cocoabeachcrab 

what is a best (and lightest) Schwinn frame with an american size bottom bracket? another grand dad/ grand daughter project in the wings....

dddd

Supersport I'd say.

JohnDThompson 

I agree with @dddd; the Super Sport. The frame is straight-gauge seamless Chrome-Moly tubing, fillet brazed by hand, rather than "electroforged" like the Varsity and Continental models. The bottom bracket shell is sized for press-fit Astabula cups and crank.

https://bikehistory.org/bikes/sport/

Rotten

Circuit, Peleton, Tempo, Premis to name a few more

I have a Circuit it is a very responsive and comfortable ride.

branko_76 

Were there Super Sports with forged dropouts? I thought I have seen them with forged and others with stamped.

dmark 

Yes up until 1970 or 69

1964Supersport

I would like to add as the original owner of a 1964 Supersport they are very lightweight.

Vintage Schwinn

My guess is the 1975 through 1977 SCHWINN TRAVELER. Its basically similar to the Le Tour, except specified by Schwinn engineers with the ONE PIECE CRANK.
This 1975, 1976, 1977 TRAVELER was lugged frame of 1020 steel if my recollection is accurate.
I think the 1975, 1976, 1977 TRAVELER has the Shimano built for Schwinn, GT-120 rear derailleur which was original equipment on the 1974-1977 Collegiate and '74-'76 Suburban five speeds before FFS came on the scene. The Le Tour came with a lighter weight Shimano rear derailleur. The GT-120 is heavier, and nearly bombproof and indestructible. The Le Tour's Shimano was great too but, the GT-120 was better suited to bicycles that were gonna be ridden and cared for by folks that routinely treated their bicycles with the same care as the angry American Tourister Gorilla treated American Tourister Luggage in those early seventies television commercials.
The typical lightest, smallest framed 1975, 1976, 1977 Traveler weighed approx. 32 pounds in factory form. The typical lightest smallest frame sized Le Tour from that era weighed approx 23 ounces less than the Traveler did in 1975, 1976, 1977 (.....so perhaps the lightest-smallest LeTour was 30.7 pounds in factory form at that time ) I might be overstating the "lightness" of both the Traveler & Le Tour of that time, so you'll need to double check the actual published specs. Imported from JAPAN built for Schwinn by Panasonic. The Le Tour has better spec caliper brakes than the Traveler does (very much like the differences between the Varsity and Continental).
For the 1978 model, the Traveler adopted an alloy 3 piece crank and was referred to as the Schwinn Traveler III.
I might be foggy and wrong on what I think I remember, so double check all of what I just mentioned for accuracy.

The bike boom era SCHWINN SUPER SPORT is going to be around the same overall weight. Now the SUPER SPORT is not an electroforged frame! The frame geometry differs some from the Varsity-Continental-Suburban. The frame angles are not as slack, and the Super Sport is more responsive to rider steering input, and is not as easy to ride with NO HANDS as the Varsity-Continental-Suburban-Collegiate...electroforged variants are.
The '71 SUPER SPORT came from the factory with aluminum wheels and the same 52/39 one piece crank as the Varsity/Continental/Suburban 10 speeds.
This SUPER SPORT has the same 32-14 freewheel gearing as the '70 and later Collegiate/Suburban five speed.
The Varsity/10speedSUBURBAN/Continental has the French made 28 -14 freewheel and the 52/39 one piece crank.
The Imported from Japan, built for Schwinn, Le Tours and Travelers of '75, '76, '77 have freewheel gearing in the 28 - 14 range, even though that GT-120 rear derailleur that is fitted to those Travelers, handles the 32 -14 range. (the seventies era Collegiate five speeds & five speed Suburbans have the Model J 32-14 freewheel)
THOSE Shimano built 32-14 Model J freewheels are very desirable, as are period aftermarket Maeda SUNTOUR 32-14 and 34-14 freewheels from both Maeda SUNTOUR and SHIMANO. WHY IS SUCH A five Freewheel A GREAT ADDITION/UPGRADE TO a period Ten Speed?? Simply because it gives you exponentially greater Hill Climbing Ability over having only the 28 tooth first gear cog, assuming that 39T is your smaller front chainring.
Certainly, you could go with a smaller front chainring , and retain the 14 -28 in the rear, but this is not nearly as practical and easy as going with the Big FIRST GEAR cog at the rear on the freewheel.


