Sram red crankset GXP vs BB30

Back by popular demand, the general all-things Road forum!

Moderator: robbosmans

Kumppa
Posts: 488
Joined: Mon Oct 13, 2014 10:05 am

by Kumppa

Couple month ago Quarq told me this when I asked weight difference on dzrero:

Thank you for contacting me. There is roughly a 25g difference from our GXP to our BB30 cranks. The GXP is lighter for our cranks.

alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

There is a pretty big difference between 68mm and 86mm spindles.

I'd be careful assuming a bb30 branded crank with a longer spindle to fit all the way through. It's a gamble. Better measure yourself to be sure.

Turning to the manufacturer might prove useless too. They might want to rebrand that crank as bb386 at a higher price, and keep the compatibility info a secret. :lol:

/a

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



jlok
Posts: 2400
Joined: Tue Jun 30, 2015 3:30 am

by jlok

you are probably right but Quarq has the manual for bb386 installation.

https://quarq.zendesk.com/hc/en-us/arti ... _site=true
Rikulau V9 DB Custom < BMC TM02 < Litespeed T1sl Disc < Giant Propel Advanced SL Disc 1 < Propel Adv < TCR Adv SL Disc < KTM Revelator Sky < CAAD 12 Disc < Domane S Disc < Alize < CAAD 10

JScycle
Posts: 260
Joined: Wed Mar 08, 2017 11:41 pm

by JScycle

Thanks everyone for your advice so far. If GXP has better bearing durability im leaning towards that.

The bike is a 2016 Scott Addict running Shimano Ultegra

hambini
Posts: 580
Joined: Tue Nov 15, 2016 8:13 am
Location: Cologne, Germany

by hambini

Here's my opinion

GXP is not the best, having a single loaded bearing on the non drive side for axial direction both ways doesn't lead to great bearing life.

BB30 in it's shorter axle length has very compact bearing spacing so the loads on it are high.

Best solution in my opinion is a BB30 with an extended length axle, some people call these BB386 but in reality they are units with a 92mm length.

Hope that helps

Hambini
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...

User avatar
IrrelevantD
Posts: 857
Joined: Sun Nov 29, 2015 5:47 pm
Location: Near DFW Airport

by IrrelevantD

JScycle wrote:
Wed May 09, 2018 9:48 am
Thanks everyone for your advice so far. If GXP has better bearing durability im leaning towards that.

The bike is a 2016 Scott Addict running Shimano Ultegra
From what it looks like online, the 2016 Addict is going to have PF86. Others have mentioned that the BB30 listed are actually BB386, which should work, but personally I'd go GXP.
* There is a 70% chance that what you have just read has a peppering of cynicism or sarcasm and generally should not be taken seriously.
I'll leave it up to you to figure out the other 30%. If you are in any way offended, that's on you.

User avatar
Rick
Posts: 2034
Joined: Sat Aug 29, 2009 4:30 pm

by Rick

hambini wrote:
Wed May 09, 2018 11:27 am
Best solution in my opinion is a BB30 with an extended length axle
How does the extended axle length make things better ?

User avatar
Calnago
In Memoriam
Posts: 8612
Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

Extended axle in a BB30 would simply add more leverage on narrower stance bearings, creating more/faster wear and greater potential for creaking. Not ideal. Better to match the axle load from the cranks as close to the bearings as possible.
Actually, maybe that’s what Hambini was implying in his post when mentioning 386, but I can see how it could be interpreted as putting a longer 30mm spindle into a 68mm shell (hence the narrow bearing stance, long axle scenario), which would not be so great.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

hambini
Posts: 580
Joined: Tue Nov 15, 2016 8:13 am
Location: Cologne, Germany

by hambini

Calnago wrote:
Thu May 10, 2018 5:03 pm
Extended axle in a BB30 would simply add more leverage on narrower stance bearings, creating more/faster wear and greater potential for creaking. Not ideal. Better to match the axle load from the cranks as close to the bearings as possible.
Actually, maybe that’s what Hambini was implying in his post when mentioning 386, but I can see how it could be interpreted as putting a longer 30mm spindle into a 68mm shell (hence the narrow bearing stance, long axle scenario), which would not be so great.
Assuming your pedal position is the same, the overall torque or leverage generated by having an extended axle or a narrow axle with more splay on the crank arms is the same.

What I was trying to say is having the bearings further apart which is more feasible on a "long" 92mm axle using 30mm bearings allows the bearing load to be reduced because the length of the cantilever is reduced.

Hambini
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...

Post Reply