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Old 07-11-12, 11:25 PM   #1
agmetal
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Differences in geometry between two similar bikes...why?

Here's hoping that thread title was helpful enough.

To get more specific, I have a Columbia Sports III. It's a 3-speed from the early '70s, with a Sturmey Archer AW hub. It has a men's frame. My friend just picked up a Ross 3-speed of about the same age, with a Shimano 333 hub, with a women's frame. We're very similar in height, and noticed some significant differences in the geometry of the two bikes, that make us both feel cramped on the Ross.

On my Columbia, the seatpost is angled toward the back of the bike, so that the pedals are slightly in front of the saddle...on my friend's Ross, the seatpost is more upright, and it makes the pedals feel too close. The head tubes are at approximately the same angles, so my bike has more of a rake, and makes the Ross's steering feel twitchy in comparison.

Is this more likely to be a difference in brand, or is it due to the men's frame on my bike, vs. the women's frame on hers? Originally, I'd thought the Ross was a British bike, and I remember being told when I first started looking at 3-speeds, that the British bikes tend to feel slightly smaller...but apparently, both are American.

I guess the real question here is, would a Columbia with a women's frame be more likely to have similar geometry to mine, or is that just how they made the women's frames then?
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Old 07-12-12, 05:02 PM   #2
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Leaving aside the fact that women tend to have shorter torsos than men, why would you expect men's and women's frames from two different companies to have the same specs?
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Old 07-12-12, 05:08 PM   #3
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Bene Sugg: get an angle finder from the hardware store , and a tape measure ..
Then you can gather hard, actual, data.
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Old 07-12-12, 07:30 PM   #4
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Yeah, and pictures would help.
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Old 07-12-12, 08:03 PM   #5
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Sure there are always differences in the dimensions of different brands. But can you not adjust around the differences by moving the saddle back on its rails and possibly getting a different stem?
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Old 07-12-12, 10:30 PM   #6
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How about just raising the seat height to ensure proper leg extension?
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Old 07-13-12, 07:34 AM   #7
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There are dozens of such subtle frame geometry differences. They not only exist between different manufacturers and models, but even between different sized bikes of the same model and year from the same manufacturer.

Everything on a bike works together. When you change one dimension for any reason, it often makes it necessary to change something else.
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Old 07-13-12, 07:36 AM   #8
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How about just raising the seat height to ensure proper leg extension?
The handlebars will still feel too close and it may force you to bend over than many people are comfortable doing.
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