Anyone up for a group build/buy of a Low Profile Frame?

I've had my eye out for a low profile frame to take a 650C for with horizontal drop-outs and idealy a rear spacing of 120mm, I also realy like the look of Scott's BMW Gangsta Track. So my thoughts have been turning to something along the lines of a reworked lo-pro version of the BMW Gangsta Track with a slightly longer seat-tube and seat stays, a downward sloping top-tube (a bit like Fort's track bikes) and the geometry adapted to take a 650C instead of a 700C fork.

I emailed BMW to see if they could be talked into building such a frame. I haven't heard back from them, but talking to Scott I get the impression they're probably way too busy to consider such a thing, so chances are they won't get back to me. So I started thinking about finding a frame builder to make one, but I think finding someone to fillet braze something like this could prove difficult and someone who is willing to build it would probably charge a major premium for doing so. So my thoughts are now turning to seeing if I could construct my own jig, mitre/get mitred my own tubes, then hand the whole caboodle over to someone who could competently fillet braze it all together. Before embarking on this all by my lonesome, seemed worth asking if anyone else wanted to play?

I'm not looking to produce something with a super radical low front end, I'm thinking in terms of something like 4 cm lower than the front end on my Soma Rush, that would equate to the top of the head-tube being around 76cm above floor level. Low enough to get an aero position if that what's you're looking for, high enough that if you're after the aesthetics of the downward sloping top-tube, but then mean to build a bike with risers that it would suit this to.

I'm after a frame to take a 650C fork because I have a carbon fibre monoblade fork I want to build a bike around, but I also know that for day to day use two wheels the same size, probably 700C, makes a whole lot more sense. If you swap between a standard 700C and standard 650C fork you need to somehow extend the head-tube by something like 55mm. Apparently when you swap a traditional (threaded?) fork and stem for a threadless fork and ahead type headset it lowers the handlebar position by 2-3cm, to compensate for this Serotta produce a press-in head-tube extender to fit to an older frame when updating to threadless fork and ahead type headset. You can see it here;

http://www.serotta.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=SCB&Product_Code=HEADSUP&Category_Code=SSAMP

In theory can't see why you couldn't produce something similar to compensate for changing between a 700C and 650C fork. It does occur to me that a 5.5cm press-in head-tube extender might look a bit messy, but I might have a solution to this as well. The BMW Gangsta Track's fork has something like 35mm more clearance than a standard 700C fork. A 650C rim has a radius that is something like 30mm less than a 700C fork. So if you built a minimal clearance 700C fork then fitted a 650C wheel to it, it would have something like 30mm extra clearance, a little less than the difference between the BMW Gangsta's fork and a standard 700C fork, i.e. not a problem technically or aesthetically. Retain the same fork for use with both a 700C and 650C wheel would mean you'd only have to use a head-tube extension of around 25mm to maintain frame geometry, a much less aesthetically challenging proposal than that of 55mm.

I'd like to retain the design of the BMW Gangsta Track fork, idealy I'd get BMW to make it, just around 35mm shorter. I also like the idea of having the option of mounting a v-brake behind the fork, aero styley. I remember seeing a jump bike frame that had a twin set of screw-in mounts for v-brake/canti studs so you could swap between 24" and 26" wheels, so why not build the fork with two sets of screw-in mounts on the back of the fork blades for v-brake/canti studs so you could swap between 650C and 700C wheels or remove the studs completely for riding brakeless.

What do people think?

I want to emphasise I'm not looking to rip off the design of the BMW Gansta Track or it's fork, idealy I'd convince them to build modified versions of these, it's because this is looking unrealistic that my thoughs are turning to DIY :)

i was originally going to get a 650 fork on my geekhouse and marty said it would be no problem ;) . he also makes singlespeed mtb's .

If you get all the jigs e..t.c built up it will prob be cheaper to get someone to tig the bike up rather than fillet braze. Just an idea

I think most frame builders have an adjustable jig anyhow so I don't think you would save any money by building your own.