I really like that idea. I think it could be very helpful.
Originally Posted by v1nce
For the wheelbase i suggest two measurements, Axle to Axle distance and possibly Rim edge to Rim edge (to discount tire variations).
I don't think the tire influences the wheelbase, does it? Axle to axle should be all you need.
Originally Posted by v1nce
For reach another three measurements perhaps. Minumum & Maximum extension. Distance of stem to saddle when they are in stock positio, perhaps a range etc.
I would measure the reach horizontally from the middle of the handlebar to the center of the seatpost (or where the horizontal meet the imaginary extension of the center of the seatpost. If the stem is adjustable, then a min. and max measurement.
Further I would add a max. seat rail height, measured from the bottom bracket to the seat rails, when the seatpost is at the max. extension limit.