Originally Posted by
LeicaLad
Great thread.
On an 18" or 20" frame, what is/are the ideal length of crank arms?
Is there a decent primer or introductory source of information about the range of specs of these bikes?
Besides brake levers, bars, 3,4-speed freewheels, and the hunt for wheel sets in general, what other key details does one need to learn?
Some of the bikes shown here are truly marvelous! Thanks for all the photos.
My interest?
I have a girl in the market for an 18" and two boys ready 20+", but not yet 24".
Regarding a primer, Tony Oliver discussed design considerations for small bicycles and frames in his book, "Touring Bicycles."
If you look at the bikes here, especially the blue Peug Mixte single shown on Page 8 of this thread (or maybe later), you can see a few features Oliver mentioned - high-looking BB, needs to be set based on ground clearance with a crank length, and with down tube/front wheel clearance in mind. Also affected by down tube is the head tube angle. You can see on the Peug that it is well laid back. It might have had bigger wheels to begin with, since the wheel clearances to look quite large.
On the Merckx on the first page of the thread you can see that the seat tube is quite laid back. This specification might just be Eddie's style, or it could be to establish enough reach to cockpit, or ... ? Chainstays can also become long to accommodate panniers, wheel-seat tube clearance, and possibly fore-aft weight balance.
Pivot brakes apply lateral and twisting forces to seat stays. A seat stay bridge near the brake pivots (CP, canti, or V) can help the rear Cps or cantis to respond firmly without added mush due to frame flex.