Bicycle Mechanics - Fulcrum or pulley to convert top pull FD to bottom?
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08-21-11, 07:43 PM
I am wondering if this possible. I have this Trek 800 I am converting to hardtail for my GF. The main problem is that I have a nearly NOS set of STX(smoked chrome), and the FD is top pull(not either/or). The frame however is a bottom pull. Aside from trying to find a larger than 28.6 cable stop, is there anything I can do? A pulley would work, but it would have to be a certain diameter or it would change the cable pull amount. Should I just suck it up and order a new derailleur?,,,,BD
Shifters are Sunrace 8x3 from a Schwinn SS hybrid.
08-21-11, 08:14 PM
Bikedued: I am not sure that this is exactly what you want but this is a nice-looking pulley: http://problemsolversbike.com/products/cross_clamps_pulleys/
I don't believe a straight pulley like this will change the cable pull, just redirect it. It might give you some ideas.
08-22-11, 08:40 AM
Might work. And cable pull amount would surely be affected by the diameter, am I wrong in assuming this? Smaller = more cable, Larger = less? I kept in mind a "travel agent", but I am not an engineer, lol.,,,,BD
08-22-11, 10:22 AM
No, the pulley diameter is immeterial. The only way it would change the amount of cable pull is if you ran the cable over two pulleys of different diameters which is how Travel Agents and Jtek Shiftmates work. A single pulley can be any size.
08-22-11, 11:24 AM
Top pull FD?, you can get a housing stop band, of appropriate size.
and clamp it to the seat tube,
run housed cable up to it , and then you have a top pull routing.
Pulley is to do the opposite, have top pull routing,
and want to use bottom pull FD's
08-22-11, 08:48 PM
Is there a reason why it wouldn't work? It's a 13 inch Trek 800, so there's only 6-7 inches of clamp area. I was figuring it could go under the BB, over the pulley, then down to the FD? It's starting to seem simpler to use a different FD.,,,,BD
08-22-11, 09:14 PM
take the leap , never mind the clowns holding the trampoline , underneath you.
08-22-11, 11:14 PM
I've done just the opposite with an old 3-speed aluminum cable pulley and a hand-made S.S.clamp. I put a bottom pull Huret F.D. onto a Schwinn MTB set up for top pull. Used the pulley/clamp to change the cable direction 180 degrees. Works fine.
Don't have a picture on the computer, but, I could take some and post if you're interested in seeing it.
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