I have an older schwinn roadbike frame that looks like its from the 70's or maybe the 80's. The serial number is on the bottom of the bottom bracket sideways. I checked schwinn serial number websites and apparently my bike frame doesn't exist because it starts with an I. My serial number is I702756. Before I had it powdercoated it was like a maroonish brown and yellow. Please help me figure out what frame this is.

Welcome to C&V.

Pictures and a list of the original components will be the only way for us to help you. Does it still have the round headbadge? If so, look for a small 4 digit number stamped in the badge. The first digit will tell us the year in either the '70s or '80s. Pictures of the lugs, seatpost collar, and rear dropouts are the most helpful along with the entire bike and the components. The "I" could be a badly stamped J or L.

I thought the last digit was the year and the first 3 were the day of the year (1 - 365).

Hi, Josh-

No "I"s (or "O's) were ever used in Schwinn SNs, I don't think, due to their similarity to 1 and 0.

All the Schwinn SNs with which I'm familiar are on the head tube (or head badge) or on the right drop out. So I'm thinking that what you're looking at is a part ID number. Look in the other spots and see if you find anything.

If that is a Serial Number, it could be a Japanese-made frame--then the letter could be J or L, as Pastor Bob says. In that case, J=September and L=November, and the second digit would be the last digit of the year (in the 1970s, I presume). That would make your bike 1977. Edit: According to a post on the Schwinn Forums by Scooper from 2006.

I think that some bikes before the 1960s had SNs elsewhere, but I'm not for sure. Edit: 1951 and before, according to "bunchobikes"--but weren't those mostly middleweight and heavyweight, with ashtabula crank?

I have an early 80s Japanese Schwinn, and it's SN, if I recall, is on the dropout.

Good quality, closeup pics of the frame (i.e., lugs, dropouts, etc.) and of the original components, if any, would help a lot.

Eric

Opps! I must have had a little brain freeze this evening.

FWIW, My 1984 Schwinn le tour has the serial number on the bottom bracket shell; it's a Greenville, Mississippi built Schwinn. The serial number starts with "SG4"

OHHHH, the Greenville-built Schwinns. Well, yes, of course they're different!

Er, actually, if they are, I didn't know that.

Oh, but of course, for me, Schwinn time ends in 1980, since the SLDB ends in 1980.

So, what's the formula for post 1980 Schwinn SNs, and what year does it stop being reliable?

At least as far as the Schwinn le tour models go, the serial numbers weren't on the bottom bracket shell until 1984; my 1983 has the serial number on the dropout, but the '84 has it on bb shell.

As far as '80's Schwinns having serial numbers that are reliable, I'm not sure many of them do, at least not the Greenville ones. The Greenville-built Schwinns often have serial numbers starting with "S" (which might indicate Greenville), then a letter representing month of manufacture, then a number representing year of manufacture. Such as the serial number starting with SG4 I mentioned above, which would seem to indicate Greenville, July, 1984. But we've discussed a bunch of these Greenville-built Schwinns here, and there are inconsistencies.

These should help some. Courtesy of Stan Cooper(Scooper)
Too early for the Greenville bikes though.

Some ...

For a Schwinn published bulletin, this has a few errors:

I. Serial number location:
C. 1952 - 1971 numbers were stamped on the left fork end.

This was moved in April of 1970.

III. Frame design:
C. Flash welding (butt welds on head and hanger projections) since 1958.

I think this has been around since 1949 (at least -- maybe I'm interpreting this wrong?).
https://www.trfindley.com/flschwinn_1...0/1949_19.html

IV. Parts innovation:
F. Middleweights introduced in 1956.

The Corvette was introduced in 1954 (for the '55 model year). Scooper's Dad is on the far left!
https://www.schwinnbike.com/heritage/...chmentid=35602

There is also the anomoly with Bridgestone using place holders for months prior to the model year (for example, November and December of 1982 for the '83 model year would be X3 and Y3, then January would be A3), but this probably started after this Bulletin was published (don't hold me to those years). I think some Panasonic (Japan) built Schwinns also had serials on the headtube (Voyageurs), but that probably came later as well. The '80s dating was crazy! We can't even get a straight answer out of Richard Schwinn.

