1974 Schwinn Sports Tourer...just Picked It Up!

[HARPO]

Thanks!

 

[Metacortex]

Interesting project none the less, and now I'll have 3 Sports Tourer's...though I don't know how long I'll keep this one after completing it. Frame is to small for me, but maybe I'll just add it to the collection.

Don't take this the wrong way but me personally I'd part that one out. It is a great find but for me it is just missing too many parts to be cost effective to restore, plus you have two other nicer ones that fit. The one thing I'd keep though is that *sweet* TA crankset! While I've grown to like the Nervar, I think the Schwinn version of the TA crankset as used on the Sports Tourer is the most beautiful there is. I've never seen a TA on a '75 model (those were Nervar only), but for '74 and earlier they came with either TA or Nervar interchangeably. In other words you could mount that TA crankset on your other '73 and it would be perfectly correct.

 

[bulldog1935]

actually, the Schwinn versions of Nervar and TA both used ersatz spacer rings in place of spacer washers to intentionally add weight to the crank and meet Schwinn minimum weight specs for the component. (ok, they can also use a spindle narrower by the distance from the ersatz ring to the outer ring, but that's how many mm?)
helluva mind set
counting down the stack, chain guard, spacer, outer ring, spacer, ersatz ring, spacer, inner ring, 3 sets of fasteners on 3 different bolt circles - that's a lot of parts for a double crank

so in all reality, it's the least intelligent version of the 50.5mm bolt circle cranks (includes Nervar, TA, Stronglight, Zeus)
This is a half-step triple that's narrow enough to use a road double front derailleur - form should follow function

here's the most complete history site for TA
http://www.blackbirdsf.org/ta/

BTW, shouldn't this thread be on the Schwinn Lightweight page?
It seems to be like a virus or maybe menstrual cycle - whenever this forum page gets a rash of activity, it then breaks out in Schwinn

 

[Metacortex]

Schwinn first introduced a ramp or "sloping annular surface" between the inner and outer chainrings as a shifting aid in 1968 when it introduced the patented Schwinn double plateau crankset that was so iconic to the brand. You can see the ramp as item 26 in the patent drawings:

In the patent it is described as: "...the peripheral portion of the blank defining the sprocket teeth is further offset outwardly to provide a curved or sloping annular surface 26 adapted to function as a guide means for the chain with which the sprocket assembly is used to assure smooth transfer movements of the chain into and out of engagement with the teeth of the sprockets..."

When Schwinn was designing the Sports Tourer they intended to produce a bike with wide-range gearing that was described by Schwinn as"...the broadest available on any production bicycle." To accomplish this they used a special 14-34T freewheel and a 36-54T crankset. Schwinn announced these cranksets to dealers in a March 1971 service bulletin where you can see the inner chain guard (ramp) in-between the inner and outer chainrings:

The ramp was obviously an important part of Schwinn's patented crankset design. I believe that Schwinn contracted with TA and Nervar to add the inner guard ramp as a shifting aid exactly like that found in its patented double plateau crankset. And it was a good idea as in practice I find they work very well, even with the extra wide range gearing in the '71 Sports Tourer models. Note that in late '71 Schwinn changed the Sports Tourer crankset from 36-54T to 40-54T and the new versions also had correspondingly larger ramps to match the 40T inner rings. And yeah, these cranksets have a *lot* of parts:

 

[bulldog1935]

or it could be Schwinn wanted a patent for business purposes

good enough design for Rene Herse

My old Raleigh is high in my rotation because I shift mostly up front for the half-steps, and it shifts wonderfully. It gets at least 30 mi/wk

Admin, can we get this thread moved where it belongs?

In 1962 SunTour patented the slant parallelogram rear derailleur.
No one could copy it until 1980. Every rear derailleur made today copies it.

Schwinn's patent "improving" on a 30-year crank design expired in 1987. No one is copying it today (not even Schwinn), but the 30-year older design is still being copied.

Dale, I agree it's great research. I don't think it's an argument for Schwinn superior design, nor is there any good reason it keeps topping on this forum page rather than on the Schwinn Lightweight forum page.

I've definitely never had a chainsuck occur on my TA Cyclotouriste. Of course the modern shifting aid and way they deal with preventing chainsuck in skinny 10- and 11-speed chains (and soon 12-) is by adding pins around the chainring.

 

[Dale Alan]

Great info Metacortex,thanks for sharing . Your research is much appeciated.

 

[Schwinn499]

 

[HARPO]

I started the tear down this morning...and its been kicking my butt the entire day. After finally getting the cranks off, I went to remove the seat post. It's in there but good. I've tried drowning it in WD-40 (not that anything is getting through as it's so wedged) and tapping the sides of the post with a hammer. If this doesn't eventually work, I'll have to do my first cut off. And of course the pedals have really grown attached to the crank arms. But I really do want to save the frame.
I'm in agreement with METACORTEX about parting it out, though I'll see how it all ends up. I have the parts here to finish it, including almost new brake levers with the gold clips. I hate giving up so early in the game.

 

[Schwinn499]

If I recall correctly, Schwinn made many design improvements to existing products (Schwinn Approved) and allowed the manufacturer to apply these improvements in their own product lines.

 

[bulldog1935]

I started the tear down this morning...and its been kicking my butt the entire day. After finally getting the cranks off, I went to remove the seat post. It's in there but good. I've tried drowning it in WD-40 (not that anything is getting through as it's so wedged) and tapping the sides of the post with a hammer. If this doesn't eventually work, I'll have to do my first cut off. And of course the pedals have really grown attached to the crank arms. But I really do want to save the frame.
I'm in agreement with METACORTEX about parting it out, though I'll see how it all ends up. I have the parts here to finish it, including almost new brake levers with the gold clips. I hate giving up so early in the game.

Boeshield does better at getting a joint like that apart than WD40. Soak and give it a week.