Component Life Expectancy



mgkaplan

New Member
Apr 23, 2006
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How many miles can I expect the following components to last?

Chain
Casette
Rear Derailleur
Chainrings
 

rek

New Member
Aug 31, 2002
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mgkaplan said:
How many miles can I expect the following components to last?

Chain
Casette
Rear Derailleur
Chainrings
Chain: it all depends on terrain, weather and maintenance regimen. A rarely-cleaned chain on a mountain bike ridden in Winter might last as little as 3-500km. A chain cleaned regularly on a road bike in summer can last over 5000 km. The general rule of thumb is to measure 12 links worth (12 inches) of the chain; if it's actually between 12 1/16" and 12 1/8" long, it's time to replace. If you leave it past 12 1/8", then you are at a very real risk of having to replace your cassette and/or chainrings as well.

Cassette: dependent on how good you are at changing the chain when worn. (The cassette teeth wear to match the wear profile on the chain). Replacing the chain 'in time' (i.e. before the 12 1/8" limit), you can get a good 3 or 4 "chains worth" out of your cassette.

You can tell if the cassette is gone, beacuse if you replace the chain and the cogs still slip, the cassette teeth have worn down to match your old worn chain. Quite often, not all of the cassette cogs wear at the same rate, your "favourite gears" will wear the most, and be the first to start skipping.

Chainrings: a long time, longer than cassettes. These are a lot thicker than cassette teeth so can withstand more punishment. But you can see that in the end, they'll also get worn down by a worn chain, albeit slower than cassette teeth.

Rear Derailleurs: a really long time, unless there is some sort of catastrophic failure. MTB derailleurs will probably have their lifespans rated in terms of "until it hits a really big rock" ;)

The part of a rear derailleur that would need replacement most often are the plastic jockey wheels in the cage.

Road derailleurs can last ages, as their cages are shorter (less of it to be hit by other things) and they generally see better conditions. For what it's worth, I have a rear derailleur on my commuter bike that's over 15 years old and still shifts OK, despite using it alongside a reasonably modern 9-speed indexing drivetrain. It does squeak a bit, but I don't know whether that's the jockey wheels, the pivots needing a bit of lube, or whether the derailleur is actually on the way out.
 

PeterF

New Member
Sep 13, 2004
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mgkaplan said:
How many miles can I expect the following components to last?

Chain
Casette
Rear Derailleur
Chainrings
I got in the habit of removing my chain (connex link) and cleaning it every month during the summer season and every couple weks during the winter. I clean the cassette at the same time (soaking both in Pedro's Bio degreaser). After a full season (5k miles), the chain still hasn't stretch anywhere near the limit and the cassette looks brand new. Keep it cleaned and lubed and it will reward you with many miles of faithfull service. I have an old Ultegra rear deraileur with about 15k miles and it's still perfect (a few scratches and I replaced some squeaky jockeys).
 

MY02_STi

New Member
May 26, 2004
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Dura Ace chain cleaned and lubed very regularly, running gear always kept very clean and only been ridden in the rain maybe 2 or 3 times but (then cleaned and lubed straight afterwards) has almost 11000 km on it and it still going strong :)
 

Eastway82

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Apr 12, 2006
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MY02_STi said:
Dura Ace chain cleaned and lubed very regularly, running gear always kept very clean and only been ridden in the rain maybe 2 or 3 times but (then cleaned and lubed straight afterwards) has almost 11000 km on it and it still going strong :)
Yep, it's largely down to maintenance - keep the chain clean and lubed, and it'll last years unless you're a seriously high mileage masher.
Most halfway decent road bike equipment will be obsolete long before it's worn out. I've been using a 1982 Benotto 6-speed as my turbo trainer hack for the past ten years. It's fitted with odd bits that I've been using since about 1980, including an old '70s suntour rear gear, a '60s campag front mech, an old SR Apex chainset and an even older no-name bottom bracket. It all works perfectly, although of course I don't take the turbo trainer out in the rain... :)
 

mnr3

New Member
Jun 11, 2006
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rek said:
Chain: it all depends on terrain, weather and maintenance regimen. A rarely-cleaned chain on a mountain bike ridden in Winter might last as little as 3-500km. A chain cleaned regularly on a road bike in summer can last over 5000 km. The general rule of thumb is to measure 12 links worth (12 inches) of the chain; if it's actually between 12 1/16" and 12 1/8" long, it's time to replace. If you leave it past 12 1/8", then you are at a very real risk of having to replace your cassette and/or chainrings as well.

Cassette: dependent on how good you are at changing the chain when worn. (The cassette teeth wear to match the wear profile on the chain). Replacing the chain 'in time' (i.e. before the 12 1/8" limit), you can get a good 3 or 4 "chains worth" out of your cassette.

You can tell if the cassette is gone, beacuse if you replace the chain and the cogs still slip, the cassette teeth have worn down to match your old worn chain. Quite often, not all of the cassette cogs wear at the same rate, your "favourite gears" will wear the most, and be the first to start skipping.

Chainrings: a long time, longer than cassettes. These are a lot thicker than cassette teeth so can withstand more punishment. But you can see that in the end, they'll also get worn down by a worn chain, albeit slower than cassette teeth.

Rear Derailleurs: a really long time, unless there is some sort of catastrophic failure. MTB derailleurs will probably have their lifespans rated in terms of "until it hits a really big rock" ;)

The part of a rear derailleur that would need replacement most often are the plastic jockey wheels in the cage.

Road derailleurs can last ages, as their cages are shorter (less of it to be hit by other things) and they generally see better conditions. For what it's worth, I have a rear derailleur on my commuter bike that's over 15 years old and still shifts OK, despite using it alongside a reasonably modern 9-speed indexing drivetrain. It does squeak a bit, but I don't know whether that's the jockey wheels, the pivots needing a bit of lube, or whether the derailleur is actually on the way out.


I would add this: chainrings wear more slowly also because they have more teeth to share the load, and that changing the chain regularly helps to save them, as implied above (if you've got an old-fashioned, i.e. no shift pins and ramps, you can rotate the rings about 90degrees and get a bit morlife out of them, since they wear fastest on the down strokes and least on the dead spot)
front derailleurs last almost forever, but rear ones will develop slop, depending on the quality of the bushings and how many times the bike gets laid on that side, intentionally or not. if you can wiggle the cage a good bit, it might be time to switch it over to the commute bike or parts bin.