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?

[anonymous-user]

Compatibility issues aside, gxp bottom brackets gave the worst seals known to mankind, you'd be far better sticking to hollowtech2 for reliability. I've had gxp bottom brackets last less than 500kms in bad weather.

[Magic919]

Sounds fine.

[upsidedownmark]

Compatibility is fine, straight 'unscrew one, screw the other one in' job.
FSA BB's are reputedly made of cheese, but I've never heard of, nor had an issue with GXP. YMMV.

I'm mildly confused about the width, but a gxp bb usually comes with a spacer or two. With a sram red crankset I needed a spacer under the drive side cup to keep the inner ring off the chainstay. With a quarq riken I couldn't use a spacer and it all fitted just fine. Also with various quoted widths, be aware that you can also get gxp cranks for mountainbikes. But the width is largely a crank issue / frame issue. If the crank and the frame match, screw-in cups are just that..

[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.

[Gren]

I've had no problems with GXP - my mountain bike is only on it's second after 4 years and thousands of miles. They only cost around £20 and are easy to replace.

That said you can just swap em out for a Hollowtech easy enough.

[upsidedownmark]

I'd also note that mountainbikes tend to give the BB a significantly harder time.. don't let that worry you. I've got a shimano 105 BB in one (road) bike that's been there for about 10k miles (over several years) and is still smooth, sram gxp 3 years old and great.

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

[scz4]

Gren said:

That said you can just swap em out for a Hollowtech easy enough.

Can you, sure? I have a press fit GXP that's 1 year old and now developing play, running it with a SRAM chainset. My understanding was you couldn't fit Hollowtech (which is a much better choice) with a SRAM chainset (X-01 single speed).

[Gren]

You can swap the BB but you'll have to swap the chainset too. I meant that the frame will cope with the swap. Mine was threaded as well.

Most make the swap because SRAM chainsets can be quite expensive to replace compared to Shimano. I have to pay through the nose even for some new rings for my X0 chainset.

[AlasdairMc]

The axles are different sizes, GXP is slightly bigger so the chainset won't fit correctly. The BB threads will be the same though so you can still use either on the same bike.

Shimano HT2 is directly interchangeable with Race Face X-Type, but not GXP.

[upsidedownmark]

scz4 said:

Can you, sure? I have a press fit GXP that's 1 year old and now developing play, running it with a SRAM chainset. My understanding was you couldn't fit Hollowtech (which is a much better choice) with a SRAM chainset (X-01 single speed).

Pressfit is a whole different ball game, and requires research (you should be able to get a pressfit bb that will fit in your frame that runs HT). The OP has an english threaded shell, which means he can screw either a HT or a GXP BB into it with no issue.

[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 !!

[upsidedownmark]

IMHO it has far more to do with the use than the BB tech. I've destroyed some and had other that last basically forever.

[gazza285]

I've found both Shimano and GXP bottom brackets to be poor, neither are sealed well enough to cope with cyclocross. I've got a conversion shim for the GXP, so I can use it with Shimano BBs, then when the bearings are knackered I replace them with standard sealed bearings 6805 2RS (Do not disassemble. Why not?), and use a Race Face top hat to shim from the 27mm bearing down to 24mm (99p from CRC). The bearings are cheap to replace, and last much longer thanthe Shimano ones.

[vwsurfbum]

gazza285 said:

I've found both Shimano and GXP bottom brackets to be poor, neither are sealed well enough to cope with cyclocross. I've got a conversion shim for the GXP, so I can use it with Shimano BBs, then when the bearings are knackered I replace them with standard sealed bearings 6805 2RS (Do not disassemble. Why not?), and use a Race Face top hat to shim from the 27mm bearing down to 24mm (99p from CRC). The bearings are cheap to replace, and last much longer thanthe Shimano ones.

I agree, done this myself. I have 3 lots of these running in bikes and when my pressfit eventually wears out i will do the same there too.

[upsidedownmark]

I must be very lucky.. at 5 years out of a 15 quid bottom bracket (road), I really can't be arsed to do anything other than screw a new one in.
Absurdly expensive wheel bearings for HED hubs that you can buy online for <10 quid, different matter..