ennchicago

Hello,

A few weeks ago I sold the 22" 1974 Sports Tourer I had bought as a project bike after realizing that it was just too small for me. But I really loved the handling of that bike, and I'd like to find something comparable. You could walk it with a hand on the saddle while paying no attention at all and the front wheel would stay in a straight line, but it didn't feel sluggish turning corners. It just felt very well balanced.

So I've been looking for a 24" Sports Tourer to turn into a singlespeed, but they seem to be hard to find. There are, however, a number of fillet-brazed Super Sports from the same era. I understand that the Super Sport was a cheaper bike with lower-quality components, but since I'll be replacing most of the drivetrain, that is not a big issue for me. What I'd like to know is, what handling/geometry differences were there between the Super Sport and the Sports Tourer?

A secondary question: On the Sports Tourer the three-piece Nervar crankset seemed fine and I probably would not have replaced it. The Super Sport has a one-piece Ashtabula crankset. Should I replace this with something newer and/or better? Or just leave it alone?

sailorbenjamin

The geometry is the same, they just changed the bottom bracket.
The one piece crank is 3 or 4 pounds. Nothing wrong with it other than that. Excellent craftsmanship and good chrome. I have one on my SS Continental. The 3 piece conversions will save you a pound or two and perhaps open up some crank options. The BMX crowd has a lot of interesting cranks to fit this BB.

mparker326

Super Sport doesn't have the chromed fork. While I like these frames a lot, I'd look for a lighter candidate for a SS conversion.

ennchicago

Thanks for confirming that the geometry is the same--it's very helpful to know that. Any idea what the biggest tires I could fit might be, if I went to 700c wheels, or 650b wheels?

My thinking was that this would be a city bike (in my very flat city) with rack, maybe fenders, usually a pannier--so I am not super concerned with weight. My current bike is a modern, light-ish (compared to a 70s Schwinn, anyway), purpose-built single-speed with more responsive steering, so I'd have that as an option when I don't want to be weighed down.

But I'm definitely open to other suggestions for frames with similar handling but lighter weight. My problem is that I don't know enough to be able to look at a frame and tell how it will feel to ride, which is why I thought I'd stick with a bike that I know feels good to me, rather than taking a chance on an unknown old steel frame and possibly ending up with something with the twitchy race bike handling that I don't care for.

Scooper

A 1973 24" Super Sport frame without headset, BB cups, or kickstand weighs 7.05 pounds, and the fork without the crown race weighs 1.96 pounds. They'd make a great handling single-speed or fixed gear frameset and with the straight-gauge 4130 fillet brazed tubing they can take abuse.

The TruVative BB adapter can be used to install a three-piece crankset with modern bottom bracket on a Super Sport frame. Also, because most of these bikes used claw mounted rear derailleurs, you don't have to feel guilty about hacking off a derailleur hanger.

sailorbenjamin

Yeah but they are stiffer than anything else out there.

Scooper

I've got 700c x 25 tires on my '73 SS, and I could fit 32s. The seat stays and fork wouldn't be a problem for an even bigger tire, but the chainstays might. With the 25mm rear tire, I have about 5mm clearance on each side between the tire and the chainstays (10mm total), but my rear has been cold set from 120mm to 130mm, so I have a little more chainstay clearance than a stock 120mm rear spacing.

zukahn1 

+1 on the BMX crank for either a 3 piece or 1 peice there are a lot of BMX cranks that will fit old Schwinns just nice for a FG/SS they bolt right in and give the right chainline and save you 1-2lbs wieght. Personnaly I would look for something a little lighter and more comaptiable with modern parts. You can get a vintage Japanese frame/bike in project condtion with SS/FG freindly drops that will take modern SS/FG parts in better quality chro-mo for less than half of what Schwinn would cost and it will be just as stiff and make better bike.

As for tire clearance on the Schwinns you can run 28's with fenders or 35's without fenders.

Scooper

35mm tires on a 700c rim would be a very tight fit at the chain stays. This is a 25mm tire, and there's only 5mm clearance on each side. When you figure 1mm lateral truing tolerance, the tire would likely rub.





Fork and seat stays, no problem.

Fork:


Seat Stays:

sailorbenjamin

Just don't use any truing tolerance

Scooper

DiegoFrogs

Correct me if I'm wrong, but from what I see in your picture, 25 + (10 x 2) ~ 45 mm. Of course, that seems like it'd be cutting it close, but I'm sure 32 or 35 wouldn't be a problem.

Scooper

Since there's only 5 mm clearance on each side, it would be 25 + (5 x 2) ~ 35 mm.

Rabid Koala

Stan, I never get tired of seeing your Super Sport (or any of your other bikes!)

Scooper

Thanks, RK. I love 'em all.

I taped pieces of paper to the chain stays at the point where the tire casing is the widest, and taped a millimeter scale across the chain stays at that point, marking as closely as I could, the inside surfaces of the chain stay tubes on both side. There is a little parallax from the camera, but those marks are within a fraction of a millimeter.

The 25 mm tire casing is actually 25.7 mm wide inflated to 115 psi. There is about 6.5 mm clearance (6 mm on one side and 7 mm on the other - the wheel must be a little out of true). It's not 5 mm as indicated above when I attempted to measure it without removing the rear wheel. The distance between the inside surfaces of the two chain stays at the point where the tire casing is widest is approximately 39 mm.

So, 39 mm - 25.7 mm = 13.3 mm, or 6.65 mm per side.

A 35 mm tire might fit if the casing of the inflated tire isn't much more than 35 mm, but it would be extremely tight. 39 mm between the stays - 35 mm casing leaves only 2 mm of clearance on each side. 32 mm wouldn't present any problem.

One other factor to keep in mind is that a 35 mm tire casing will be at its widest about 5 mm closer to the BB shell than the widest part of a 25 mm tire casing; the chain stays will be even closer together providing even less clearance.

kroozer 

I have a 1972 Super Sport with 27x1-3/8 tires--they barely fit, without fenders.
Is there any difference in the frames besides the dropouts (different tubing, etc.)?

peazweag

FYI 1970 and before does have a chrome fork

rhenning

This is a 1973 SS SS I built out of a $20 Schwinn SS. 700C wheels and and 32mm tires and complete with the one piece Astabula cranks. If was heavy anyway so what is a pound one way or another. A very nice riding bike. The paint looks better in the pictures than in real life. Roger

ennchicago

Unfortunately they seem to go for a bit more than $20 around here. I love the yellow color.

Did you find that going from the 27" wheels to the 700C wheels affected the handling at all?

Scooper

In my case, the answer is no. It's only a 4 mm difference in rim radius (630 mm bead seat diameter for 27", 622 mm BSD for 700c).

I did have to use long reach brakes (Tektro Silvers), though. Also, the BB drop is 75 mm, so it's a little bit lower than most frames built for 700c wheels (my 1972 P15 Paramount has a BB drop of 70 mm). This could create a slightly higher risk of pedal strike in a sharp turn if you have long crank arms and/or long pedal spindles.

DsmBerg

On my 72 super sport I have had 1.25 x 27 paselas and to me that's as big of a tire as I would ever want. I also dig the 27" weinmanns for their durability.

If the crank arms are long enough and you don't care about weight, I would stick with the one-piece crank. I like being able to buy new chainrings for $8 and replacing them in 5 minutes. If you don't have hills you will get tired of the original Schwinn-branded 39t inner chainring but it works pretty well for me since this is not a masher.

rhenning

Ennchicago there is no difference in the ride between the ride with 27s or 700. I live with in 90 miles of Chicage and find SSs all the time. The most I have paid is $125 for a 1966. I had a twin to the one you see in very dirty condition given to me for free by a bike shop owner in Crystal Lake last fall. Cleaned 1/8 of an inch of grime off of the bike and it is one of the best I own and that one is a 1973. The single speed one is actually a 1970 which is my mistake. More SS pictures of the others I own. Roger