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Frame BB genius services needed!
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Frame Nerds,

I want to put a SRAM Red crank into a BBright shell (Cervelo NP2). GXP = correct, BB30 = incorrect, yes??

Thanks,
G
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Re: Frame BB genius services needed! [apache] [ In reply to ]
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You are correct. You can, however install GXP crank by replacing the BBRight BB with a converter BB.

No coasting in running and no crying in baseball
Last edited by: Tri3: Mar 9, 17 10:32
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Re: Frame BB genius services needed! [Tri3] [ In reply to ]
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That's what I thought.

Now I am reading that SRAM FORCE 22 BB30 cranks will fit into a normal BBright bracket. All this stuff gets very confusing with all the standards, not to mention OEM standards clouding the picture even more. I am wanting to replace my Rotor 3D+ crank with a SRAM crank (preferably a carbon Red crank).

My goals: to move to a longer crank arm from 165mm (easy). To not have any increase of Q Factor either through aftermarket BB and/or spider design (not so straight forward). To get a crank with smooth spider to crank arm interface that's easy on the ankles (the Rotor can be brutal when I get the occasional ankle strike).
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Re: Frame BB genius services needed! [apache] [ In reply to ]
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apache wrote:
Frame Nerds,

I want to put a SRAM Red crank into a BBright shell (Cervelo NP2). GXP = correct, BB30 = incorrect, yes??

Thanks,
G[to/quote]

You didn't specify whether the crank is a gxp or a bb30. They come in both types. Either will work in bbright with the correct adapter or BB. For bb30 it's a straight install using pf30 cups, with gxp you need an adapter.
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Re: Frame BB genius services needed! [goodboyr] [ In reply to ]
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Most BB30 axles aren't long enough to work in BBRight.
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Re: Frame BB genius services needed! [jimatbeyond] [ In reply to ]
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Whoops. Apologies. SRAM red BB30 cranks have too short an axle. However SRAM Quarq Red 22 BB30 are long enough as are SRAM Force 22 BB30.
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Re: Frame BB genius services needed! [apache] [ In reply to ]
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Going through a similar issue trying to figure out how to verify an S900 or Force 22 can work with a 10 speed spider that has my Powertap C1 on.

One thing I found so I can verify spacing.

https://sram-cdn-pull-zone-gsdesign.netdna-ssl.com/...t_spec_2017_road.pdf


Go to page 41 and 42.
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Re: Frame BB genius services needed! [shoff14] [ In reply to ]
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shoff14 wrote:
Going through a similar issue trying to figure out how to verify an S900 or Force 22 can work with a 10 speed spider that has my Powertap C1 on.

One thing I found so I can verify spacing.

https://sram-cdn-pull-zone-gsdesign.netdna-ssl.com/...t_spec_2017_road.pdf


Go to page 41 and 42.

Thanks for the info. I am leaning towards the Force 22 crankset. I am trying to minimize the Q Factor distance while maximizing the U factor clearance (another darn term to add to our cycling lexicon). One of the things that I don't understand are the aftermarket conversion BBs that have external bearings and q factor. How are these designs not increasing Q factor distance??

I have a 10 speed system on my Cervelo. Based off some reading that I've done, I am assuming that there should be no issues running a 10 speed chain on a crank designed for a 11 speed chain, right? :-)

Thanks!
G
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Re: Frame BB genius services needed! [apache] [ In reply to ]
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A bottom bracket doesn't affect a crank's Q factor.
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Re: Frame BB genius services needed! [apache] [ In reply to ]
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apache wrote:
shoff14 wrote:
Going through a similar issue trying to figure out how to verify an S900 or Force 22 can work with a 10 speed spider that has my Powertap C1 on.

One thing I found so I can verify spacing.

https://sram-cdn-pull-zone-gsdesign.netdna-ssl.com/...t_spec_2017_road.pdf


Go to page 41 and 42.


Thanks for the info. I am leaning towards the Force 22 crankset. I am trying to minimize the Q Factor distance while maximizing the U factor clearance (another darn term to add to our cycling lexicon). One of the things that I don't understand are the aftermarket conversion BBs that have external bearings and q factor. How are these designs not increasing Q factor distance??

