Bicycle Mechanics - road bike cassette replacement
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05-18-09, 03:48 PM
Hi, my employer just bought a used road bike, the chain slips in almost any gear. I have seen the chain slip over the sprocket under load. I am thinking the sprocket and chain should be replaced. The bike has downtube shifters, with the flip of a lever it is friction or index shifting. I have counted 5 clicks with the index, that would tell me a six speed cassette is needed, is that correct? It has an 8speed cassette on it now....... http://i661.photobucket.com/albums/uu339/bobby-ricigliano/IMG_4229.jpg Will this rear wheel accept a six speed cassette? If not, can the 8 speed cassette be used with the friction shift? This bike was purchased from a guy who sells lots of used bikes, so it may be a bit of a parts bike. Thanks for any help.
Sounds like a new chain and cassette are needed. If the current shifter will access all 8 cogs in friction mode then it would also access 9 or 10. The 9 speed cassette is the same overall width as the 8 speed cassette. The 10-speed cassette is slightly narrower than the 8 or 9. You cannot easily mount a 6 speed cassette on that hub and it would be better to run 9 or 10 anyway. The chain needs to match the number of cogs on the cassette. The outside width of the chain gets narrower with more cogs. A 10-speed chain may not run well on the crankset. I would try a 9-speed cassette and chain on this bike.
garage sale GT
05-18-09, 06:06 PM
If you have a hub which can accept an 8 speed cassette, it probabaly won't take a 6. I don't think there is one available which would fit the splines, not sure, but it wouldn't be the correct width.
If he MUST have index shifting, you could look into the cost of modern downtube shifters for a modern cassette. I believe you can still get them.
I hope the frame was steel because you're not supposed to change an aluminum frame to take a wider, modern mountain hub (deore), but people do it anyway. It can crack.
05-18-09, 07:36 PM
Now I am wondering, is it possible the chain is too wide for the 8 speed cassette? Allowing the chain to slip over the sprocket?
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