Bicycle Mechanics - 105 double fd on a triple crank...... help please
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03-30-12, 11:41 PM
so as the title says ive got a 105 fd on a triple 2300 (not sure if that makes a huge difference) ive got it fairly adjusted but im still getting lots of chain rub both both ends, i rarely ever use my granny gear so i figured why not throw a double fd on.
ive got the rd angled out to help with shifting and height is off but its works, i would like it to be lower. and i took about 4 maybe 5 links out of the chain (i read that might).
basically any tips to help with the chain rub, for whatever reason the high and low limits aren't doing a damn thing from what i can tell. tension, no tension adjustments are not happening (at least not visible) also the fd is a "new" its a take off, i got a great deal on ebay on it, but now im worried im gonna wear a whole through it or blow through chains cuz of the rubbing.
03-31-12, 12:37 AM
Sight unseen , No. Take it to your LBS.
03-31-12, 12:43 AM
that was helpful thanks.
03-31-12, 08:12 AM
"i took about 4 maybe 5 links out of the chain" BAD IDEA!
You had better be very sure that you have not made your chain too short or you risk severe damage to your derailleur or possibly your frame if you thoughtlessly shift into your big chainwheel/big cog combination with a too-short chain. Here are some time-tested instructions for setting your chain length: http://sheldonbrown.com/derailer-adjustment.html#chain
You state that your derailleur is too high and that it is angled to help shifiting; fix the height and you may not need to have it angled, which makes chain rub more likely. Then follow these instructions from start to finish without skipping any steps. http://www.parktool.com/blog/repair-help/front-derailleur-adjustments
If your bike lacks cable length adjustment (not tension, actually, that is set by the derailleur spring) you may need to splice in an inline adjuster.
After all of that you may find that your double derailleur is just not suitable for a triple setup.
04-01-12, 06:17 AM
I assume you're using an STI shifter?
I ask because I recently resurrected an ancient MTB that uses what looks like a double front mech with a triple crankset. The original crank was a double crank with extra-long chainring nuts (is that what we call them, guys?) that allowed it to have a third chainring inboard of the standard double, so I'm not entirely sure it was meant to run three rings. The shifting to the granny ring is just about acceptable with friction levers, but I have a suspicion that it wouldn't work with indexed shifting.
In short, it CAN be done, but it would probably be an order of magnitude more difficult with indexed shifting.
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