Bicycle Mechanics - Ultegra Front Derailleur Q
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Hi there I was wondering whether the low gear adjust on a Shimano Ultegra FD is on the outside or inside. And just to confirm, if the chain is scraping the outside of the derailleur when I am in a low front gear and high rear, would I loosen the low gear screw?(all of the written faqs are confusing me!!!)
10-09-08, 09:55 PM
No. Your problem is the indexing. You need to turn your barrel adjuster counterclockwise in ~1/4 turn increments until the rubbing goes away. Then check to see if it rubs in the small front big rear combination. If it rubs in small-big, turn the barrel adjuster clockwise until there isn't any rub. If this happens, you will not be able to use the small-small, but you're not supposed to anyway.
To read more go here (http://parktool.com/repair/readhowto.asp?id=75).
10-09-08, 10:07 PM
+1 to the above post.
To explain it further, what you'll be doing is taking up the slack in the shift cable, which lets the indexing work correctly.
When you move the shift lever, it pulls a certain amount of cable, but no more. The "click" is basically a ratchet mechanism which regulates the amount of pull. If there's slack in the cable, the shifter has to take it up before the derailleur moves at all. Then, you're left with a portion of the cable pull only taking up slack and not moving the derailleur.
When the derailleur is in the small chainring, you want just enough cable tension so that the shifter can act instantly, but not so much that it holds the derailleur away from the limit screw.
Sweet, I got it working. Thanks for your help :)
10-10-08, 09:12 PM
Cool -- yeah, it's fairly easy once you get the principle figured out.
And just to confirm, if the chain is scraping the outside of the derailleur when I am in a low front gear and high rear, would I loosen the low gear screw?
That's called cross-chaining, and if you're using a double crank (with two chainrings, not three), your front shifter should have a "trim" position -- a sort of small click that only moves the FD far enough to avoid rubbing the chain, but not far enough to shift onto the big ring.
When you get the limit screw and cable tension correct, the trim position works just as it should.
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