Offset or non-offset seatposts

[htono]

I understand that non-offset seatposts raise ugly emotions in this space, but I struggle to understand why.
Please educate me.
Offset seatposts were the norm when materials and design led to the single bolt post, and space was needed behind the tube to locate the mechanism. It is not ideal and places nonlinear stresses on the seat tube. I understand that frame fitting evolved around the unique (awkward?) position required.
With the simple and elegant solutions that have been developed around non-setback posts, it would seem to me that it is a preferable way to go. If fitting is consistent with the new position, isn't it an inherently better design?
What gives?

[Saab2000]

Many bikes just don't look as sorted with non-offsets. A lot of what goes on here is aesthetic, whether anyone wants to admit it or not. But there is often some bike design reason for it too. For me? I can't get back far enough with a non-setback post. I can barely get back far enough with most setback posts. Everyone has their own reason.

[davids]

You need the setback you need. So if you're buying an off-the-peg frame, you should be considering how much setback you need (or don't need) and then buy a post with the appropriate setback.

If you're having a frame built, well then, it's something to discuss with your builder. I prefer the look of a setback post, but leave the other design considerations to the effbuilder. For what it's worth - all my bikes have posts with setback.

[Curt Goodrich]

As far as one design being better than the other, I would say only theoretically. In practice the setback seat post has a solid 50+ years of use to back up it's design. As others have pointed out, use whatever puts you where you want to be. Fit aside, I think the reason that some find the non-setback post ugly is because it deviates from their norm or if they've been riding for more than a few years. Back in the not so long ago there were only set back posts. Personally I don't get too worked up about this sort of thing but do prefer a setback post. But then again this princess isn't very sensitive to setback. I can ride a range of setbacks without any issues.

[Dave]

I get the proper look to the offset, however I love thomson posts, but their offset look is terrible. So I use their straight one. only reason for me. the only custom bikes I have ever had made for me I told them I would be using it. They did the rest.

[caleb]

If fitting is consistent with the new position, isn't it an inherently better design?
What gives?

First, the setback post isn't a problem to be fixed. It doesn't break, so the straight post isn't a more functional design. 0 = 0.

Second, for anyone riding a bike properly who isn't a midget, the fit can't be consistent. Look over these four bikes plucked pretty much at random from the gallery:





Here's a thought experiment: Imagine keeping all the contact points the same, but substituting a straight post for the setback one. The only way to keep the saddle in the same spot is to make the seat tube angle significantly more slack. And if you do that, you either physically run into the rear wheel with the seat tube or significantly compromise tire clearance. As a basic geometry problem the straight post doesn't work.

[DOOFUS]

where Caleb is going

weight distribution is better with a setback post. stock geo as we know it evolved with the premise that the rider was using a setback post. fit is about where the weight balances, not about KOPS....

a custom frame with more setback (or, slacker STA, if you must) to compensate for the straight post is another matter.

[caleb]

a custom frame with more setback (or, slacker STA, if you must) to compensate for the straight post is another matter.

Except you'll end up with either really long chainstays (and front end) or very limited tire clearance, both of which can suck.

[Jason Musgrave]

visual

A saddle perched on a straight post is to 'nose heavy' visually--doesn't look balanced on top of the post unless it's shoved all the way back (like all the SpeedVagens).

*edit: imho the thing looks right when the transition from the nose attachment point to post clamping surface (rails of saddle) is bisected by the front of the ST/post--pic added for clarification

[suhacycles]

Also depends on what saddle is on that post... a women's Terry saddle doesn't have the same 'look' as an Arione.

In defense of the zero setback post (yeah, I own 2 Thomsons) at least it's a standard, consistent dimension. Can anyone off the top of their head recall the setbacks for a Ritchey post? Campy? Kalloy?

[962]

the one that fits??

Not to mention personal preference for say cleat position

That reminds me, I think I should get my friend a zero-setback post for his slightly-large frame, rather than see him slam his saddle forward. More than the top tube length etc it's really the seat-tube angle on the larger size that makes him do that.

