# Seat Post, Setback vs. Zero Setback



## Weav (Jun 21, 2009)

Not sure I posted this question initially in the right thread so here it is... Is there a preferred seatpost (setback vs. zero setback) to use or is it strictly a fitting tool. I have a bike that has a 25mm setback and I think I'm going to have to get a little closer for reach and think I'll use a zero setback seatpost to move me forward. Anything I need to be aware of in doing this? I'm using a 100mm stem currently and don't like to go shorter than that.


----------



## frdfandc (Nov 27, 2007)

Its used as part of the fitting process. If you need to reduce your reach, you don't do it with saddle position. Its done via a properly sized bike, or stem length if the stock stem is a tad short/long.


----------



## Weav (Jun 21, 2009)

so how is the seatpost setback used in the fitting process? Thanks.


----------



## danl1 (Jul 23, 2005)

Weav said:


> so how is the seatpost setback used in the fitting process? Thanks.



That's a long story, but essentially, to establish your balance over the BB. Exactly how that is established is part of the art and science of good fitting. 

The easy (but correct only by coincidence) answer is to get KOPS correct, once saddle height has been correctly figured.


----------



## rx-79g (Sep 14, 2010)

KOPS is Knee Over Pedal Spindle. Essentially, a plumb line hanging from the soft side of the knee just behind the kneecap should intersect the spindle when the cranks are level. If you start with the correct seat height, KOPS sets your fore/aft seat location. Then you set reach with stem length. 1,2,3.

Unless you have short femurs (or a strange road bike), a standard setback seatpost will usually work. Zero posts are for short femurs, extra long setback posts for long femurs.

Zero posts started with mountain bikes and are loved by weightweenies because they are usually lighter. But they rarely make sense on road bikes.


----------



## Weav (Jun 21, 2009)

So changing out for a shorter stem or changing out to a bar with a shorter reach would be the better way to go? I have the 3T Ergosum bar and could switch to the Ergonova bar and shorten the reach 12mm.


----------



## rx-79g (Sep 14, 2010)

Weav said:


> So changing out for a shorter stem or changing out to a bar with a shorter reach would be the better way to go? I have the 3T Ergosum bar and could switch to the Ergonova bar and shorten the reach 12mm.


It might be. But if you haven't established where your seat should be, that's like buying the dress before finding the bride.

Once you have your saddle position, look for a reach to the drops that puts your bent elbows 1 to 2 inches forward of your knees. That can be achieved with different bar shape or stem lengths.


----------



## Weav (Jun 21, 2009)

rx-79g said:


> It might be. But if you haven't established where your seat should be, that's like buying the dress before finding the bride.


I know, I'm just trying to figure out my options while I wait for my pedals to arrive.



> Once you have your saddle position, look for a reach to the drops that puts your bent elbows 1 to 2 inches forward of your knees. That can be achieved with different bar shape or stem lengths.


I assume you mean when the knees are at the 3 o'clock position for this test?


----------



## rx-79g (Sep 14, 2010)

Weav said:


> I know, I'm just trying to figure out my options while I wait for my pedals to arrive.
> 
> 
> I assume you mean when the knees are at the 3 o'clock position for this test?


Correct. I'm sure you can find pictures and more detailed instructions on yee olde internets.


----------



## MR_GRUMPY (Aug 21, 2002)

Weav said:


> So changing out for a shorter stem or changing out to a bar with a shorter reach would be the better way to go? I have the 3T Ergosum bar and could switch to the Ergonova bar and shorten the reach 12mm.


Changing the bar/stem length will not position you over the bottom bracket correctly. That's a rookie mistake that I made, my first few years of riding. When "power riding" I would be so far back on the saddle, that I would be off the back of it.
The traditional way of gettng the correct position for a long legged rider was to use the standard (for the time) medium setback seatpost, and to slam your saddle back all the way back, as far as it went.


----------



## masont (Feb 6, 2010)

Weav said:


> Not sure I posted this question initially in the right thread so here it is... Is there a preferred seatpost (setback vs. zero setback) to use or is it strictly a fitting tool. I have a bike that has a 25mm setback and I think I'm going to have to get a little closer for reach and think I'll use a zero setback seatpost to move me forward. Anything I need to be aware of in doing this? I'm using a 100mm stem currently and don't like to go shorter than that.


A couple things:

1. First, what sort of physical issues are you having?

2. Don't adjust your saddle position to compensate for reach. Do that with the stem. If you don't want to go shorter than 100mm (why? aesthetics?), you need a smaller bike. 

3. It's just a fitting tool. You've gotten the right answer, and it has to do with femur length.


----------



## Fai Mao (Nov 3, 2008)

Also remember that the "KOPS" is a starting point.

In addition to femur length you have to look at riding position. On a bike where you are up right you may very well be "Behind" the KOPS position and on a bike with very steep angles like a triathlon bike you may be a bit in front of it.


----------



## Mel Erickson (Feb 3, 2004)

rx-79g said:


> KOPS is Knee Over Pedal Spindle. Essentially, a plumb line hanging from the soft side of the knee just behind the kneecap should intersect the spindle when the cranks are level. If you start with the correct seat height, KOPS sets your fore/aft seat location. Then you set reach with stem length. 1,2,3.
> 
> Unless you have short femurs (or a strange road bike), a standard setback seatpost will usually work. Zero posts are for short femurs, extra long setback posts for long femurs.
> 
> Zero posts started with mountain bikes and are loved by weightweenies because they are usually lighter. But they rarely make sense on road bikes.


Zero setback posts are often seen on time trial bikes.


----------



## rx-79g (Sep 14, 2010)

Mel Erickson said:


> Zero setback posts are often seen on time trial bikes.


And KOPS never is. 

My comments are addressed to the traditional road bike. The fit of TT bikes is more different than even MTB to road bikes in many ways. TT bikes have the most forward seat position of any bike and determining reach is very different.


----------

