Chain rubs on large Chainring when on smaller rear cogs

"busterb" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Yesterday I thought the chain was rubbing on the
derailleur when in small front small rear combo. I
adjusted derailleur and it does not touch chain. The
noiise is due to the chain catching in the big chainring
slightly and rubbing. I know I can bring it to where I
bought it a week ago but if I can fix it Ill save the
trip. Bike info. 2001 Cannondale xr800. cannondale expert
cranks, 105 sti f&r derailleurs. Any ideas would be
appreciated. Is it an alignment issue?

"Doctor, it hurts when I do this" "Don't do that!"

Avoid extreme gear combinations, i.e. biggest to biggest and
smallest to smallest. They're not meant be used.

-Jens

It depends on the length of the chainstay and the size of
the large front ring.

For example, on a Cervelo frame -- which has a very short
chainstay, if you use the small cog in the rear and the
small front chainring, there's an excellent chance the chain
will rub the inside of the large chainring. This is normal
and expected. This is a bad chainline anyway, so it
shouldn't be used. You want to keep the chain as straight as
possible, not curved. Chains work best and last longest when
used in a straight line.

Additionally, if you have a very large chainring in the
front, it could rub the chain in the small small combination
no matter how long or short the chainstay. Again, it's best
to stay out of that combination. You are putting undue
lateral stress on the chain. This causes added friction and
power loss. Plus you scratch up the inside of the big ring
doing that.

AB

"busterb" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Yesterday I thought the chain was rubbing on the
derailleur when in small front small rear combo. I
adjusted derailleur and it does not touch chain. The
noiise is due to the chain catching in the big chainring
slightly and rubbing. I know I can bring it to where I
bought it a week ago but if I can fix it Ill save the
trip. Bike info. 2001 Cannondale xr800. cannondale expert
cranks, 105 sti f&r derailleurs. Any ideas would be
appreciated. Is it an alignment issue?

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jab-<< The noiise is due to the chain catching in the big
chainring slightly and rubbing. I know I can bring it to
where I bought it a week ago but if I can fix it Ill save
the trip. >><BR><BR>

No fix necessary, it is NORMAL with yours and just about
everyother modern road setup.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St.
Boulder, CO, 80302
(303)440-3535 vecchios.comvecchios.comOpen ↗ "Ruote convenzionali
costruite eccezionalmente bene"

busterb said:

Yesterday I thought the chain was rubbing on the
derailleur when in small front small rear combo. I
adjusted derailleur and it does not touch chain. The
noiise is due to the chain catching in the big chainring
slightly and rubbing. I know I can bring it to where I
bought it a week ago but if I can fix it Ill save the
trip. Bike info. 2001 Cannondale xr800. cannondale expert
cranks, 105 sti f&r derailleurs. Any ideas would be
appreciated. Is it an alignment issue?

Your subject and body conflict with each other. Which is it?

--
Phil, Squid-in-Training

"ZeeExSixAre" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

busterb said:

Yesterday I thought the chain was rubbing on the
derailleur when in small front small rear combo. I
adjusted derailleur and it does not touch chain. The
noiise is due to the chain catching in the big chainring
slightly and rubbing. I know I can bring it to where I
bought it a week ago but if I can fix it Ill save the
trip. Bike info. 2001 Cannondale xr800. cannondale
expert cranks, 105 sti f&r derailleurs. Any ideas would
be appreciated. Is it an alignment issue?

Your subject and body conflict with each other.
Which is it?

Pretty simple to picture: Chain on inner front chainring and
smaller two rear gears. Chain rubs on the large front
chainring (double) making awful racket. I just wanted to
know if shimming something or adding a washer would correct
this as I would like to use these gear combos.

-----BEGIN PGP SIGNED MESSAGE-----

In article <[email hidden]>,

busterb said:

"ZeeExSixAre" <[email hidden]> wrote
in message
news:<[email hidden]>...

Quoted message said:

busterb said:

Yesterday I thought the chain was rubbing on the
derailleur when in small front small rear combo. I
adjusted derailleur and it does not touch chain. The
noiise is due to the chain catching in the big
chainring slightly and rubbing. I know I can bring it
to where I bought it a week ago but if I can fix it Ill
save the trip. Bike info. 2001 Cannondale xr800.
cannondale expert cranks, 105 sti f&r derailleurs. Any
ideas would be appreciated. Is it an alignment issue?

Your subject and body conflict with each other.
Which is it?

Pretty simple to picture: Chain on inner front chainring
and smaller two rear gears. Chain rubs on the large front
chainring (double) making awful racket. I just wanted to
know if shimming something or adding a washer would correct
this as I would like to use these gear combos.

_ Yes, adding a 0.6 or 1.2mm washers to all the chainring
bolts will fix this problem[1]. Buy at least 10 since they
are pretty easy to crunch while being installed. You should
avoid using those gears if you can as it wears the chain
faster and is less efficient, but the bike is there to serve
me, not me to serve the needs of the bike.

_ Booker C. Bense

[1]- Make sure that you don't end up with chainrings far
enough apart that the chain can jam between them. On
bikes with short chainstays, it may not be possible to
use the small/small gears without creating a much bigger
problem. If you have to choose between small/small with
rubbing and the potential for the chain jamming between
the rings stick with the small/small rubbing.

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