Bottom Bracket assistance

Looking for some guidance please gents.
My bike frame has a hollowtech BB and I am considering upgrading my groupset to SRAM etap. I am however confused about BB's.
If I remove the hollowtech can it be replaced with say a GXP or BB30 or is the bb frame specific ? I understand that I can continue using my 11 speed chainring but if I'm going todo this upgrade I want Togo all out and replace the entire groupset.
The frame is a btwinn Mach 720.
Thank you
My bike frame has a hollowtech BB and I am considering upgrading my groupset to SRAM etap. I am however confused about BB's.
If I remove the hollowtech can it be replaced with say a GXP or BB30 or is the bb frame specific ? I understand that I can continue using my 11 speed chainring but if I'm going todo this upgrade I want Togo all out and replace the entire groupset.
The frame is a btwinn Mach 720.
Thank you
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Posts
24/22 GXP cranks can be used in 24 mm HT2 BB's with a simple adaptor, in fact as GXP BBs seem to use balls of cottage cheese for bearings they are preferable - it's what I have on my commuter.
30mm GXP cranks can't be used in a conventional threaded BB shell frame.
retired 9.6kg Carrera Kraken
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Thanks for the reply, Yes I assume it is hollowtech II, attached are some images which may help ? I believe these are screw in.
The options i have for purchasing the bottom bracket are as below
So BB30 which is a press fit into a totally different BB she'll is not going to work on your bike.
If you want to go GXP it has to be the screw in option with the 24/22mm axle and not the 30mm axle that works with that BB.
retired 9.6kg Carrera Kraken
The Carrera Hardtail combined thread - come on all you Carrera's!
The Sons Scott Genius RC20 build
There is no such thing as 30 mm GXP, it's always 22/24 mm.....
GXP will fit perfectly and I've only ever encountered one troublesome set of bearings. Don't waste your money on the ceramic bearings.
retired 9.6kg Carrera Kraken
The Carrera Hardtail combined thread - come on all you Carrera's!
The Sons Scott Genius RC20 build
If you have a hollowtech, you can't go to BB30
but you can to go GXP very easily with a small adaptor
https://goo.gl/XXoAI4
A Lot of people, including myself, wish BB30 was never invented.
So Hollowtech is referred to as a hope bracket ?
I've cleaned up the bracket and can see its marked "BC 1.37 x 24 Road" Which i've read is referred to as English thread ? Would this be a straight install without the need for any adaptor https://goo.gl/7nI1Ih - It looks like the width is 68mm.
Why not change to DI2? That way you don't even have to worry about your BB
retired 9.6kg Carrera Kraken
The Carrera Hardtail combined thread - come on all you Carrera's!
The Sons Scott Genius RC20 build
Bottom Bracket standards
BSA/English 1.37 x 24TPI threaded, 68mm shell width
BB30 68mm x 42mm pressfit bearings directly into the frame
From that you then have a number of Crank systems listed below, there is confusion here because BB30 is used for both bottom bracket standards and crank standards:
Sram GXP 90mm wide, Axle 24mm on Drive Side, 22mm On Non Drive Side
Shimano Hollowtech 2, axle is 90mm wide, 24mm diameter
BB30/PF30, axle is 68mm wide, 30mm diameter
To cut a long story short, the BSA bottom bracket will work with the SRAM and Shimano systems, it will not work with the BB30/PF30 crank because it cannot accommodate a 30mm axle.
I hope that helps.
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