Originally Posted by Binky

I noticed that my new-to-me 1986 ALAN Record has a slightly flattened oval top tube.
At the front and rear of the bike, where it fits into the seat post lug and head tube lug the top tube is round, and about 1 inch in diameter.

In the middle of the tube the top tube is slightly flattened, and measures about an inch and an eighth wide ( looking down from the top ) and about seven eighths of an inch ( when seen from the side ) at the middle cable guide.

The way the reflected light hits the frame makes the difference obvious. (See picture).

I'm wondering if this is of structural benefit and if it is why isn'y it a more common design feature ?

Bink

Originally Posted by Surfer77

Yes, totally original. I have seen a number of Alan road frames with this flattened top tube.
Not sure what the reasoning behind this feature is!

-Robyn