Chain Wear

Just got my Trek 7200 back from the bike shop after a service. They
mentioned that is had "50% chain wear". I didn't have the forthought to
ask how long before I'd need to replace the chain.

Is it a straight linear relationship between km cycled & chain wear
(I've done 5000 km or so to get to 50% chain wear ... so another 5000km
to 100%??). Do you wait to 100% before you replace the chain? Or some
other number?

Thanks!

H


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cirrus

cirrus wrote:
Just got my Trek 7200 back from the bike shop after a service. They
mentioned that is had "50% chain wear". I didn't have the forthought to
ask how long before I'd need to replace the chain.

Is it a straight linear relationship between km cycled & chain wear
(I've done 5000 km or so to get to 50% chain wear ... so another 5000km
to 100%??). Do you wait to 100% before you replace the chain? Or some
other number?

Thanks!

H


Greetings,
This is an old one. Put the chain onto the largest front chain ring.
Take a screw-driver, or key or whatever, and place it under the edge of
the chain at the leading edge of the chain wheel.
See how far you can lift the chain clear of the chain wheel teeth. If
the answer is more than 1 cm, it's rooted. Simple as that. It has
stretched itself out of existence. So have fun getting it replaced if
this is indeed the case.
Regards,
Ray.

cirrus wrote:
Just got my Trek 7200 back from the bike shop after a service. They
mentioned that is had "50% chain wear". I didn't have the forthought to
ask how long before I'd need to replace the chain.

Is it a straight linear relationship between km cycled & chain wear
(I've done 5000 km or so to get to 50% chain wear ... so another 5000km
to 100%??). Do you wait to 100% before you replace the chain? Or some
other number?

Depending on the performance you want from your drivetrain, expecting
10,000km out of a chain is possibly a little over-ambitious

As the chain wears (it doesn't stretch, the rollers wear away) it
elongates, and thus doesn't mesh properly with the gears on the bike.
This leads to wear on the gears you use the most, and poor performance
on the other gears and until such time as things start to jump and skip
this is probably bearable - you're riding a hybrid, it's odds-on you're
not sprinting or anything likely to cause chain skip etc until it's
*very* worn.

The decision re chain replacement comes down to a compromise between
regular (say every 2 or so thou) chain replacement, which preserves
your gears for longer, or let the chain wear to the point of death, and
then replacing all the rest of the gears at the same time.

So it's up to you, regular chain replacement (which you can easily do
yourself) or less regular but much more expensive replacement of most
of the drive train. It sounds simple except that by replacing the
chain you don't get infinate life out of the gears (alas!), so you'll
still have to replace them every now and then, but less often than if
you let the chain go all the way. The decision is swayed by the sort
of riding you do and your preference.

Bleve wrote:
The decision re chain replacement comes down to a compromise between
regular (say every 2 or so thou) chain replacement, which preserves
your gears for longer, or let the chain wear to the point of death, and
then replacing all the rest of the gears at the same time.

Yeah, better earlier than later. I replaced my chain on my winter
commuter which has only done 3500kms. I'm now getting skipping when
jumping hard in my cruising gear. Guess I didn't replace it early enough.




--
..dt

cirrus wrote:

Is it a straight linear relationship between km cycled & chain wear
(I've done 5000 km or so to get to 50% chain wear ... so another 5000km
to 100%??). Do you wait to 100% before you replace the chain? Or some
other number?

Listen to the good advice already given, and then read this too. Oh, and
bookmark this site.

http://www.sheldonbrown.com/chains.html


--
..dt

"cirrus" wrote in message
...

Just got my Trek 7200 back from the bike shop after a service. They
mentioned that is had "50% chain wear". I didn't have the forthought to
ask how long before I'd need to replace the chain.

Is it a straight linear relationship between km cycled & chain wear
(I've done 5000 km or so to get to 50% chain wear ... so another 5000km
to 100%??). Do you wait to 100% before you replace the chain? Or some
other number?

They may be mis-using the Park Tools Chain Checker. I have one of these
devices and it's fantastic.
It recommends replacing a chain before it's 1% elongated. Your chain may be
0.5% elongated and therefore 'half way to buggered'.
That said, most Shimano chains start off with 0.25% elongation from new :-)

Gemma

This topic gets a run pretty often. If you do a search for 'chain' you
will find the earlier threads.

Donga