Bicycle Mechanics - 8 spd cassette to 7 spd?
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07-23-08, 07:44 AM
I've got an 8 spd cassette on 650B wheels w/ Deore hubs. Can I use the same wheels with a 7 speed cassette? My situation is that the wheels are mounted on a frame that's a bit too small for me and I'd like to pick up a mid 80's steel frame (the right size) which will probably have 126mm spacing and would accommodate a 7 speed cassette (with some prompting) but not the 8. Thanks!
07-23-08, 08:25 AM
You will need a 4mm spacer to fit a 7speed cassette on an 8/9 speed freehub.
I've got an 8 spd cassette on 650B wheels w/ Deore hubs. Can I use the same wheels with a 7 speed cassette? Splines are the same, but the 7 spd cassette is narrower, so you'll need to add a spacer to keep it in place.
..I'd like to pick up a mid 80's steel frame (the right size) which will probably have 126mm spacing Sorry but the 8-spd wheel has a wider body, so merely swapping out the casssette won't help.
What I'd do first is simply to try to use the wheel as it is in the frame as it is, I have yet to encounter a frame whose dropouts have been that precise.
Another option is to replace the body as well. It's a simple job, anyone comfortable with adjusting bearings can do that.
A 3rd option is to tinker around with the spacers on the axle, often there is one on the NDS side that can be removed. This might require redishing the wheel though to get it centered in the new frame.
Then, assuming we're talking steel frame, it can always be spread and cold set to the new dimension.
07-23-08, 08:44 AM
What I would really like to do is get a new frame, use my same wheelset, but also use a 7 spd cassette instead of an 8. But if I understand what you're saying, the wheel body is wider w/ the 8/9 spd hub than it would be on a wheel meant for a 7 spd hub? If so, how wide would the frame of my bike need to be to accommodate the 8 spd wheel? 130mm?
07-23-08, 11:35 AM
If you have an 8 speed hub,you can put a 7 speed cluster on with a spacer.Dropout spacing for road bikes is 126-130(unless an early 5 speed 120).A 130 hub will fit in a 126 space with little problems.
07-23-08, 11:49 AM
I bet that you'll get yourself a steel frame and find this is not an issue. Either spread the drops a little bit every time you pop the wheel in, or cold-set the frame (sounds drastic, but really easy and harmless).
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