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NBD - 1984 Trek 620

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NBD - 1984 Trek 620

Old 09-10-19, 10:09 AM
  #101  
nesteel
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Compare your contact point measurements from your modern bike against the ones on the Trek as it currently sits. Pedal spindle to saddle distance with the pedal at the bottom of the stroke, bar to saddle drop (or vice versa) and saddle distance, horizontaly, from the bars.
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Old 09-10-19, 10:27 AM
  #102  
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Originally Posted by nesteel View Post
Compare your contact point measurements from your modern bike against the ones on the Trek as it currently sits. Pedal spindle to saddle distance with the pedal at the bottom of the stroke, bar to saddle drop (or vice versa) and saddle distance, horizontaly, from the bars.
Ok thanks! I'm not sure what the 2nd two measurements are. Can you explain that to me?

The 1st I measured center of pedal spindle at bottom of stroke to top of saddle. 34" on the Trek, 34.5" on the Jamis. That is measuring at an angle to the center top of the saddle, and the saddle is further back on the Jamis.

The last measurement, I measured center of handlebars to tip of saddle. 19" on the Trek, 19.25" on the Jamis.

Last edited by riverdrifter; 09-10-19 at 10:31 AM.
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Old 09-10-19, 10:39 AM
  #103  
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If I do this...
Measure from the floor to the top of the saddle and call the value "A". Then measure from the floor to the top of the bars and call the value "B". Value A minus value B = saddle-to-bar drop.

I get Trek - 37.5 saddle 35 center of bars = 2.5" drop
Jamis - 38 saddle 37.5 center of bars = 0.5" drop

So obviously the 2 bikes are set up quite differently.
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Old 09-10-19, 10:43 AM
  #104  
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How long are the cranks on the two bikes?

Can you slide the saddle back on the rails 5-10 mm?

Saddle-to-bar drop/rise is simply the difference in height (from the floor) between the saddle and the bar. Looking at your Jamis in your gallery, it looks like you have the stem at almost the same height as the saddle, but on the Trek, there appears to be more drop.

That said, looking at the two bikes overall, the sloping top tube can trick the eye, but still, the Jamis does appear to be a bit bigger frame.

Edit - yes, you got the saddle-to-bar thing right. Doesn't look like 2" difference from the photos, but the tame measure doesn't lie. Also, if you're comparing riding positions on the hoods, the brakes are lower on the bar on the Trek. At the risk of proposing blasphemy, if you're used to a more modern position on the hoods with the brake levers more "integrated" with the bar, a new-ish set of Tektro levers, and possibly a newer-style bar to match, might help with that positioning.

Last edited by madpogue; 09-10-19 at 10:49 AM.
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Old 09-10-19, 10:58 AM
  #105  
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I've had good success with raising the bars on the vintage touring iron I have, and going to a wider bar to match up closer to what the norm would be on the modern Jamis you have.
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Old 09-10-19, 11:02 AM
  #106  
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Originally Posted by madpogue View Post
How long are the cranks on the two bikes?

Can you slide the saddle back on the rails 5-10 mm?

Saddle-to-bar drop/rise is simply the difference in height (from the floor) between the saddle and the bar. Looking at your Jamis in your gallery, it looks like you have the stem at almost the same height as the saddle, but on the Trek, there appears to be more drop.

That said, looking at the two bikes overall, the sloping top tube can trick the eye, but still, the Jamis does appear to be a bit bigger frame.

