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-   -   Frame sizing on vintage bikes (https://www.bikeforums.net/showthread.php?t=1256663)

Lbxpdx 08-10-22 01:31 PM

Frame sizing on vintage bikes
 
My recently purchased Schwinn VSP is a fun ride. Nimble with nothing in the bags, yet planted and comfortable when the bags are filled with groceries. It is a 21”, 21.5” top tube, 170mm cranks, 74 degree head/seat and 27” wheels. With the amount of stem and seatpost showing, it looks like the frame is too small for me, but when I bought the bike I also tried a 23” version and it was too big for me. My nice bike is 56/56, 73/73 with 650b and it fits quite nicely and looks proportionate.

I’m trying to figure out why this bike looks small though it fits perfectly the way it is set up. Would a dirtdrop stem make the bike look more proportional?


https://cimg7.ibsrv.net/gimg/bikefor...310c21349.jpeg
https://cimg1.ibsrv.net/gimg/bikefor...607a01722.jpeg

52telecaster 08-10-22 01:36 PM

Looks pretty good to me. If you want the 23" your stand over might be too much. Personally I don't worry about stand over but it's not a bad thing to be aware of. If that works for you and you have enough stem insertion I think you're golden.

icemilkcoffee 08-10-22 01:38 PM

People typically eyeball frame sizes by looking at the headtube length. But on a bike like this- there is a huge amount of air space between the fork crown and the top of the tire. So the fork is longer and the head tube shorter, and that makes the frame look like it's a size smaller than it is.
But to answer your question- yes a 90 degree (or more) stem would look better in this situation.

smd4 08-10-22 02:27 PM

Looks OK to me. The stem is up high, but that isn't an indicator of proper frame size; more like a comfort thing. Seatpost is right there in the range.

Classtime 08-10-22 02:53 PM

Why do you think the 23” version is too big? Was it too tall or too long? By how much?
I’d say that if you need that much stem to get the bars where you want them, AND you have an opportunity to get the next larger size, get the next larger size.

Lbxpdx 08-10-22 02:59 PM


Originally Posted by Classtime (Post 22605845)
Why do you think the 23” version is too big? Was it too tall or too long? By how much?
I’d say that if you need that much stem to get the bars where you want them, AND you have an opportunity to get the next larger size, get the next larger size.

The 23” hurt. It pressed on my taint. Plus I bought this while on vacation, so I’m nowhere near the bike. The 23” was only a few dollars less and nowhere in as good of condition.

52telecaster 08-10-22 03:46 PM


Originally Posted by Lbxpdx (Post 22605853)
The 23” hurt. It pressed on my taint. Plus I bought this while on vacation, so I’m nowhere near the bike. The 23” was only a few dollars less and nowhere in as good of condition.

With that info I'd say you bought the right bike. All my stems are pretty high. It's an arthritis thing and I don't care what people think!

wrk101 08-10-22 03:59 PM

You like it so thats all that matters.

Back in the day, bikes tended to the bigger size seat tube wise. I remember the Varsity in the early. 1970s coming in 22, 24. and 24 inch frame size. Typical was about one hand width worth of seat post showing. I was sized to a medium, 24 inch. Now I am comfortable on a 21 1/2 inch. Sold my 24 inch bike years ago.

I like dirt drop style stems for comfort too. Its one reason I am attracted to the drop bar conversion on a rigid frame MTB.

nlerner 08-10-22 04:01 PM

With that short of a head tube, looks more like a 19” frame than a 21”.

John E 08-10-22 04:52 PM

You must be about my size. The bikes which fit me best are the Bianchi, the Carlton, and the three Capos, all of which are 55cm C-T. The UO-8 is a 21-incher, but proportionally long in the top tube.

https://cimg6.ibsrv.net/gimg/bikefor...a283de0622.jpg
1959 Capo with Nervar Star crank and Campag. 980 derailleur upgrades and new Brooks Pro saddle.

bikemig 08-10-22 04:55 PM

That bike looks on the small side to me given how high the bars are. That said, it seems to work for you. I hope you have enough of the stem inserted into the head tube for that to be safe. You are running a Nitto technomic stem (or a tall stem from a different manufacturer), right

smd4 08-10-22 05:26 PM


Originally Posted by bikemig (Post 22606014)
That bike looks on the small side to me given how high the bars are.

