Seatpost question

Discuss light weight issues concerning road bikes & parts.
kgibbo1868
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by kgibbo1868

Is there any benifit to a set back vs no set back seatpost?

Also, with the differnt diameter options what do you think is ideal?

This would be for a fully custom Ti road frame, so what do you think?

Thanks!
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wheelbuilder
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by wheelbuilder

27.2 with a lot showing is my choice. Definitely aids compliance. (if carbon)
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kgibbo1868
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by kgibbo1868

wheelbuilder wrote:
Wed Sep 26, 2018 4:56 am
27.2 with a lot showing is my choice. Definitely aids compliance. (if carbon)
How much is "a lot"?? I am wanting a HZ TT so I don't think I will get heaps of post showing, but that is not a big deal to me as I suspect I will get all the compliance I want with a Ti frame that is fully butted to spec.
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vejnemojnen
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by vejnemojnen

setback posts can be more comfortable due to greater compliance, esp if you ride with your saddle placed back as well. and look 99% of the time better.

I've found them more knee friendly, comfortable, and enables me to use my hamstrings and glutes more (and these muscles in my case far superiior to my quads)

I'd get a setback post.

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silvalis
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by silvalis

Setback looks better :D
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pdlpsher1
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by pdlpsher1

+1 on a setback post which will be more compliant. However a setback post that is barely showing will still be way less compliant than a zero setback post with a lot showing. The key to compliance is a small diameter post and a lot of post showing.

Frame compliance/ride quality on a Ti frame is determined by tubing diameter and geometry. Butting will have a very little effect on compliance.


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LionelB
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by LionelB

A road bike should always be designed around a setback post for proper look and rear tire clearance too.

Nefarious86
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by Nefarious86

LionelB wrote:A road bike should always be designed around a setback post for proper look and rear tire clearance too.
R5 RCA would beg to differ...
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LionelB
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by LionelB

Nefarious86 wrote:
Wed Sep 26, 2018 9:46 am
LionelB wrote:A road bike should always be designed around a setback post for proper look and rear tire clearance too.
R5 RCA would beg to differ...
I am talking about a proper road bike.

Nefarious86
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by Nefarious86

Last time I checked they were a proper bike... Unless you're caught up in the nostalgia of poor geometry and compromised biomechanics.
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kgibbo1868
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by kgibbo1868

I was thinking using a setback post was just to compensate for a frame that is a bit small? I guess my question is if I have custom geometry I can get the same position with either post by changing the frame dimensions, so is there much benefit to either option? We can leave asthetics out of the discussion as that’s not my question at this point.
Thanks
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Nefarious86
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by Nefarious86

Straight post is lighter.
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Calnago
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by Calnago

Nefarious86 wrote:
LionelB wrote:A road bike should always be designed around a setback post for proper look and rear tire clearance too.
R5 RCA would beg to differ...
The RCa was specifically designed around a zero setback seatpost, and has slacker seat tube angles than a “proper” Image road bike in the same size would typically have. Simply a design choice by Vroomen and Co. But slacker seat tubes decrease the amount of clearance for the rear tire, particularly where shorter chainstays are being used. Setback posts have been used traditionally for years simply because on average, they were needed in order to get the rider in the most optimal riding position while maintaining a nice tight road race geometry. Today I think a lot of basic reasons for design have been either forgotten, ignored, or simply thrown out the window for some stupid marketing reason in an attempt to depart from the norm to sell more bikes to the easily swayed consumer. In the case of zero setback seatposts, that reason might be lighter weight for example, a dumb reason to compromise fit. And nothing looks dumber than a saddle clamped at either extreme of the rails. Well, I suppose there are much dumber things but don’t get me started.
As for skinny 27.2mm posts, they are fine but I don’t like the aesthetics of them sticking out of today’s rather large diameter seat tubes. Positionally, if you really want to get aero, then that will often require moving the saddle forward some, and a zero setback post may be fine, at the expense of a more traditional (and comfortable) position. I think very few people have such morphological abnormalities that makes a zero setback post a preferred option on a normal road bike. Mostly I think some folks might think it looks cooler (I don’t), or they don’t really have an ideal fit.
For the OP, who is getting a custom frame with a horizontal top tube, my personal opinion would absolutely be to go with a setback post. Especially with today’s trend of larger tires you want to keep as much clearance between the tire and seat tube as possible. Thus, all else equal the builder can go with a slightly steeper seattube than would be possible if the bike was being designed around a zero setback post.
Go with the setback post.
Last edited by Calnago on Wed Sep 26, 2018 1:01 pm, edited 1 time in total.
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LionelB
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by LionelB

Calnago wrote:
Nefarious86 wrote:
LionelB wrote:A road bike should always be designed around a setback post for proper look and rear tire clearance too.
R5 RCA would beg to differ...
The RCa was specifically designed around a setback seatpost, and has slacker seat tube angles (than a “proper” Image road bike) in the same size would typically have. Simply a design choice by Vroomen and Co. But slacker seat tubes decrease the amount of clearance for the rear tire, particularly where shorter chainstays are being used. Setback posts have been used traditionally for years simply because on average, they were needed in order to get the rider in the most optimal riding position while maintaining a nice tight road race geometry. Today I think a lot of basic reasons for design have been either forgotten, ignored, or simply thrown out the window for some stupid marketing reason in an attempt to depart from the norm to sell more bikes to the easily swayed consumer. In the case of zero setback seatposts, that reason might be lighter weight for example, a dumb reason to compromise fit. And nothing looks dumber than a saddle clamped at either extreme of the rails. Well, I suppose there are much dumber things but don’t get me started.
As for skinny 27.2mm posts, they are fine but I don’t like the aesthetics of them sticking out of today’s rather large diameter seat tubes. Positionally, if you really want to get aero, then that will often require moving the saddle forward some, and a zero setback post may be fine, at the expense of a more traditional (and comfortable) position. I think very few people have such morphological abnormalities that makes a zero setback post a preferred option on a normal road bike. Mostly I think some folks might think it looks cooler (I don’t), or they don’t really have an ideal fit.
For the OP, who is getting a custom frame with a horizontal top tube, my personal opinion would absolutely be to go with a setback post. Especially with today’s trend of larger tires you want to keep as much clearance between the tire and seat tube as possible. Thus, all else equal the builder can go with a slightly steeper seattube than would be possible if the bike was being designed around a zero setback post.
Go with the setback post.
Agreed completely


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