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For those with setback seatposts . . .

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Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway
View Poll Results: Which best describes your setup and anthropometry?
Don't have a setback seatpost
13
25.49%
Setback post, saddle back, long legs
9
17.65%
Setback post, saddle in middle, long legs
14
27.45%
Setback post, saddle forward, long legs
3
5.88%
Setback post, saddle back, short legs
2
3.92%
Setback post, saddle in middle, short legs
7
13.73%
Setback post, saddle forward, short legs
3
5.88%
Voters: 51. You may not vote on this poll

For those with setback seatposts . . .

Old 04-09-10, 01:37 PM
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For those with setback seatposts . . .

How is your saddle positioned? And how would you describe your limb length relative to your height?

Just curious.
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Old 04-09-10, 06:35 PM
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Why are you only interested in bikes with setback posts? You do realise that setback seatposts aren't there for individual riders' anthropometry, but are provided to get the saddle in the right place on frames with steeper seat tube angles?
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Old 04-09-10, 06:47 PM
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because the STA is too steep on 50cm frames.
because I'm using 165mm cranks.
because my femurs, I guess are longer than normal.

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Old 04-09-10, 08:43 PM
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No normal leg option ?
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Old 04-10-10, 10:17 AM
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Originally Posted by scirocco
Why are you only interested in bikes with setback posts? You do realise that setback seatposts aren't there for individual riders' anthropometry, but are provided to get the saddle in the right place on frames with steeper seat tube angles?
I suppose we could argue about what constitutes a 'steeper' STA, but generally you would use STA and setback to position the saddle relative to the bottom bracket, which will be influenced by one's anthropometry.
Originally Posted by idcruiserman
No normal leg option ?
Forgot about that. This is a *very* casual poll anyway.
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Old 04-10-10, 10:28 AM
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I've got bikes with each. It totally depends on the STA whether I need a setback or not. Can't answer your other question as I have no idea.
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Old 04-10-10, 06:14 PM
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Originally Posted by serpico7
I suppose we could argue about what constitutes a 'steeper' STA, but generally you would use STA and setback to position the saddle relative to the bottom bracket, which will be influenced by one's anthropometry.
Well, "steeper" would mean, say 74 or 74.5 degrees or higher, where most people would need a setback post to get in a sensible position over the bottom bracket, whereas a straight post is usually okay for 72 or 73 degrees.

This applies regardless of the rider's anthropometry. Leg length on its own doesn't affect the issue, although very long or short femurs in relation to tibia length can affect it. There is usually enough fore-aft adjustment on the saddle rails to cope with variations in individual femur-to-tibia ratios, once the seatpost setback (or lack of it) has got the saddle in roughly the right place for that particular frame.
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Old 04-10-10, 09:37 PM
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Originally Posted by scirocco
Well, "steeper" would mean, say 74 or 74.5 degrees or higher, where most people would need a setback post to get in a sensible position over the bottom bracket, whereas a straight post is usually okay for 72 or 73 degrees.

This applies regardless of the rider's anthropometry. Leg length on its own doesn't affect the issue, although very long or short femurs in relation to tibia length can affect it. There is usually enough fore-aft adjustment on the saddle rails to cope with variations in individual femur-to-tibia ratios, once the seatpost setback (or lack of it) has got the saddle in roughly the right place for that particular frame.
I have short legs and even shorter femurs in comparison to the rest of my body.

51cm frame, 76º STA, saddle dead center of zero-setback seatpost, 160mm cranks.

