SRAM chainsets BB30 vs GXP

graeme_s-2

I have a SRAM Rival 22 double chainset on my bike with a GXP bottom bracket. I would quite like to change it to 1x, and had been intending to buy a 3rd party narrow wide chainring and keep my existing cranks, spindle and spider.

However, I've seen a second hand SRAM Rival 1x complete chainset at a decent price, so I'm tempted to get that instead. The chainset's come off a BB30 bike, but the seller seems to think the chainset and spindle are the same, and for BB30 it just has an adaptor fitted, which I'll be able to remove and then fit with my GXP bottom bracket. Does that sound right?

Wheelspinner

Nope. GXP is a 24/22mm spindle. BB30 is a 30 mm spindle.

GXP is the SRAM BB standard that fits into a typical BSA shell (English thread). You *can* fit BB30 cranks in a BSA/GXP frame with a special BB, although opinions vary on the longevity of them as it leaves the bearings fairly small. Your existing GXP bottom bracket will not work at all - you need a new one altogether to fit the BB30 cranks.

graeme_s-2

See this weird, as the seller says the spindle IS 24/22mm.

When I've googled I've seen it's possible to buy adapters to fit a GXP spindle into a BB30 bottom bracket, so had wondered if that's what was going on with this chainset. What confused me is wouldn't you expect the spindle to be shorter for BB30, as the bearings are internal, vs external on GXP BB.

Wheelspinner

Not sure what the comparative spindle lengths are. BB30 shell itself is just wider than the standard BSA. A typical old road bike standard was 68mm wide shell, plus the external bearings (or square taper axle protruding). The BB30 and or other press fit ones are 83 mm or 86 or 92 or.... all sorts of "standards"

timothyw

It's entirely plausible that they are GXP cranks with a bb30 adapter, but by no means certain.

Have you seen pictures of the cranks? Seems like it should be reasonably obvious when you look at them, 30mm axles are noticeably thicker (and if there are adapters fitted they should be obvious too).

whyamihere

A very easy way to tell: Sram BB30 cranks have the axle attached to the non driveside arm, GXP had the axle connected to the driveside arm.

joe_totale-2

Also it's often just written on the crank whether it's GXP or a 30mm one!

graeme_s-2

I have photo's now confirming the spindle is fixed to the drive side.

Part of the problem is I've never fitted a bottom bracket or a crankset myself before, so I'm just not used to looking at this stuff! I'm sure it is reasonably obvious from the photographs, it's just not reasonably obvious to me.