My ADVICE on this project subject that you are considering is just find the exact Size & exact COLOR that you LOVE of any of the ELECTROFORGED VARSITY-SUBURBAN-CONTINENTALS......
.........buy a NEW set of AFTERMARKET aluminum wheels for around ~ $100 for set of two with free shipping in 27 x 1 1/4 (630mm) or you could go with New set of AFTERMARKET aluminum wheels in 700C (622mm) for perhaps around ~$115 for a set of two with free shipping.
Now these basic cheap aluminum 36 spoke wheels are not perfectly true as you'll receive them but they are close enough that you should be able to get them pretty darn close to perfect, if you've never done any truing before and you only have a basic spoke wrench and your bicycle turned upside down.
Now are these currently available AFTERMARKET New Wheelsets, as good or better than factory equipment wheelsets as seen on various 1981 through 1985 ten and twelve speed bicycles with 27 INCH (630mm) aluminum wheels? NO!! No, they are not, but chances are that most 40 year old used aluminum 27"-630mm wheelsets that you might have access to, are going to be slightly battered and out of round/with significant run-out. Chances are, if they were a near perfect 40 year old aluminum 27"-630mm wheelset, they would be currently in use on on of your other vintage bikes or being used currently by one of your riding buddies on one of his/her classic rides.

Now, it is possible to build & lace your own set of wheels from the hubs of your choice, but this realistically is beyond the skills of at least half of the cycling population.
Sure, it isn't rocket science, but it requires patience and skill, that you could learn from doing it, but for some it will be biting off more than they can chew at this point in time. You might need assistance to get it decently together......very much like someone with no prior experience attempting to tune any stringed musical instrument for the first time ever..........they are gonna need someone to get it in tune( ...someone to show them, what they have done wrong..) so that something musical can be played on the instrument).

I'd recommend keeping the 27" (630mm) wheel size. BUT YOU COULD GO WITH 700C (622mm) or the NON-SCHWINN (590mm) wheelsets. Yes, believe it or not, you can buy NEW aftermarket 590mm 26 x 1 3/8 (NON-SCHWINN) wheel sets. Yes, it becomes slightly more difficult if you go with 700C-622mm or the 590mm but it is still easy enough. THE COLLEGIATE & other 26(597mm) Schwinn 3 speed variants like the Breeze, Speedster, Racer, sixties era chicago built Traveler, WILL HAVE THE WEINMAN 810 sidepull brakes which are known as L.S. 2.8 schwinnWeinmann sidepulls from 1969 model year onward. THESE 810 / L.S. 2.8 ARE THE EXACT SAME THINGS, it just depends on year era as to what the heck is stamped into them, so they read 810 or L.S. 2.8 depending on if pre 1969 or 1969 & later.
THESE 810 / L.S. 2.8 sidepulls are the LONGER REACH calipers that allow the 26"(597mm s5/s6 26 x 1 3/8 schwinn WHEELS) to work on Schwinn's "lightweight" ELECTROFORGED frames. Electroforged frames are not really lightweight but Schwinn classified them as lightweight at that time, so this is why the word lighweight has been placed in quotation marks when referring to Schwinn's "lightweight" ELECTROFORGED frames.
Now, the VARSITY/SUBURBAN has WEINMANN side pulls which are marked L.S. 2.4 from 1969 model year and later. The mid sixties through 1968, 27"(630mm) VARSITY has these exact same Weinmann side pulls......they have a Weinmann number instead of that Schwinn LS 2.4 code that the '69 and later versions have. They are the same sidepulls though whether a '65, '66, '67, '68 27" 630mmVarsity or a '69 and later 27" 630mm VARSITY-SUBURBAN.
Now as you may have imagined, there are potential upgrades & part swapping within the ordinary early seventies era VARSITY-SUBURBAN-CONTINENTAL (schwinn parts bin)
The seventies (...certainly the '72 - '75..) CONTINENTAL has a very desireable (S) alloy stem . ***YOU DO NOT WANT THE LATE SIXTIES ERA aluminum Schwinn stem that was seen on deluxe and some ordinary Collegiates, Varsities & Continentals**** those late sixties versions look distinctly different, very much like the notorious death stems...
The Continental's drop bars are also lightweight comparatively speaking compared to drop bars of the Varsity.
As mentioned earlier the Model J 32-14 freewheel from the 1970 - 1977 Collegiate & 5 speed SUBURBAN model '70-'76 will give you excellent HILL climbing compared to the ordinary typical 28-14 of the VARSITY-10speed Suburban--CONTINENTAL---Le Tour---and most seventies era ten speeds.
****You Will need a JAPANESE REAR DERAILLEUR cabable of 32 cog teeth, the EUROPEANS can't get the job done, reliably anyway, on anything beyond 28 cog teeth. Suntour and Shimano brought the world 32 cog and 34 cog teeth First Gear-LOWEST GEAR five freewheels and rear derailleurs that could reliably & perfectly shift these teethy animals that made HILL CLIMBING much better for normal mortals during the 10 speed Seventies bike boom era.
The SUBURBANS have the TUBULAR front fork that is original equipment on the Schwinn Continental.
The VARSITY and all of the Collegiate-597mm electroforged variants of the sixties and seventies HAVE the FORGED Ashtabula BLADE front fork.
The SUBURBAN has the Tubular front fork of the Continental, but the SUBURBAN has the same exact Weinmann sidepulls (L.S. 2.8) as the VARSITY has.
The CONTINENTAL has weinmann CENTERPULL brakes, while the SUBURBAN has the sidepulls of the VARSITY.


