Bicycle Mechanics - Are all 8spd Cassettes the same?

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View Full Version : Are all 8spd Cassettes the same?

roguehippie
01-02-05, 01:07 PM
Hi all,

I'm switching from STI 9 spd shifters to bar end 8spd shifters. Long story. Of course, the cassette on back is a 9spd, but I've got an older Shimano Hyperglide 8spd Cassette on my MTBike, and it fits onto the freewheel of my road rim, but when I put the wheel back into the frame, and extend the rear derail. all the way, the biggest cog of the 8spd and the pulleys on the derail. seem to clear, but with something like 1mm to spare.

My question, are cassettes MTB or Road Bike specific? Can I use this Shimano 8spd cassette with the Shimano 8spd bar-end shifters that are on their way or will I need to buy a road-specific (or 105 derail. specific) 8spd cassette?

Thanks!

sydney
01-02-05, 01:19 PM
Hi all,

I'm switching from STI 9 spd shifters to bar end 8spd shifters. Long story. Of course, the cassette on back is a 9spd, but I've got an older Shimano Hyperglide 8spd Cassette on my MTBike, and it fits onto the freewheel of my road rim, but when I put the wheel back into the frame, and extend the rear derail. all the way, the biggest cog of the 8spd and the pulleys on the derail. seem to clear, but with something like 1mm to spare.

My question, are cassettes MTB or Road Bike specific? Can I use this Shimano 8spd cassette with the Shimano 8spd bar-end shifters that are on their way or will I need to buy a road-specific (or 105 derail. specific) 8spd cassette?

Thanks!4 considerations. Tf the mtb cassette is loose on the freehub with the lockrng properly tightened,it needs a 1mm spacer on the hub before the cassette.The road derailer has to be able to shift to the big cog, and depending on big cog size,the road RD may not handle it. The B tension screw needs to cause trhe upper jockey wheel to clear the big cog.The chain needs to be long enough to handle the big/big combination.
royalflash
01-02-05, 03:53 PM
is the largest cog of the 8 speed larger than the largest cog of the 9 speed cassette?- count the teeth - as Sydney has indicated rear derailleurs have a maximum cog size that they can cope with. If your new largest cog is larger than the old largest cog then it could be that the rear derailleur cannot cope with the new largest cog. You will probably also need a longer chain so you could try measuring the chain and seeing whether it it still long enough. This article tells you how to check the length of your chain

http://www.parktool.com/repair_help/FAQchainlength.shtml