Edit - yes, you got the saddle-to-bar thing right. Doesn't look like 2" difference from the photos, but the tame measure doesn't lie. Also, if you're comparing riding positions on the hoods, the brakes are lower on the bar on the Trek. At the risk of proposing blasphemy, if you're used to a more modern position on the hoods with the brake levers more "integrated" with the bar, a new-ish set of Tektro levers, and possibly a newer-style bar to match, might help with that positioning.
Both bikes have 170 mm cranks. I might be able to slide the saddle on the Trek back maybe another 2 mm, if that. It's back about as far as it can go.
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Old 09-10-19, 11:23 AM
  #107  
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@nesteel , good point about the handlebar width. A difference like that could make the vintage bike feel "smaller".
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Old 09-10-19, 01:20 PM
  #108  
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@riverdrifter, I know you live in a bit of a bike desert, but if you'd like to try a raised/wide cockpit, I can loan you a spare setup I have. That way you could try it out with no financial risk other than the cost of return postage.
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Old 09-10-19, 01:26 PM
  #109  
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Originally Posted by nesteel View Post
@riverdrifter, I know you live in a bit of a bike desert, but if you'd like to try a raised/wide cockpit, I can loan you a spare setup I have. That way you could try it out with no financial risk other than the cost of return postage.
Thanks that would be great! I'll PM you.
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Old 09-10-19, 01:27 PM
  #110  
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Lovely Trek! I have the same frame and use it as my main bike (at least this year) including a century coming up. You have done a nice job on yours! Enjoy it!
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Old 09-10-19, 08:28 PM
  #111  
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Originally Posted by riverdrifter View Post
I hate to admit it, but after riding this bike for awhile, I think it's too small for me. I've got the stem and seatpost at max height and I still can't quite get the extension I need.

My other bike is a 51 cm modern compact geometry road bike with a sloping top tube. It's 51 cm and the fit is okay. I thought this Trek, being a 21", would be just marginally bigger. Instead it feels just a bit smaller. Doing some additional reading, it looks like that is common, that vintage bikes tend to "fit smaller" than comparable sized modern bikes. The next size up is 22.5", that converts to 57 cm and seems like it would be too big. Maybe not? Of course that doesn't change the fact that this is the bike I've got, and finding a bigger 620 might not happen.

I know lots of people run taller stems on these, but that isn't really my issue. I'm not sure that it would be practical to fit a longer seatpost on it, and if that would really even correct the problem?
Your seat post is not nearly as far out of the frame as many. Just look around this forum for some examples. I ride a 21" or a 54 cm with the saddle at 27" from the crank axle. I'm 5-7 (bare feet) or a little more (used to be 5-8) with a 30" pants inseam. I've got plenty room for adjustment either way.
I've found that I can go as small as a 19" Trek 620 (which mine is) because the top tube is about the same as a 21" Trek 720. I used a slightly taller seat post and a slightly taller stem with randoneer bars and the fit is very close to the 21" frame that I have. The Nitto Technomic stem will get the bars way up there, maybe higher than you want, because with a 21" frame the fork steerer is pretty short, not allowing you to drop a tall stem very much. There is another Nitto stem, I believe its called the Technomic Deluxe, that is medium tall, that would probably work for you. The Technomic is 225mm vs 190mm for the Technomic deluxe, with at least 70mm of that inserted. A Cinelli stem like the one in the Trek 720 is about 120mm tall, with 55mm of that inserted, minimum, for comparison. Be aware that different stems sometimes have different handlebar clamp diameters, and older Cinelli stems use 26.4mm bars vs 26.0 or 25.4 used with Nitto stems. Randoneer bars sweep upward about 10 to 15 mm higher than regular road bars.
The SR Laprade seat post came in several lengths, and a new longer seat post is easy to find, although I like the way Laprades look better on a vintage bike. I found a Gipiemme thats taller than the Laprade that came on my 620 and looks appropriately vintage.
I think we determined we were about the same height in an earlier post, more or less, and I believe you got the right size. I can ride a 22.5" (center to top) bike but its a lot taller than a 21", with a 2" longer top tube (with a Trek), and the seat post is barely protruding out of the frame. Its really too big for me, with about zero stand over clearance. Sorry for the long post but I think you got the right size, and the fit is very adjustable.
As far as handlebar width goes, I would experiment to find what you like. I can get comfortable with a range of widths, between 38 cm and 44 cm, with 40 or 42 being my favorite.

Last edited by Hobbiano; 09-10-19 at 08:44 PM.
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