Actually the spring in a Simplex Retrofriction down tube shift lever operated as a clutch and not as a spring to oppose the force of the rear derailleur. The wonderful light action they have is from the the lack of friction needed to pull the lever back due to the clutch releasing. Pushing the lever forward involves the normal friction of a down tube shifter.
Chuck Schmidt South Pasadena, Southern California
Jerry & Liz Moos wrote:
>
> 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.
>
> Regards,
>
> Jerry Moos
>
> from Houston, "Winter? What winter?" Texas
>
> ----- Original Message -----
> From: <Gjvinbikes@aol.com>
> To: <classicrendezvous@bikelist.org>
> Sent: Monday, November 12, 2001 11:13 PM
> Subject: [CR]WTB: 135mm Campy rear axle ?
>
> > I got a bit lucky at a thrift shop today and bought a Centurian Cycle
> Works
> > "Super LeMans" bike (Tange Champion No. 5 PG tubing) for $7. Mainly, I
> > wanted the low-flange Campy Record hubs and SunTour Superbe sidepulls and
> > SunTour bar end shifters (are these what is meant by "retro-friction"
> > shifters ?)
> >
> > Got it home and was rebuilding the warped rear wheel and noticed I
> couldn't
> > true it past a certain point because the axle was a bit wiggley. Sure
> > enough, though not split completely through yet, the rear axle (6-speed
> > freewheel, 1984 dates) is cracked.
> >
> > Can I replace this axle with just any old modern steel axle the right
> length,
> > say from the local shop ? The cones are marked CAMP 10 x 26 and the axle
> is
> > 135mm long.
> >
> > Anyone able to sell me a real Campy rear axle to replace it with - or
> would I
> > be better of with a replacement that might not break as easily ?
> >
> > What is the rear bearing size (no calipers) ?
> >
> > Amazing how good shape this hub still is. The bike was ridden so much
> that
> > the Grab-On style foam bar covers were worn through and the rear axle
> seemed
> > to have been ridden cracked quite a while. The quick release was holding
> the
> > whole thing together - I need to straighten it up.
> >
> > Glenn Jordan - Durham, NC