The shifters in the photo are Simplex Criterium, the all-alloy top Simplex shifters in the late 60's and very early 70's. Retrofrictions, introduced circa 1973, were a completely different and novel design.
They incorporated an internal spring which aided the user in shifting the rear derailleur to a larger rear cog against the resistance of the RD spring. And more importantly, the shifter spring opposed the force of the RD spring tending to force the chain to a smaller cog. This is what was meant by "Retrofriction".
The most important advantage of these shifters is that they largely eliminated the problem of the rear deraillleur slipping out of gear on steep climbs. With conventional friction shifters one has to try to prevent this by tightening the fixing bolts, which has the undesirable effect of requiring more force to shift to a larger cog. The Retrofriction design used the shifter spring to oppose the RD spring, eliminating the need to overtighten the fixing bolts. In addition, it aided the user in shifting to larger cogs as the shifter spring worked counter to the resistance of the RD spring to such shifts. Besides eliminating slipping out of gear, the design more nearly equalized the forces needed for upshifts versus downshifts, giving an allround smoother feel to shifting, particularly on the RD.
I would generally agree these were the best non-indexed shifters ever made, or at least the best non-indexed design. The best-known variation of the Campy C-Record shifters used fundamentally the same design and also shifts wonderfully. Not sure if Campy licensed the Simplex design or somehow circumvented the patent.
Regards,
Jerry Moos Big Spring & Houston, TX
John Hurley <JHurley@jdabrams.com> wrote: Recent posts about Simplex retrofriction shifters raises the question of what makes them the best. Also saw pictures from wooljersey of various Simplex shifters. I am going to try to create a link to a photo of Simplex shifters on my bike. What model are they and how do they differ from the mystical Simplex Retrofrictions?
John Hurley, Austin, Texas, USA