What would happen if...

[chris414]

What would happen if i tried to put a wheel with 10spd ultegra cassette on a bike that only has a tiagra 9spd?  Would i just be loosing out on one of the 10 gears on the cassette or would i risk jumping the chain off the cassette?  Or would it just not work?

[Witrot]

Depends, there is ways you can modify it so that the gears can work, but you will have always problems when you use other wheels. I did it years back in the days when i had 8 speed with a 9 speed cassette. I recomend that you rather get the same cassette or other group sets.

[EdoardoBianchi]

My guess is the "just not work" or not work properly option, since the chain is wider on 9s. I don't think it is as extreme as getting jammed between cogs, but there will be some rub at the very least, affecting shifting and wear on all interfacing components.

 

Take a look at the Shimano website for compatibility pointers (although I guess they have to make you believe it will not work because they have profits and legal issues to be concerned about...

[OcTaLL]

Depending on how thick the chain is, 9sp compatible or not, if it is to thick it won't work, just put a 9sp cassette on.

[Guest Big H]

Nine speed cassetes will not fit on desinated 10 speed freehubs. 10 speed cassetes will however fit on 9 speed freehubs. Make sure what freehub you have on the bike. 9 speed chains are wider than 10 speed and will not work on a 10 speed casstte

[Joss]

Just put the 9 speed cassette on the wheel. 10sp will not work with 9sp tiagra does not matter how much you modify. If the 9sp cluster does not fit on the wheel with current 10 sp i suggest you upgrade you group.