Weight Weenies

If the crank actually fits BBright it'll put the pedals in the right place. The NDS is no wider than external bearing cups on a BSA BB or BB92/86.
Many cranks have spindles long enough for BBright. It's just the short spindle BB30 ones that don't fit.

With all the lightweight cranks available at present I just don't get the continued fascination with mating a Hollowgram to a BSA BB

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just pulled the trigger on a cervelo edition 3d+ crankset incl. q-rings. better looking than regular graphics IMO.

will pair them w rotors ceramic BSA bearings.

Not what I was gunning for but its getting me exited all the same - i love new gear! cant wait.

bricky21 wrote:I just don't get the continued fascination with mating a Hollowgram to a BSA BB

Yeah, that it a valid point but that argument is not quite as valid when you are talking about mating a 'hollowgram SRM' on a time trial bike with a BSA 24 bottom bracket shell and have even considered having the alloy insert in the carbon bottom bracket shell machined to accept PF30 bottom bracket.

Clavicula M3 SRM is cheaper and would be really close in weight possibly even lighter after modifications to the Hollowgram. It fits on everything too. Has anyone actually machined out a BSA frame to take a PF30? That would be an interesting read. I suppose I get it if you already own the crank.

To answer the SiSL2/bbright question: according to my measurements, using the 109mm spindle but accepting the too-narrow chainline that the 104mm spindle gave, you are still about 2mm short. The left arm will contact the lip of the pf30 cup. I wanted to try it on an r5ca (which is bbright but with direct bearings, so no extra lip), but my friend that owns one wouldn't let me mess with it...

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thisisatest wrote:using the 109mm spindle... you are still about 2mm short. The left arm will contact the lip of the pf30 cup.

Again, all cojecture but sounds like a Cannondale Hollowgram 122mm Mountain Spindle with the ridge machined off would solve that problem.

Would the Q be the same on both sides? And what would the total Q be?

All I know is member "Rogntudju" did just that cannondale sisl2 on a Open O 1.0 bbright frame. See pictures here.viewtopic.php?f=10&t=103751

Jrock,
mountain bikes are a completely different story. the SiSl2 mountain crank uses a 132mm spindle, there is plenty of axle to fit it to whatever you want, once the lip is machined off...

From the other thread

He used a 122 spindle 104/109 + 11 = 121

The real issue is that the spindle has raised bearing races that are not in line with the PF bearings.

He had to have the old raised bearing races machined down and new ones built up

C

So I can't let this drop... and I need some help/reassurance

The math on BBright and hollowgram was that the 104 spindle was 11mm short on the non drive side...

So the new spindle is 109 and the bearing races on the spindle are bigger and at the ends of the spindle

So now we are 6mm short and it can come from either side....

Dropping the shields gets you 4mm so we are looking for 2mm more

You have to leave the 2.5mm SL2 to keep the chainline perfect, however wave washer and "up to" 1.5mm of spacers on the non drive side implies that that there might be 2mm of "wiggle" room/tolerances.

What if you don't install the bearing shields and and the BB30A spacer? anybody know how wide the BB30A spacer is? Is my math right? Are the tolerances really this tight?

http://media.cannondale.com/media/uploa ... r_1012.pdf

Thanks
C

has somebody achieved it?

Q. What is the difference between BBright™ and BB30™?
A. For the crank, BBright™ uses the same diameter axle as BB30™, with the addition of 11mm length on the left side of the spindle, and the left crank is straighter, (similar to existing arms for external bearing cranks).

Just putting a BB30 crank on a longer spindle will put the NDS pedal 11mm to the left, and increase the Q factor as well as making it asymmetric.

It requires a different, actually more conventional, shaped NDS crank.

http://bbright.net/faq.aspx

pritchet74 wrote:

It's been done, but it required a custom fabricated bottom bracket that you can't get anymore. I had 2 and sold both. I really wish that I had kept both of them....

What's the history of that custom bottom bracket? Who made it and sold it? Curious why they don't keep selling it after investing time and cost into the custom bb. Why not keep selling it to keep recouping some of the costs?

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