What is the purpose of a setback seatpost?
02-23-12 | 05:44 AM
#26
Voice of the Industry
Joined: May 2007
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and the answer is?? just fit? if so, then i can see that. ive never used a setback post, and tend to ride pretty big frames with traditional/ish geometry. maybe if i were riding something compact id see the benefit. so for the record, is a seatpost with cradle that curves back slightly (not centered with the seat post, and seat tube) considered a set back post? or are we talking major set back like those bendy thomson posts?
As to the saddle cradle as you put it curving back..yes, that is what a setback seat post is...when the centerline of the clamp is well behind the centerline of the seat post itself. For the record, a Thomson post with its bend rearward is one of the least setback posts out there...only 16mm...because the clamp Thomson uses has no offset and the bend is only about 10 degrees or so. Not to tell Thomson their business but they limit their market by not offering a setback post in the 20-25mm range. They do this so they don't have to tool another clamp and their std clamp has enough angle range to work with the slight bend in the seat post.
But...for many riders a 16mm offset is not enough with the contemporary shift toward more upright seat tube angles which promote shorter chainstays and shorter wheelbase. I prefer a carbon post at the end of the day anyway so no big deal to me. Thomson makes a good Al post tho.
Last edited by Campag4life; 02-23-12 at 05:47 AM.
02-23-12 | 09:16 AM
#27
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02-23-12 | 09:53 AM
#28
Gluteus Enormus
Joined: Dec 2007
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From: Raleigh, NC
Bikes: Yes
From Cervelo:
"To save a few more grams of bike weight, the R5ca is designed to use a zero offset post. Accordingly, with the saddle setback fixed, the seat tube angle has been decreased to achieve a 25mm rearward offset at the saddle height. This means the R5ca with zero offset post fits exactly the same as any road bike with 73 degree seat tube angle and traditional 25mm offset post."
02-23-12 | 09:57 AM
#29
Voice of the Industry
Joined: May 2007
Posts: 12,572
Likes: 8
His setup isn't relaxed, that frame has a slack STA.
From Cervelo:
"To save a few more grams of bike weight, the R5ca is designed to use a zero offset post. Accordingly, with the saddle setback fixed, the seat tube angle has been decreased to achieve a 25mm rearward offset at the saddle height. This means the R5ca with zero offset post fits exactly the same as any road bike with 73 degree seat tube angle and traditional 25mm offset post."
From Cervelo:
"To save a few more grams of bike weight, the R5ca is designed to use a zero offset post. Accordingly, with the saddle setback fixed, the seat tube angle has been decreased to achieve a 25mm rearward offset at the saddle height. This means the R5ca with zero offset post fits exactly the same as any road bike with 73 degree seat tube angle and traditional 25mm offset post."
02-23-12 | 07:16 PM
#32
Resident Alien
Joined: Jul 2007
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From: Location, location.
Here's a more successful rider:
and another:
Of course this guy was stripped of a bunch of results
Last edited by Racer Ex; 02-23-12 at 07:22 PM.
02-24-12 | 10:31 PM
#34
Señor Member
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From: Australia
https://sheldonbrown.com/kops.html
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