# How 'free spinning' should a new bottom bracket & cranks be?



## GeeTee (Oct 16, 2011)

I have had a new custom build built for me which comes with a Sram Force Bottom Bracket and cranks and I'm a little surprised by how little they spin backwards when I back pedal.

I've put the bike in my work-stand and when I flick the cranks backwards by hand they struggle to make 1 full rotation.

Comparing them to the Tiagra cranks and BB I have in my training bike, which will do 2-3 turns, they do feel a bit tight/stiff.

Now it may be that they are new and full of manufacturers grease and will take a few runs to properly bed in, but I'm also wondering if over tightening them during fitting might make them a little stiff?

Knowing the bike shop as I do I'd be surprised if it's down to the fitting as the mechanics are known to be really good with a strong attention to detail. But then again, I don't know for sure.

So guys, looking for your advice here. Do you have any thoughts/experience of this?

Thanks in advance!


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## danl1 (Jul 23, 2005)

GeeTee said:


> I have had a new custom build built for me which comes with a Sram Force Bottom Bracket and cranks and I'm a little surprised by how little they spin backwards when I back pedal.
> 
> I've put the bike in my work-stand and when I flick the cranks backwards by hand they struggle to make 1 full rotation.
> 
> ...


The primary driver of this is the drag of the rubber seals on the bearings. They'll wear in a bit in relatively few miles. 

And the amount of power we'll talking about is extraordinarily small. Doesn't matter a bit.


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## Ventruck (Mar 9, 2009)

Assuming brand new and everything properly installed, there will be a bit of drag - or at least it will seam so. As said the seals are still tight. Same case for new wheels. It is true though that some bearings spin freely better off the bat, but nothing to take away from those that don't.


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## -dustin (Jan 11, 2009)

GeeTee said:


> I have had a new custom build built for me which comes with a Sram Force Bottom Bracket and cranks and I'm a little surprised by how little they spin backwards when I back pedal.
> 
> I've put the bike in my work-stand and when I flick the cranks backwards by hand they struggle to make 1 full rotation.
> 
> ...


I don't think you can overtighten SRAM cranks without totally jacking up the crank bolt. If the bearings are indeed overloaded, it's because the BB was installed improperly.


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## Jay Strongbow (May 8, 2010)

I had the same concern when I got a new Ultegra (so this isn't SRAM specific) crank. It loosened up quite a bit from about 1 to threeish revolutions backwards with a moderate pressure spin. I didn't know it at first either, but like others are saying its a non issue.


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## arctic biker (Jul 31, 2008)

as my own experience and expert advice; Gxp spins really more easily than Shimanos Ht.2
How many watts does this mean is something I dont know, I use Sram, with my old legs...


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## cxwrench (Nov 9, 2004)

as long as it feels smooth, it doesn't matter. i'd be pretty worried if a brand new bottom bracket spun for more than a revolution or 3...it would mean there was very little grease in the bearings, and also that the shields were probably crap. i recommend finding something more important to worry about.


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## arctic biker (Jul 31, 2008)

> recommend finding something more important to worry about


thank you, there really is, as my opeartionb








Thank you, there is some more important, as my operation next week, cancer, kääk. but if something is spinning more easily, I gladly use it!


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## trailrunner68 (Apr 23, 2011)

cxwrench said:


> as long as it feels smooth, it doesn't matter. i'd be pretty worried if a brand new bottom bracket spun for more than a revolution or 3...it would mean there was very little grease in the bearings, and also that the shields were probably crap. i recommend finding something more important to worry about.


^^^This. 

Low viscosity grease and crappy seals are the way that manufacturers convince the gullible that ceramic bearings make a difference.


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## cxwrench (Nov 9, 2004)

arctic biker said:


> thank you, there really is, as my opeartionb
> 
> 
> 
> ...


best wishes for a successful surgery!


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