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Going with a shorter seat tube but longer top tube?

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Going with a shorter seat tube but longer top tube?

Old 02-20-16, 02:20 AM
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Going with a shorter seat tube but longer top tube?

I've always ridden 55cm frames and they seem to fit me well. Most of the frames I've ridden have always had similar seat tube/top numbers...like 55cm TT/54.5 ST or 55cm for both.

I'm looking at picking up another frame (horizontal top tube/classic type geo) and was curious what a shorter seat tube does to geo. I know a shorter top tube will immediately be noticed because you're closer to the handlebars....but what about a bike with your correct top tube length (like a 55cm for me) but a short seat tube? Say a 52cm/53cm seat tube for example.

Of course the standover height will be lower but that's really not that important. I've just come across some frames that are 55cm top tube/53 or 52.5ish seat tube. Not sure if I should look into or ignore.

Anyone here have a frame with a longer top tube/shorter seat tube?
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Old 02-20-16, 05:48 AM
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Depends on the seat tube angle, and the head tube angle. If they're both the same degree or close to being the same - the effective top tube measurement (c-c) will be the same measurement you're seeing on the chart. If the seat tube angle is say "73.5" or lower, the saddle will be further back from the BB. If the head tube angle is say "74" or higher, the handlebars will be further away from the BB. With a slack seat tube (lower number) and a steep seat tube (higher number) this will create a longer effective top tube.

I think what is "key" here is asking you "if you're built short leg/long torso"? If so, A short seat tube and long top tube will be better for you.

For me, my inseam is 50% of my height, I personally need a short top tube, and a tall seat tube to fit long leg/short torso body.

Hope this helps
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Old 02-20-16, 10:38 AM
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If all other angles are the same, there will be a greater saddle-to-handlebar drop.
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Old 02-20-16, 01:00 PM
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Are you just referring to modern road bikes? They are all going to shorter seat tube lengths for ze stifffness since it makes the triangle smaller.
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