Hollowgram crank in a BSA30 BB? How to?

[Lewis Moon]

I have a power meter spider on a set of Hollowgram cranks. I'd like to swap that into my road bike, which has a BSA bottom bracket. I know it can be done but I want to do it correctly without a bunch of futzing around. Any suggestions?

[Mark McM]

Unfortunately, it can't be done. A HollowGram crank has a 30mm spindle, and are intended to be used on BB30/PF30 bottom brackets, which use bearings internal to a 68mm wide BB shell. A BSA bottom bracket uses a 1.37" (= 35mm) shell, which leaves no room for bearings between the spindle and the shell.

Some cranks with longer 30mm spindles can be used with BSA shells by using bottom bracket with external bears (bearings sit between crankarms and BB shell), but HolloGram cranks don't have spindles long enough to fit bearings between the crankarms and the BB shell.

[yinzerniner]

Originally Posted by Mark McM

Unfortunately, it can't be done. A HollowGram crank has a 30mm spindle, and are intended to be used on BB30/PF30 bottom brackets, which use bearings internal to a 68mm wide BB shell. A BSA bottom bracket uses a 1.37" (= 35mm) shell, which leaves no room for bearings between the spindle and the shell.

Some cranks with longer 30mm spindles can be used with BSA shells by using bottom bracket with external bears (bearings sit between crankarms and BB shell), but HolloGram cranks don't have spindles long enough to fit bearings between the crankarms and the BB shell.

Pretty sure you can order the longer spindles that would fit the wider BSA30 config but the issue then becomes your q factor will be widened by 16mm or so. Also the chainline will be moved out roughly 9mm. If that’s ok then you can find them here:
https://cannondaleexperts.com/produc...uperx-ai-kp451

The next issue is removing the spindle since it’s installed via double blind bolt. If you have the cannondale tool or can visit the lbs that’s great, but otherwise it’s a hassle.

[Wunder]

As others said don’t think this can be done, at least not well. I had a Hollowgram with power meter and sold it when I got a new bike as it wouldn’t play well. Great cranks, but paired best with a true BB30/PF30 frame.

[Lewis Moon]

I've also come to the conclusion that it can be done, but not well. Thanks all

[zzy]

I don't understand this thread at all. It absolutely can be done well.

First of all, what is a "BSA30" BB? You mean BSA english threaded BB? There are plenty of BSA 30mm spindle external cup BBs you can run.

A Hollowgram is a 3 piece crank. 103 (BB30) or 109mm (PF30 typically) spindle for road. If you have a 109 you're probably fine. A few spacers will be needed too. Regardless you can swap the spindle to the desired length - a nice bonus for Hollowgrams vs. conventional 2 piece cranks. And yes you will need the CDale tool.

[NHAero]

Originally Posted by zzy

I don't understand this thread at all. It absolutely can be done well.

First of all, what is a "BSA30" BB? You mean BSA english threaded BB? There are plenty of BSA 30mm spindle external cup BBs you can run.

A Hollowgram is a 3 piece crank. 103 (BB30) or 109mm (PF30 typically) spindle for road. If you have a 109 you're probably fine. A few spacers will be needed too. Regardless you can swap the spindle to the desired length - a nice bonus for Hollowgrams vs. conventional 2 piece cranks. And yes you will need the CDale tool.

I am confused about what you have written so I'd appreciate an example of the BB that will work. My Supersix has a PF30A 73mm wide BB shell, and the spindle I am almost certain is 109mm long. The BB I'm using is the Wheels Mfg PressFit PF30. The cranks are pretty snug against the exterior of the BB cups, so even with a 5mm narrower 68mm shell, it's hard to imagine how an external cup BB works here. I do understand one can get longer Hollowgram spindles, but that will move the chainline outwards as well as increase Q factor.

Happy to be corrected, but as they said in high school, please show your work

[cvbm]

I've tried on two separate occasions.

If you can find a very low width 30mm bsa cup (I think Rotors is low) and couple it with either the orange cannondale spindle or a certain Easton spindles you can almost make it work but the q-factor is all wrong since the cranks are meant for a more narrow bb than you're trying to put them on

Chainring can be solved with a wolf tooth direct mount chainring flipped around

[NHAero]

Originally Posted by cvbm

I've tried on two separate occasions.

If you can find a very low width 30mm bsa cup (I think Rotors is low) and couple it with either the orange cannondale spindle or a certain Easton spindles you can almost make it work but the q-factor is all wrong since the cranks are meant for a more narrow bb than you're trying to put them on

Chainring can be solved with a wolf tooth direct mount chainring flipped around

Is there a similar chainline hack for a 2X system, or only 1X?

[Lewis Moon]

I have a set of the Rotor BSA 30 cups coming so I'll try that and report back.

[rooney]

Every time I've looked into this, I turn up answers similar to what's being posted in this thread. The only attempt I've seen was in this post. No mention of the resulting q-factor.

[yinzerniner]

Originally Posted by zzy

I don't understand this thread at all. It absolutely can be done well.

First of all, what is a "BSA30" BB? You mean BSA english threaded BB? There are plenty of BSA 30mm spindle external cup BBs you can run.

Yes, a bsa30 BB is a bb made to fit 30mm diameter spindles in bsa bb shells.

Originally Posted by zzy

A Hollowgram is a 3 piece crank. 103 (BB30) or 109mm (PF30 typically) spindle for road. If you have a 109 you're probably fine. A few spacers will be needed too. Regardless you can swap the spindle to the desired length - a nice bonus for Hollowgrams vs. conventional 2 piece cranks. And yes you will need the CDale tool.

This is not true. The 109 spindle is measured as total length, not length between crankarm faces. The 109 spindle leaves roughly 69mm between the crankarm faces, and can only be used on native bb30 (42mm bore, 68mm wide shell, bearings pressed in) or pf30 bb (46mm bore, 68mm wide shell, with cups pressed in that contain the bearings) shells.

The 3 piece crank will therefore need a wider spindle just to fit in a bsa 30 bb, since the bsa bb plus bb shell is min 18mm wider than the bsa or pf30 shells. And even if you get the wider spindle the chainline will be moved outboard since tbe chainrings are mounted to the ds arm, either directly or on a spider.and similarly since the arms are moved out 9mm each way, Q factor / pedal position will be moved out 9mm each way

The “bonus” of that 3 part crankset is a negative since a spider to compensate for the offset chainline isn’t available, and the Q factor changes so much.

Just look at the shape of the cannondale crank arms and how they splay out from the axle/spindle.


Vs the straighter arms of cranksets made for installation in either bsa, bb386 or other wider bb systems.


Or this photo showing fsa crankarm differences, top are bb386 arm and bottom is the bb30/pf30 arm.

[Hank Scorpio]

There were several threads on Ww regarding this type of conversion. The last time I considered it you needed the mtb spindle with the shoulder machined off and the Zipp Vumaquad bb. Not sure if that is still the case as I see cannodaleexperts selling a few different length spindles.

[zzy]

Ah good clarification above. I was thinking put on a wider spindle and space it out with shims. I suppose the chainline would be too far off. FWIW I've had good luck running newer PF30 cranks on external BB30 BSA BBs the few times I've tried it.