Truvativ/SRAM GXP bottom bracket question

[TK421]

Fitting a Truvativ/SRAM GXP crankset on my project. I bought a generic bottom bracket with external bearings from the dreaded Ebay. It came with 3 x 2.5mm spacers. Me being me, watched a couple of videos on YouTube and looked on Google for more information as the videos said that I didn't need the spacers. Problem was that I had a lot of lateral movement without any spacers, so I have fitted 1 spacer on the non drive side between the frame and the bearing. Is this correct?
Before with a lot of play

And after with no play

 

[faster]

Something doesn't sound right.

In a GXP crankset, the number of spacers shouldn't have any impact whatsoever on the amount of lateral movement. Unlike Hollowtech 2, in GXP the lateral movement should be restricted by the non drive side bearing being clamped between the left crank and the shoulder on the spindle.

Is it definitely a GXP bottom bracket? In a GXP bottom bracket, the non drive side bearing should have a smaller diameter inner race than the drive side.

 

[TK421]

It is definitely a GXP bottom bracket. It has a 22mm reducer for the NDS. As I said earlier the Internet is as clear as mud about correct installation. It will teach me to buy cheap with no instructions.
As I said, the videos said to use no spacers, some forums said a spacer between the bearing and the chainset, some said all 3 spacers with 2 on the NDS and some said just 1 spacer each side.
Given that the tension is supposed to be on the NDS and that without the spacer the 24>22mm reducer didn't seem to fit properly I decided that 1 spacer on the NDS should solve the problem.
Must admit that I am kicking myself and already planning to get something shimano.

 

[faster]

What do you mean by a reducer? A genuine GXP doesn't have a reducer as far as I can remember - the left hand bearing just has a smaller inner race.

If the reducer is what I am imagining (ie, a sort of top hat shaped thing), the way round this installed will be important. The 'brim' of the hat would need to be towards the drive side. If it is just a reducer with no 'brim' or shoulder (ie just a cylinder of metal), it's unlikely it'll ever work properly - certainly not in the way intended by the designers.

You should have no play whether or not there are any spacers. No spacers should be required imo. If you really need to fill in a gap, you need to be sure the clamping force of the bolt on the non drive side is all going in to clamping around the left hand bearing and not across the whole BB.

 

[TK421]

A genuine GXP doesn't have a reducer as far as I can remember - the left hand bearing just has a smaller inner race

As I said, I bought generic not genuine

If the reducer is what I am imagining (ie, a sort of top hat shaped thing), the way round this installed will be important. The 'brim' of the hat would need to be towards the drive side

The reducer insert has a small lip to stop it sliding through the bearing and I Installed the same way round as it came fitted to NDS bearing with the retaining lip external between the pedal and the bearing. It seemed a better idea to fit it with it with the reducer trapped inside the bearing rather than outside but that wasn't how it came in the box. Ii shall swap it round for my own peace of mind.

 

[faster]

As I said, I bought generic not genuine

I know what you said - just highlighting the difference between GXP as designed and what you have.

Ii shall swap it round for my own peace of mind.

This should fix your problem. It won't work the other way round.