SRAM Ceramic Blackbox BB...

Discuss light weight issues concerning road bikes & parts.
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addicted
Posts: 1017
Joined: Tue Mar 20, 2007 5:56 pm

by addicted

So I just got one of these, new, and installed on my bike.
Now, I know that spinning the cranks in the workstand doesn't mean a whole lot.
But I found it odd that when spinning the cranks on my newly installed SRAM GXP ceramic BB, they have more resistance than a typical shimano BB.
In fact, the non-ceramic SRAM truvativ BB cups I've used in the past spin with a lot less resistance than this ceramic version.

Do they purposely use tighter seals on the ceramic version??

Mr.Gib
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Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

That's not what you want to find out when you go for the high end BB. Assuming proper installation, hopefully it will free up with some use.

I do want to put in a good word for the SRAM press fit BB that I have just installed. It is absolutely free spinning from the first turn of the pedals. Much superior the the Shimano press fit it replaced. When I first tested the bike it felt super smooth in my feet and I assumed it was the new cranks or just in my head. However on the workstand later without the chain, I could confirm that indeed this was an excellent part.
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.

by Weenie


timzcat
Posts: 315
Joined: Thu Sep 30, 2010 5:50 am

by timzcat

My experieince with SRAM PF30 is that on initial installation it was not that free spinning but after 50 miles or so it spins nicely with chain off.

I would say give it some miles and it will probably spin well.

spandexboy817
Posts: 192
Joined: Fri Apr 18, 2008 12:55 am

by spandexboy817

Bearings have a break in period. Some wheels take a couple hundred miles to get spinning smoothly and the same can be said for bb bearings. Give it a couple of weeks and it should be good!

inertianinja
Posts: 102
Joined: Wed Jan 26, 2011 3:14 pm

by inertianinja

I think in SRAM's tech videos on youtube they tell you to expect a break-in period.

thisisatest
Shop Owner
Posts: 1980
Joined: Sat Jun 13, 2009 4:02 am
Location: NoVA/DC

by thisisatest

hopefully you got the new version with the GutterSeals n such. their seals have much less drag than their old ones.

addicted
Posts: 1017
Joined: Tue Mar 20, 2007 5:56 pm

by addicted

How would I tell if it had the new seals on it? I still have the original box it came in, would there be something specific marked on it?
Thx

thisisatest
Shop Owner
Posts: 1980
Joined: Sat Jun 13, 2009 4:02 am
Location: NoVA/DC

by thisisatest

the new ceramic bottom brackets have red cups.
gxp ceramic 2011.jpg


the old ones had polished silver cups that are a bit more square-edged
gxp ceramic 2009.jpg

addicted
Posts: 1017
Joined: Tue Mar 20, 2007 5:56 pm

by addicted

I gots the old... :(

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StuTheWeak
Posts: 767
Joined: Sat Apr 09, 2011 11:29 pm
Location: Springdale, AR

by StuTheWeak

I gots the new... :D
Specialized Allez 06' "Rain Bike" 21.50lbs
Neuvation F100 11' "Road Bike" 16.80lbs
Specialized Tarmac Pro 11' "WW Bike" 14.25lbs

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StuTheWeak
Posts: 767
Joined: Sat Apr 09, 2011 11:29 pm
Location: Springdale, AR

by StuTheWeak

addicted wrote:So I just got one of these, new, and installed on my bike.
Now, I know that spinning the cranks in the workstand doesn't mean a whole lot.
But I found it odd that when spinning the cranks on my newly installed SRAM GXP ceramic BB, they have more resistance than a typical shimano BB.
In fact, the non-ceramic SRAM truvativ BB cups I've used in the past spin with a lot less resistance than this ceramic version.

Do they purposely use tighter seals on the ceramic version??


I believe it's the seals on the SRAM GXP BBs. They are tighter to begin with, but break in quickly. Just give it a week or two...then recheck it.
Specialized Allez 06' "Rain Bike" 21.50lbs
Neuvation F100 11' "Road Bike" 16.80lbs
Specialized Tarmac Pro 11' "WW Bike" 14.25lbs

kentbrockman
Posts: 36
Joined: Fri Feb 08, 2008 11:37 pm
Contact:

by kentbrockman

Never been a fan of ceramic bearings. I've had several fail within 1000 miles where standard steel balls (sounds painful) are still going strong.

by Weenie


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