Now, if I recall correctly, PANASONIC also offered a PANASONIC badged bicycle during the mid to late seventies, that was about exactly the same as that Schwinn engineering specified ONE PIECE CRANK lugged Schwinn Traveler of 1975, 1976, 1977.
It was a good move, in that it produced an unbreakeable, extremely durable 10 speed that was perfect for those who didn't have a care at all except that the bike would as the old Timex watch slogan that John Cameron Swayzee would always repeat, "It takes a lickin' and it keeps on tickin'.
The one piece crank is simplicity at its finest, designed to withstand more torture than any other crank design can from crazy riding imbecile 12 year olds and the drug crazed teen-agers of that wild 1968 to 1977 era. (imagine period tv characters Jody Davis, Danny Partridge & Julie Cooper livin' the hi life on their 10 speeds in the early seventies....)

Most importantly, find the size bike that you feel is best for you, and build from that.
The Weight isn't gonna matter a whole helluva lot.
People have shown that they can keep the One Piece crank on an early Seventies VARSITY and get that same Varsity to the 30 pound mark or even less.
Yeah, that is still heavy by any 21st Century measurements.
GEARING that is best suited to your typical riding and a very comfortable and enjoyable bike that doesn't beat you to death when you ride it, is probably what you should strive for. Steel delivers a comfortable, old Cadillac, Rolls-Royce like ride but like those old vintage luxury autos, they do weigh two tons. If you can get it geared to have the best suitable GEAR range for how and where you will ride, then you're all set, assuming that you can adequately stop the beast, and also assuming that all of your mechanical choices are bulletproof and flawless, problem free, so that everything works perfectly so that it is a joy to ride anywhere, anytime that you want to ride.
Remember that something that looks cool but doesn't work reliably is not cool at all, you will find that out very very soon, if you don't just let said bike with the cool but unreliable component, just gather dust hanging in your basement, while you routinely ride other more dependable bikes.
Do build it the way that you want to! That is nearly as fun as riding them and showing off the superb example that you have built.
Don't worry about keeping anything original equipment or year correct. Have it your way.
Consider yourself the corporate product planner & chief engineer, as if you were heading that bicycle manufacturer way back in the day.
There are no rules except have fun. Have fun riding them. Have fun building them.
Don't worry if you realize later that you want to modify or change something. Sometimes you gotta just try and then ride it and evaluate your findings and then maybe make a few changes, etc Don't worry about keeping the exact factory decals, or even period correct decals... Heck, its your creation and if you see it a certain way with particular mix-match of decals from that original mfr, that is the way to go, or if you want to badge it of your own creation, that is fine too........You are the boss. Anything that you want to do is possible. Nobody else matters. Have the most fun building and designing it, and assuming all goes right, you will have the most fun riding it because you did build it your way.

branko_76 

wow

some great info