Bicycle Mechanics - Cassette compatability?!?

I have an old road bike (89-90 vintage) w/Ultegra 600 components that I'm rebuilding over the winter. My question is, I have heard you can take an 8 speed rear cassette, remove one of the cogs, and use it on this older 7-speed Ultegra 600 drive train. Is this infact possible? (Or are their spacing issues concerning the 7 vrs. 8 speed cassette?) Also, what is the largest gear (28, 30 tooth) the rear deraileur will handle? (As I said this is a road bike originally set-up w/a 39-53 front, and 13-21 rear). :confused:

Originally posted by MHub
I have an old road bike (89-90 vintage) w/Ultegra 600 components that I'm rebuilding over the winter. My question is, I have heard you can take an 8 speed rear cassette, remove one of the cogs, and use it on this older 7-speed Ultegra 600 drive train. Is this infact possible? (Or are their spacing issues concerning the 7 vrs. 8 speed cassette?) Also, what is the largest gear (28, 30 tooth) the rear deraileur will handle? (As I said this is a road bike originally set-up w/a 39-53 front, and 13-21 rear). :confused: Why not just buy a 7 speed cassette? 7 speed cog spacing is 5mm and 8 is 4.8mm.Close enough, that mismatched shifters usually work.Sheldon Brown at www.harriscyclery.com has an article or two on modifying cassettes for different applications.Your rear deralier was speced for a 28 large cog,but will likely handle a 30. Easy enough to swap in a MTB rear derailer to shift an even bigger cog.

Originally posted by pokey
Why not just buy a 7 speed cassette? 7 speed cog spacing is 5mm and 8 is 4.8mm. Close enough, that mismatched shifters usually work.

I have an 8 speed cassette that I wasn't using. (LBS I think said it could be done). Anyway, I thought I could save a few $$. Thanks Pokey!

Yes, 8 and 7 speed have similar spacing for practical purposes. So if you have an extra 8-speed lying around, you may remove the small bolts or rivets and install 7 cogs on a 7-speed hub.

It will even work with indexed shifting.