Bob

I'm in the same position as the original poster - I have bike, headbadge says Schwinn Chicago, 4 digit code is 0267, has been repainted, so no decals to look at, has a serial number on the bottom bracket I637212 - and it is definitely an I - see photos of it in this thread
https://www.bikeforums.net/classic-vintage/571060-help-identifying-bike.html

I have a schwinn world, i think it is an 88 but i am not sure. The serial number is GL823390.

Does the serial number tell you what model the bike is?

No, unfortunately.

I have a "project bike" I got and am almost done- now trying to accurately date and get right decal. Atypical S/N on head tube is J1035494 I'd think this was a 1971 except for the 7 numerals instead of 6. It is a 5 speed tandem, I was told it was a twinn, but I'm thinking deluxe twinn now. Will get pix on soo, as I also need to assure rear reflector I got with it is period correct. Thanks!

My frame begins with "sf4" what could you tell me about it? The plaque on the front reads schwinn chicago with a stamp that reads 1734

F=June, 4=last digit of the year, and is probably 1984 but can be confirmed by paint scheme, decals, and components. The assembly date stamped into the head badge, 1734, is the 173rd day of the year ending in 4. So the frame was made in June and the bike was assembled in the third week of June.

I see [MENTION=38510]Scooper[/MENTION] beat me to it. I can add that the 1734 on the badge indicates a bike assembled on Friday June 22nd, 1984.

So, are post 1984 Schwinn's ID'd by: 1st letter = month, 1st number = year (ie 1977 or 87 if the number is 7) and the remaining numbers are just the production run?

For what it's worth, I have a 87 Schwinn Circuit Headbadge#0257 and SN#I637223

Someone on this thread has an unknown bike w/Headbadge#0267 and SN#I637212

This means that the badges of said user and mine were stamped on consecutive days - mine being a day older
My Circuit also has the "8" stamped on the bottom bracket.

I wouldn't want to infer too much as I don't know about the production process but seems like someone with that kind of knowledge could perhaps look at how close the Headbadge and SN numbers are on these two bikes and form some kind of hypothesis about ID'ing via SN.

Of course all this out the window if I missed the elephant in the room about later model Schwinn ID methods that exist somewhere out there now - in which case - please forgive.

The serial number format depends on who built the bicycle. I'm not an authority on Schwinn but I'm pretty good with Asian serial number formats and that format is consistent with Bridgestone, who were a known source for Schwinn. The first character in a Bridgestone S/N was a month, but then it changed to fortnight, sometime in the late 1980s. So, it could represent the 9th fortnight or September of a year ending with '6'. Based on the head badge code, September is more likely.

While some manufacturers do code model identification and further stratification into the serial number, it is quite rare to go beyond month or fortnight. When looking at the sequential frame number, two numbers that are fairly close to each other may be from the same batch but you really don't know when one batch ends and another starts. Once you have a manufacturer, year and month or fortnight, you are typically better off identifying the decade and model via frame features and/or components.

I have a 1989 Schwinn Tempo 7 speed road Bike with Shimano 105 components. The SN on the B.B. Shell is: 0978381. SN on head badge is: 0939

I always find myself wishing that when sellers post pics on CL they would take pics from the drive side and show close ups of the rear sprocket area.

I just picked up a sweet Kool Lemon yellow Schwinn Continental at an estate sale. It's in excellent condition and just needs some cleaning and detailing. My question is the serial number -- I want to identify the year of the bike. When I entered the serial number on the Schwinn serial number lookup , it came back as invalid. So, the serial number which appears under to theft of the name place is
J 006609.
Any help deciphering this would be greatly appreciated.

I suspect you're missing a character. There should be two letters at the beginning of the serial number - "JJ" would be September of 1973 while :"JK" would be September of 1974. Yellow Continentals were in the 1972- 1974 catalogs:
Schwinn catalogs, 1971 - 1980 (59 of 579)
Schwinn catalogs, 1971 - 1980 (113 of 579)
Schwinn catalogs, 1971 - 1980 (172 of 579)

That is all that is stamped on my bike - I tried to upload a picture but I received a message that I am not allowed to upload photos until I've made 10 posts??