# saddle height and fore/aft setup



## scapegoat.ipa (Oct 26, 2015)

I borrowed a 2003 58 cm trek 5200 until I was able to save to purchased my first road bike. Had a bike fit at a LBS . Rode the bike for a few months. Fast forward, I purchased a 2014 56 cm Specialized Roubaix this past spring and the LBS with a customary bike fit. I was hardly ever comfortable on the Roubaix saddle setup. While the setup on the trek fit pretty well Changed and tried half dozen saddles. So I decided to do the Specialized body geometry fit.

I notice that the Roubaix seat height is about a quarter of a inch or so higher than the Trek. I researched the forums on seat setup/ etc for riders that have more than one road bike. 

Regardless the make of the bike and saddle, should the seat height be the same? AND if lower the seat height of the Roubaix to match the Trek, Do I need to move the saddle for/aft and about how much?


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## Jay Strongbow (May 8, 2010)

If you're riding two bikes for the same general type of riding (as opposed to one TT bike and one mountain bike) yes their position relative to the bottom bracket should be the same. 

As for your second question that depends if the seat tube angle is the same or not. You'd want them to be the same relative to the BB so do with you gotta to to achieve that.

(both points assuming you know what position works for you. Obviously you wouldn't want to copy a position that sucks)


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## woodys737 (Dec 31, 2005)

scapegoat.ipa said:


> Regardless the make of the bike and saddle, should the seat height be the same? AND if lower the seat height of the Roubaix to match the Trek, Do I need to move the saddle for/aft and about how much?


Ideally yes. The saddle height should be the same as measured from the center of the BB to the top of the saddle up the seat tube. Don't forget to take into account the crank length difference if any. For example if your Trek has 172.5mm while the Specialized has 170mm the Trek saddle would need to be 2.5cm lower.

In general, the rule of thumb for moving saddle up/down if you move it fore/aft is: 10mm vertical change will = 3mm horizontal change. Move saddle forward = raise saddle. Move saddle aft = lower saddle. If the geometry of the two bikes are the same make it easy and get the same saddle for both, set the height you know works and then measure how far behind the BB the tip of the saddle is via a plumb line. Then set the second the same as the first...


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## PJ352 (Dec 5, 2007)

I'm confused. Are you experiencing discomfort after having the BG FIT done, or are you just curious why the saddle height on the Roubaix differs by ~6mm's from your Trek?

That aside, to add to the above comments for reasons saddle heights may vary, also consider pedal stack height. This, of course, would only apply in cases where clipless pedal systems differed, bike to bike.


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## Jay Strongbow (May 8, 2010)

PJ352 said:


> That aside, to add to the above comments for reasons saddle heights may vary, also consider pedal stack height. This, of course, would only apply in cases where clipless pedal systems differed, bike to bike.


ah yes, good point.. Different saddle too. Some compress, some don't, and also some have differently positioned sweet spots so while they may be placed the same you don't necessarily sit in the same spot.


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## scapegoat.ipa (Oct 26, 2015)

In response to PJ352 comments and others . 1) using same pedal system. 2) Yes even after the BG fit, it seems that with the current riding position on the Roubaix bike, when leaning over, I'm riding in the end portion of the Ischiopupic ramus. This pressure point is resting on the nose section of the saddle. See attached picture. Area marked with a yellow circle.

Woodys737: thanks for the rule of thumb info


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## 9W9W (Apr 5, 2012)

setting up the seat in the same position relative to the BB is all well and good, but once you introduce the front end into the equation "when leaning over.." it can't feel the same way unless the front end is set up identically as well. Even then, bars have different lengths and reach measurements... I confused myself.. what was the original question again?


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## Kerry Irons (Feb 25, 2002)

woodys737 said:


> Don't forget to take into account the crank length difference if any. For example if your Trek has 172.5mm while the Specialized has 170mm the Trek saddle would need to be 2.5cm lower.


Uh, that would be 2.5 mm, not 2.5 cm.


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## PJ352 (Dec 5, 2007)

scapegoat.ipa said:


> In response to PJ352 comments and others . 1) using same pedal system. 2) Yes even after the BG fit, it seems that with the current riding position on the Roubaix bike, *when leaning over, I'm riding in the end portion of the Ischiopupic ramus. This pressure point is resting on the nose section of the saddle. *


The bold statement brings up what Jay posted earlier re: saddle, shapes/ contours... but it's fundamentally a fit issue, and (IMO) the primary cause (or fix) isn't going to be saddle height. 

Different saddle? A _slight_ adjustment to tilt (down at the tip)? Reach? More likely fixes. 

I suggest going back to the fitter and describing the issue in the same detail you did here. Specialized recommends different saddle widths for more aggressive or more upright riding styles. 

A number of factors will influence rider comfort (as was mentioned, reach). Key is finding your fix, but start by treating the Roubaix as a separate entity.


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