Specialized carbon crank on BBright?

Discuss light weight issues concerning road bikes & parts.
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dalex
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by dalex

Putting a Specialized Fact carbon crank on a BBright frame - is this possible? My guess is not, but I have searched and not found a verification. Perhaps it could be done with a Lightning BBright bottom bracket? FWIW I'm looking at different SRM possibilities for a BBright frame.

thisisatest
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by thisisatest

You cannot. The SWorks crank spindle is only 68mm long, and symmetric. The bbright frame is 79mm wide and asymmetric.

spud
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by spud

as above - spindle is part of the crank arm, so there is no reasonable way to utilize a longer spindle to bridge the difference. Crank arms are also dished, which if mated to an appropriate length spindle, would result in a Q factor of 165mm+

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prendrefeu
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by prendrefeu

Would a 10mm hirth extension work in this case?

It would essentially move the nds crank arm out. I understand the difference is 11mm, not 10mm, however 10mm extensions are available via experimental's shop.

Anyone else have success in applying an Sworks crank (BB30) into a BBright shell?
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hambini
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by hambini

prendrefeu wrote:Would a 10mm hirth extension work in this case?

It would essentially move the nds crank arm out. I understand the difference is 11mm, not 10mm, however 10mm extensions are available via experimental's shop.

Anyone else have success in applying an Sworks crank (BB30) into a BBright shell?



The sworks cranks taper inwards so you can't put the extension on.

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prendrefeu
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by prendrefeu

Taper? Yes. Looks fine with an extension here though, and extensions are being used successfully out in the field.

http://images.ttcdn.co/media/i/product/ ... g?size=500
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JimboP
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by JimboP

prendrefeu wrote:Taper? Yes. Looks fine with an extension here though, and extensions are being used successfully out in the field.

http://images.ttcdn.co/media/i/product/ ... g?size=500


Any luck with this and any idea where i could source the extension? I have an s-works srm which i'd love to be able to use on my cervelo.

topflightpro
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by topflightpro

Prendrefeu, do you know how the hirth extension affects the chain line?

I remember a few years ago, someone machined a Cannondale spindle to fit Hollowgrams on a non-BB30 frame, and while it worked, the chainline was pretty screwy.

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prendrefeu
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by prendrefeu

JimboP wrote:
prendrefeu wrote:Taper? Yes. Looks fine with an extension here though, and extensions are being used successfully out in the field.

http://images.ttcdn.co/media/i/product/ ... g?size=500


Any luck with this and any idea where i could source the extension? I have an s-works srm which i'd love to be able to use on my cervelo.


I've contacted Mattias Hellöre (he's the guy behind Experimental Prototype, which is also "Experimental" as a Tictail shop). No response.
The tictail shop for Experimental always seems to be in development... and I know how that goes, so I don't have any blame there, just empathy despite my need for an 11mm hirth extension.

I'll have to design one myself. If other people are interested I may then have to place a multi-order from a manufacturer... whomever that may be.

topflightpro wrote:Prendrefeu, do you know how the hirth extension affects the chain line?

I remember a few years ago, someone machined a Cannondale spindle to fit Hollowgrams on a non-BB30 frame, and while it worked, the chainline was pretty screwy.


It shouldn't on BBright since the extension would basically push the NDS arm out. BBright has the width different on the NDS anyway, it's asymmetrical on the frame (hence BB"RIGHT")

Anyway, waiting for crank arms to arrive, need to tune those first, then make the extension.
any BBRight+BB30 bottom bracket would work. It looks like the Wheels MFG is the lightest in the 'threaded connection' version, but a person could also run a usual press-fit BBRIGHT/BB30 into the shell, subtract the spacer, and be around 50g.
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prendrefeu
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by prendrefeu

I should also add that an extension means a longer bolt, but it's just an M12 x 1.0 bolt, which is relatively common. Buy one that is long enough and cut it down to size. For true tuning a person can also remove the unnecessary threads on the bolt since only the end portion of the thread is used, the majority would not be used at all.
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Alpine318is
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by Alpine318is

Wouldn’t that mean that the width between the pedals of you are looking down at the bike are 11mm wider than standard?
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prendrefeu
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by prendrefeu

So your new q-factor would be 158mm.
Typical mountain bike cranks have a q-factor of 165mm.
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