Bicycle Mechanics - Front derailleur messed up somehow

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futuresealsnipe
06-05-08, 06:28 PM
I searched but didn't see anything pertaining to this. I have an old MTB that works decent for what it is except for the FD. It has a friction shifter and when I turn it up to the max, it still only gets the bike in 2nd gear (on a 3 speed crankset). The FD itself is very far from the chain on the lowest sprocket and gets really close to the seat tube and like I said, when I crank it up it still only goes to the next gear. Is this just my L and H screws needing adjustment or is it something in the shifter?
Thanks in advance and let me know if I left out any important info.


operator
06-05-08, 06:29 PM
http://www.parktool.com/repair/readhowto.asp?id=75

futuresealsnipe
06-05-08, 06:53 PM
Thanks for the link. I did see that earlier and that's why I suspect it might be my L and H screws but I'm not totally sure because it does not rub at all while in either gear and it is so far off on both sides (and I haven't had the chain slide off on the lowest sprocket yet, but then again I'm not hammering down).


DannoXYZ
06-05-08, 09:59 PM
Post a picture of your FD. The two most critical adjustment from that Park site is the height above the biggest chainring and the lateral rotation. You MUST get the outer cage as close to the chainring as possible without touching, I use a dime rather than their penny. And the rotation of the outer-cage IS NOT parallel to the chainring, but parallel to the CHAIN. Most bike-shops teach their employees the "parallel to chainring" technique because a lot of time, the chain is off the bike and this technique yields consistent results. But it yields consistently mediocre results, if not downright poor and non-functional.

Post a picture of your FD from the side and from above, we'll see if it's a positioning problem. Only when you have the FD positioned correctly can you move on to making cable-tension and limit-screw adjustments.

Also it helps moving the chainring from small-to-big if you bend the tip of the inner cage outwards a little. Newer Shimano FDs have a built-in bubble that does this same function. Bending older flat-cage FDs improves their performance.

Bill Kapaun
06-05-08, 10:47 PM
Sounds like maybe you have to screw in the L screw a bit, and then remove the slack from the cable.
When in doubt, follow the instructions posted.

Al1943
06-06-08, 12:03 PM
Sounds like maybe you have to screw in the L screw a bit, and then remove the slack from the cable.
When in doubt, follow the instructions posted.

+1