stampz

Slightly stupid questions, and I suspect the answer(s) will be "it doesn't matter", however out of curiosity...

I have been running a Giant Approach saddle on all 4 of my bikes for a couple of months, but I just cannot get on with the shape at all (https://giant-bicycles.com/gb/approach-saddle) so I have swapped to a Pologo Kappa PAS (https://prologo.it/products/kappa-pas) which suits me a lot better.

However, as you can see they both have very different rail setups, to get my normal position of around 5cm setback on the Giant Saddle I had to run it pretty far forward on the second the last marker, yet on the Prologo I have to run it ALL the way back on the max setback suggested line.

I have questions around this
1) Does it matter as long as my position is the same? The saddle width and length are the same, so reach to hoods etc has remained the same as well
2) What would I have done if I needed more setback? I know you can buy a new seatpost but this is the same on ALL of my bikes, they are diff bikes and I have had to run the saddle pretty much all the way back on everyone to achieve the setback I need.
3) Is this a known thing with Prologo seats? Do they just have weird rails?

Thanks all :-)

Kontact 

The Approach appears to be a "short nose saddle", while the Prologo looks normal. So you can't compare them via the nose.

Find the point on each saddle where your sit bones dig in, and use that as the reference for set back.

stampz

I don't believe it's short nosed, online says it's standard and it certainly looks standard, other than the more curved shape the profile on both are the same

nomadmax 

Make your reference point the exact middle of the saddle length wise, IE 240mm L saddle @ 120mm (it's what I do). Not an exact science, but it's a start of continuity.

Iride01 

You still need to find where your butt is comfortable on each saddle. If that has the position of it all the way back or forward on the rails, then I'd probably consider getting a different seatpost with the appropriate offset to put the clamp back about the middle of the rails.

Just measuring the old and putting the new saddle in the same place is unlikely, IMO, to get you in the proper place your butt wants to sit on the new saddle.

Kontact 

Regardless, find out where you actually sit and use that point to adjust set back rather than the nose.

oldbobcat

Instead of measuring to the rail position or distance to the nose, measure to the widest point at the butt end of the saddle. That's the closest indicator of where your butt goes.

79pmooney

RIde it. Observe how natural the reach to the bars feels and whether it is similar to what you had in the past. Look in shop windows to see if your back angle is the same. (Now I am guessing you didn't do this before so you don't have a comparison but it is very useful, That profile view tells a lot.

Seat setback - ultimately critical to getting perfect fit. At the end of the rails? This may be preventing you from ever getting to perfect. It can also be a ride ender by causing the seat rails to break. Need to buy X seatposts with 15mm more or less setback? My bikes have: 2 custom seatposts with 65mm setback, an ancient SR MTB post with variable setback up to something like 70mm, a lugged Nitto with tons of setback (and not cheap). I can relate. And compared to custom frames and even some high end fit sessions, really not all that expensive.

Ultimately and ideally I should be riding bike s with more laid back seat tubes except for good handling on fast downhill and rough corners, short chainstays serve me far better. Tire clearance becomes an issue. (My best downhill bikes require fenders that are cut out at the seat tube.) Someday I might be riding a custom with a curved seat tube but 'til then, I'll invest in big setback seatposts. (Ordinary Terry Flys (railwise) - being my butt's seats of choice.)

Edit: Get the post for one bike that will put the clamp where you best guess now would be centered along the rails. Ride that bike lots, carrying the wrench to adjust the setback. (2-bolt posts are a real blessing here. With them, it is easy to adjust just the rail position and not touch the tilt. Also dial in tilt very exactly and repeatably.) When you get this bike perfect, you will know exactly what you need for posts for you other bikes.

cyclezen

I find it best to NOT 'standardize' on anything when comparing any saddles. Even visually similar designs might find you riding/sitting differently on any saddle, compared to another.
As noted, best to determine where you mostly sit/perch your sitzbones on your current saddle. My best way to do setback from one saddle to another is to measure the sitzbone position forward to the vertical line thru the BB axis. That's a 'start' point, and then I might adjust fore/aft a bit after doing further riding.
Your 2 saddles are quite different, so this process takes into account some of those differences...
Other considerations
Saddle height - rail to top of 'sitz' area distance/height
Many older design saddles may be taller than many modern saddles, this is not by manufacture date, more by design...
Rail to saddle sitz height will change your seatpost extension height... a consideration in setting height and setback.
... of course, there's nothing to say that your CURRENT saddle and position is at the 'optimum' setup for you...
Best to get out and ride, and then do the 'adjustment' game... but always note the 'home' position before you really get into the game, and make only ONE slight adjustment at a time, then evaluation.
Thx
Yuri

BFC

Always best to do a quick recheck of your position