Tiagra 10speed ?

The 9sp and 10spd cassettes are not the same width - in fact the total width of the 10spd is greater but the width of the 10spd cassette actually engaging the splines of the freehub is narrower. The explanation is that the largest sprocket actually overhangs the end of the freehub - this sprocket does not engage the freehub but is driven by a spider.
Consequently, an inboard shim is required when using a 10spd cassette. Your Tiagra wheels will work with a 10spd cassette.

will i need to buy this "shim" or is will it already be associated with the cassette that i am using on my 105 hubs?

hammex said:

Can i put a 10 speed cassette on a new Tiagra back wheel. Some sites (e.g. wiggle) say that the wheel is 8/9 speed compatible only. I thought that the 9 speed and 10 speed cassettes were the same width in total so were interchangeable......If not, any other inexpensive shimano compatible wheels you might recommend....(i want to stop using my nice wheels for my commute!)

Yep. Only DA 7900/7810 rear hub, DA and ultegra complete wheels are 10s only.

hammex said:

will i need to buy this "shim" or is will it already be associated with the cassette that i am using on my 105 hubs?

Comes with the 10s cogset..DA/Ultegra and 105.

Thanks, all, for your advice.

hammex said:

Thanks, all, for your advice.

Just as extra confirmation, I have a 10 speed cassette (SRAM) on my Tiagra hub.