Bullseye cranks

[Swede]

Re:

It's a 68mm shell and the frame is an '87 Cannondale. Another "issue" could be the oversized stays but I don't have a steel frame to test the the theory.

 

[elite504]

I think the stays must be part of the problem. They slimmed the profile of the stays in the next generation 3.0 series frames. I think the only way to get this to work will be to compromise the chainline slightly in order to fully pinch up the non driveside on the spindle.

 

[Swede]

Pace Spider....

The pace spider has the raised circle to push the chain line back with the wider BB, The normal version doesn't. I "think" the pace version also has countersunk bolts to fix it to the crank arm. It does look like the small chainring bolt holes are threaded though.

Any chance you take a photo of the other side of this? I think this might be part of the solution to my problem.... Could it be used the otherway around or at least made to work that way?

See photo from shedfull's RC-100 build

 

[24pouces]

Re: Re:

Next problem.... with the chainline at around 47mm the clearance between the chainstay and crank arm is a few millimetres (at best!). If I move the arm out to give around the same clearance as the otherside the spindle is 10mm too short. I’ve checked the total spindle length and that’s around 150mm.

So……… do I need a “special” 160mm spindle or do I compromise on the chainline? I’ve tried this and with roughly equal clearance on the chainstay’s the chainline is 40mm. Too short? Anyone got any ideas?

I got the same problem with my C26. The crank was for a BMX or Track frame…


Mojo Ti machined me an aluminum cap for more security. The tighten bolt is on the spindle (as you could see on the drawing) and with the Mojo Ti part, I could use this crankset. But impossible to use the granny ring, too near of the frame.
On other hand, it doesn't matter : my C26 is quite a garage queen

 

[Swede]

Re:

What is the "part" in the drawing? I can see the cross section of the arm and the spindle. I guess you're using a keeper?

 

[24pouces]

Re:

The drawing was only for showing that the arm use only 2/3 of the spinder (only 16mm of the whole 24mm needed)
I have to do it a picture of what Mojo ti made me

 

[Swede]

Re:

That would be very helpful; thanks.

 

[Swede]

Re: Re:

After a lot of measuring and re-measuring I decided the best option was to cut the spindle in two in order to extend it by 13mm. Chris (Rampage) knocked up the “extension” in super quick time and the welding and filing was done in day. Everything seems to work but now I don’t have enough spacers to pack out the non-drive side spindle; back to Chris…. :facepalm:

 

[pete_mcc]

Re:

Did you use the opportunity to have the spindle machined down to 22mm so you have a wide choice of Euro BMX bottom brackets. Did that with one of mine, means I don't have to worry about crappy Durham bearings again!

 

[Swede]

Re:

Durham bearings? I'm not familiar with the term, can you explain?

I've left the spindle at 22.2mm as the outboard (Durham?) bearings seem to work fine, plus the crank wouldn't fit on Rampage's lathe.

I'm estimating the Q factor will be around 180mm.... :roll: