Vintage Trek serial number?
 

What can you tell me about my vintage Trek with serial number Thanks

Vintage Trek Bikes- Information on Steel Road Bicycles made by the Trek Bicycle Corporation, bike

http://vintage-trek.com/SerialNumbers.htm

Looks like a model 310 made in 78 according to the vintage trek site.

But it seems to be a 1980 750 Pro with Cinelli BB and Shimano semi vertical dropouts

Paging @JohnDThompson

My frame looks like this one except for color and is built with Reynolds 531:

http://veloclassics.blogspot.com/201....html?spref=pi

Help us out; post some pics. Both of the entire bike/frameset, and some detail shots.

If your frame is Reynolds 531, and has the Shimano UF semi-vertical dropouts and Cinelli bottom bracket shell, it is an early production 750 frame. Those dropouts and shells were only used on the 750/950 series frames.

I'm quite confident it is a 750 but the serial number date of 1978 and the A prefix don't fit in with the normal serial number pattern. Is it possible a 750 was made in 1978? My understanding is that the 750 was designed by Tim Isaak and he wasn't hired until 1979 according to the Trek timeline.

I know what my bike is, I'm not trying to identify it. I don't understand how it's serial number relates to it.

Compare the geometry against the specs in the 1981 catalog. Perhaps its a custom with an odd serial number?

No. The 750/950 series frames were the first to use investment cast bottom bracket shells and UF dropouts, and they didn't start production until 1981. The 1970s production used Nikko bulge-formed bottom bracket shells and Campagnolo 1010 dropouts.

I measured and the seat tube is between the numbers shown. Mine is 57, stock is 56 and 59. This measurement varying from the stock specifications, along with the apparently strange serial number, may indicate a custom frame.