So now I've finally got the amazing "BikeCAD" online Java-based design app to work on my Mac, I've done this design 'properly'. You key in some of the dimensions and it does the rest... It's really an amazing program - have a go with it here:

http://www.bikeforest.com/CAD/index.php

Here's my .bcad file if anyone wants to play with it. Apparently - some frame builders can literally work from the bcad file as it works out all the tube lengths to be cut, the mitre angles and all. I'm pretty amazed - and this isn't even the Pro version of the app.





I think I might need to raise the Bottom Brack a bit (though at the same height as my Twenty it's probably ok) and probably fit a taller steerer/stem combo for a more comfy riding position, but I'm really getting to think I might get one made....