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Is there any way to identify an unmarked Trek frame?

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Is there any way to identify an unmarked Trek frame?

Old 05-23-20, 05:11 PM
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channelz28
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Is there any way to identify an unmarked Trek frame?

It has a powdercoat that's too thick to read a serial number. I can just barely see "Trek" stamped into the seat post, that's all I have to go by. I have been told "it's probably one of the twenties." Is there any way to identify which one? I got it just as the frame. None of the components are stock.

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Old 05-23-20, 05:24 PM
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Definitely a tourer. Triple bottle cages, double eyelets front and rear.
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Old 05-23-20, 05:28 PM
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Okay. I'm going to go out on a limb and say '82 720, base on double dropout eyelets, double water bottle bosses on downtube, no cantilever bosses, and really long chainstays.
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Old 05-23-20, 05:35 PM
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The steerer tube could be stamped Reynolds 531 and it's a 720? I'm working on a '82 710 that is so marked.
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Old 05-23-20, 05:49 PM
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Like this in the for sale section: 1982 21" Trek 720 frame

Last edited by Hobbiano; 05-23-20 at 06:36 PM.
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Old 05-23-20, 06:24 PM
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Originally Posted by natterberry View Post
Definitely a tourer. Triple bottle cages, double eyelets front and rear.
Actually a double bottle cage, there isn't a mount on the seat tube.
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Old 05-23-20, 06:26 PM
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Originally Posted by Classtime View Post
The steerer tube could be stamped Reynolds 531 and it's a 720? I'm working on a '82 710 that is so marked.
Where exactly could I potentially find this stamp?
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Old 05-23-20, 06:39 PM
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If you go to the vintage Trek site you'll be able to eliminate the 520 & 620.
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Old 05-23-20, 06:41 PM
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Originally Posted by channelz28 View Post
Where exactly could I potentially find this stamp?
Take the fork out, Look on the steerer tube.
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Old 05-23-20, 07:20 PM
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Originally Posted by Hobbiano View Post
Okay. I'm going to go out on a limb and say '82 720, base on double dropout eyelets, double water bottle bosses on downtube, no cantilever bosses, and really long chainstays.
I concur. The 720 was the only Trek frame that got double eyelets. Later production had cantilever bosses, and the final year they even dropped the double eyelets (labor-saving: we had to mill the dropouts and braze the additional eyelets onto them).
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Old 05-23-20, 07:38 PM
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Originally Posted by channelz28 View Post
Actually a double bottle cage, there isn't a mount on the seat tube.
Ahh yes, didn’t look close enough at that pump. Panels over hydration.
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Old 05-24-20, 06:22 AM
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Originally Posted by Classtime View Post
The steerer tube could be stamped Reynolds 531 and it's a 720? I'm working on a '82 710 that is so marked.
720 has a chainstay around 47 cm, 710 has a chainstay more like 42 - ish cm.

Sorry, the 710 had a 44.0 for 1979, 44.5 cm for 1980, 43.5 cm CS in 1981, back to 44.0 in 1982.

Last edited by Road Fan; 05-24-20 at 08:47 AM. Reason: Self-correction!
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Old 05-24-20, 08:01 AM
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The powdercoat definitely muddies things. Harder to use braze-ons or bottle cage mounts as diagnostics for model.
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Old 05-24-20, 08:11 AM
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Originally Posted by Road Fan View Post
720 has a chainstay around 47 cm, 710 has a chainstay more like 42 - ish cm.
They are both full 531 so the OP would know if it was a 700 series.
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Old 05-24-20, 08:22 AM
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Looks like a dead ringer for the '82 72x, if no braze-ons were changed before powder coat.

https://www.vintage-trek.com/images/trek/Trek3pg8.jpg

Interesting that the '82 in the classifieds has the cable above the chainstay and the '82 in the catalog scans it goes under. The '82 catalog does show a mix of above and under chainstay cable routing throughout the model line. Maybe a running change trickling down from the upmarket end.

Last edited by scarlson; 05-24-20 at 08:31 AM.
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Old 05-24-20, 09:13 AM
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Originally Posted by channelz28 View Post
Actually a double bottle cage, there isn't a mount on the seat tube.
My 1982 Specialized Sequoia is the same way.
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Old 05-24-20, 09:33 AM
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My 1982 Trek 720 has the number "720" cut into the steerer with, I presume, a rotary to like a Dremel. I don't know if they did that to all the forks, but it's worth a look.
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Old 05-24-20, 09:47 AM
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Seriously great score! Ultimate touring bike for the day. Congratulations!

So the entire time I'm reading this post I have the B-52s' "Channel Z" song in my head... it wasn't until I got back up to the top to look at the pix again that I realized why.
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Old 05-24-20, 09:51 AM
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Most of the Treks I have serviced worked on have had some tubing or model info on the steerer tube also there is a very good chance that some original paint can be found on thee steerer which help confirm the exact model and year.
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Old 05-24-20, 11:27 AM
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Originally Posted by scarlson View Post
Looks like a dead ringer for the '82 72x, if no braze-ons were changed before powder coat.

https://www.vintage-trek.com/images/trek/Trek3pg8.jpg

Interesting that the '82 in the classifieds has the cable above the chainstay and the '82 in the catalog scans it goes under. The '82 catalog does show a mix of above and under chainstay cable routing throughout the model line. Maybe a running change trickling down from the upmarket end.
The first production run of the 720s used Cinelli bottom bracket shells with brazed-on guides on top of the shell; later production used the Trek shell with cable guides cast into the underside of the shell.
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Old 05-24-20, 02:37 PM
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Originally Posted by JohnDThompson View Post
The first production run of the 720s used Cinelli bottom bracket shells with brazed-on guides on top of the shell; later production used the Trek shell with cable guides cast into the underside of the shell.
That and the info about the eyelets on the fork ends/dropouts is fascinating- You can guess *something* is going to change during production- I personally find the eyelet thing interesting as the 84 and 85 720s are identical- with many of the 84s only having 1 set of eyelets.
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Old 05-24-20, 10:27 PM
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Wow, I can't believe you guys could eyeball it so accurately, you are some serious bike nerds. The steerer has 720 stamped in it, I checked it today. A quick google looks like it was a nice bike for it's day. The only issue I have with it is when I'm clipped in, I can't turn the front wheel sharply or it will hit my shoes.
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Old 05-24-20, 10:27 PM
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Originally Posted by The Golden Boy View Post
Seriously great score! Ultimate touring bike for the day. Congratulations!

So the entire time I'm reading this post I have the B-52s' "Channel Z" song in my head... it wasn't until I got back up to the top to look at the pix again that I realized why.
Yep, that's where the name comes from. Very few people ever get the reference. Best band ever.
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Old 05-25-20, 08:52 AM
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Originally Posted by channelz28 View Post
Yep, that's where the name comes from. Very few people ever get the reference. Best band ever.
I think Cosmic Thing is one of the best sounding records ever.
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Old 05-25-20, 12:17 PM
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Boy -- there are bike nerds around. Back in college (very early 80's) ... I was planning a trip to France -- was working through a local bike store to get a 720/728 made up for the trip. I did not like the top tube cable ... it's been so long I can't remember if they had time to send me one of the ones on the bottom or not. Talked to the factory about it ... They did them in batches based on models and size.
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