Identify this Schwinn triple crankset

[momo608]

Anyone know what this was used on?

 

[Metacortex]

The crank dates from the 17th week of 1971. There were no triples from Schwinn that year, and none ever to my knowledge using that style of chainrings. In other words it appears to be homemade, not factory issue.

IMHO whoever did this did a very good job. They used what appears to be the earlier chrome "Sprint" style chainring bolts to attach the inner ring, and the ring they chose does not look out of place with the others. They also correctly used a spacer behind the fixed cone to correct the chainline.

 

[GTs58]

I'm not aware of any later production bike that had 15 gears using the one piece crank. Must be a hot rod part that was available at the dealers. That style was first used in 1968 and everything having three rings then and after had the three piece cranks. I'm sure Meta will know for sure.

Duh, I'm to late

 

[momo608]

Thanks! I bid on this and lost, blessing in disguise probably. I figured the new crank and chain guard were worth something at least. I did some checking before that in the catalogs and like both of you came to the same conclusion that there were no applications for this. I agree that whoever did this made it look factory. Since we are taking guesses here, it probably was done many years ago and didn't work very well or at all with the derailleurs that would have gone along with something like this. I was hoping it was some factory freak I never heard of.

 

[Metacortex]

Thanks! I bid on this and lost, blessing in disguise probably. I figured the new crank and chain guard were worth something at least.

It went for only $42.35 including shipping: http://www.ebay.com/itm/391374377710

Very interesting. I'd have probably bought it for that money but not much more though. Another clue to the home-made nature is looking at the close-up backside pic you can tell that the tooth profile on the inner ring is different from the others. Still a very well done piece and a cool idea I'll save for a possible future project.

 

[momo608]

Still a very well done piece and a cool idea I'll save for a possible future project. They also correctly used a spacer behind the fixed cone to correct the chainline.

It would be something out of the ordinary that's for sure. I had some ideas on how to make it work. Take the cage assembly off one of these and swap it over to a Schwinn approved. The stem shifters should work, they used those on some 70's Paramount triples. The only thing I am not sure of, can a Schwinn approved front derailleur handle the spread.

Maybe on the spacer. It could have been hitting the inner ring on the chainstay. I had this worry on that triple I put on that green Varsity. It is close, the bottom bracket actually protrudes into the chainrings. I had to do a little filing on the kickstand tube. Just by shear luck, my chainline was excellent with the parts I had on hand, but this tells you where you need to be to get a good chainline.


The more I think about this, the worse it gets. He has a really thick spacer in there. This could very well have had disastrous results on the kickstand side. Not enough exposed threads for the jamb nut and or the crank hitting the kickstand. This has all the signs of a good idea going really bad. Could have used that crank though.

 

[Eric Amlie]

I think the front derailleur will handle the triple.
The old Huret and later Sprint derailleurs handled the triples on the Super Continentals, Sierras, & Superiors from the early to mid sixties.
I would think the Schwinn Approved that replaced the Sprint would be a pretty similar design.

 

[momo608]

Good points. This inner ring looks to be 30T or 31T. What did the those old 15 speed bikes use? I have doubts the front derailleur cage on a typical Schwinn approved could accommodate this chain ring, not long enough.

 

[Metacortex]

The '62-'64 OPC triples had 40-47-52T chainrings so the smallest ring wasn't that small. The '68 S/S Tourer had a triple crankset with 38-45-52T rings, not really that much different, plus the new doubles that year were 39-52T.

The Schwinn Approved (aka Huret) front derailleur does work with 36-54T chainrings as that is what came on the '71 Sports Tourer and the one I ride shifts quite well. However Schwinn did change the ST from a 36T to a 40T small ring in late '71 because of shifting problems and there is a big difference between 30 and 36T rings so I can't say for sure if it would shift that small a ring very well if at all. I have the parts to build up a 32-40-54T triple crankset I was planning on installing on a Sports Tourer or Super Sport, if or when I do I guess I'll find out how well that works.

 

[momo608]

Yes, it is very unlikely any off the shelf Schwinn derailleurs would work with this set up. I have some experience with these wide ratio triples with very small inner rings. They require very long cage derailleurs front and rear specifically designed for wide ratio triples.

I guess you could call the Schwinn triple of the 60's a close ratio chainring assembly. You can see some great detail pics of a Super Continental here. Everything looks correct except the rear derailluer.


http://s1103.photobucket.com/user/drker/library/1962 Schwinn Super Continental?sort=3&page=1