Ultegtra 8spd cranks with 9spd Cassette

[SAB]

I'm collecting parts to build up a Surly Crosscheck. Can I use my old 8 speed ultegra cranks and front derailleur with a new 9 speed cassette and rear derailleur?

[Racing Aardvark]

I haven't had any problems with that on either of my bikes.

[flythebike]

I you check out Leonard Zinn on velonews.com - he writes their techincal Q & A column, he runs all kinds of stuff like that 9 speed chains on 10 speed, 9 speed Chainwheels with 10-speed cogsets, etc.

[BlastRadius]

If you run a double 8 speed chainset and front derailer you may get slower shifts to the small ring. 8 speed chains are a bit wider than 9 speed chains so the space between the two chainrings are a little wider. When you get it adjusted so that the derailer doesn't drop the chain off the smaller ring in a downshift, the chain _may_ sometimes ride on top of the smaller ring's teeth before settling fully onto the ring.
You can adjust the low limit out further for faster shifts but you'd need to use a third-eye chain watcher to keep the chain from dropping off the ring.

I know this because I ran 9 speed Ultegra on 8 speed RX100 cranks and FD for a while before I got an awesome deal on Dura-Ace cranks.