Can someone explain GXP shell/GXP Frame?
 

I've got a frame with a GXP standard bottom bracket. It's English threaded. The frame is a 2010 BH GC Aero TT Medium Frameset.

I'm wondering what kind of crankset I can use. Is it possible with adapters and so on to use a standard 68mm BSA bottom bracket? I've got a shimano 105 crankset I'd like to use.

If I had to it would be OK to just buy a new bottom bracket and crankset. However, I've read bad stuff about the GXP bottom brackets. Seems there are issues with fit, play, and durability of the bearings.

Thanks,

Steve

GXP is the BB (as in SRAM's branding), not the shell, it uses the standard English thread (i.e. your 68mm), just like a Shimano HT 1 (Octalink) or 2 or square taper.

Just pull your current BB and replace with the one required for the 105, which depending on generation, could be square taper, Octalink or HT2. The GXP won't work with any Shimano crank anyway.

OK, so do you think the frame will accept
 

this: Shimano Ultegra 6800 SM-BBR60 Bottom Bracket.

There's nothing on the frame. I just bought the frameset and I'm building it up.

The frame was described to have a "GXP Standard" bottom bracket type. I wonder if this is not accurate.

the 105 crankset is brand new, black 4 legged spider (not sure that makes complete sense, but I think you know what I mean). This crankset works with the bottom bracket above.

What I'm wondering if the frame will accept that bottom bracket.

Thanks!

Steve

yep... direct replacement/installation... go for it, and be glad you've gotten away from GXP... the GXP bottom bracket bearing assemblies tend to require frequent replacement if you don't repeatedly coat the seals with waterproof grease, and you don't live in a rainless desert.

the ultegra/105, etc. bottom brackets tend to last at least twice as long where i live... i live in a RAIN FOREST.

smear a thin layer of waterproof grease on the spindle before assembly to ease future removal, and to prevent easy water intrusion...

the GXP BB assemblies use a different sized bearing on one end to avoid patent hassles from Shimano... one end requires a bushing to shim out one of the bearings... that plastic bushing seems to be what lets water/dirt into the bearing... i regularly grease the provided seal... most folks don't, and the bearing ends up rusting and failing/getting sloppy.

OK great.

Thanks so much for your responses.

It seems to me like the person who described the frame bottom bracket type as "GXP Standard" doesn't know what they're talking about. Sounds like the frame bottom bracket type is simply English threaded 68mm.

Shimano Hollowtech II cranks aren't compatible with SRAM GXP cups (the latter have 24mm/22mm bearings and the former requires 24mm/24mm). If you want to use the Shimano cranks, you need a Shimano-compatible BB.

I have the shimano compatible BB. I'm just wondering if the BB will fit into my frame.

Assuming that the threading/width (English, 68mm) is the same you should be good to go.

Yes, both Shimano and SRAM/Truative GXP cranks fit in a standard BSA shell. Each needs the corresponding BB though.

I did that exact swap a year ago, major upgrade.

I love FSA's logic -- "Hey, let's make a bottom bracket that's 3x as expensive as Shimano and requires a proprietary tool, but here's the kicker -- it needs replaced every time it even thinks about rain!"