Front derailleur chain rub in high grears
Hi
I've got a new bike with an Ultegra 11 speed compact double and when on the front large chain ring there's a progressively loud chain rub coming from the front derailleur from about the third cog when moving up from small to big. By the middle of the cassette it's rather loud and I can almost feel the friction through the pedals despite using any fine adjustment facility in the shifters. On the small front chain ring all seems well going through the gears (I seem to be able to use all of the cassette without stressing the chain) and shifting between the two front chain rings is fine. What do I need to do to iron this out assuming I should at least be able to use the middle of the cassette when on the front 50 tooth chain ring before risking cross chaining? Any advice much appreciated as ever.
Note: the front derailleur has a small piece of plastic on the inside left of the mechanism. I've checked other forums and pictures on the net and I think it should be there (rather than should have been removed during set up) but I could be wrong?
I've got a new bike with an Ultegra 11 speed compact double and when on the front large chain ring there's a progressively loud chain rub coming from the front derailleur from about the third cog when moving up from small to big. By the middle of the cassette it's rather loud and I can almost feel the friction through the pedals despite using any fine adjustment facility in the shifters. On the small front chain ring all seems well going through the gears (I seem to be able to use all of the cassette without stressing the chain) and shifting between the two front chain rings is fine. What do I need to do to iron this out assuming I should at least be able to use the middle of the cassette when on the front 50 tooth chain ring before risking cross chaining? Any advice much appreciated as ever.
Note: the front derailleur has a small piece of plastic on the inside left of the mechanism. I've checked other forums and pictures on the net and I think it should be there (rather than should have been removed during set up) but I could be wrong?
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Comments
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Assuming your front derailleur is located correctly with the appropriate clearance between the bottom of the outer derailleur plate and big chain ring teeth, and is aligned correctly with the frame (should be if you have braze on, but check - and if you have band on, worth looking at). The next thing I think you should be checking are the front derailleur limit screws. From the way you describe your problem, it sounds like the outer plate of the derailleur is too far outboard of the big chain ring, meaning that as you change down, the chain is hitting the inboard plate on the derailleur way before you reach the biggest two or three cogs on the cassette. When you are in the big ring, the outer derailleur plate should be about 0.5mm from the chain - it needs to be just not touching.
If all looks good with those settings, I would then take a look at your chain line between front cogs and rear cassette. If it's a manufacturer-specced bike, there shouldn't be an issue, but it has been known for mechanics, etc., to forget to put spacers between axle and crank - my XT crankset has spacers to allow for different bb widths (68mm v 72mm).
Post a couple of pics and someone on here will help sort you out.0 -
If it's rubbing on the front mech near the smaller sprockets when in the outer chainring, then it would suggest that the FD is rotated (anticlockwise looking from above) and a SMALL adjustment clockwise would help - the inner side od the front mech cage should be parallel to the chainring. The pastic lump is supposed to be there.
Download the relevant Shimano tech doc are have a read.
Oh, here it is....
http://techdocs.shimano.com/media/techd ... 671268.pdf0
