doubravsky 

I recently purchased this Cannondale tandem. How do I go about determining the model year? The info I found on a vintage cannondale site pointed to looking for a serial number under the crank, but I don't think that works for tandems.

doubravsky 

I did find this stamped on the bottom of the rear triangle... will that number help?

doubravsky 

here are a few more pics....

Philly Tandem

If you post details of the components, that would help date it. My guess is mid-late 90s, but I can't quite make out the components. 7, 8 or 9 speed? What model RD? The quill stem also dates it as an older bike.

doubravsky 

It is a 7 speed with Phil Wood freewheel.... definitely older... I figured somewhere around early nineties..... RD? is that short for rear derailleur? I'll have to check when I get home..stuck at work right now... the serial number is under the rear chainstay... which according to the vinatge cannondale site makes it between 86-92, but the numbering system doesn't seem to fit what they say about it for those years.
It has sti shifters but the seller indicated that they were an upgrade. cantilever brakes.... the stoker stem on it when I bought it was a santana with cinelli drop bars, which must be replacements.

Paul J

Looking at the catalogs I'd say it is an 89 or 90.

https://www.vintagecannondale.com/year/1990/1990.pdf

mulveyr 

It looks just like my '91 Cannondale, except the lettering on mine is the thicker style that I believe they started using in the early 90's. So Paul J's guess of a 1990 model seems reasonable.

For what it's worth, my serial number is etched inside the left chainstay very close to the dropout, and is almost impossible to read without shining a light obliquely on it.

doubravsky 

Thanks for the info! That's the same spot where my serial # is too.

Also, on the downtube, just above the bottom bracket, are what looks to be a couple of bottle holder screws. Seems like a weird place to put a water bottle. Are they there for a different purpose?

mulveyr 

I believe those are guides for a drum brake cable.

Paul J

Early touring bikes had water bottle bosses low on the down-tube for a bike of that vintage. If you look at the touring bike in the catalog I linked above you'll see that on one of the higher-end bikes.

Tom Spohn

Ummm My 2011 Cannondale has the bosses also.

specbill

It is a first generation C'dale Tandem. The first four digits of the serial # (Under the left chain stay) will give you the month and year the frame was welded up. It looks to be in nice shape and pretty original for the type of builds of the day. We had two of them, put in a lot of miles and great memories on one of them.
Bill J

TandemGeek

The pin-dot number is your serial number; a bit hard to read but it looks like this:

First four digits are the frame size: 2321 (As in 23" front & 21" rear)
The next four digits are the month/year of manufacture: Looks like 0488, or April 1988
the next three digits are the sequence number for that month: 009 = 9th tandem frame made in April '88

So, what it looks like you have there is one of the first-year Cannondale tandem frames, noting that Cannondale didn't start selling fully assembled tandem until 1993.

doubravsky 

Thanks to all for the help! It's a little older than I expected, not that the difference between being 20 and 25 years old matters much. I'm excited to have found it.... now I just have to get my wife to love it too

Paul J

My experience was back to the days I worked at Trek where we didn't have bosses on the seat tube as that was where your pump went and rather they were on the down tube top and bottom. Our 98 Cannondale tandem had them too but I haven't taken notice on the later models so didn't know they were still putting them there. We used those bosses for our repair kit when we wanted to add bottles. Trek stopped putting them on the bottom of the down tube in the early 80's if memory serves me right.

specbill

What TG says....the Manufacture month and year are the second four digits...not the first four.

Philly Tandem

Bottle bosses under the down tube have been common on touring bikes for a long time, and you'll still find them on many touring-specific frames. Those of us with liquid-fuel stoves sometimes use that location to carry the fuel bottle (in a regular bottle cage) so there aren't any worries about it leaking in a pannier.

Cannondale was originally mainly focused on touring, so it's not surprising that their early tandem frames had those bosses. I still have a Cannondale sleeping bag from the 1980s that I bought while I was in Boy Scouts. I guess it's a collectors-item now!