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F Der. problem...and the 'F' don't just mean front plz help(5 posts)

F Der. problem...and the 'F' don't just mean front plz helpIll
Jun 28, 2002 1:43 PM
I have triple full ultegra drive train and i can't get my front derailleur to not rub. and I don't mean just a little on cross gears, i mean it will rub in 4 cogs in almost every chainring. Can anyone please give me some suggestions? I've followed the directions in Zinn's maintence book and I've spaced the BB out further but nothing works. please help before I'm turn my road bike into a single speeder.

I'll try, but I need more information.Spoke Wrench
Jun 28, 2002 2:17 PM
First of all, was it ever right? Are all of the components original? What kind of bike?
Also need more infoKerry
Jun 28, 2002 4:42 PM
But here are some thoughts. If the chain is rubbing the derailleur, then perhaps you need to ajust it a bit. You don't say which cogs result in rubbing, so I can't say which way to turn the barrel adjuster, but you should be able to do that easily while riding. Spacing out the BB has little to do with the chain rubbing the derailleur - if you move the BB 2 mm, then you change the derailleur adjustment so that it moves 2mm as well. Your "almost every chainring" suggests you have 3, although it sure would have been clearer to say "it rubs in the big and middle" or something like that. Assuming a triple, adjust the derailleur so that it is centered on the chain when you are in the middle cog in the back. If you still get lots of chain rubbing on the derailleur, then look carefully at the cage - could it be bent? Compare to a known good derailleur to find out. Beyond these generalities, you're going to have to provide more information.
Did you try trimming the front derailleur?High Gear
Jun 30, 2002 7:38 AM
Those little half shifts of the shifter should take care of most of the rubbing other than extreme chain angles.
Jul 1, 2002 9:37 AM
The alignment of the front der. is really critical on a triple. The outer cage must be as close to perfectly parallel as humanly possible if you're going to get the thing to work. You also want to have it around 1 mm above the big chainring. All of this is much easier to do with the chain out of the way. Also realize that some of the pivots can become loose with age or the bolts can start working themselves loose. If your front der. is all sloppy at the pivots it will never dial in - it takes to much movement to achieve a shift and then the cage comes to rest at someplace other than where it needs to be. It may also be worth your while to do a chainline check. Once you have the front der. in the proper orientation you can then start dialing it in. It takes practice and setting up a road triple is pretty demanding - many people don't have the patience for it.