Recently bought a monocog and I would like to mount a fixed cog to the unused 6 bolt iso disk mount on the rear wheel for a fixed gear option. Boone makes an amazing Ti cog that does exactly this but the time to machine and cost are prohibitive. The instructions on www.63xc.com cite using a shimano DX cog. That and every other cassette cog or driver cog I can find are 3/32". So, where can I find a 1/8" cog suitable for drilling?

Go to a LBS that sells BMX gear and ask for a cog. Shimano has 1/8 splined cogs for BMX and SS use.

pm kogswell

a splined miche track cog might work as well.

3/32nds will work fine till you find an appropriate one...

somone who is handy with a drill should really make a whole bunch and start selling them.

i'd be down for one!

I think for now I'll use one of the spare cogs that came with the bike. I think the pack had 14,15,17,18. They just seem low quality is why I haven't gone for it yet.

what about one of these?

not sure where to get it though.

fsnl
sparky

I've done a convertion that way. I used a cog from an old cassette I had and drilled it. The cog was tempered steel so I had to untemper it before I could drill though it by heating it up almost red hot and then dunking it in water. Drilled through no problem after that. Of course I had ruined 2 drill bits by then. The Boone cogs look awesome for this type of convertion. Too bad I stripped some of the threads on the hub trying this before. Should have spent a bit more time paying attention to bolting steel to aluminum. Good luck.

How about "anywhere"? Why couldn't you drill out any cog you can lay your hands on? You'll more than likely have to grind off the lip, and you probably can't use a 16T or smaller, cuz the bolt heads will contact the chain (What's the smallest cog anyone has successfully drilled yet?) Of course, if chainline requires a wider cog, it's different. BTW, I'm pretty sure you can get away with putting in a spacer if you need to.