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Setback seatpost - why not smaller seat tube angle?
Why most seatposts are made with some setback?
Clearly the same rider's position could be achieved with slightly less steep seat tube and no-setback seatpost. Looks like "straight" posts are marginally lighter/stiffer, naturally because there is no extra material and because there is less leverage applied when the rider is positioned closer from the post axle. I guess that in days of old when there were only plane pipe seatposts the setback was there because there was no other seat clamping mechanism (or was it?); but now is it dictated by anything else than traditions in frame geometry, with steeper than needed seat tube? Thanks! Konstantin. |
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#2
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Setback seatpost - why not smaller seat tube angle?
Konstantin Shemyak wrote:
Why most seatposts are made with some setback? Clearly the same rider's position could be achieved with slightly less steep seat tube and no-setback seatpost. For one thing, most modern bikes have very tight clearance. Making the seat tube angle slacker would require longer chainstays to keep the rear tire from rubbing against the seat tube. That might not be a bad thing, but it goes against modern fashion. Secondly, since most seat posts have setback, frame makers assume that when designing their frames. Which came first, the chicken or the egg? I don't know, but as long as I can remember, most quality seat posts have had some setback. Art Harris |
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Setback seatpost - why not smaller seat tube angle?
Art Harris wrote: Secondly, since most seat posts have setback, frame makers assume that when designing their frames. Which came first, the chicken or the egg? I don't know, but as long as I can remember, most quality seat posts have had some setback. Indeed - "in-line" micro-adjust seatpins seem a fairly modern phenomenon popularised by MTBs. David Belcher |
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Setback seatpost - why not smaller seat tube angle?
On 7 Apr 2006 04:34:55 -0700, "Art Harris" wrote:
Konstantin Shemyak wrote: Why most seatposts are made with some setback? Clearly the same rider's position could be achieved with slightly less steep seat tube and no-setback seatpost. For one thing, most modern bikes have very tight clearance. Making the seat tube angle slacker would require longer chainstays to keep the rear tire from rubbing against the seat tube. That might not be a bad thing, but it goes against modern fashion. Secondly, since most seat posts have setback, frame makers assume that when designing their frames. Which came first, the chicken or the egg? I don't know, but as long as I can remember, most quality seat posts have had some setback. I've never used a seatpost with a zero-offset clamp, but perhaps one reason seatposts have some offset is that, at least with single-bolt clamps, it's very easy to ge to the bolt? JT **************************** Remove "remove" to reply Visit http://www.jt10000.com **************************** |
#5
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Setback seatpost - why not smaller seat tube angle?
In article
. com, "Art Harris" wrote: Konstantin Shemyak wrote: Why most seatposts are made with some setback? Clearly the same rider's position could be achieved with slightly less steep seat tube and no-setback seatpost. For one thing, most modern bikes have very tight clearance. Making the seat tube angle slacker would require longer chainstays to keep the rear tire from rubbing against the seat tube. That might not be a bad thing, but it goes against modern fashion. Secondly, since most seat posts have setback, frame makers assume that when designing their frames. Which came first, the chicken or the egg? I don't know, but as long as I can remember, most quality seat posts have had some setback. What is set-back, and what is not set-back? I understand the classic seat post to have the front of the hold-down clamp centered on the seat post tube itself. -- Michael Press |
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Setback seatpost - why not smaller seat tube angle?
Michael Press wrote:
What is set-back, and what is not set-back? I understand the classic seat post to have the front of the hold-down clamp centered on the seat post tube itself. Most classic road seat posts have the clamp set back from the centerline of the post. No set-back: http://www.lhthomson.com/images/sp_elite.jpg Set-back: http://i8.ebayimg.com/03/i/06/b5/fe/13_1.JPG Art Harris |
#7
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Setback seatpost - why not smaller seat tube angle?
On 7 Apr 2006 04:34:55 -0700, "Art Harris" wrote:
Secondly, since most seat posts have setback, frame makers assume that when designing their frames. Which came first, the chicken or the egg? I don't know, but as long as I can remember, most quality seat posts have had some setback. Back before micro-adjust, when seatposts were plain pipes and saddles had separate clamps, the relationship those clamps made between the top of the seatpost and where it clamped the saddle rails involved a bit of setback or setforward (if you wished, few people did), due to the natural geometry of the clamp. That's why modern seatposts have setback, 'cause they had to deal with frames that already assumed that geometry. That old clamp type was, as far as I know, already ubiquitous and standard before WWII. Jasper |
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