Chain rub inevitable?

A bit is going to happen. Don't put the chain in small/small or large/large, though. Use the front shifter to move the deraileur slightly and you can eliminate most of the rubbing. You'll end up going to large chain ring accidentally a few times but you'll learn where the shifter needs to be to make it quit rubbing.

if you are going to crosschain you've got two options.

- live with some chain rub
- buy Di2

Or you could just put a chainstay sleeve on it.

Edited by UWMadTri 2010-09-21 7:05 PM

Thanks for asking the question.  I have the same issue and was going to take it back to my LBS but I have learned to avoid getting the chain into that position.  

If you are using bar end shifters then your FD shifter should be a friction shifter, meaning you can set it in between where you would have no chain rub on the FD. But really you should avoid the small chainring unless your using the bigger cassette gears.

i never rub my chain.....

I think he's talking about hte chain rubbing on one side of the front derailleur, not rubbing on the chainstay.  

If you're running in this configuration alot.... You're going to wear components faster.   To solve the problem, you can:

1.  move the front derailleur slightly to avoid the rub.   (you're still wearing your chain and chainrings faster than "normal" )

2.  Switch to a different rear cassette.   An 11-23 would probably keep you in the "lower" gears and not cross-chained as much.  You might not have enough range to keep your cadence happy, however.

3.   Instead of being in the small/small gear configuration, switch to the large chainring in the front, and the middle cog in the back.   You should have a comparable gear ratio, and no cross-chaining.   There is a considerable amount of overlap in most drivetrains.   Use this calculator to find out the equivalent gear ratio of each position combination on your bike.

As has been mentioned you should be able to trim your front derailleur in order to minimize the chain rub.  However, you should avoid cross chaining; if you find yourself in a cross chained situation, you should just shift into or out of the big ring as the situation requires.

Shane

The main thing is to reduce cross-chaining. I usually only use 7 out of the 10 possible gears in back depending on which ring I am in on the front. I can use all ten in the large ring and about 8 in the small ring without any rub, but I try to not cross chain whenever possible to avoid wearing out the components faster than need be.

haha, no i do when i'm cleaning it (yeah, right, i do this all the time....).

clean it, lube it, wipe it down.

Silly point, but please check your rear dropouts. Be sure they're not bent askew from the bike falling. Also, be certain the wheel is correctly seated and the quick release snug.

From someone who knows...

Yeah, just don't cross chain.  I try to ovoid the smallest to cogs if I'm in the small chain ring and the largest two cogs while in the large chain ring.  That's even a bit conservative since I really only hear an issue when it's big/big or small/small.

If you have a couple thousand to drop, you can get the electronic shifters.  They supposedly trim the FD on every shift no matter what the gearing is to avoid rub.

Edited by Kido 2010-09-22 1:36 PM

Cross chaining is not good and will cause the derailleur to rub... Campy does allow micro adjustments of the F/D which does help a bit when cross chaining can't be avoided (some racing situations for example)

... and yes, barend shifters will allow micro adjustments as well as they are friction and not index.

Edited by audiojan 2010-09-22 5:02 PM

Another way to say this is that a "small-small" combo can probably be matched by a large-not so small combo.

Sheldonbrown.com 's site has a calculator where you can print out all your gear ratio combinations and you can learn from math (rather than trial and error) where your next biggest gear combo is instead of just continuing to shift to the smaller and smaller rear cog.