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Vimal June 26th 06 10:31 AM

chain rings
 
Should a chain be replaced when front chain rings are replaced? I ask
because I've replaced the chain rings and found that there is what seems
to be a regular "lag" when pedalling ... the chain seems to take a half
a turn before it takes effect. There are no broken teeth in the rear
casette, which along with the chain were replaced about 100 miles ago.
Is there a solution.

Thanks for any help

Pete Biggs June 26th 06 01:24 PM

chain rings
 
Vimal wrote:

Should a chain be replaced when front chain rings are replaced?


If the chain is quite worn. Otherwise no need if the chain is still fresh
or hasn't elongated by more than 1/16" per 12 inches. Maybe 1/32" inch if
you're more fussy.

The idea that chain and sprocket wear has to be perfectly matched doesn't
make any sense when you think that with derailleur systems, some gears are
used more than others. Say you have a triple chainset and only use the
inner ring very occasionally, you wouldn't think after a while: "I better
change this ring for a more worn one so it matches the chain".

I ask
because I've replaced the chain rings and found that there is what
seems to be a regular "lag" when pedalling ... the chain seems to
take a half a turn before it takes effect.


Half a turn of what? Is there a great crunch noise and a violent skip?
If not, I suspect the chain is working well enough with the ring.

It is normal for there to be a slight lag somtimes due to the way the
(usual type of) freewheel or freehub on your rear wheel works. The pawls
have to move a certain amount before they engage with the ratchet.

There are no broken teeth
in the rear casette, which along with the chain were replaced about
100 miles ago. Is there a solution.


Need to know what the problem is first, or if there is one at all.

~PB



Clive George June 26th 06 01:25 PM

chain rings
 
"Vimal" wrote in message
...
Should a chain be replaced when front chain rings are replaced? I ask
because I've replaced the chain rings and found that there is what seems
to be a regular "lag" when pedalling ... the chain seems to take a half a
turn before it takes effect. There are no broken teeth in the rear
casette, which along with the chain were replaced about 100 miles ago.
Is there a solution.


So : you've got a chain, cassette which are 100 miles old and chainrings
which are brand new? Should be no problems there.

When you say "Chain seems to take about half a turn before it takes effect",
is this just your freewheel ratchet sticking? When you freewheel, is the top
part of the chain going slack?

Is anything making horrible noises? (If it's the freewheel, I'd expect not)

cheers,
clive


Simon Brooke June 28th 06 01:39 PM

chain rings
 
in message , Vimal
') wrote:

Should a chain be replaced when front chain rings are replaced? I ask
because I've replaced the chain rings and found that there is what
seems to be a regular "lag" when pedalling


If you let a chain wear beyond its wear limits it will rapidly wear both
cassette and chainrings. It will continue to work because the worn chain
will 'fit' the old chainrings and cassette - they've all worn together.
If you replace any one component once you've exceeded that critical wear
point things will no longer fit - a 'stretched' (worn out) chain won't
fit standard chainrings and will rapidly wear them.

So yes, you /must/ replace the chain (and usually the cassette as well)
when you replace chainrings, /if/ you are replacing them because they
are worn. Otherwise, you will very quickly trash the new ones.

... the chain seems to take
a half a turn before it takes effect. There are no broken teeth in the
rear casette, which along with the chain were replaced about 100 miles
ago. Is there a solution.


Using a new chain with worn out chainrings will put unfair pressure on
the chain which will lead to accelerated wear. 100 miles sounds very
little to me, so you may get away with it; but... without being able to
see it, I suspect you may need to replace the lot. Again.

Go and talk to an experienced bike mechanic locally. I'd love to be
wrong.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

Morning had broken, and there was nothing left for us to do
but pick up the pieces.


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