I have a 10 speed system on my Cervelo. Based off some reading that I've done, I am assuming that there should be no issues running a 10 speed chain on a crank designed for a 11 speed chain, right? :-)

Thanks!
G

Somebody at SRAM needs to be kicked in the head for making bottom bracket naming even more confusing. They say BB30 to refer to ANYTHING with a 30mm diameter spindle with no reference to the width of the spindle. The actual width of the crank (We could also call it Q factor here) doesn't change between BB30 or GXP. It doesn't change because the bottom bracket it goes through doesn't make the crank any more narrow or wider. The crank just is what it is as far as width, but there's several ways to attach it to a bike.

Their RED (except the Quarq RED) has a 30mm diameter spindle and a 68mm width. A true BB30 or PF30 (essentially the same thing, but one is bearings sitting in cups inside a frame and the other is bearings sitting directly in the frame) is 68mm wide on a road bike or 73mm wide on a mountain bike. CX/gravel bikes use road specs of 68mm. That means a true BB30 crank would have ~68mm of spindle showing if you had it assembled outside of a bike. GXP and BSA usually mean that you thread some bearings into a frame. The frame itself was 68mm (or 73mm for mountain bikes) and then the bearings you thread in add a little width to each side for a final number in the 86-92mm range. Your Rotor 3D+ crank assembled should show about 86.5mm of spindle. A Shimano crank spindle is also about 85.5mm, but only 24mm in diameter. Same thing with GXP. A true SRAM Red BB30 crank assembled would show ~68mm of spindle. A SRAM Force BB30 crank would show ~86.5mm of spindle when assembled.....because it's not actually a BB30, it's a BB386EVO (also called BB386 for short). Something with an 86.5mm spindle fits the 79mm wide BBRight no problem. A 68mm spindle would never fit. SRAM is really making things a pain by calling both their 68mm wide cranks and 86mm wide cranks BB30 or PF30. Sure, they'll fit a BB30 or PF30 bottom bracket with some spacers added, but so does a BB386EVO crank. BB386 is what BB30/PF30 and PF86/92 should have been

10 speed chain on 11 speed rings is just fine. Most cranks and chainrings don't have any actual different between 10 and 11 speed chainrings.

The bottom bracket has nothing to do with the crank q factor and u factor (never heard that before). It's all about the crank. Then seeing if you can fit that crank to your bike!

In theory, a BB30/PF30 crank should have a more curved crankarm to provide more ankle/heel clearance.
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Re: Frame BB genius services needed! [dangle] [ In reply to ]
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Thanks for your write-up Dangle.

The whole impetus behind my thread is ankle-clearance. My anatomy requires a semi duck-footed stance in terms of cleat placement (I run Speedplays). Rotors 3D+ cranks have almost no curvature/angle in the crank arms. The crank arms also have a very sharp edge (literally) towards the center where they interface with the spindle/spider assemblies. Having your medial ankle bones crash into these crank arms is hell. Running short cranks arms exacerbates this.

Having done research, some cranks formats have even less ankle clearance (U factor) on the non-drive side (left) crank as compared to the right. Consequently, I get far more ankle strikes on my left than right. Having said this, my Mark I eye-ball can't detect a difference with the Rotor crank arms in terms of curvature/angle between right and left crank arms (haven't called Rotor to confirm or deny this).

I could increase my Q factor distance via longer Speedplay spindles, but I don't want to. For me, that just presents other problems. I want to keep my Q factor as narrow as I can and have ankle clearance at the same time.

Unfortunately, Like most things bike parts related, these problems can't be solved like running down to Home Depot & dry fitting a bunch of PVC parts for a plumbing fix.

Hence, asking all the questions trying to build a picture with all of you and your findings/experiences.

Cheers,
G
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Re: Frame BB genius services needed! [apache] [ In reply to ]
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You're welcome. I run Rotor3D30's for CX and have sure marked up the ankle bones then. I really like a wider q factor, so I run cleats all the way inwards and will likely try the 4mm Ultegras as a replacement road pedal for some old 6600's.

Good luck with the search.
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