In designing a small size frame, there are several issues that most be addressed. The name of the game is to shorten the top tube while maintaing enough front center so that the foot does not overlap the front wheel "too" much.
Many frames have been built which avoid foot overlap but have such poor design that they are dangerous to ride. Some Treks from years ago were horrible. Among Italian bikes, I once saw a Grandis that was real bad. These bikes are bad because the trail is all wrong. Often a very shallow head angle is used to increase front center and the forkrake is not increased appropriately. In my opinion foot overlap is better than a bike that is dangerous at speed.
Many builders use an extremely steep seatangle to increase front center. This may or may not be a real issue. The knee over pedal spindle rule is rather crude at best - but many riders really want to be further back so many vintage frames may push the rider too far forward.
In my experience, the best compromise frame has as much foot overlap as can be tolerated and has a relaxed head angle and longer fork rake. Use of 26" wheels is a good solution. Remember that rolling resistance rises for smaller wheels (but there are aero advantages) and tire selection gets lousy. My wife has 26" wheels on her Waterford and tire choice is a limitation.
Just some thoughts.
Mike Kone in Boulder CO
> Bob Freitas said:
>
> >My daughter has expressed some interest in something CLASSIC
> >LIGHTWEIGHT ,,how do you size a bike for someone who is long of leg and
> >arm but short in body.Looks to me like she could straddle a 53/52 but a
> >53CM top tube would be a stretch.
> > Hints and tips appreciated,I am thinking a 51CM with more
> >post showing and a longer stem or a 53 or so with shorter
> >
>
> Bob - how old is your daughter? She sounds pretty much like every teenage
> girl who comes in to the store with Mom and Dad looking for a bike. Most
> of them end up on very small size MTBs with longer posts - anything else is
> too long in the top tube for real comfort, and in some cases, safety. A
> bike that is too long can be hard to control, especially when one has not a
> lot of upper body strength.
>
> Still, many women remain proportionally longer in the leg and arm than in
> the torso, making fit a challenge as they grow up. (me me!)
>
> If she has to have a vintage bike, your instincts are correct to fit her by
> top tube and use a taller stem and long post. If you want to do a fit kit
> long distance, I'll be happy to help, email me off list.
>
> Ann Phillips, Decatur GA