sram gxp bb question

Discuss light weight issues concerning road bikes & parts.
cymans
Posts: 95
Joined: Sat May 28, 2011 10:17 pm

by cymans

hi, what other options is there regarding bottom brackets for the sram red gxp 2013 cranks.
are the red b/b the same width as the force b/b ?
any other recommendations.
thank you.
cyman

by Weenie


eric
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by eric

The GXP Team BB will fit Red or any GXP cranks. It's about $35, with steel bearings instead of ceramic of the Red BB. I have one on my race bike. The bearings are very smooth, even after a couple years use.

Mr.Gib
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by Mr.Gib

I second the approval of the less expensive "Force" level BB from Sram. When they first debuted they had a problem with seal drag but for the last few years they have been excellent. I recently installed one on my wife's winter bike and I was very impressed with how free spinning it was. I don't think you'll find anything better for the price. If you want to spend extra the Ceramic "Red" version is nice of course.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

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Tinea Pedis
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by Tinea Pedis

I run a Chris King BB with my SRAM GXP cranks.

Big :thumbup:

eric
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by eric

I looked at the King BB, but from what I can tell its design eliminates a big advantage of the GXP design. With GXP, the NDS side of the spindle is stepped down to 22mm and the bearing ID is sleeved to suit. The NDS bearing locates the crank side to side and it is free to float in the DS bearing. The standard deep groove bearings used are sufficient to handle the small side forces involved.

With this design there is no way that the bearings can be over preloaded, and there is no need to adjust preload. That's pretty cool, especially if you have ever roached a bearing because the preload adjustment tightened up.

But from the instructions, the King BB seems to do away with the NDS bearing locating the crank. You have to shim it correctly to get the preload right. That's going backwards in my opinion.

cymans
Posts: 95
Joined: Sat May 28, 2011 10:17 pm

by cymans

thanks for all your comments.
I agree with your thoughts eric..
cyman

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Tinea Pedis
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by Tinea Pedis

I'm no mechanic eric, it takes one NDS shim and you're sorted with an amazingly smooth BB.

Seems a 'no brainer' to me...

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HakeemT
Posts: 181
Joined: Thu Mar 18, 2004 7:39 pm

by HakeemT

I currently run the RED ceramic GXP BB, but haven't noticed any improvements over the Force level BB that I used before (other than the 10 odd grams it saves). The other thing to note is that the manual says you should regrease the ceramic BB every couple hundred km's, and after every ride in the rain! Not that I know of anyone who does this, but if you're sensitive to that kind of stuff stay clear from the RED one.

genesis692
Posts: 60
Joined: Sat Dec 18, 2010 11:54 am
Location: Brisbane, AU

by genesis692

I'm running the Red ceramic GXP BB and had to put a wave washer in there to get enough preload anyway.

It's nice. Like Hakeem I haven't regreased it either....still running very smooth.

Teletori
Posts: 34
Joined: Thu May 27, 2010 2:36 pm

by Teletori

If you need a wave washer to get enough preload on a GXP crankset, something seems wrong...

Was it a new crankset? If so, that needs quite a bit more force than you would imagine to fasten properly the first time.

Rob1519
Posts: 55
Joined: Thu Mar 17, 2011 7:29 pm

by Rob1519

I installed a VCRC ceramic BB this season. So far, it performs well. VCRC offers an ultrasonic cleaning and rebuild service for $22.00. At the end of the year I will send mine in and presumably receive an essentially new BB back.

eric
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by eric

You shoudn't need a wave washer on a GXP BB. The NDS bearing's inner race (or rather the insert inside the inner race) should be captured tight between the shoulder of the crank spindle and the NDS crank arm. I always torque them to spec (about 50nm) and then check again after a few rides.

I recently bought a VCRC ceramic BB too but have yet to install it. I know bike-quality ceramic bearings aren't better than steel, etc etc but I'm a sucker for fancy parts and the people at VCRC are nice. Maybe the .2 watts I will save will be the difference between 25th and 24th place!

genesis692
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Location: Brisbane, AU

by genesis692

Yeah the wave washer is just a temp fix as I couldn't torque the new cranks enough to get adequate preload. The washer will come out soon now that the cranks have a few kms on them.

The point I was trying to make is that the washer hasn't really affected the performance of my BB detrimentally.

cymans
Posts: 95
Joined: Sat May 28, 2011 10:17 pm

by cymans

thankyou for all your suggestions.
cymans

by Weenie


PoorCyclist
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by PoorCyclist

eric wrote:You shoudn't need a wave washer on a GXP BB. The NDS bearing's inner race (or rather the insert inside the inner race) should be captured tight between the shoulder of the crank spindle and the NDS crank arm. I always torque them to spec (about 50nm) and then check again after a few rides.

I recently bought a VCRC ceramic BB too but have yet to install it. I know bike-quality ceramic bearings aren't better than steel, etc etc but I'm a sucker for fancy parts and the people at VCRC are nice. Maybe the .2 watts I will save will be the difference between 25th and 24th place!


Hi.. how is your experience with the VCRC GXP BB? Any creaking sounds? and is this BB correctly sized for the different NDS side and better than Chris King design you mentioned above?
I am also considering using phil wood + SRAM NDS adapter but I don't really like adapters..

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