worn components - how to know when to change

[MattDB]

Hi I try to do most bike maintenance myself to save money and get to know my bike. Something I've never really understood is how to tell when things need changing.

I was recently told by a mechanic to change chains after 1000 miles. I know there's tools for checking the amount of stretch but are these all compatible or do you have to use an expensive laser one.

The biggest mystery to me is the crankset and fear cassette, I've had a few changed in lbs's before after they said 'look can you see how much that's worn' I agreed but tbh couldn't tell at all. Is this very subjective or is there a foolproof way to make a judgement?

All tips much appreciated!

 

[oldroadman]

Simple tool for chain stretch. Using a new chain, measure centre to centre of adjacent rollers, mark up a template, then check every now and then. Once it's over 10% stretch it will start to damage sprockets and chainrings which will start to "hook", one side wearing more than the other. Only cure is to change them. Which will help gear change. Plenty of info from people on here to help. As a rider, I know the team mechanics used to change chains sometimes as much as every 500km or even less on dirty//extra dusty days, simply to reduce wear elsewhere. Usually it was about 1000km intervals, BUT they were cleaned and lubed every day (in my race days diesel was the oil of choice, nowadays there are all sorts about but I'm not sure if they are any better).

 

[Levo-Lon]

Buy a maintenance book and have a good read..or look on here http://www.parktool.com/blog/repair-help

 

[Rickshaw Phil]

I use the old-fashioned method of a steel ruler. If you measure a 12 inch length of chain it will line up exactly with the centre of the pins when the chain is new. If the centres of the pins are 12" and 1/16th you will probably be able to use a second (or third) chain with that cassette, if it's 12 and 1/8th a replacement chain will likely slip under load. If a new chain does slip under load it's time for a new cassette regardless.

1000 miles seems a little short to me. I live in an area with a mix of clay and sandy soils (so road dirt is sticky and abrasive) and can usually get around 1800 to 2000 miles from a good quality chain.

Edit: After reading gbb's post below I should clarify that I'm running 7 and 8 speed systems which use slightly chunkier chains than 9, 10 and 11 speed.

 

[Yellow Saddle]

Simple tool for chain stretch. Using a new chain, measure centre to centre of adjacent rollers, mark up a template, then check every now and then. Once it's over 10% stretch it will start to damage sprockets and chainrings which will start to "hook", one side wearing more than the other. Only cure is to change them. Which will help gear change. Plenty of info from people on here to help. As a rider, I know the team mechanics used to change chains sometimes as much as every 500km or even less on dirty//extra dusty days, simply to reduce wear elsewhere. Usually it was about 1000km intervals, BUT they were cleaned and lubed every day (in my race days diesel was the oil of choice, nowadays there are all sorts about but I'm not sure if they are any better).

Are you sure of your figures?

 

[gbb]

There is a general rule of thumb (is that the right term ?)...
Cassette will usually need replacing every three chains.
Chainrings may last a bit longer, depending on type / quality. Mine usually do about 6000 miles.
A chain, 10 speed, usually lasts me 1200 miles with regular care.
If you change chains at 1000 miles, theres every chance you are erring on the safe side so would save money in the long run by not excessively wearing your cassette.
If you delay replacing a chain too long, you cause excessive wear to your cassette. If you replace your chain before its due, you can extend the life of your cassette.
Cranks themselves rarely need replacing...just the chainrings. Unless you're replacing the cranks for cosmetic reasons, or perhaps pedal thread damage.

 

[gbb]

Are you sure of your figures?

I suspect he probably Is.
Oldroadman is talking about proper racing types (I think).. The stress they put through a chain is probably far greater than us mere mortals. My chains are worn at 1200, It seems quite reasonable a pro or serious racers chain wouldnt make it that far.

 

[uclown2002]

I've managed 3500 miles out of my last few kmc chains without replacing the cassette. Although I keep mine reasonably well cleaned and lubed, 1000 miles seems ridiculously low.

 

[oldroadman]

Are you sure of your figures?

Note what I said, this was in a competition environment and I'm just noting how the mechanics worked. Probably to keep their workload reasonable. Never let down by chains or transmission though, just flippin' punctures!

