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Bottom Bracket assistance

sizeablesausagesizeablesausage Posts: 10
edited January 2017 in Workshop
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

Posts

  • The RookieThe Rookie Posts: 27,748
    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.
  • 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.

    image.jpg

    image.jpg

    image.jpg

    The options i have for purchasing the bottom bracket are as below

    image.png
  • The RookieThe Rookie Posts: 27,748
    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.
  • keezxkeezx Posts: 1,311
    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.....
  • StillGoingStillGoing Posts: 5,207
    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.
    I ride a bike. Doesn't make me green or a tree hugger. I drive a car too.
  • The RookieThe Rookie Posts: 27,748
    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.
  • drshoedrshoe Posts: 27
    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.
  • 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.



    image.png
  • whyamiherewhyamihere Posts: 7,404
    English thread using that BB is correct.
  • hsiaolchsiaolc Posts: 492
    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 RookieThe Rookie Posts: 27,748
    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.
  • hambinihambini Posts: 113
    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.
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