Bicycle Mechanics - Front der. won't make it all the way to the big ring... eh?

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MWPdx
02-15-10, 09:20 PM
Am I doing it wrong???

I'm building a bike pretty much completely from "scratch" (got a frame and am slowly accumulating the necessary bits and pieces, most of which are cheap/used).

I got a really cheap looking front derailleur a while ago and I just now got and installed the crankset (TruVative triple somethin' or other). The problem is that the FD won't swing out far enough center over the largest chainring. It looks like it would need to go out maybe a centimeter more or so for it to work.

I know it's not the limit screw (already tried that)... what else could it be?? I did take apart the bottom bracket when I first got the frame and may have put the spindle back in the wrong way but it seemed to be pretty much the same on each end so I wouldn't think that would do it.

I checked on my friends old bike (fairly similar frame, etc) and the large ring sat quite a bit closer to the frame than mine does.

What'm I doing wrong???


operator
02-15-10, 09:36 PM
Is the derailleur for a triple (what is it)? Is the bottom bracket the correct length for the crankset? What shifter are you trying to use with it? Can you get the derailleur to travel to the outermost stop by pulling on the cable? Or is the shifter the problem?

Need. More. Info.

BCRider
02-15-10, 09:42 PM
A cm is a HUGE amount. Either it is setup to for no more than a road double or your crankset isn't mounted in close enough to the bottom bracket. If you're using a square taper BB then you may have too long a BB axle for this crankset. A way to tell is the clearance of the ring teeth from the chain stay. The teeth of the rings should be REALLY close to the stay. In fact a lot of frames dimple in the chain stay where the inner ring sits to provide clearnace for the ring. If your frame has such a dimple in the stay and the smaller ring isn't sitting into the clearance it provides then chances are your BB is the wrong size.