So i got me this 1994 pre "coda" branding magic motorcycle crank. its unused with new 44/32/22 rings.
It does NOT have a spindle or bb cups though. So the question is, what can i do with it, besided hang it on the wall or try to flip it to somone else who will hang it on a wall? I feel like it should get ridden.
Ive drawn up some BB cups I can machine. that's not too hard. not super different than a new shimano bb. But the spindle shaft is a hard one. The spine needs to be "right" and I don't see any spec for it - unlike bb30 which came after. The magic spindle is sorta "bb25" I guess and I don't think ever put out as a standard.
Does anyone have any information that could help replicate the splines?
I think if I can get a spindle made, ill also machine a "style matched" narrow wide 32t ring for it... cause, why not?
Yeah, it is, but those were selling for a pretty penny last time I checked a few years ago. Even more so being NOS as you said. Sell it, buy a new crank, and have a ton of change rattling around in your pockets for a long time.
Lucky! I'll get back there someday, soon I hope. That was a great time in my life. Enjoy the rare crank, I do have some machinist friends locally, but not sure about asking them regarding the project.
the machining is the easy part. finding out WHAT to machine, that's where im a bit stuck here. If I had a used spindle I could measure it... but even then, that's a tricky one.
I found an eBay listing that is complete, and it lists the spindle length for that set as 139mm long. You could also try to reverse design it for the best chainline/your BB cups you make and might come up with an oddball number like 132.3mm. I've always liked reverse figuring out things. My old shimano/nukeproof hybrid freehub body is still rolling on someone's bike somewhere
After I cracked my non-drive side crank, I sold my drive side crank, BB, and tool on eBay. I think someone from the VRC forum here was the buyer. Maybe if you post over there you will find that person or someone else with parts they can measure for you.
well it seems alex was a sensible mathematical machinist about it - like me!
this should work. I think ill machine only the tapered end and blue it out to see if I have the taper angle right before I commit to machining the whole thing. I have 2 degree per side, 4 degrees total. due to common tooling choices, its must be 1, 1.5, 2 or 3... and the measurements are telling me 2.0 degrees - not much taper at all.
spindle for me ends up at 118mm long end to end. this gives me a q factor of 150mm. I want it as narrow as I can without hitting the stays. I will machine a 32t narrow wide ring with the right offset to fit. I actually have a second coda branded 130mm bcd road available to me, might as well do both at once it seems - could give that one a 42t cross ring.
the cups take 3805 double row ac bearings, and have 2 rings for o ring seals on the OD that will glide inside the crank arm, keeping dirt out. cup will take a shimano tool. there will be a little wave washer on one side and spacer on the other to tune chain line and prevent side to side slop.
cups will be 7075. spindle will be 7075 or 7050 if I can find some.
so it seems a shimano bb without the plastic shim actually would work. its not as nice as my double row idea with outside seals, but its $11!
i just tried placing the arms over an xt bb, 73mm shell with one spacer (in my cannondale 29er), and the cranks can go waaaay inboard to the point they hit the stays. so, that gives me a ton of lattitude in spacing the spindle where i want it.
i guess the next step is to just make that test fitting spindle. my machinist is swamped so maybe ill 3d print that part on shapeways for now. should be precise enough to know if its "right".
so I decided for the road crank on a 122mm spindle. so ive drawn up a 42t 1x ring with the right offset. also a fixture to actually make the thing. will weigh under 100 grams.
Chainring design done for 30t mountain and 42t road. Mountain spindle will be 130mm and road 122mm. This gives a 160mm and 152mm q factor respectively.
Because the spindle is so much shorter, both rings sit in the "big ring" position instead of the usual middle. Offsets are default 49mm (I prefer to bias to the big cogs. There's still adjustability of the cups with shims of course.
Hopefully I can get these machined up in the next 3-4 weeks. my guy is busy but should be able to make time.
30t ring weighs 42 grams. the mountain crank is 394g (180mm). shimano bb is 88 grams. spindle is 100 grams. that puts us quite near what a new XTR9100 crank is. Pretty good for 25 years old!
Road is 81g ring, 375g crank (165mm), 88g bb, 96g spindle - basically the same - and not too different from a dura ace 9100.
I just took my old mountain bike out and I'm looking at switching it from a 3x to a 1x. I'm interested in keeping my CODA Magic crank set up. If you haven't done so already, I can try to provide any specs that you need if we can work something out in which you help me with the chain ring?? I'm gonna have my son use the bike. It's on a '95 Parkpre Pro 825.
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