Cheers to Jerry Moos, for his nice discussion of the retrofriction design! (below).
<snipp> Retrofrictions, introduced circa 1973, <snip> 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. ++++++++++++++++++++++++++++++++++++++++
NOt having used the Simplex, I don't know if they're the best ever friction design, but I'd modestly suggest that they have competition. At least in bar-end configuration, Shimano made a similar design. When set up with low cable friction, the effect is almost eerie light action. Suntour made its ratcheting shifters, which are extremely nice, very robust, and still available (DT and bar-end, I believe) as Rivendell "Silver" units. These are based on the later design with finer ratchet teeth. I have, but have not used, a set of Shimano L422 DT shifters with a very fine ratchet, which I'd expect to meet their usual high standards. In my experience, it has been somewhat easier to get high performance from the better ratchets than to balance the counterspring designs, but ain't a big deal.
And then, last and least, I have some affection for the Suntour units that mounted on top of the DT and linked the two levers: as you shifted the rear toward smaller cogs, it also moved the front up and out a bit. Very elegant for a friction unit!
So, there are lots of ways to do a great job with friction shifting.
harvey sachs
mcLean va