BB compatibility

[GaryQLD]

Hi - I am new to road biking been biking now for 12 months and taken my 40.6k from 110mins to 65mins, I am looking to upgrade my compact to a standard 53/39 but my bike has a B.B. of 90 and looking to put a SHIMANO ULTEGRA FC-R8000 CRANKSET will this fit my Trek SL5 Emonda with a BB90 ? Thanks for any comments

[koshari]

what have you got now? you may simply be able to replace the chainrings. regarding the bottom bracket, you shouldnt have to replace it, the shimano outer bearing BBs all generally have a 24mm spindle diameter

[Duck!]

BB90 is a Trek-specific format that matches the assembled dimensions of an outboard-bearing threaded and standard press-fit bottom bracket. If you currently have a Shimano or FSA crank the R8000 will be a direct swap. If your current crank is a SRAM model you will need to replace the bottom bracket, as the left bearing has a smaller inner diameter. There are a few aftermarket options around, but the easiest source for a new botoom bracket, if required, is a Trek dealer.