SRAM GXP Bottom Bracket question

[rphetteplace]

I just installed a SRAM Rival crankset with the GXP bottom bracket on my bike. The directions say that there will be some initial stiffness as the seals break in. How stiff is stiff? When I spin my cranks backwards they spin maybe 1/2 revolution. Kinda scary to me. any mechanic studs able to help?

[keithreynolds]

I talked to a SRAM mechanic in the know and voiced my concerns about the inherent drag. He mentioned trimming the seals a very small amount around the outer portion with an exacto knife. It will open the bearings to some possible crud, but it does reduce the drag to what the ceramic 'display' models feel like. My guess is those [ceramic] displays don't have any seals at all.

[David Kirk]

I'm sure you took care of this but on the of chance that you didn't - is the BB properly faced?

Dave

[tv_vt]

Facing could be an issue, but I'm not sure if it's all of it. I had the same issue last year with a gxp bb. No, I did not have the bb shell faced, so that definitely could be part of the problem, but the darn cranks just did not spin much. Less than a full revolution, more like 1/2 to 3/4. Sobering. I had three long rides (80-100 miles) where I really bonked on that bike last year. Big time bonks. And I wonder if the bb friction had something to do with it.

I'm back to an Octalink bb and crank on that bike - we'll see how this year goes. It's too bad the gxp bb seems so tight, cuz I've got a 177.5 compact crank that only works with that bb, and I'd much rather be using that length than the 175s I've got on now.

Thom

[David Kirk]

I've installed a few of those BB's and never had this issue. I wonder if they made a change in the bearing seals.

dave

[jtferraro]

It appears to be a known problem:

"The bottom bracket is really the only letdown here as the GXP design continues to run with more friction than we would prefer. Thankfully, smoother-running aftermarket upgrades are readily available.

Not surprisingly, the new Rival also makes do with the same GXP bottom bracket as before, along with the same could-be-better levels of seal friction.

Cons: GXP bottom bracket still has more seal drag than we'd like"

sniped from:
http://www.cyclingnews.com/tech.php?id=tech/2009/reviews/SRAM_rival09

I have an '08 Rival OCT crank but can't say I've noticed the drag. Then again, I've only used that bike for racing cross. Going to take a closer look at mine now and consider replacing the BB w/the Red one for next year.

[runtimmyc]

The had the exact same problem when I installed the GXP cups on a Leader time trial team. At first, I thought it was a BB facing issue because they are pretty cheap frames.

I ended up taking the cups off of the bike and putting them back on. That fixed the problem. I don't know exactly why this worked, but the cranks spun freely after I installed them a second time.