Positron Il Schwinn's Unappreciated Shimano Marvel

[momo608]

I like these and no serious Schwinn lightweight collection is complete without one. From what I've been able to deduce, Positron refers to the friction freewheel or FF system and not the indexed solid cable shifted derailleur that usually but not always went along with it, as evidenced by AMF's positron equipped bikes that used a standard stranded shifter cable. The weak link in the Schwinn system is the solid cable operated positron derailleur and not the friction freewheel or the freewheeling pedal cranks. The Positron II introduced in 1977 and on Schwinn 10 speeds, was the most perfected and final use of the positron system. The introduced in 1982 FH positron was a six speed derailleur identical to the positron II derailleur but with a longer throw for 5 and 6 spd. FF's. I do not believe these were used on any Schwinn. The Positron I was a two cable operated rear derailleur that never saw use on a Schwinn. These were too complex and thus prone to adjustment problems.

Anyway, I like looking down and seeing that constantly moving chain and the ability to shift while coasting is pretty cool too, a marvel. Read over the adjustment procedure and it will immediately become apparent why this was a failure. Too bad Schwinn did not use a standard cable operated derailleur with the FF system that served them so well for so many years. The solid cable indexed derailleur and shifter are not bad, it's simply too complicated for the typical consumer to figure out how to adjust and care for it. You know Schwinn must have thought long and hard that this was indeed a solid system before putting it on thousands of bikes and It is in the right hands.

The forgotten AMF positron system

Positron I two cable system

Hard to find a good photo of these. It appears only oddball bike used them. This example is from a Oxford International.

 

[rhenning]

One of the many things Shimano invented that there was no reason for except marketing. Roger

 

[Schwinn499]

Call my collection amateur if you must...but I tried....couldn't do it...

 

[momo608]

Yes I know, unappreciated along with my efforts. LOL


I forgot because I researched some of this info a long time ago but it looks like that AMF has nothing in common with what we came to know as the FF system. That's not a freewheeling crank set! So the only thing Positron about this is the name on the derailleur.

BTW, I have several of these NOS derailleurs for cheap if anyone wants one

 

[Metacortex]

The Positron derailleur and Front Freewheel (FF) System were completely separate systems that could be used individually or together.

Here are links to some Shimano catalog pages describing the setup:

http://www.sheldonbrown.com/shimano1982/pages/35.html
http://www.sheldonbrown.com/shimano1982/pages/36.html

Positron was introduced in 1975 and was one of the first indexed shifting systems. The original Positron derailleur used dual cables in a push-pull configuration while Positron II used a single thicker cable.

The Front Freewheel System was introduced in 1977 and had the "freewheel" on the crank instead of the rear sprockets. This allowed one to shift even while not pedaling since the chain and front/rear sprockets would always be turning while the bike was moving whether you were pedaling or not. Although the rear sprockets were fixed (not freewheeling), there was an override such that they would freewheel if enough force was applied due to a jammed chain or other obstruction.

Here is a good video demonstrating both the Positron derailleur and the Front Freewheel system combined on a Varsity:

These systems were used both together as well as individually on certain Schwinn bikes including versions of the Suburban, Caliente, Varsity, Collegiate, Cruiser/Spitfire/Klunker, Hurricane and World Tourist from 1977 through 1990.

The first Schwinn with the FF System was the 1977 Suburban 10-speed. On this model the FF System was combined with a conventional friction shift rear derailleur (Shimano 400FF) and standard Schwinn Twin-Stik shifters:

Also for 1977 the FF System combined with a Positron II rear derailleur first came on the Caliente:

While most FF System cranks were one-piece, they did make a version for 3-piece cranks, which Schwinn used on the World Tourist from 1981 through 1990.

Several bikes came with Positron II derailleurs and standard (non-FF) cranks, including the Cruiser/Spitfire/Klunker and Hurricane 5-speed models:

The last Schwinn with these systems was the 1990 World Tourist:

Due to the proprietary components, funky cables and (in my opinion) ugly appearance I try to avoid both Positron and FF System components as much as possible.

 

[drglinski]

The FFS system is kinda neat....but also kinda stupidly pointless. My buddy that's a Schwinn enthusiast calls the FFS; For F**'s sake!

 

[momo608]

Jeez Loueez, I didn't say it had to be the centerpiece of a collection but seeing how it's completely different and unique from any other Chicago Schwinn 10 speed lightweight. That it represents an example of what would be the end of Chicago production.The fact that an excellent example can be had for $100 dollars or less. So yeah, I think it would have to be part of any serious Chicago Schwinn lightweight collection. That's what we're into right! What I don't understand is the emotional snobbishness against their existence. Properly tuned they are good bikes and very interesting.

 

[Schwinn499]

Like I said, I had one, its not for me. With the limited space I find myself with lately and having to shave down the collection a little with all the bikes ive been picking up, had it still been here, id be up on the block. My focus has turned to mostly fillet brazed bikes and a few of the uncommon electro forged models.