# Moving saddle position to bike with longer cranks



## notwist (Feb 26, 2009)

How do I transfer my saddle height and setback to a bike with 2.5mm longer crank arms? Can I just add 2.5mm?


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## PJ352 (Dec 5, 2007)

notwist said:


> How do I transfer my saddle height and setback to a bike with 2.5mm longer crank arms? Can I just add 2.5mm?


Because the geometry of both bikes may differ, IMO the best approach is to measure your current saddle height and KOPS for reference and set up the 'new' bike with the same KOPS setting. Saddle height may change very slightly because of the added crank length, but I'd initially set the saddle height the same on the new bike and tweak from there. 

Saddle height and KOPS are both easy measurements to take, so if decide to go with this suggestion and need instructions post and we'll assist.


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## Camilo (Jun 23, 2007)

I agree with PJ352. Recently added a new bike w/ different crank length and geometry. I simply measured from a constant point on my saddle (I used saddle rails) to spindle of pedal when lined up w/ seat tube, down position. I also measured from the nose of my saddle down w/ plumb bob and meaured distance to crank spindle. Duplicated these two measurements with new bike (identical saddle) and it was pretty much good to go in that department, very tiny tweeking was needed, possibly due to inaccurate measurements or a less broken in saddle. 

The handlebars and shift levers were more difficult since I have brifters on one bike and aero road levers and slightly differnt bars on the other. I did measure as much as I could to try to get a close starting point, but have had to tweek quite a bit.


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## bikerjulio (Jan 19, 2010)

My personal experience and opinion is that you should do nothing.

There are 2 issues:

KOPS is not the be all and end all of saddle position. I prefer to get my saddle to bars dimension right (or saddle to hoods if you prefer). Changing cranks does not change this.

Saddle height. At the point of max power the crank will be horizontal or near so. Again, the length will not affect this. So leave it.

I run bikes with cranks of 175, 177.5, and 180. Set them up all the same. No problems.


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## Kerry Irons (Feb 25, 2002)

*Misuse of terms*



PJ352 said:


> Because the geometry of both bikes may differ, IMO the best approach is to measure your current saddle height and KOPS for reference and set up the 'new' bike with the same KOPS setting. Saddle height may change very slightly because of the added crank length, but I'd initially set the saddle height the same on the new bike and tweak from there.
> 
> Saddle height and KOPS are both easy measurements to take, so if decide to go with this suggestion and need instructions post and we'll assist.


KOPS means Knee Over Pedal Spindle. I think you mean saddle setback. KOPS is a starting point for positioning on a bike. When you are trying to set up two bikes to be the same, you measure the saddle setback relative to the BB axle, and make that the same.


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## PJ352 (Dec 5, 2007)

Kerry Irons said:


> KOPS means Knee Over Pedal Spindle. I think you mean saddle setback. KOPS is a starting point for positioning on a bike. When you are trying to set up two bikes to be the same, you measure the saddle setback relative to the BB axle, and make that the same.


Yes, I know KOPS is knee over pedal spindle, but IMO setting KOPS +/- is a more accurate measurement because (by its very nature) it take variances in saddle dimensions (and geo, if applicable) into consideration. In the OP's case, it'll also take crank length into consideration.

As an example, I always want my position about 5-8mm's behind KOPS, so redoing IT on a new bike set up is more reliable than measuring setback, which FWIW has _its_ position dictated by KOPS.


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## Jay Strongbow (May 8, 2010)

bikerjulio said:


> My personal experience and opinion is that you should do nothing.
> 
> There are 2 issues:
> 
> ...


I don't think anyone is suggesting KOPS is the end all be all but and we are talking about duplicating a fit not acheiving KOPS so I really don't where your comment came from. Assuming he is trying to duplicate a fit because it's good for him then yes where in relation to KOPS is very important.

Granted 2.5mm is close to nothing so you might be right it won't matter but your logic for saying it is kinda bizzare. Reach at the bottom is a pretty important factor in pegging saddle height too. Again 2.5 mm might not be noticable but reach does indeed matter.


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