64 BCD Cog Carriers
Between steeper trails, shorter cranks, and an older body I've been looking for bigger single speed cogs. With 160mm cranks I'm already at a 30-22 gear. I wouldn't mind running bigger rings and cogs on both ends to get less tension on the chain and therefore a longer life and better efficiency.
Many moons ago I lasercut some 64 BCD spiders that fit an obsolete Shimano spider pattern so you could run tiny 1X setups on wider chainlines than the usual granny position. I don't use them any more since Shimano never made any short versions (and honestly still doesn't). The spline on the spider was almost HG so it wasn't a big leap to change the spline in the CAD drawing and get some more made.
On the spider, the holes were big enough for a chainring nut, but since 64 BCD rings are only drilled for the chainring bolt on these spiders I made the holes smaller, so that I could tap them to take the bolts directly. This gave a bit more clearance for running the smaller rings.
I had 6 made by SendCutSend out of 1/4" 6061. Deburred, the total was about $50 plus shipping. Two were spoken for, one was gifted to Andrew Major, and one went on my singlespeed.
After one ride I gave the bolts an extra dose of torque, and the cog has been working just perfectly. But it's a cog, I don't expect it to blow my mind.
Some of the nice things about the design:
- Affordable
- Thick base, and could be cut from thicker material
- Run 22-28 or maybe 30 tooth cogs
- Run steel cogs, narrow-wides, titanium ones?
Andrew just posted his mini-review part 1 and the cog is going to get some testing with a 26 tooth ring by his pal Crash Test next. His picture below.
Now, you may be asking, can I buy one too? You bought a Neuhaus Nova and didn't realize the big wheel gears everything up?
Sorry, I don't want to be in the business of selling them. Instead, here's the CAD drawing. I offer it with no warranty or guarantee, for you to get your own laser cut. You'll need an 8mm extra-fine tap for the chainring bolts. If you want to sell them, I don't care. Have fun. Maybe call it the MCC. Note: SendCutSend can also powdercoat or anodize things, if you want even cooler looking parts. They can tap holes too, though they don't have the right tap size at the moment.
I'll also warn you that different cutting outfits may run different tolerances so the carrier might be tight or it might be loose. It may appear tight because there's a tiny taper. You're an adult spending your own money. If you're a kid using your parents' credit card to make some then you rock, but still, not my problem.
Some might also be wondering if you can run a cog on each side for dinglespeeding. The answer is yes and no. You can't fix them in the regular way because the chainring nuts don't fit through the rings. You'd have to find extra fine nuts or use different M8 bolts in a common pitch. What does work is to run both rings on the same side of the carrier with spacers in between them, the same way the granny ring would normally be offset from a crank arm. I haven't tried it, so it's your journey to experience.