Does anyone make a split seat clamp? I built an 'Urban Mountain Bike' and I sometimes like to take it off drops. Accordingly, I cut the 'nub' that sticks up above the top tube so that the seat can be removed without a scary open pipe waiting for my sensitive parts.



The problem I'm having is in relocating the seat post clamp beneath the top tube. I have cut a vertical I shape under the top tube in the steel frame so that it can collapse into the post. If I remember correctly, it's a 28.6mm OD seatpost with a 31.6mm or so OD (a bit more now with a coat of Herculiner).

Right now I'm using 2x Problem Solvers cable clamps, but I cannot get them tight enough to stop the seatpost from dropping a bit, and if I go any tighter I'm in danger of stripping them out. I'd also prefer a quick release to be able to take it out without an allen wrench.

Does anyone make Quick Release clamps that split to get around my top tube? 

The best I can find so far is this, but I have to lose any quick release features:



Does something like this exist already, and I'm reinventing the wheel? Or is there some way I could use two quick release levers on the split clamp?
DMR make hinged clamps for mounting chain devices and bottle cages. 3 different sizes and there is a 31.8mm which should be perfect. Easy job to retro-fit an existing QR lever and bolt I reckon?

Part Number: DMR-CLP-286

 

Alternatively here is something from a different application that would probably work. You might be able to contact the company for a 'sample' :)

URL: Staff-Lok Collar


(it's steel)