I recently put together a very sweet street-fixie from a TT "funny bike" frame. It came with a 650c tubular front wheel and fork etc. The tire installed was, admittedly, old and worn and I wondered just how much life it might have left with a bit of tread totally sheared off of one side....

So this morning it got a flat in a rather unspectacular manner (I didn't even notice it until I was on the train). Now I'm wondering if riding a tubular, 650c front tire on the street isn't asking for trouble just due to scarcity and the apparent fragility of tubulars.

My tire of choice on the rear of this bike and on my other 700c bikes has been Rubinos of late- they seem quite flat resistant, cheap, etc. I cringe a little at the thought of the rear tire being a no-brainer and gingerly dodging tiny glass shards in the gutter with the front.

So my questions are thus: can one replace a front fork with one of a different tire diameter (650c to 700c) without throwing geometry and handling totally out of whack? Would I be better off simply sourcing a new 650c clincher front wheel? Are there tubulars out there that aren't too pricey that can be counted on for flat resistance (within reason), or are they all a little milquetoast?

Bummer, really, I love the feel of that front wheel.. The fork is really sweet, too.

Oh yes, and who has really good prices on tubulars, in case I decide to stay the course?

Thanks,
rcc