Now that my Miele is almost done (pics to come!) I need a new project and I want a faster bike for myself. I've been riding my Raleigh Superbe everywhere and although it's lovely to ride, it would be nice to be able to go a little bit faster. It's a bit of a slug, especially going uphill!

I'd like to try a road bike (having never really ridden one much) and would prefer a diamond frame, except I have extremely short legs and need a 48cm (tried a 50cm and it was too big - just). I know I have the option of a mixte or a step through, but I just love the way a nice diamond frame with lots of chrome looks.

So I had a brainwave today and was wondering if a 650b conversion of a smaller (say 51 cm) bike is the way to go. How much can I realistically expect to lose, standover wise? a 50 cm frame touches...soft tissue but not bone.

And obviously there are other considerations - but what are they? clearance between the frame and tire, width wise I presume.

But budget is limited, so I'd love to have some guideline measurements for how much clearance. Also, how much is this going to cost, approximately? I see the need for different brakes, rims, spokes, hubs. Anything else?

Or should I forget it and either wait it out for the right tiny frame or suck it up and get some sort of mixte or step through?

Thanks!