I’m no bearing design expert but I recently ran into some issues with Truvative’s GXP bottom bracket that I thought I should share. 

First of all my setup is an SRAM crankset with a GXP spindle.  What this means is that the crank spindle is tapered from the drive side being 24m OD to the non drive side being 22mm.
Picture 6015
My problem was rapid wearing of the bottom bracket. I started getting creaks then soon there was simply play in the arms that rendered the crankset non operational.  I tried greasing, cleaning, shimming, and tightening the spindle bolt but nothing worked.  The BB was worn beyond repair in less than 1k miles.

I found that one issue with the BB lead to its early demise

The drive side of the BB uses a 23.95 ID bearing that fits snugly to the crank spindles with steel on steel contact.  This works gear and is still fitting tightly.
Picture 6014
The Non drive side, however,  uses the same bearing with a 23.95 ID bearing.  In order to make it fit the spindle they used a 21.98 ID Aluminum Sleeve that fits between the bearing and the spindle.  This works fine at first but the aluminum gets Crushed quite quickly and in turn the system develops play.  Had a been a 21.95 ID bearing on the non drive side the system would last much longer.
Picture 6012
That was some time ago and I recently decided to put the crankset back in use and bought a new Sram bottom bracket.  Problem is SRAM bb’s are made by Truvative!

The first problem, and this is not really Truvative’s fault, I bought it off a cycle store on eBay, The BB came with a missing sleeve/bearing cover on the non drive side!

Now I have to figure out how to make a sleeve and being aluminum it’ll likely wear out quickly again unless I can find some stainless to work with.
Picture 601
The other problem…  the new bottom brackets now use a 25mm ID bearing on the Drive side with a plastic cover/sleeve!  The one bearing that they got right on the earlier version is now wrong too! If an aluminum sleeve was wearing out too fast, why would they replace it with a plastic piece??  AHHHhhhhhhhhhhhhhh
Picture 6018
Just to be fair though, these BBs are the cheaper alternatives.  I cant speak on how the higher end ones are designed.  I’m just curious what the price difference is between a 25mm ID bearing and a 23.98mm ID bearing or a 22.1 ID bearing vs a 21.95 ID bearing.