masi61

Usually folks are trying to take a bb30 pressfit bottom bracket and make it compatible with a 24mm Shimano HT2 crank but I am curious about doing the opposite.....

I would like to mount a Cannondale BB30 (30mm crank axle) crankset into a standard English threaded 68mm bottom bracket. I found one at the Kogel bearings site but it is over $200 and it says it is for Rotor, RaceFace and Easton. Not sure if Cannondale would work.

I was wondering if folks knew if such a bottom bracket could be set up like this. Bonus points awarded for an English threaded 68mm 30mm bottom bracket of good quality for less than, say - $60.

Cheers! From, Bill in Dayton, OH.

aggiegrads

Even if you can find a compatible bb, I wouldn’t use one, because the bearings that would have to be used would be far too small to be reliable.

The bb30 spindle is too short for outboard bearings on a 68mm BSA shell, so the bearings would need to sit between the bb shell and the spindle. The thread diameter is about 35mm, which means that the bearing assembly needs to be less than 2.5mm thick. That isn’t enough room for threads, races, and balls.

as far as I know, a solution for this does not exist.

masi61

OK. Thanks for your reply. I guess I will go with a Shimano HT2 crankset then for my project. I will plan on using the Hollowgram BB30 crank on my CAAD9 BB30 project road bike then.

Dan Burkhart 

External bearing English threaded bottom brackets for 30mm spindles do exist. Here is one example. and not too unreasonably priced. https://www.raceface.ca/products/bsa-cinch-30mm

cxwrench

I'm thinking this would work as well. I was looking at one today...should work but the balls are tiny so it won't last long.

Dan Burkhart 

It uses 6806 bearings which are the same as what is found in press fit 30mm BBs.

masi61

So I guess if I were to try it, that bearing life might be a bit questionable? Noise (clicking, creaking) would be a no-go. If it would not be silent, it would not be worth the effort.

Thanks for your reply BTW.

Thanks Dan Burkhart for the link.

dsaul

As has already been said in post #2, the spindle of the BB30 crankset is not long enough to work with an external bearing like the Kogel or Raceface bottom brackets. Those bottom brackets work with cranksets like the Raceface cinch or 386EVO, which have longer or replaceable spindles.

aggiegrads

Yes, but none exist for BB30, which is what the OP is asking about using. The BB30 spindle is too short for an external bearing.

30mm spindle is not the same as BB30.

aggiegrads

This will work for some 30mm spindle cranksets, but I am 99% positive that the BB30 crankset that the OP has will not work with that BB.

cxwrench has much more experience than I have so he is really the authority, but I would double check with the crank manufacturer before you buy the BB.

Dan Burkhart 

Yes, you are correct. I missed that part in the original post.

HillRider

I'm not sure this is correct. I used to read the same claim about Octalink bottom brackets, that the large spindle required small, low durability bearings that would wear out fast. I had an FC-6503 Ultegra crank with a V1 Octalink bottom bracket that had more than 26,000 miles and was still running smoothly when replaced as part of a 10-speed upgrade. I don't consider that poor durability.

The similar and contemporary ISIS bottom brackets did have a reputation for poor durability but that was because of poor materials and workmanship, not inherent weakness. The Shimano Octalinks were good.

masi61

Bumping this thread to maybe jumpstart the conversation thanks to an idea I have about how to custom fit a Cannondale Hollowgram BB30 mtb axle onto a BSA road frame and take the guess work out of which spacers to use. My idea is to use a Cane Creek or Kogel 30mm pre-load adjuster. I think it just might work for "trekking" triple chainring set I mounted on the Hollowgram crank spider.

Kontact 

If you take a Hollowgram BB30 crank for a 68mm shell and mount it on a different length spindle, your chainline will be off - usually by at least 11mm to clear the external bearings.

There's a reason you were told there is no good solution to mounting this crank on a BSA frame.

masi61

No one told me there was no good solution, just that I was on my own to come up with “A” solution. Since I’m using a triple spider on the Hollowgram BB30 crankarms, I mated it with a Hollowgram MTB axle that is like 131mm instead of the road double one which is 109.5. It might actually be 134mm, I’ll have to measure again with my calipers.




