BB Size / Compatibility
I currently have a Truvativ Elita SL crank and Truvativ ISIS GigaPipe SL Bottom Bracket (68/108) and would like to swap in an Ultegra 6500 crank and Ultegra 6500 Bottom Bracket. I see the Ultegra 6500 BB listed in 68/109.5. Bike is an 05 Cannondale R700. Will this size work, any issues I am missing, will this swap work anyway? Opinions?
Yup. Looks to me like a straight bolt-up. This is a good place to use a torque wrench particularly on an aluminum frame.
The bb length is specified by the crank maker and the fact that the Shimano and Truvative bb's are similar in length is just a coincidence. Use the maker's specified bb.