Bicycle Mechanics - 8/9 cassette wheel upgrade from 6 speed freewheel
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05-25-05, 09:26 AM
I want to upgrade my suntour 6 speed bike with an aero wheelset. The wheelset Im looking at is compatible with 8/9 shimano cassettes.
If I use an 8 speed shimano cassette, from my understanding the issues I face with the upgrade are 1) rear wheel spacing of 130mm vs 126mm 2) index downtube shifter must be converted to friction.
Am I missing anything? such as will my 6 speed rear del. need to be swapped for a 8 speed compatible.
05-25-05, 09:39 AM
Spreading the rear triangle can be done if your frame is steel. The rear der should be OK with friction shifting, unless you are going for a much bigger bottom cog, in which case you may need a longer cage. Get a new chain.
05-25-05, 11:38 AM
Does a 8/9sp wheel fit in the frame with clearance for the cassette? On one of my old bikes, the frame could be spread to 130mm for the wheel but the cassette hit the chain stay. I am now thinking about a NOS 7sp cassette wheel with 126mm clearance. Getting dual pivot brakes installed is another problem. Good luck.
05-25-05, 11:50 AM
Suntour and Shimano rear derailers are different. To go from a suntour cassette to a shimano cassette, you probably should change the rear derailler.
If you are already upgrading, just go straight to 9 speed. 8 speed is getting phased out and even 9 speed is going away.
I have a bike which has a 126mm rear chain stay spacing. Expanding that to 130mm is no problem what so ever. The only issue is with wheel changes, it requires a bit more finesse to get the wheel in and out. When you are putting your wheel in, just pull the chain stays apart a couple mm and pop the wheel in.
05-25-05, 11:52 AM
I see you are going with friction shifters. If so, you can probably use the suntour rear derailler.
Down tube shifters for 9 speed are still available if you don't want a halfway measure.
05-25-05, 12:33 PM
Thanks for the replies.
I would go with a 9 speed cassette but I just bought a 6/7/8 speed chain a week ago and intend to use it instead of buying a new 9 speed chain. From what AndrewP said I understand that I can use my current chain as long as the cog sizes in the new and old wheels are similar.
So if I understand correctly I can use the new wheels with my current setup. The only modifications required are expanding the rear triangle, and upgrading the rear derailler if I decide to go with an indexed system.
Am I missing anything else?
I'd give it a go with indexing (if you want it) and the Suntour derailer. Sometimes thing can work well enough if you tweak things.
Check with Sheldon Brown's web site for serious mechanical stuff.
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