Worn chain?

[Tall Paul]

I have a 20 year old 300LX rear mech running with an almost new Cook Bros front ring. I noticed today that the 3 year old chain doesn't fit well on the front ring, the pitch of the two barely match. I find it difficult to believe either the chain or front ring have worn so much.

The chain also jumps under load, although that might be due to a poorly adjusted rear mech. :roll:

If i need a new chain what do i need, I've seen lots of different Shimano part numbers.... Thanks.

 

[jimo746]

It does sound like you might need a new chain.
With the chain on the nearly new Cooks Bros ring try pulling the chain away from the ring at the front, if you get oodles of slack then it's pretty well worn.
What gears do you currently have at the back? 7 speed? if so then Shimano, KMC, sram etc all do chains that will work, which exact one you get depends on how much you want to spend.

http://www.ebay.co.uk/itm/Shimano-IG51- ... 1e7ff8d91e

http://www.ebay.co.uk/itm/KMC-Z51-Cycle ... 43c35e6c1e

http://www.ebay.co.uk/itm/Sram-PC850-7- ... 2ec8762d75


You may find that your rear cassette has become worn to your old chain, so when you fit a new chain the chain will hop about all over the cassette, in which case it's probably time for a new cassette as well!

I can reccommend using a chain wear checker, mine was less than a tenner but has probably saved me many times that by letting me know when the chain is getting worn and due for replacement, before it's too far gone and requires the replacement of the cassette as well.

 

[Tall Paul]

yes a 7 speed. I suppose that I could fit any 7,8,9 speed chain on?

 

[Tall Paul]

That's really helpful information, thanks very much!

 

[jimo746]

6,7,8 speed chains are pretty much the same, when they went to 9 speed they started to make the chains narrower (I think), and continued this with 10 and 11 speed.

Just go on Youtube and search "Chain wear" etc, loads of helpful videos.

 

[integerspin]

6,7,8 speed chains are pretty much the same, when they went to 9 speed they started to make the chains narrower (I think), and continued this with 10 and 11 speed.

Just go on Youtube and search "Chain wear" etc, loads of helpful videos.

I have a new chain hanging up and when I oil chains I hang them on the rod with the new bit of chain. It's easy to see the % of wear, you look down the chains and you can see the worn chain is longer. I bought X8 speed KMC chains in Evans a year ago, they work on 7 and 9 speed OK.

 

[cyclotoine]

3 years is a very very long lifespan for a chain, depending how much your ride of course.

6,7,8 are the same.
9 is narrower
10 is narrower still
11 is the same internal width as 10 but the chains are different. Just like how shimano 10 speed mountain chains are different from 10 speed road (as are the cassettes).

I use shimano chains, maybe sram has improved their chains in the last 3 or 4 years but before that they wore quicker and did not shift as smoothly as shimano.

 

[benjy]

forgot what the mesurement is but you can mesure so many links an it gives you an idea of how worn it is, also chains are long gone before they begin to skip an what you might find is you put a new one on an it still skips due to the cogs being worn to the old chain, if its been on for years best bet is swap it all

 

[hamster]

measure 24 links (12") of chain. If stretched by more than 1% (3mm) then it's bin time. The stretching is the wear in the link pins and faces. I reckon an MTB chain lasts about 500-1000 miles in UK muddy conditions.

 

[legrandefromage]

A good image if you dont have a chain wear tool: