace them. Some roadies are able to keep their chainwheels for ages, while others, particularly MTBers swap the whole drive line every time.


TallRider
02-19-09, 11:43 AM
In a word, No.

Chainrings rarely have to be replaced. If you replace your chain at reasonable enough intervals, depending on its wear, you'll probably never need to replace the chainrings. Only reason to replace the rings is if the new chain skips on the chainring teeth.

Chainrings have more teeth to engage the chain at a given time, and since they have more teeth than a rear sprocket, the angle of difference between teeth is much less also.
Steel chainrings are virtually indestructible, but aluminum chainrings rarely wear out if the bike is cared for properly.

There are instances where chainring teeth get worn out, like on my brother's bike where he rode over 10,000 miles without ever changing his chain and probably not cleaning or lubing it as often as he should have either. Just ridiculous.

http://www.unc.edu/~cupery/pics/bike_parts/IMG_1534--Campy_30t_chainring_worn_teeth.jpg

HillRider
02-19-09, 01:35 PM
Tim's illustration is an extreme example of what neglect and abuse can do but is hardly typical. I've had chainrings last over 30,000 miles and they never looked anywhere near that bad and that's with chain changes at 5000-6000 mile intervals.

My son-in-law managed to wear out a 52T Shimano chainring but it took him 25,000 miles to do it and he is a racer and stronger than almost any other rider I know.

DaveSSS
02-19-09, 02:04 PM
The picture above would be an example of the type of wear produced by an extremely elongated chain. As the chain pitch gets longer, the chain rides higher up on the teeth. With normal wear, the teeth do get noticeably pointed in shape.