Bottom Bracket assistance

sizeablesausage

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

The Rookie

When you say hollowtech BB, do you mean hollowtech II (hollowtech is cranks arms) and screw in (rather than a press fit option)?

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.

sizeablesausage

The Rookie wrote:

When you say hollowtech BB, do you mean hollowtech II (hollowtech is cranks arms) and screw in (rather than a press fit option)?

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

The Rookie

Yup that is screw in HT2.

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.

keezx

The Rookie wrote:

30mm GXP cranks can't be used in a conventional threaded BB shell frame.

There is no such thing as 30 mm GXP, it's always 22/24 mm.....

StillGoing

sizeablesausage wrote:

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

GXP will fit perfectly and I've only ever encountered one troublesome set of bearings. Don't waste your money on the ceramic bearings.

The Rookie

Keezx wrote:

The Rookie wrote:

30mm GXP cranks can't be used in a conventional threaded BB shell frame.

There is no such thing as 30 mm GXP, it's always 22/24 mm.....

Indeed my bad, meant BB30, same though he can't fit the 30mm axle cranks he's looking at into a threaded shell.

drshoe

Basically:

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.

sizeablesausage

Drshoe wrote:

Basically:

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.

whyamihere

English thread using that BB is correct.

hsiaolc

sizeablesausage wrote:

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

Why not change to DI2? That way you don't even have to worry about your BB

The Rookie

sizeablesausage wrote:

Drshoe wrote:

Basically:

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.

Would WHAT be a straight install? As above you can use a GXP crank either with a screw in GXP BB (which the cranks will come with) or an adaptor into the Shimano BB, but the cranks you mention above (but haven't linked to) have a suggested BB30 bottom bracket which suggests they are BB30 and so won't fit.

hambini

Reading through this there is a bit of confusion here, the list below shows the two BB standards that were discussed:

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.