Nonsense.

Lbxpdx 08-10-22 05:39 PM


Originally Posted by icemilkcoffee (Post 22605757)
People typically eyeball frame sizes by looking at the headtube length. But on a bike like this- there is a huge amount of air space between the fork crown and the top of the tire. So the fork is longer and the head tube shorter, and that makes the frame look like it's a size smaller than it is.
But to answer your question- yes a 90 degree (or more) stem would look better in this situation.

there is a fair amount of room. That makes sense.


https://cimg7.ibsrv.net/gimg/bikefor...5fc6b3619.jpeg

Lbxpdx 08-10-22 05:41 PM


Originally Posted by nlerner (Post 22605953)
With that short of a head tube, looks more like a 19” frame than a 21”.

that’s probably why it looks like a small frame, but it does measure 21” and 21.5”.

bikemig 08-10-22 05:42 PM


Originally Posted by smd4 (Post 22606056)
Nonsense.

You're kidding right? Did you bother to read the rest of my post? If the OP is happy with that set up, who cares right as long as the stem has sufficient insertion.

I dunno about what kind of expertise you may have but I worked in a bike shop selling and fitting bikes throughout the 80s. . . .

Classtime 08-10-22 06:27 PM

Do the Voyageur SPs have high BB? That is the only way taint pressure can occur with so much seat post showing.

ps: I’m a pretty good internet fitter given woefully imperfect information.

repechage 08-10-22 06:30 PM

I would need to see the rider on the bike

smd4 08-10-22 06:32 PM


Originally Posted by bikemig (Post 22606075)
You're kidding right? Did you bother to read the rest of my post? If the OP is happy with that set up, who cares right as long as the stem has sufficient insertion.

I dunno about what kind of expertise you may have but I worked in a bike shop selling and fitting bikes throughout the 80s. . . .

I did read the rest of your post. That was all well and good. Obviously, I took issue with your assertion that the stem length had anything to do with proper frame sizing.

If the rider gets proper leg extension with the saddle at that level, it’s not too small at all.

Worked as a wrench, also selling and fitting, 10 years, 1985-1995.

embankmentlb 08-10-22 07:10 PM

Do manufacturers still make some sort of rando handle bars? The kind that allow a couple of centimeter height to the bars relative to the stem? I am sure there is a proper name for those. Just an idea.
Your frame size looks correct. A 23 could be very challenging.

P!N20 08-10-22 07:33 PM

I never worked in a bike shop, but I feel there are straps missing from the clips.

bikemig 08-10-22 07:35 PM


Originally Posted by smd4 (Post 22606132)
I did read the rest of your post. That was all well and good. Obviously, I took issue with your assertion that the stem length had anything to do with proper frame sizing.

If the rider gets proper leg extension with the saddle at that level, it’s not too small at all.

Worked as a wrench, also selling and fitting, 10 years, 1985-1995.

Good, then you know that your post was nonsense. A super tall stem is not a sure fire sign that the bike is too small since you have to see someone on the bike but it is often a sign that a bike may be too small. Of course you have to see the rider on the bike since dimensions do vary. And obviously as you wrote that setting up a person correctly on a bike involves proper leg extension as well as having the proper stem length, etc.

Steel Charlie 08-11-22 07:52 AM

It may just be me, but I can't tell you how grateful I am that I don't have to ride that saddle position. No wonder the stem is so high.

Trakhak 08-11-22 08:01 AM

Frame angles of 74 degees parallel for a 21" touring bike? Seems unlikely. That's '80s Italian criterium bike/track bike territory.

Century Bob 08-11-22 08:34 AM

I agree with Steel Charlie. I would address the seat first by leveling it. That would also require adjusting seat height. Then the reach to the bars would be improved allowing the rider to drop the stem further into the head tube. This set up looks very uncomfortable and the bar position is compensating for poor saddle position.

himespau 08-11-22 08:51 AM

I have to agree that it looks like that saddle angle would be uncomfortable for me and everything else might change if that did. On the other hand, if that saddle angle works for you, go for it.


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