bulgie 

So it sounds like you're saying there were Pro 5-vis triples on some Sports Tourers? I only remember seeing doubles.
The one on the Playboy cover is a double for example. Here's a better photo of that setup showing the ramp/spacer thingie between the two rings, and the pants guard. Look how many bolts, nuts, washers and spacers, it boggles the mind!


-Mark Bulgier, Seattle

pastorbobnlnh 

@bulgie, Sports Tourers (as well as Super Sports and fillet brazed Superiors) only came equipped with double cranksets. I did modify the Nervar double on my '75 Sports Tourer and added a granny chainring. I had a friend who's business had a pretty good machine shop drill the extra holes needed to mount the granny.

I believe with the TA crankset you could add a granny by purchasing the needed TA chainring and longer mounting bolts.



The key in the case of the Nevar was finding a chainring with the correct BCD that fit nicely between the existing bolt holes.



IIRC this was an 86 BCD, so somewhat rare but it split the difference almost in half. As you can see I still use the chain guards, the original SA FD, and original BB.

TenGrainBread 

I've already replaced the OEM Huret FD with a 28.6mm clamp Cyclone. I filed and sanded out the clamp to the 29.6mm of the Schwinn seat tube. Only took about 15min. The spring in the old Huret was not returning the cage well at all.

Regarding the shifting aids Schwinn had TA put into OEM cranksets, @Metacortex has a lengthy post either here or on the CABE detailing his research into the design.

TenGrainBread 

They are going to be TIG welded. We'll be doing small production batches of various lengths and angles, with a few finishes. My expertise is in TIG welding and I have no plans or desire to do brazed stems.

Llewellyn Cycles has a cast lug kit for making a lugged stainless stem available through Nova Cycle Supply for $61. So if you have a local framebuilder who would do it for you that would be a relatively easy way to get a stainless lugged stem. Only comes in threadless though. To be honest I find the lug pattern somewhat gaudy, especially for a stem. And while there are no material specs available for the lugs I would assume they are the common 304 alloy, which is actually weaker than chromoly. They look like really nice castings though.

dddd

My mistake, I was thinking that these had a triple chainset (what it looks like, lol).

In the case of a double crankset having a "ramp ring" between the two chainrings, it is to better control shifts between rings with a larger tooth count difference.

Much as has been done with modern Shimano "compact" chainsets (with their greater spacing width and thicker big ring), the idea is to have the chain falling more directly over the small ring's teeth during downshifting.
Since the chain derails off of the big ring at a considerable angle (due to the chain's plates falling to one side of one tooth and the other side of the subsequent teeth), having wide-ratio chainrings spaced the normal amount would have the chain tending to fall to the inside of the small ring's teeth, onto the bottom bracket shell.
With a larger tooth-count difference between rings, the angled chain tends to bow inward further as it drops down to the small ring, so this sort of supplemental chain guiding is there to support the use of more widely-spaced chainrings.

It might also be that the ramp ring improves upshifting as well, since the increased chainring spacing it allows has the chain angling outward more sharply over the big ring's teeth, improving the chances of the chain actually engaging the teeth quickly.

Schwinn made a study of chain control and had patents on some of their steel chainsets. They also had Huret make a radically huge and heavy rear derailer cage to prevent careless shifting from derailing the chain "off of the upper pulley and/or off of the small freewheel cog" when the shifter was yanked too hard. A previous attempt by Schwinn to prevent the chain from derailing off the small freewheel cog during careless shifting to larger cogs (when the chain might be engaging no teeth at all and slipping) amounted to the addition of a shield ring outboard of the small freewheel cog.
None of this seemed very intuitive to me, that is until I read some of Schwinn's literature on the subject.
Although some might term the pictured Schwinn-modified rear derailer a monstrosity, they really were focused on making the most reliable bikes possible for the casual rider who might otherwise be immediately turned off to derailer shifting.
And indeed, unless the derailer suffered corroded pivots or had it's mounting bracket bent, this setup provided very robust shifting even with the original 1970's chain.
(Shown here running C9 chain, and with modded parallelogram for use with a standard-spaced, 14-30t 6s freewheel)

Jeff Wills

Ooohh… that does make it difficult. A quick trip to the pile o' parts identifies late '80's SunTour doubles as possibilities. A braze-on derailleur on an adapter clamp gets it the rest of the way there. Shimano definitely was getting wacky with the cage contouring by then.

dddd

I ran an old Cyclone FD on a Miyata tourer having an SR Apex crankset with 34-47-52t spread and it worked really, really well.
I even ran that bike with arc bars and an indexed mtb triple shifter and the indexing was perfect. All very unexpected.

Note that spindle length can affect the shifting behavior of a front derailer, not just the travel limits but the cage's vertical path as well. There may be a little room to tweak things in that regard, but I doubt that the Cyclone has a huge travel range to offer.