I've been thinking about what to do with an 8 year old mtb frame I have for a while. Last week I was browsing online and found this fixie solution from Velo Solo that enables you to fix the cog onto the disc brake mount. This means that on the freehub side, you can run another cog, making a hybrid flip-flop fixie & free wheel bike (flip-flop because you can flip the wheel over to change ). See picture it makes way more sense... so that's the project. A hybrid front suspension freehub street bike or a super fast fixie for getting to and from work nice and quick.