Cyclone BB size, I just dont understand

[DanGT86]

I feel really dumb here but I just dont understand the dimensions of this Cyclone bottom bracket I bought from luna. Hopefully someone can explain this too me.

This is advertised as the 68-100mm bottom bracket. The bearings on the non drive side are pressed on such that they look right for a 100mm bottom bracket frame.

If I'm supposed to press the bearings on 30mm further then it looks like the Non Drive side will stick out way too far. This doesn't add any extra length on the drive side for a FW bottom bracket which I thought was the entire point of these extra long spindles.

So what is the deal here? Is the movable bearing really supposed to be on the Non-drive side?

Are the threaded cups on the wrong sides? That seems like it would make way more sense.

Do people using these on 68/73mm BB frames just accept that the non drive pedal sticks way out compared to the drive side?

 

[ferret]

Hi Dan.

>>Is the movable bearing really supposed to be on the Non-drive side?
Yes

>>Are the threaded cups on the wrong sides? That seems like it would make way more sense.
No, the drive side spacing is fixed so that the chainring is at a fixed distance from the frame.

>>Do people using these on 68/73mm BB frames just accept that the non drive pedal sticks way out compared to the drive side?
Yes.

Avner.

 

[DanGT86]

What a strange thing. Almost looks like these companies just bought fat bike bottom brackets and turned them down so they are adjustable. If the extra spindle length cant be used on the Drive side then I don't really see the point of buying a long spindle.

I need to find a regular ISIS bottom bracket and compare the spindle length on the drive side. I'm curious if there is the same amount of shaft length from the bearing as this goofy long BB.

Thanks for the info.

 

[pwd]

For reference here are the "bottom bracket" spindles available from Cyclone:
https://www.cyclone-tw.com/product/12/data/36

and a couple of others here:
http://sickbikeparts.com/bicycle-parts-and-tools/

 

[DanGT86]

Thanks.

Looks like the thing they all have in common is the same spindle length on the Drive side. I guess I just always figured these were for providing more room for FW BB. They don't seem to provide any benefit over a standard ISIS BB.

Time to go list my unused cyclone BB in the for sale section.

 

[pwd]

One thought I have is that the Cyclone BB spindle *may* be a tad longer than a stock BB spindle to allow a motor bracket to be fitted on each side between the bottom bracket shell and the threaded flange on the bottom bracket. Can anyone confirm that? Otherwise it also makes me wonder why replace the stock bottom bracket at all? Sorry if that throws a wrench into your thinking.

 

[DanGT86]

You are correct. It is definitely longer overall than a standard 73mm BB. This one that I bought is around 150mm long. I think a standard 73mm BB spindle is something like 118 long.

This style of internal bearing bottom bracket does allow you the freedom to run some spacers under the cups such that you could get it closer to centered while still having some bearing inside the frame. But it's still not going to be enough to make up for the crazy amount of spindle sticking out of the Non-drive side.

My external bearing bottom brackets on other bikes don't have very much thread length.

If I really wanted to mess with a custom Freewheeling bottom bracket I would probably experiment with switching these bearing cups. Seems like it would be nice to have a precise machine turned extra long spindle on the drive side for a support bearing to support the freewheel. This could provide some nice spacing to have multiple front chainrings.

One additional thing this BB has to offer is the separate threaded lock-ring around the non drive side cup. All of my normal ISIS bottom brackets have a cup without a shoulder. You just tighten them until they bottom out on the internal spacer tube of the BB. They dont have the lip that bottoms against the bike frame. So using a standard ISIS there would not be a way to positively clamp on a motor mounting plate on the Non-drive side.

 

[Chalo]

It looks like you could put 10mm or at least 8mm of spacers under the drive side cup, and buy back some of the discrepancy.

 

[DanGT86]

Agreed. The question then becomes why. I feel like the point of a longer bottom bracket spindle would be to allow room for freewheels and support bearings. Adding too much spacer under the cup means whatever extra stuff is on there needs to have a large enough diameter to fit over the cup.

I guess there are a few issues one of these could solve but I'm not really impressed. Just wondered what I was overlooking.