I have an '85 620 frame (in need of TLC) set to arrive here in a few days. Just got an '83 520 frame too, beautiful bike.

I've been reading up on the geometries of various 620s and have found that Trek seems to have played with the geometry of the bike. If it truly is an 85, mine should come with 47cm stays. Only the year before, it had 44 or 43 cm stays and geometry that otherwise matched the '84 520. What's the story with the changes?

The '85 620 has pretty much the same geometry as the 720, only I think with 73 degree ST and HT angles instead of the more relaxed 72.5 of the 720. The overall wheelbase is very close.

I'm especially wondering how the 620 will handle with a rack above the front wheel rather than low riders.

My thinking is to build a tourer that manages to be lightweight, stable, aerodynamic, and spacious. (in that order of importance as I make compromises) I have some pretty serious lightweight camping gear, so I doubt I'll ever have to do anything "fully loaded" like some of the folks I've seen out on the roads.

As I look into componentry, I'd love to see photos and build lists of your 620 builds, especially '85's with the longer stays. Has anyone toured on theirs?

Based upon the color, I think the 620 I'm sending you is a 1984.

had an 85 painted like an 86 elance (different decals, silver headtube)

good bikes, traded the frame for a specialized expedition which fit me better and used real lugs. the trek has a one piece headtube lug combo cast thing...

geometry is great, a real land yacht.

uh oh, that'll definitely make for a different build direction than I had been thinking! I went right to the brochures on vintage-trek.com to look up the geometry on the '85 before going ahead and picking it up from ya. Guess I should have double checked the colors, too. Oh well, that's what C&V is about sometimes. It's hard to 100% ID older stuff -- I'm sure you didn't know that one year would make that much diff.

Here's a 1984.


Looks like what you're sending.

The Chainstays on this one are clearly more like the 47cm of the '85:

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Oh well. Guess I'm going to have to find an '85 or track down a 720.

Go here: https://www.vintage-trek.com/SerialNumbers.htm to use the serial number to determine the year of production of older Trek bikes.
Good luck finding a 720, they have quite the following. My wife and I both tour on them.

All of the older Trek bikes have one real weakness: where the seat stays attach to the seat tube. They just didn't get enough metal in there. It's pretty, but it is the most likely place to break. Check for cracks regularly. If it does crack, no worries. Just take it to a framebuilder and have him/her replace them with a stronger configuration. It's a good time to get better spacing in the rear dropouts too. I paid about $150 to have that done on one of mine.

just for the record, the 620 and 720 have completely different seatstay/seattube attachments. the 620s have a one piece forged "lug" where the 720 had the more typical hand-brazed situation... this part was not a problem on my or my former roommates 1985 620s

the 85 620 is a great bike.

Yeah, I was really excited to see the geometry of the '85. NoahScrape made an honest mistake in ID (we've talked it over and everything is squared away.) NBD.

Anyway, it's never a bad thing to have a cool 531 frame on the way in the mail!

Honestly, with my lightweight silnylon camping gear, I really might be happy with a minimalist lightweight touring bike. It might not be such a bad a frame to build up for long distances-- I really shouldn't need large panniers at all.

Or maybe I should venture over to the CX forum with my frame...

Good to know, and good to know what to expect as a repair cost. At that, I could probably look into getting longer seatstays done, which might be a cool option. I'll never be able to afford a $2k touring bike, but gradually building one up might be feasible.

It looks like that varied by year. I just looked at my wife's '84 720 next to her sister's '84 620. I just don't see a difference in the seatstay/seattube attachments. Looking at low-resolution images from the '84 and '85 catalogs, it looks like they fixed this problem in both bikes in 1985. Of course, I could just be missing the obvious. Maybe I'll have to get off my flu-weakened hiney and put a picture up so you can school me.

As far as the attachment being the weak link, it isn't all that bad. I'm a large guy (190-200 lbs.) and I ride hard and often carry large loads off-road. The longest any of these joints held up under me was 250,000 miles prior to failure. The shortest was 10,000 miles. One more failed after 100.000 miles and another hasn't yet failed after an unknown number of miles by other users and about 25.000 miles under me. Most riders would likely get many more miles out of these than I do. In fact, my wife has about 250.000 miles on hers. These old Treks are indeed great bikes and I would not hesitate to buy another if it becomes available. It just looks like your '85 620 is a little greater than my '82 720.