timmyquest

I guess i don't understand why this is. It seems to me that a setback seat post would be an accommodation to a frame that doesn't quite fit right, yet the rare seat post is a zero setback seat post. Is it due to more attractive frames? Stronger frames?

Pasqually

allowing the saddle to go far enough back while keeping a decent seat tube angle.

AEO

probably something to do with the clamping mechanism. simpler to design and make a setback as opposed to a thomson with more parts.

roshea

A lot of current bikes have steeper seat tube angles (not sure why but see here for example), putting the saddle further forward relative to the bottom bracket. Setback seatposts move the saddle back to compensate.

timmyquest

seat angle is adjustable on any post, so if you are able to move the seat forward or backward i'm not sure what that has to do with anything. I know there are "more aggressive" seat tube angles on some bikes compared to others, but even still...these are things that stem and setback can account for thus negating the aggressiveness.

Pasqually

saet tube angle is built into the frame.

keeping your saddle level is what you would adjust on the seat post. Hopefully with a spirit level.

roshea

The seat tube angle is 74 degrees on my CR1 (see link in my previous post). With a "regular" seatpost (ie with only a small amount of setback), I can't get the saddle back far enough, even when it is at the end of the rails. You need to get the saddle position right before you start altering reach (via the stem).

timmyquest

I understand this, but my argument would be that your bikes geometry is a bit off. I will admit this is all pretty trivial as setback seat posts work just fine, but it just strikes me as odd that they are the rule and not the exception

ridethecliche

People are being fit to smaller bikes now, and setback seatposts allow people to get KOPS on a smaller frame without being sky high on a saddle. It allows for longer reach to the pedals without having a sky high saddle.

They might be easier to make and might be a sturdier design et all. My 84 trek has a seatpost that's only 180mm long but has about as much setback as the stock cannondale post on my caad9. They've been around a while.

timmyquest

My logic is telling me the same and as i read your post i thought of yet another thing that i completely overlooked. The rear triangle is attached to the seat post, do the angles use tend to give a stronger rear end as well as perhaps a shorter one and thus a tighter handling bike?

ridethecliche

Well I think it allows more weight to be behind the bike than a straight seatpost which is advantageous for increased rear braking power.

timmyquest

I was with you until you hit me with the heart of your thesis...what good is rear braking power?

ridethecliche

No idea, but it seems like it'd be an advantage. Modulation perhaps?

It probably helps with compact frames too since the seatpost doesn't have to be super high to get the pedal reach.

That's it from me, I'm going to bed. Orgo exam tomorrow. I'm dreaming of organometallic compounds tonight!

Geoff326

ionno, but I just ordered a zero setback seatpost the other day

teterider

Which is why Ritchey made the Wayback post, and only in 31.6, first seen on Chris Horner's CR1.

https://www.cyclingnews.com/photos/20...cntdf05-scott1

BillyD

I don't think setbacks are the norm, I think they're a growing fad, and although any fad has the potential to become a norm one day, most fads usually fade away once it's recognized to have no real substance.

Hocam

I don't think you could be more wrong. If anything zero setback is the fad. It's really been the influence of triathlon and TT bikes on the road bike industry. They put the rider at a more forward position so their knees won't hit their stomach when they're body is low and stretched out in an aero position.

Look at any road bike from the 1930's to the early 1990's and see if you find a zero setback post. I have never seen one, and I doubt you will either.

The reason for this is that racing oriented bicycle manufacturers want to bring the rear wheel in as close as they can to shorten the wheelbase and make turning quicker. This means a sharper seat tube angle. It's done on cyclo-cross bikes too in order to add clearance for mud shedding and tire width but still have a fairly short wheelbase. With a 74 degree seat tube most people would be a bit too far forward, so they use a setback seat post to put the rider further back.

Some bikes used to have seat tubes curved around the rear wheel for the same reason, with the added benefit of aerodynamics.

marengo

Cyclists have been convinced that they need shorter chainstays and all the stiffness they can get. A steeper seattube angle allows that, but for every degree steeper the seattube gets, the saddle moves forward about 2cm, hence a setback post.

WheresWaldo

This is simply incorrect. Saddle position is saddle position is saddle position. So once you figure out just how much setback you need this position is fixed regardless of the seat tube angle. Here is the deal. Originally we had KOPS (Knee Over Pedal Spindle), where your saddle position was dictated by where a plumb line dropped from just under your patella should be over the pedal spindle, hence the name. Its a good starting point. Many tri guys like the knee further forward as it makes the transition from bike to run easier for them, many roadies like it just a little behind, some think its spot on. Once that is set you can look at any bike in your size and measured from the center of the bottom bracket to the tip of the saddle and that is the setback you need. Now whether or not you need a setback seat post will depend on where this saddle measurement places the rails of the saddle. In general you want to try to get the seat post clamp to fall in the middle of the saddle rails as it provides the most support for the saddle, if the saddle position places the rail/clamp interface way forward you are probably a candidate for a zero setback seatpost, conversely if all the way back you may need a setback seat post.

teterider

Wrong.


Right.

merlinextraligh

Bingo.

MichaelW

I think you have to look to tradition to find the reason for the setback post.
Originally, seatpost/saddle clamps were like this.

Even Campagnolo made this style originally.

Setback was built into the design (although some time triallers reversed the clamp for more forward saddle position).
When Campagnolo and Cinelli etc designed the first modern style posts they had to retain communality with current frames, designed with std seat-tube angles.
If you wanted to change the saddle-pedal horizontal distance by any serious amount you needed a custom frame with different angles.
Now we have a variety of different post styles with more or less layback so unusual leg sizes can be accomodated using std frame angles. I use an in-line post to match my short femurs and long lower legs.

Dubbayoo

I didn't see Zero setback much before the advent of compact frames.

Zouf

That's my seatpost... Haven't seen any other like it - until now. I bought mine new back in the mid 70's...

itri-45

And the setback gives the riders more options (to ride steeper) and yet still meet one of the UCI's rules about the saddle has to be ?? cm/in behind the BB.