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-   -   chainline? I think (https://www.bikeforums.net/bicycle-mechanics/23240-chainline-i-think.html)

Phatman 03-17-03 07:15 PM

chainline? I think
 
I bought a new lemond Alpe d'huez this weekend. (pics will be up shortly) I really like it, beleive it or not, the ride is actually SMOOTHER then my touring bianchi! Anyway, the drivetrain is a bit loud. It is a double, and when in the big ring, I can access all of the rear cogs (9-is a 105) without noise, but in the little ring, which is what I ride 90% of the time, I can only get to the second or third from the smallest cog without a grinding sound from the BB/front derailler. I realize that i shouldn't be doing this, as it causes unneccesary drivetrain wear, but I would prefer to just go through the 9 gears in the back before I go to the big ring. seems that it would be easier.

The bike has about 50 miles on it, and it didn't have this problem on the test rides i did (two 30 minute rides-I had a hard choice whether steel of aluminum, but in the end, steel is real:D ) How long do you think it will take the cables to stretch? is it possible that this is what is happening?

moabrider47 03-17-03 07:44 PM

Sounds like you might just need some front derrailleur adjustment. The sound is probably coming from the chain rubbing the front derrailleur. After 50 miles of shifting, the cables should have set. It's a fairly simple adjustment that can be done quickly at your LBS (You just bought it - they'll probably do it for free) or on your own. If you don't know how, Sheldon Brown's site or nearly any basic mechanics book should explain it well enough. On one bike, I can't completely eliminate chain rub on the front derrailleur while in the extreme combos, but it is very light, and I tend to avoid these combos anyways. Good luck!

-Moab

EDIT: If you're bike is this new, you should be due for a free LBS tuneup in a short amount of time anyways.

John E 03-18-03 09:02 PM

Is the chain rubbing on the outer chainring or on the derailleur cage? I hate indexing of front derailleurs because it can preclude proper centering of the cage over the chain.

You should indeed avoid riding in the small-small combination(s), because this will greatly accelerate chain and cog wear. You will also find that there is a fair amount of ratio range overlap between your two chainrings, such that small-small corresponds to something like large-middle, e.g., 39/12 falls between 53/17 and 53/16.

RainmanP 03-24-03 02:18 PM

You may have noticed that your left shifter has an extra click, ie 3 clicks for only two chainrings. That extra click is for for "trimming" the derailleur. If the chain is rubbing give one click on the appropriate lever to move the der just enough to get it away from the chain. If the der wants to go ahead and shift when you do this, try making this click without pedalling. This should fix you up.

Phatman 03-24-03 05:29 PM

no offense, but I actually hadn't noticed the extra click...

RainmanP 03-25-03 07:24 AM


Originally posted by Phatman
no offense, but I actually hadn't noticed the extra click...
Did it seem to do the trick?

pat5319 03-26-03 02:10 PM

If you're running a 53X39 set-up, the chain will rub on the TEETH of the 53 ring when the chain is running on the outermost cogs of the cassette, ( there's no way around it). You'll have to get used to using the "Big" ring for taller gears.

( I didn't notice mine at first either)

Ride Fast
Pat


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