MarcBurger Posted February 2, 2018 Share I know bottom brackets have been discussed endlessly before, but the more I read up the more confused I become. Essentially need some feedback before I pull the trigger on my shopping list: My frame has a 73mm BSA threaded bottom bracket.GX eagle groupset comes in both BB30 or GXP.Hope have both a 30mm threaded BB cups and a BB for 24mm spindle cranks (I assume this means for GXP) Is it just a matter of choosing one or the other? Or is there a clear better choice? Lastly BOOST nonsense: My rear is a 12x148 boost. Do I need boost cranks? Spacer? Magic? Link to comment Share on other sites More sharing options...
Kalahari Vegmot Posted February 2, 2018 Share I know bottom brackets have been discussed endlessly before, but the more I read up the more confused I become. Essentially need some feedback before I pull the trigger on my shopping list: My frame has a 73mm BSA threaded bottom bracket.GX eagle groupset comes in both BB30 or GXP.Hope have both a 30mm threaded BB cups and a BB for 24mm spindle cranks (I assume this means for GXP) Is it just a matter of choosing one or the other? Or is there a clear better choice? Lastly BOOST nonsense: My rear is a 12x148 boost. Do I need boost cranks? Spacer? Magic?You need a Boost specific crankset, as it's offset. Bb30 bb cups are available that fit in 'standard' threaded frames-their bearings are quite small, and they are very expensive. If a bb does not say gxp specific, it's not. Gxp tightens against the bearing so special design. Also, gxp crankset spindles are 24mm drive side, 22mm non-drive. Get the Boost GXP Eagle crankset and a GXP BB and you're golden. MarcBurger 1 Link to comment Share on other sites More sharing options...
Rudi Pollard Posted February 2, 2018 Share The 24mm spindle is shimano specific. GXP is a sram standard which is 24mm on the one side and 22mm on the other. Brands like token do one standard 24mm BB with a shim on the one side to step it down to 22mm BB30 is a 30mm axle. For your frame you can either get a GXP threaded BB or a 30mm threaded BB and then buy your crank accordingly. For boost you just swop out the chainring on the eagle crank. Non boost has a 6mm offset on the ring whereas boost has a 3mm offset. Link to comment Share on other sites More sharing options...
MarcBurger Posted February 2, 2018 Share Get the Boost GXP Eagle crankset and a GXP BB and you're golden. Brilliant. Thank you. Edited February 2, 2018 by MarcBurger Kalahari Vegmot 1 Link to comment Share on other sites More sharing options...
Kalahari Vegmot Posted February 2, 2018 Share The 24mm spindle is shimano specific. GXP is a sram standard which is 24mm on the one side and 22mm on the other. Brands like token do one standard 24mm BB with a shim on the one side to step it down to 22mm BB30 is a 30mm axle. For your frame you can either get a GXP threaded BB or a 30mm threaded BB and then buy your crank accordingly. For boost you just swop out the chainring on the eagle crank. Non boost has a 6mm offset on the ring whereas boost has a 3mm offset.Have you seen GXP work with a shim in a different bb type? Link to comment Share on other sites More sharing options...
droo Posted February 2, 2018 Share Have you seen GXP work with a shim in a different bb type? Yebo. Hope supplies a spacer kit that means that their 24mm BBs are compatible with both Shimano and SRAM cranksets. OP - For my money, I'd go with a GXP30 BB and BB30 crank. Best of both worlds - threaded BB and the stiffer 30mm axle. Link to comment Share on other sites More sharing options...
Kalahari Vegmot Posted February 2, 2018 Share Yebo. Hope supplies a spacer kit that means that their 24mm BBs are compatible with both Shimano and SRAM cranksets. OP - For my money, I'd go with a GXP30 BB and BB30 crank. Best of both worlds - threaded BB and the stiffer 30mm axle.Dammit. I just sold a nice GXP crankset because I thought it wouldn't work. Doesn't the side force of a GXP on the bb cause problems for bb's not designed for it? Eddy Gordo 1 Link to comment Share on other sites More sharing options...
Rudi Pollard Posted February 2, 2018 Share Have you seen GXP work with a shim in a different bb type?Yup. My current BB is run like that from Token... BB - http://tokencycling.co.za/shop/tk878tbt-external-bb-threaded-w-tiramic-bearings/Shim - http://tokencycling.co.za/shop/m383-gxp-adaptor-for-mtb/ Link to comment Share on other sites More sharing options...
Kalahari Vegmot Posted February 2, 2018 Share Yup. My current BB is run like that from Token... BB - http://tokencycling.co.za/shop/tk878tbt-external-bb-threaded-w-tiramic-bearings/Shim - http://tokencycling.co.za/shop/m383-gxp-adaptor-for-mtb/Shot, thanks! Link to comment Share on other sites More sharing options...
droo Posted February 2, 2018 Share Dammit. I just sold a nice GXP crankset because I thought it wouldn't work. Doesn't the side force of a GXP on the bb cause problems for bb's not designed for it? Should have just bought a new BB... N+1 Edited February 2, 2018 by droo Kalahari Vegmot 1 Link to comment Share on other sites More sharing options...
shaper Posted February 2, 2018 Share Dammit. I just sold a nice GXP crankset because I thought it wouldn't work. Doesn't the side force of a GXP on the bb cause problems for bb's not designed for it?I have the Hope BB on my TT bike...when am racing I have the Quarq DZero GXP power meter on the bike. During the off season and the bike is on the trainer, I switch crank and use an ultegra crank with shim.as it is a smart trainer so do not need the PM crank. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now