Rotor conversion BB with C'Dale Hollowgram?

[FastforaSlowGuy]

I'm sure this has been asked before, but I can't find it. Has anyone tried to use a Cannondale hollowgram with the Rotor BB (the one that allows use of their BB30 crank on a BSA bike)? I thought I read somewhere the axel length is off, or something.


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[primov8]

Although the spindle on the Hollowgram is 30mm in diameter, its the length that won't work with BSA BB30 bottom brackets. Its a native BB30 crankset, therefore the spindle length is only long enough to fit on BB30/PF30 bb (68mm) shells.

[FastforaSlowGuy]

Although the spindle on the Hollowgram is 30mm in diameter, its the length that won't work with BSA BB30 bottom brackets. Its a native BB30 crankset, therefore the spindle length is only long enough to fit on BB30/PF30 bb (68mm) shells.

Bummer. I've got a threaded BB on my CAAD9 an the new Hollowgram would look awesome on there.

If it's a native BB30 crank, why isn't the spindle diameter 30mm? What is the diameter then?


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[stuckey]

The spindle Diameter is 30mm, the problem is the length of the spindle. The Cannondale BB30 cranks have a 68mm long spindle for pressed in BB30 bearings. The Rotor BB30 conversion is a threaded in bearing cup that adds something like 10mm to the width of the bottom bracket. I am pretty sure Rotor cranks are the only ones that work with the conversion bottom bracket.

[kramnnim]

I am pretty sure Rotor cranks are the only ones that work with the conversion bottom bracket.

BB30 SRAM Quarqs have the long spindle...and Force22? And Zipp.

[primov8]

The spindle Diameter is 30mm, the problem is the length of the spindle. The Cannondale BB30 cranks have a 68mm long spindle for pressed in BB30 bearings. The Rotor BB30 conversion is a threaded in bearing cup that adds something like 10mm to the width of the bottom bracket. I am pretty sure Rotor cranks are the only ones that work with the conversion bottom bracket.

Actually, several "universal" BB30 spindled cranksets would work with a BSA BB30 bottom bracket. i.e. Rotor, THM, Lightning, Force 22 BB30, Sram S9xx, FSA 386EVO, and even the new Campy OT cranksets.

[stuckey]

Wow, I did not know there are so many options for the conversion bottom bracket. The only reason I know anything about it is I use Rotor 3D+ cranks on my threaded bikes.

[FastforaSlowGuy]

Some update on this:

I emailed Cannondale tech support, which had zero guidance either way:
"We have never tried using the BSA30 bb with our SiSL2 cranks. This set up may work but we do not have any information on how you should set up the spacers. We currently do not have a BSA30 in our tech area to try this set up. I would talk to your local Cannondale dealer to see if they have had any expereince with this BB and SiSL2 set up."

I also reached out to a couple of LBS that carry Cannondale, and nobody had any real feedback other than to parrot what Rotor says on their web site. I.e., No sign that anybody had tried this.

I have inquiries out to Ceramic Speed (which makes a BSA30 BB) and Stages (my ultimate goal is to use a Stages SiSL2 crankset on my threaded bike). It's a long shot, but I'm hoping somebody has tried this.

Cannondale sells other spindle lengths, but nothing appears to line up perfectly. Assuming a BB30 needs all 109 mm of the SiSL2 spindle (which isn't clear, given all the crazy spacers they include), then a BSA30 would presumably need a spindle about 127 mm long. The closest I could find is 132 mm. One option would be to use that, and machine it to 127. For now I'm planning to just swap my Shimano crankset back and forth, so I have some time to sort through this. Nothing here is straight-forward, but it seems like a solvable problem.

[gospastic]

Even if you can make this work, the Q factor will be huge. Do you want that?

[FastforaSlowGuy]

Even if you can make this work, the Q factor will be huge. Do you want that?

Avoiding that, and keeping the chainline right, are open questions. I may be chasing a white rabbit here, but if all that stands in the way is a couple mm of spindle length, that seems like a problem capable of being solved (somehow).

[John H.]

Why would you do this?
You are complicating a system that works great (threaded bb).
Hollowgram cranks are light and stiff but they are often noisy and creaky and need constant care.
You can run a threaded bb and any good cranks to match your group- campy, shimano, or sram.
Stick with easy I say-

[gospastic]

Avoiding that, and keeping the chainline right, are open questions. I may be chasing a white rabbit here, but if all that stands in the way is a couple mm of spindle length, that seems like a problem capable of being solved (somehow).

It's not possible to avoid the q factor problem. The arms are shaped to be used with a certain length spindle. Using a longer spindle will push them out. There is no way around that.

[stuckey]

If you are really that set on doing this... Search Weight Weenies someone made a longer spindle when BB30 first came out. I think the Q-factor was something like 173 or a 176mm's.

[FastforaSlowGuy]

The thing is I really hate bb30! I just sold my last bb30 bike and will never get another. But damn that SiSL2 I pretty. I'm weak and petty.


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