I know that there are a good number of people on this forum who have strange proportions. There's someone here with such short legs he's had to get custom ~130mm cranks.
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Old 04-11-10, 06:51 AM
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Total leg length has little to do with setback, it is femur length. I have short legs for my height, but my setback is high because I have long femurs
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Old 04-12-10, 08:44 AM
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Originally Posted by scirocco
Well, "steeper" would mean, say 74 or 74.5 degrees or higher, where most people would need a setback post to get in a sensible position over the bottom bracket, whereas a straight post is usually okay for 72 or 73 degrees.
I think there was an earlier thread that talked about how most of the pros are using setback posts. While you're right that a steep STA can make a setback post more necessary, it would seem that the pros mostly favor setback posts, and I think it's fair to say they aren't all riding steep STA frames.
Originally Posted by scirocco
This applies regardless of the rider's anthropometry. Leg length on its own doesn't affect the issue, although very long or short femurs in relation to tibia length can affect it. There is usually enough fore-aft adjustment on the saddle rails to cope with variations in individual femur-to-tibia ratios, once the seatpost setback (or lack of it) has got the saddle in roughly the right place for that particular frame.
Interesting point. I've been messing around with setback recently, and trying to apply Peter White's principle about fore/aft position. With a zero setback post, and the saddle all the way back, I'm not near the balance point he talks about. With a 25mm setback post, and the seat shoved back, I'm a lot closer. I have long legs relative to my torso, and not really sure if my femur are unusually long relative to my tibia.
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Old 04-14-10, 04:02 AM
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Originally Posted by serpico7
I think there was an earlier thread that talked about how most of the pros are using setback posts. While you're right that a steep STA can make a setback post more necessary, it would seem that the pros mostly favor setback posts, and I think it's fair to say they aren't all riding steep STA frames.
I suspect that most pros ARE riding steep STA frames, simply because race-oriented geometry frames have short chainstays, not much more than 400mm. This forces a steep STA for wheel clearance.

You can get comfort frames with chainstays around 420mm that don't need a steep STA and thus can use a straight post. But I doubt many pros are racing on them.

Last edited by scirocco; 04-14-10 at 04:08 AM.
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Old 04-14-10, 06:39 AM
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This entire thread rests on the idea that the knee must be in a certain position relative to the BB. There are a number of professional fitters who totally ignore KOP and base the saddle fore/aft position on the rider's weight balance over the saddle. The idea is keep the weight on the hands at a minimum by having the saddle back far enough. There's some trial and error to it, but once you get back far enough, you'll find greater hand and arm comfort, plus the ability to tolerate more saddle to bar drop, if you want to try a more aerodynamic position.

With the balance concept, the real issue becomes torso length to leg length. A short torsoed rider like myself (169cm height/83cm cycling inseam) should require less setback and a long torsoed rider should need more. Even so, I have my saddle set at least 6cm behind the BB with a 73cm saddle height. Most frames in my size have STA of 74-74.5 degrees, so I need 25-32mm of seatpost setback. The only time I've been able to use a nonsetback post was with a 72.5 degree STA (used to be standard on LOOK frames prior to 2004).
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Old 04-14-10, 07:13 AM
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The balance concept is interesting, but you have to get your cleats/feet aligned in a comfortable position somehow, don't you? How do you go about doing that? Change the crank length? Change the saddle height? Do you find that once you're centered over the saddle the feet tend to fall in a natural position?

Say, for example, I feel centered with my saddle pretty far back and I can't clip in comfortably. When I put my feet down it feels like I should be pedaling with my toes. It wouldn't make sense to change my cleat positioning, right?

Or do you move fore/aft in a range that feels comfortable to your knees? If so, how do you find a starting point without KOP?
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Old 04-14-10, 07:16 AM
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It's probably a bad idea, but can you push the saddle all the way back to where the bents are, or should you stay in the marked zone of the rails? I have a Look 566 with the stock seat post.
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Old 04-14-10, 07:29 AM
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the saddles are fine along the entire length of the flat rails. if they weren't, why would manufacturers allow that much adjustment?
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Old 04-14-10, 07:34 AM
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Originally Posted by DXchulo
The balance concept is interesting, but you have to get your cleats/feet aligned in a comfortable position somehow, don't you? How do you go about doing that? Change the crank length? Change the saddle height? Do you find that once you're centered over the saddle the feet tend to fall in a natural position?

Say, for example, I feel centered with my saddle pretty far back and I can't clip in comfortably. When I put my feet down it feels like I should be pedaling with my toes. It wouldn't make sense to change my cleat positioning, right?

Or do you move fore/aft in a range that feels comfortable to your knees? If so, how do you find a starting point without KOP?
KOP is the starting point, and work from there.
too much weight on hands, move the saddle back
if you feel like you should be on your toes while pedalling, move the cleats forward or buy shorter cranks.

just mark everything down and try changing the position of your equipment in 1/16" increments until you feel more comfortable.

knee pain is usually a problem with leg extension, poor cleat alignment or not spinning fast enough.
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Old 04-14-10, 07:43 AM
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Yeah, but if you start at KOP you don't "totally ignore" KOP.
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