[hampco]

In defense of the zero setback post (yeah, I own 2 Thomsons) at least it's a standard, consistent dimension. Can anyone off the top of their head recall the setbacks for a Ritchey post? Campy? Kalloy?

setback posts are usually, but not always, 21mm

ymmv

[steve575]

The seatpost setback puts your but where it needs to be on a stock frame. Custom is a whole different story. I have had a couple of custom frames built by very reputable builders, and they have built my frames around zero setback posts. I don't know if it's my body or their preference. It doesn't matter. The bikes work.

[ineff]

I have fit somewhere between (I'm guessing, I really have no idea) 400-500 people on bikes, I've worked at a shop as the (only) fitter for a few years and have been working at a shop for 10+ years total. I see very few people, in my opinion, that don't need a set-back post on a road bike and usually the people who need a zero set-back post are pretty short and female. Mountain and cross race bikes are totally different, often a more forward position will be the best for the rider.

Also when talking about set-back vs no set-back seat posts I always take into consideration what saddle the rider is using, for example a brooks saddle almost ALWAYS requires a set-back post, they are very forward positioned saddles. Also I think people often position their saddle wrong (clamps and rails) so they can use a straight Thomson post, I've done this with a regal or rolls and a thomson...

[jlwdm]

Campagnolo 25mm although different companies measure setback differently.

My two customs are 72 degree sta with 25mm setback. Would not want a shallower sta.

My non-custom 73 degree requires a 35mm setback - fewer choices, especially in silver. I have one now but getting a new one from Bold Precision.

Jeff

[solfege]

I get the proper look to the offset, however I love thomson posts, but their offset look is terrible. So I use their straight one. only reason for me. the only custom bikes I have ever had made for me I told them I would be using it. They did the rest.

I'm using a Thomson setback because it's the only decent 26.8 post available for my 9 year old NOS IF frame. It wouldn't have been my first choice aesthetically, but it's grown on me rather a bit.

[CalD]

I think caleb's response is spot on. Look at the pics he posted of the Time and the Crumpton in particular. Given a 700c wheel, a slightly shallower st angle would potentially hit the wheel. Granted, you could make the chainstays longer to accommodate a shallow st angle, but that affects desired handling characteristics for these particular bikes. As for aesthetics, meh... I prefer setback but that's probably cuz that's what I know and have grown up with. Had we all grown up with zero setback posts, then we'd probably all hate setback posts at this stage. I think the setback seatpost solved a geometry issue that provided the best solution to a well balanced road race bike, as I think caleb is suggesting.

[962]

My own substantive data points to make up for earlier snark...

Prob 30+ mm (to center of rails) on other frame—Colnago with steep seat tube angle in small size

This bike, between 20-25mm with 1° slacker seat-tube angle after moving saddle forward and up, and cleats rearward at least 5mm

I don't think there's anything wrong with them. On 55cm and up they seem fine from a functional point of view. Or for very short like the 46cm Pegoretti in the gallery. Or short femurs.

With saddle slammed forward on an MTB they look ridiculous though...

[sacha white]

visual

A saddle perched on a straight post is to 'nose heavy' visually--doesn't look balanced on top of the post unless it's shoved all the way back (like all the SpeedVagens).

How to say this tactfully?...

Designing a bike that requires the saddle to be slammed all the way back to get proper saddle setback would be some rookie assed shit, right? I know that knowing a lot is the name of the game on forums, but please don't subject my bikes to these kind blanket statements. I take design seriously and put a lot of time and thoughtful consideration into each bike.

Speedvagens are designed so that the saddle is clamped somewhere in the middle of the rails, not "slammed all the way back". Pushed back a bit from center, maybe, but rarely, and only if the options are considered and the choice is deliberate will the saddle be pushed back all the way. This is as it should be.

To the OP, I like straight posts. They're all business and don't (in my experience) compromise fit, aesthetic, or design.

[ergott]

I could swear that the "chainstay length" thread is right around the corner.

-Eric