The granny ring is pretty small like a 26, I’ll need to re-check. There is maybe a mm or two too much clearance so maybe a difficult chainline…

I might use a “dub” pre-load adjuster in place of whatever drive side spacers I have on there right now in order to get the correct pre-load on the bearings. Also, this triple crank is going to need a really good triple compatible front derailleur like a Deore XT, XTR900 or SunTour. Shifting will be friction front with either a bar end, a SunTour Command paddle shifter or a retrofriction lever mounted on some Gevenalle Audax brake lever pods.



But with the BSA cups hand mounted (not yet torqued to spec) and some stack of spacers that seems close to what I am after, the “granny” ring has decent chainstay clearance so far on my oversized aluminum tube Cannondale Silk Tour 1000 frame.

My main issue is coming up with the right amount of pre-load on the bearings so that not only is there no slop, but also that I have not overtightened the preload.

The chainring set is 104/64 bcd, https://www.ebay.com/itm/25468409010...mis&media=COPY

choddo

Isn’t (131-109.5) / 2 circa the 11mm Kontact said the chainline would be out? That seems quite a lot.

Kontact 

You were told:
Now you have a set of chainrings that are so far from the seat tube that you won't be able to get a front derailleur to shift to them correctly,

Mackers

Surely TS has a custom clamp for that

masi61

I was really hoping to get these 104/64 bcd chainrings to work for this application. I will continue to work to take some more measurements and maybe play around with a preload adjuster, wavy washers or different length of 30mm hollow axles. Worst care scenario, I will scrap the plans for this crank on this bike and most likely put a shimano triple on there.

Kontact 

There is no room between the spindle, chainrings and BB shell for bearings.

Mackers

But why?

You will never be able to get those chain rings closer to the center than they are right now.
Should you ever be able to get the front derailleur to swing that far out to shift to the big ring with a custom clamp, you'll just be faced with the next problem; an impossible chain line.

As an aside, I am positive at one point in time in the early 2000s someone did produce semi-internal BSA bearings for Hollowgram cranks but unsurprisingly those quickly disappeared. They came with double rows of tiny balls that disintegrated in no time at all and required the use of the 122mm spindle.

masi61

I flipped the axle the other way around where the lip I believe is now on the non-drive side. This shortened the drive side axle a bit which is tucking my 24 tooth granny ring a bit closer to the chainstay.

I’m trying to come up with my own pre-load system for Cannondale Hollowgram cranks. But,…

This bottom bracket system could fail based on a possible “bodge” where some were that lip on the axle I would think the inner bearing race could get worn out prematurely.

This is why I am considering moth-balling this project & instead - grafting the chainrings onto some Deore XT Octalink chainrings with a 104/64 triple spider.

masi61

Is this your opinion or is this just how the Cannondale system is intended to work? I still am trying to wrap my mind around the way that these Hollowgram cranks attach to the spindle. It seems to me that the bolts need to be torqued to the correct spec using a torque wrench. But this could be done prior to preloading the bearings. So one of the things I plan to try out is to torque both crankarms to spec with a cheap chinese 30mm dub preload adjuster and see if it is possible to dial out the play in the system for optimal bearing function after the arms are already torqued to spec. I envision some re-flags with this idea though, to me a preload adjuster where the inner ring is super glued to the spindle, well this sounds bound to fail. I am at a loss here but I suspect that custom BB30 Hollowgram crank adjustable chainline bottom brackets should be achievable.

Kontact 

It is a fact, not opinion. Those cranks are intended for a 68mm wide BB shell with the bearings inside that 68mm span. If you use a longer spindle and external bearings your are moving the crank arms and chainrings out too far. The most obvious result will be that your front derailleur will not reach far enough to shift.

This is not a new concept. Square taper and Octalink used 22mm or smaller spindles inside a 68mm shell that is 35mm in diameter. BB30 did the same thing, but the bearings are between a 30mm spindle and a 42mm diameter shell. 30mm spindles don't leave room for bearings inside a 35mm shell.