 

[gbb]

I've managed 3500 miles out of my last few kmc chains without replacing the cassette. Although I keep mine reasonably well cleaned and lubed, 1000 miles seems ridiculously low.

Whenever chain life Is discussed, we always see large variations in life between members, even the same make chain will get different figures.
Always in the saddle..or do you get out and give it some ?.
Lots of hills or mostly on the flat ?
Weather ?...all weathers or mostly summer dry mileage ?
Steady plodder, or push for all yoir worth all the time ?
Clean and maintain your transmission or just ride it to death ?

They're just a few differences I can immediately think of that have minimal..or a big effect on chain life.

BTW...Do you mean your cassette has done a total of 3500 miles on the last few chains...or each chain has lasted 3500 miles and your cassette is still ok ?

 

[raleighnut]

Its a good idea to keep your partworn chains, when you fit a new one and it skips you can normally get a used one to run quite happily on a slightly worn cassette. I just keep em in a little tub or jam-jar covered in oil.

 

[uclown2002]

Whenever chain life Is discussed, we always see large variations in life between members, even the same make chain will get different figures.
Always in the saddle..or do you get out and give it some ?.
Lots of hills or mostly on the flat ?
Weather ?...all weathers or mostly summer dry mileage ?
Steady plodder, or push for all yoir worth all the time ?
Clean and maintain your transmission or just ride it to death ?

They're just a few differences I can immediately think of that have minimal..or a big effect on chain life.

BTW...Do you mean your cassette has done a total of 3500 miles on the last few chains...or each chain has lasted 3500 miles and your cassette is still ok ?

I ride pretty much every day for 2-3 hours, and up until my accident in all weathers. Just got myself a turbo so will now avoid the truly horrible, filthy days but happy to go out in the rain and wind. Lots of hills, and plenty of time out of the saddle. I tend to mix up my intensity. I keep my bike reasonably well maintained so the transmission is cleaned regularly. My cassette has about 7000 miles on it, as I've just put chain No 3 on it.

 

[MattDB]

Also impressed that you keep track of all your miles everyone!! My speedo fell off a few weeks back so I'm guessing I'm up to about 500 miles.

 

[gbb]

I ride pretty much every day for 2-3 hours, and up until my accident in all weathers. Just got myself a turbo so will now avoid the truly horrible, filthy days but happy to go out in the rain and wind. Lots of hills, and plenty of time out of the saddle. I tend to mix up my intensity. I keep my bike reasonably well maintained so the transmission is cleaned regularly. My cassette has about 7000 miles on it, as I've just put chain No 3 on it.

Just goes to show how its impossible to compare with other people. When i was riding, i'd have been similar circumstances as yours, perhaps not the time in the saddle each day, but i (used to) like to attack hills, out the saddle, on the flat i'd often push as hard as i reasonably could, usually 100 to 150 miles a week...but whatever chain i used, 105, KMC, Sram...1200 miles was all i'd reasonably get ..with a good maintenance regime.

 

[Yellow Saddle]

Note what I said, this was in a competition environment and I'm just noting how the mechanics worked. Probably to keep their workload reasonable. Never let down by chains or transmission though, just flippin' punctures!

OK, I'll take that as a no. In our out of competition, physics don't change.

Note, chains should be replaced when they have elongated (through wear in the pins and bushes) by 0.5%. If you leave it to 1%, it would already have destroyed the cassette. No chain can wear by 10% It would just be impossible since by then there will be no teeth left on the sprocket. Chains wear sprockets and the more the chain is out of pitch, the more the sprocket is worn down by it. A chain that's 10% out of pitch would have worn through all available meet on the sprocket teeth*.

Further, a worn chain does not affect shifting and conversely, when you fit a new chain, shifting doesn't improve. The two are not linked in that way.

A competitive environment chances nothing. People often say they ride hard or rough. That has no effect on chain wear or spoke wear for that matter. I only mention the latter because that is also often stated but is also a myth.

* The correct term for one tooth on a sprocket or a gear is a cog but I'm farthing against thunder when trying to stick to the definition on that one.