So I’m in the process of fitting a SRAM NX chainset to my new whyte hardtail.

I’ve installed a new SRAM gxp bottom bracket as per the instructions so no spacers on the cups as the frame is 73mm.

The non drive side arm sits flush against the bottom bracket but on the drivetrain side there is big gap and I can’t get the chainset to sit flush on that side ………

Non drive ……

Drive side……..

Is this correct then ?

There seems to be an equal gap between the arms and the chainstays ?

Cheers.

Steve.

Ha, following on from this thread of mine a few days ago

http://singletrackworld.com/forum/topic/sram-gxp-crank-and-bb-install-issuespic-heavy

I had exactly the opposite problem of the face of the BB grinding right up against the chainrings, using a Non SRAM BB with a shim.

My recently gained understanding is that this gap is correct and should be taken up with spacers and wave washer. Have a look at that thread and some of the links and pictures.

Currently awaiting a sram bb of my own to alleviate the situation. 🙄

Hmmm ok.

Ive never had SRAM cranks before as have only used Shimano so don’t know keep if it’s right or not ?

I had a look at the thread linked to above and it mentions spindle spacers etc but I got none of that with the new bb

Our bottom bracket came with two spacers and a wavy washer. Have you got any play in the cranks or do they feel tight.

No spacers or wave washer required. The gap is fine and normal on those.
Torque it up and make sure no play, then good to go.

Something about a floating driveside bearing with a stepped axle or summink or uvver

What theocb said however a 24mm o ring or two on that side does help bearing life.

Ok cheers for that.

There is no play at all.

Like the idea of an oring.

Google
gxp gap

Normal. The loading is on the non driver side.

I asked the same question first time I came across this and was worried about the gap until I found out why.

As said, shove o-rings in there which will hold the dust cap in place (though newer versions seem to stay in place better these days).

Just noticed that your dust cap might be off – hence why you can see grease on the inside of the crank arm. Be sure to check that before you ride.

@benpinnick…. Im sure the dust cap is on, thats a layer of grease I put on for the interface between chainset of bb face, didn’t realise they wouldn’t touch though !!

Ahh.. Makes sense.

My understanding is that there is a step down in main axle diameter that sits on the inside of the inner race of the non-driveside bearing.

The non-driveside crank then tightens up against the outer side of the inner race of the same bearing, or very close to it once the crank/axle splines reach their limit.

So although people talk about it being a ‘floating’ axle, I think in practise it doesn’t move side to side if all fitted correctly, but there’s nothing holding it in position on the drive-side.

Yep, should be a driveside gap which you shouldn’t try to take up by packing with spacers or you wreck bearing life. The wave washer is very much a thing and isn’t always present. If you don’t have one it’s worth getting. Do make sure the dustshields are on properly.

It does look like this one might be a bit excessive though – can’t quite make out with the grease.

It’s typical SRAM I think, they always seem to find ways things need to be installed that are different than Shimano and that’s where a lot of the problems come from.

Regards nothing holding driveside in place – it’s just that the whole approach to preloading and retaining is totally different to Shimano. Properly torqued, it’s not going anywhere… 😀

I’ve got a SRAM ceramic Gxp bb and NDS bearings are not running smoothly after 1y. DS are fine. I’ll need to check my set up but pretty sure it is as the manual says. Is it doomed now?

Normal. sram used to supply a wavy washer that retained the seal and filled the gap, but they changed the seal to retain itself.

As above you can just stick an o ring there, helps stop crud migrating along the axle.

As a sanity check you could just measure your chainline and check its to spec.

If you don’t like the gap you can space the DS cup (few 1mm spacers).It won’t effect the chainline at all.Ultimately makes no odds but may calm your OCD a bit. Just don’t go overboard.

How do I measure chainline ?

There is an equal space between each crank arm when level with its respective chainstay.

It’s only Americans who get overly obsessive about chainline 😉
That’ll do.

http://www.sheldonbrown.com/chainline.html

assuming your seat tube is central

vernier caliper from left side of seat tube to middle of chainring

subtract half the diameter of the seat tube

should be 47.5-49mm