Weight Weenies

I'm thinking out loud here, but I found something that id be interested in trying out if possible.

Say I have a frame with a 68mm threaded bsa bottom racket, would this work ?

Cannondale hollow gram SiSl2 cranks
109mm spindle
Wheels manufacturing Threaded to 30mm bottom bracket ( http://wheelsmfg.com/bottom-brackets/th ... black.html )

It should work right ? The 109mm spindle makes the crank bb30a compatible, and the 30mm threaded be accepts bb30a cranks.

Anyone tried this or notice any issues with it ?

Short answer, no. A BB30 frame has a bottom bracket shell that is nominally 68mm wide and the bearings are pressed into the shell, but for a threaded bottom bracket shell, even if you use the Zipp Vumaquad which has the narrowest bearing cups, it still alters the chainline, pushing the chainrings out from the frame by the width of the bearing cups.

Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com

That's true, but bb30a is different to bb30

Check the link to the bb I included above.
The bottom bracket allows the use of rotor 3D+/ FSA bb386 / bb30a compatible with bsa bb shells.

I just want to know if the hollow grams will work as bb30a

BB30a is the same as BB30, just with 5mm more width on non drive side.
SISL2 will fit.

caballero wrote:The bottom bracket allows the use of rotor 3D+/ FSA bb386 / bb30a compatible with bsa bb shells.

While someone else has replied in regards to BB30A, in the statement above you are mixing apples and oranges as Rotor 3D+ and FSA PF386 are for 86.5mm wide bottom bracket shells, thus are not true BB30 cranks.

ms6073 wrote:While someone else has replied in regards to BB30A, in the statement above you are mixing apples and oranges as Rotor 3D+ and FSA PF386 are for 86.5mm wide bottom bracket shells, thus are not true BB30 cranks.

This is correct. Rotor and FSA have much longer spindles than the SISL2.

I'm running a 109 spindle right now. It's long enough to fit in a 68mm wide bb shell with both crank arms attached, the wavy washer, and then about 6mm of spacers (one 5mm on NDS and one or two thin spacers on the DS. That's it. I could not fit external bearings in there unless they were less than 3mm for each side.

Do the math on it. You have 68mm is in the frame, about 15mm for each arm, and about 10mm for each outboard bearing. That adds up to 118mm. That's a full 11mm more than the spindle.

That said, you could certainly try it and hope that the arms are engaged enough on the spindle to not fall off, though the crank arm bolts are pretty thin.

For Hollowgram cranks to fit in a 68mm threaded shell with BSA30 cups you need to use at least 119mm spindle. Than your chainline is 5mm too wide and your q-factor is 10mm wider.

I don't think that is acceptable.

It might be OK for a 1x drivetrain and run the chainring on the inside of the spider to get the chainline back to normal.

grover wrote:It might be OK for a 1x drivetrain and run the chainring on the inside of the spider to get the chainline back to normal.

That is what I tried and failed to express in my first post. Having actually tried setting up an SRM Hollowgram using the 109 mm road spindle and Zipp Vuma Quad external threaded bearings on a frame with a threaded 68 mm bottom bracket shell, and know first hand that while the arms can be installed, the chainline was bad in the small chainring and really bad when I could get it to shift into the large ring.

Doesn't the SRM hollow gram use a special spindle length? I had thought I had read that somewhere.

From what I have read it will work when you use the 109 mm bb. Plus it allows you to move the spacers back and forth to adjust chain line. I have a cad3 I was thinking about doing this too. When I measured it with the arms on a 109 mm spindle it looked like it was correct.


Sent from my iPad using Tapatalk

Sorry, this is a little off topic but I was hoping to hear from people with Hollowgram experience. I just picked up a set and I'm wondering if this looks correct? I'm used to Sram cranksets, which sit flush against the bearing shield and the gap here looks wrong to me.

Also, should the space between each arm and the frame be the same? In other words, should the arms be perfectly centered with respect to the center of the frame? Right now, the non-drive looks about 1mm closer to the frame. Thanks for any info!

I could chime in, I own 4 of them currently, all flavors of hollowgrams. You need to tell us which spindle you are using, 104 or 109 mm. Both will work on a 68 mm frame but the spacer arrangement is different. Also if you have a newer Dale the frames are 5 mm wider.

From your photo it appears it's a 104 mm spindle
Sent from my iPad using Tapatalk

It's a 104 and the frame is 68mm.

Lol, looks like I'm not the only one, and also looks like it's all good! viewtopic.php?t=96807

Well then it's the easiest one to set up. No extra spacers on non drive and follow instructions on line for spacer arrangement on drive side. Which I think from memory is your wavy washer and 3-4 thin washers. I just put one on a friends Specialized over the weekend using a 104 mm and i didn't even have to tweak his front derailleur. It was a perfect chain line match to his carbon specialized crank that lost its pedal insert.



Sent from my iPad using Tapatalk

Those instructions are what I always used for setting up my older Hollowgrams.

And no, the spacing is not the same for each arm. The DS sits flush, while there is a bit of space on the NDS. The 104 spindles I have all have a little lip - shown on the instructions - that sits flush against the bearing, but the arm does not press all the way up to the lip.

On the 109 spindle, which I am running on BB30, not BB30, the DS sits flush, but there is a spacer on the NDS to take up the extra 5mm. In this case, there is no gap between the arm and the spacer, as Cannondale removed the little lip from the spindle.

I had my bike with BSA 68mm setup with SRM SI cranks.

Runs spindle 122mm. DS goes with no spacer, cranks sit directly with the BB seal, NDS sits with a 1mm spacer, 1 thin plastic spacer n the wave washer.
I reckon I could go with the 121mm spindle with a narrower Q-factor. 1mm difference ain't that big and I can have 1mm difference from the pedal/cleat adjustment easier then to replace a new spindle.

When I tried to switch the SRM spider out for a SL spider, the chain is not able to shift onto the big ring.

System runs 7970 Di2 system with 54/42 Qrings. Front Deraileur cage goes all the way out on its limit.

This SRM setup on a TRI Bike have a very wider Qfactor. Seems okay for my knees n ankles since I broke my right knee and my left ankle earlier

I have Lightning Cranks on a road bike(BSA 68) and the Qfactor difference can be felt if you jump on the other bike, both bikes uses the same shimano wide SPD-SL pedals n on the same shoes.

Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com