I have a Trek 1200 which on which i recently upgraded the front from Tiagra (bleargh) to 105, so it's 105 front and rear, with Tiagra 9spd shifters.
if i was to stick on a 9spd Ultegra rear, would it work with my Tiagra shifters or would i have to upgrade to 105/Ultegra shifters (lord help me they're awfully expensive...)
and also, if you were to stick on 10 speed hubs, 10 speed cassette, 10 speed everything except 9spd front derailleur and crank, would that make it a 10spd or 9spd? i've heard that it would be a 9spd but dont see why... anyone explaining that would be nice :)
thanks!

I have a Trek 1200 which on which i recently upgraded the front from Tiagra (bleargh) to 105, so it's 105 front and rear, with Tiagra 9spd shifters.
if i was to stick on a 9spd Ultegra rear, would it work with my Tiagra shifters or would i have to upgrade to 105/Ultegra shifters (lord help me they're awfully expensive...)
and also, if you were to stick on 10 speed hubs, 10 speed cassette, 10 speed everything except 9spd front derailleur and crank, would that make it a 10spd or 9spd? i've heard that it would be a 9spd but dont see why... anyone explaining that would be nice :)
thanks!
Part 1 - For 9-speed: All Tiagra, 105 and Ultegra are compatible.

Part 2 - The front end makes no difference.

In general, the only things different between 9 and 10 are the cassette, chain and shifters (also DA hubs). You could also run 9-speed with 10-speed shifters with a trick rear derailleur attachment.

TF

You could run 9 or 10 speed bar end shifters which are cheaper than STI's. I'm always leery of buying used STI's off the Internet or garage sales. I purchased a few pairs of 9 speed barcons from Bikeman a few months back at resonable prices. Just don't overlook all your options.