Compatibility BB GXP v Hollotech

[Andy JB]

So i have the option of purchasing a SRAM chainset which uses the GXP bottom bracket which is english threaded.

My current set up is Shimano with Ultegra Chainset 7800 & DuraAce 7900 BB which is english threaded (not pressfit).

Question is will this be a straight swap the Shimano BB to the GXP BB - note there are spacers with the GXP 68-73, or am i missing something here before i purchase the CS?

[Andy JB]

Great sounds possible & a straight swap or play with a spacer which is what i hoped.

I have read negative things about the GXP BB's but also the external BB's I currently use which i've had no problems with. They appear cheap enough to replace.

I am somewhat reluctant to remove the DA7900 BB as its only had a season of use, its just the weight saving offerred during the bike rebuild between Ultegra and Sram Red chainsets is a significant opportunity not to let pass. Its also an opportunity to try a smaller crank arm length.

[Andy JB]

upsidedownmark said:

Bit of a lol at the weight saving tho, what 80g? Red is of course more flexi, and doesn't shift as well as DA

Well i agree - but my main driver is to shorten my crank length arm, however, my chainset is Ultegra (not DA per my BB) so the saving is around 130g, a fairly significant saving on a rebuild targeting weight loss!

The discussion over BB life & external bearings is interesting & shows progress (or lack of) when my steel winter bike circa 1977 has a Campag Athena internal BB square taper which i replaced in the 90's and still spins sweetly after many thousand of miles !!