Bicycle Mechanics - Chain Rubbing on Big Ring

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FatBomber
01-23-04, 12:16 PM
I've never had a double ring set on a bike until now, but I have noticed that on my new bike that the chain will rub on the big ring if I am in the small ring in the front and in one of the three outer sprockets in the rear. The third sprocket makes noise occasionally, but the last two outer sprockets cause the chain to rub against the big front ring making a lot of noise. Is there anything I can do about that?
demoncyclist
01-23-04, 12:23 PM
The chain is most likely rubbing on the outer plate of the front derailleur. There should be a "trim" position on the front shifter. Push the front shifter one click over towards the big ring, and the noise should go away. A second click would actually cause a shift. These instructions are for Shimano drivetrains. Campy uses a modified index/friction shift on its front changers that gives you a couple of clicks before a shift.
FatBomber
01-23-04, 12:25 PM
Unfortunately it is not. I have looked and adjusted and rode and looked and adjusted and rode...
It is definitely the big ring.
demoncyclist
01-23-04, 12:28 PM
Something isn't right. Do you have the correct chainline? Is your bb spindle the right length for your crankset? Is your rear deraileur hanger straight? Are the chainrings bent? Are your cranks and chainrings compatible with each other?
Grasping at straws.
tommy2pants
01-23-04, 12:29 PM
I've never had a double ring set on a bike until now, but I have noticed that on my new bike that the chain will rub on the big ring if I am in the small ring in the front and in one of the three outer sprockets in the rear. The third sprocket makes noise occasionally, but the last two outer sprockets cause the chain to rub against the big front ring making a lot of noise. Is there anything I can do about that?If it's actually rubbing on the big ring,rather than the derailer,and the spindle length is correct for the crank,you can get a different frame with a longer chainstay, or use a 2mm bottom bracket shim on the drive side. Sometimes a narrower chain will help. On shimano 9 speed doubles, the small ring has to be mounted so the tooth # side of the ring faces the frame.It's just good practice to stay out of the smallest cogs when in the small ring anyway.
ChezJfrey
01-23-04, 01:08 PM
I have the same problem (with the stock setup of my '99 LeMond Zurich). But I just figure the gears above the 5th cog in the small ring are near enough to the 3rd, 4th, 5th cog in the big ring that I don't worry about it.
tommy2pants
01-23-04, 01:43 PM
Something isn't right. Do you have the correct chainline? Is your bb spindle the right length for your crankset? Is your rear deraileur hanger straight? Are the chainrings bent? Are your cranks and chainrings compatible with each other?
Grasping at straws.It happens. Short chainstays,correct spindle,corrct chainline correct everything.
Unfortunately it is not. I have looked and adjusted and rode and looked and adjusted and rode...
It is definitely the big ring.
Grasping at straws here, but are you running a 7/8 speed chain on a 9sp chainring set?
tommy2pants
01-23-04, 06:07 PM
Grasping at straws here, but are you running a 7/8 speed chain on a 9sp chainring set?New bike.
I had that problem with my stock Trek 5200. If it rubs I just shift like chez said. Nothing like a mountain bike
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