I obtained a set of Simplex stem shifters that are ratcheted. There is/was a little black plastic sprung bit about the size and shape of a fingernail clipping in each lever that ratchets over toothed fixed disks on the shifter frame. Since these don't serve as clutches, there is no real purpose for the added complexity of this system at all, except to make noises.
The SunTour Powershift levers, like the BarCons, are much easier to pull cable with than to release it, which is the point. The difference between clutch-free pulling and clutch-engaged pushing balances the derailers spring's power very nicely, enabling friction-free shifting agaainst the derailer's resistance.
I do not understand the issue of the reverse-action SunTour derailers, like the "Spirt", as regards the usefulness of this system, as that's what I'm using it with on one of my bikes. The pull direction, against the front derailer's spring, is still the friction-free direction as it should be. The only difference is that when you pull the cable, the shift is to a smaller instead of to the larger chainwheel. An odd thing to have to remember, especially when trimming, but the PowerShift system still works perfectly.
So far, it seems to me that the SunTour PowerShifter system and BarCon's are identical in design and function to the Simplex Retrofriction systems, unless the Simplex stem shifters I examined are examples of "retrofriction", in which case the SunTour system is superior.
I still think I like the steel Huret Jubilee downtube shifters on my 72 Competition the best, though. The SunTours are somehow a bit "slippery" feeling, maybe tending to overshift a bit, compared to the Hurets ! :-)
Glenn Jordan - Durham, NC
In a message dated 11/17/01 9:40:28 AM Eastern Standard Time, jerrymoos@sbcglobal.net writes:
> The SunTour barcons as well as some of their DT shifters of the era were
> ratcheted, which served the same purpose of preventing the derailleur from
> slipping into a higher gear, but I don't know if "retrofriction" is
> strictly
> applicable to them. "Retrofriction" is most closely associated with the
> Simplex DT shifters which were introduced in the middle 70's and used by
> Bernard Thevenet in his TdF victories, and by many other pros. They were
> so
> called because they incorporated a spring that resisted the forward motion
> of the shift lever, i.e. opposed the force of the derailleur spring. The
> main idea was to prevent the force of the rear derailleur spring from
> pulling the shift lever forward, which is the cause of friction shifting
> systems slipping into a higher gear on steep hills. A secondary, but still
> important effect was that less force was required to shift the rear
> derailleur onto a larger cog, as the shift lever spring aided the force
> applied by the rider in overcoming the resistance of the rear derailleur
> spring. Many people regard these as the best DT shifters ever made. I
> believe Simplex used the word "Retrofriction" in their advertising, and it
> may even have been a registered trademark. Later, some of the Campy
> C-Record shifters incorporated the same design, and these are sometimes
> referred to "retrofriction". Neither the Simplex nor Campy shifters were
> ratcheted. The uncertainty of the applicability of "retrofriction" to the
> ratcheted SunTour shifters is increased by the fact that some SunTour front
> derailleurs had a reverse action in that pulling the shift lever backward
> shifted the chain onto a smaller chainring rather than a larger one, making
> the benefit of a retrofriction shifter design rather dubious for the front
> derailleur.