Trek 520 question
 

I have a Trek 520 and was measuring the seat post tube to get a spacer for my USE post to fit. I measured that seat tube several times and am still not sure if it is 27 or 27.2. Thoughts? I am starting top think that the difference is bunk.

I have a Mieta Lupa frame that I was told was 27.2 and I am having a hell of a time get a 27.2 post down easy enough to make hieght adjustment easy. It is really tight and I even polished it. Is the seat tube clean, yes.

Seat post are driving me crazy:mad:

My guess would be 27.2 based on Sheldon's seat post database. It seems to have been a fairly common size for the older Trek's. If you want to be positive you could take it down to your LBS and have them measure it with a special post they ought to have.

Have you gently spread the "ears"?

Yes, on the Mieta I have worked it quite a bit. It is STILL tight :mad:
Makes me want to turn down the seat post if i could work my leth better. I have a same leth but i am a beginner.

My 1988 has a 27.2 mm seat post, but that was the last year of the 531 main frame. Trek used several different tube sets over the years, so I can't say if mine is the same as yours.

My wife had a slightly later 520-- we bought the frame only as a closeout in 1991, it was NOS a couple years old by then; and it took a 26.8 post. It was purple, and the tubing was TrueTemper, if that helps narrow the year down.

Ironically, in 1991 the closeout price on the 520 frame was $335, exactly the same as I paid for my 720 frame brand new in 1983.