chainline induced noises

mlee-<< My campy centaur triple group makes a bit of noise under certain chainring/ cog
combinations. It seems to be the roughest when the chain run at an angle. Unfortunately, 42/28 is
something I use quite often since I ride a lot of hills. >><BR><BR>

Frameset and BB length? You may have a 115mm BB when the 111mm would be the preferred one...

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MLee388407 said:

My campy centaur triple group makes a bit of noise under certain chainring/ cog combinations.
It seems to be the roughest when the chain run at an angle. Unfortunately, 42/28 is something I
use quite often since I ride a lot of hills. I was thinking to reduce the noise I could use a
spacer to move the cassette closer to the outside of the bike. If I did that the angle would
not be so acute. Has anyone tried this or has a different solution? tia

In my experience with Campag triples, it is possible to fit a 0.5mm spacer behind the cassette (if
lockring is done up tight), but you might not have enough frame clearance and it'll only make a tiny
improvement anyway.

I find the largest cassette sprocket is simply best avoided for anything more than a few yards at a
time from the middle ring. I suggest changing the middle ring for a 40 or 39T and using the inner
ring more often as well. This would also enable you to use the smaller closer spaced sprockets from
the middle more often, too - which is great for cadence control. Front-shifting performance and
differences to outer ring may be compromised but it's worth it, IMO.

A 26T second largest sprocket will also be nice to use from the middle instead of the 25T - possible
if cassette is 9-speed Mirage/Veloce (take sprocket from a 13-26 cassette). This really makes a
worthwhile difference and jump up from 23T is fine; nevermind that it's so close in size to the 28T
when used from the granny. I think Campag should make 13-27 and 14-30 cassettes with 21, 24, 27 and
23, 26, 30 cogs at the end. So much more practical - for non-racing at least. I customize my own
(9sp) to get these gears (using Marchisio sprockets as mentioned recently).

If BB is 115.5mm, you may be able to use a 111 by filing a bit off the front derailleur body (this
is what I do). 115.5 is specified for larger diameter seat tubes where the front der. would strike
the frame when it couldn't move in far enough. A 111 will also provide the pro (or con depending on
personal prefernce) of a narrower q-factor and a theoretically stiffer BB.

~PB

In article said:

My campy centaur triple group makes a bit of noise under certain chainring/ cog combinations. It
seems to be the roughest when the chain run at an angle. Unfortunately, 42/28 is something I use
quite often since I ride a lot of hills. I was thinking to reduce the noise I could use a spacer
to move the cassette closer to the outside of the bike. If I did that the angle would not be so
acute. Has anyone tried this or has a different solution? tia

I have the same gearing and parts on my cyclocross bike, I replaced the 42 with a cheap 40 tooth
ring from eBay.

Also, if you have the 115.5mm bottom bracket, that can contribute to the problem. Better to use the
111mm if at all possible.

--Paul

Quoted post said:

Originally posted by Mlee388407
Hi group

My campy centaur triple group makes a bit of noise under certain chainring/ cog combinations. It
seems to be the roughest when the chain run at an angle. Unfortunately, 42/28 is something I use
quite often since I ride a lot of hills. I was thinking to reduce the noise I could use a spacer
to move the cassette closer to the outside of the bike. If I did that the angle would not be so
acute. Has anyone tried this or has a different solution? tia

Mike

Can you trim the front delailer a little more?
The cassette spacer won't help that much.
What does you chain line measure?
Check to see if a shorter BB spindle will help.
Look at the gearing numbers on Sheldon Brown's web site to see if you can get nearly the same gear inches in a combination that doesn't put the chain at a higher angle. This would also likely help effieciency and increase chain life.
URL I suggest its:
http://sheldonbrown.com/gears/
It takes a bit of time to input the numbers, but once you have your results, you will see some duplication and know how best the chain should move with you particular cogs and chain rings.
It is also good to know this before you start changing things.

Peter wrote

Quoted message said:

Frameset and BB length? You may have a 115mm BB when the 111mm would be thepreferred one...Peter

====

Univega Modo Vincere was the frameset...Im thinking they have pretty short chainstays.

I followed campy recommendations using the 111mm bb spindle on a 28.6 seatstay

Mike

Pete Biggs wrote

I find the largest cassette sprocket is simply best avoided for anything more than a few yards at a
time from the middle ring. I suggest changing the middle ring for a 40 or 39T and using the inner
ring more often as well. This would also enable you to use the smaller closer spaced sprockets from
the middle more often, too - which is great for cadence control. Front-shifting performance and
differences to outer ring may be compromised but it's worth it, IMHO

=====

I could give that a try...changing the mid chainring to a 39 could let me avoid the largest cog on
the cassette. I pretty much dont use the inner chainring unless wiped out or on really steep grades.
I ended up using the inner more on my last ride since I didnt like all the noise using 42/28

Mike

Dave wrote

Can you trim the front delailer a little more? The cassette spacer won't help that much. What does
you chain line measure? Check to see if a shorter BB spindle will help.

===

Im using the 111mm and the front der cage isnt touching if I trim out. I think the noise is due to
the meshing of the chain and teeth. When the chain isnt squared up with the teeth you get a bit of
rubbing there.

Mike