I know there are better bikes but no bike I have tried fits me better than this bike. I have short legs and a long torso. My 87 520 has a 21" frame.

I don't use any of the other bikes I have, I use the Trek 520 for commuting, going to the post office, taking 100 mile trips to the nearest city and so on. I used it loaded down and naked.

I do need a backup bike and don't know if I will find another 21 inch 520. Trying to find another bike that fits me this well I think will involve trying too many different bikes and there is no LBS in my county to look at other bikes.

Since I have not been able to find another lugged 21 87 520 I wonder what other bikes used this same frame.

Here's a link to the 87 brochure.
https://www.vintage-trek.com/TrekBrochure1987.htm
The last page has he measurement for your frame as well as other. Important numbers are set tube and top tube length and seat tube and head tube angle. Also, it looks like measurement D is incorrectly labeled. should be top tube length.

A quick looks shows the 500/400/330 is similar with shorter stays. Should fit you the same and be easier to locate.

See the frame geometry project.

Thanks, unless I am mistaken the 520 in 87 is unique and other bikes don't share an identical frame. I don't know how much the difference will affect fit so maybe I should hold out till I can get another Trek 520. I will start comparing years of 520s to see how much different they are.

I will take another look. Maybe the difference will not affect fit.

Thanks for the link.

I got a backup 520, I know it will fit since I have a pair of identical bikes now. Very happy now.