BD and jesseh627,
The Shimano site indicates that they both come with a bottom bracket, the numbers I gave are for separate order of the bottom bracket for the Tiagra. Ultegra does list the bottom bracket number as SM-BB6700 on the website, it is not listed as a separate item or link. The bottom bracket number link for Tiagra is in the same link as the crank. I take this to mean that the bottom brackets come with a crankset for both groups. the Ultegra is a Hollowtech II construction with Hyperglide Ultra-thin for 10 speed, the Tiagra is Hyperglide Ultra-thin for 9-speed.
My experience in swapping 10 speed 105 in place of 7 speed RSX says the narrower 10 speed will work with the Tiagra if it is the 9 speed. I am ot sure of any difference in the widths for Shimano's 9 and 10 speed Hyperglide. Again, check the website for your application and what you want to accomplish first, please.
Bill
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Semper Fi, USMC, 1975-1977
I Can Do All Things Through Him, Who Gives Me Strength. Philippians 4:13
Last edited by qcpmsame; 12-31-12 at 02:29 PM.