Saddles: Size, Shape, And Saddle "geometry"

Jun 17, 2015
I'm in the market for a new saddle, having just gotten a new Domane 4.5 Disk and finding that the new geometry makes clear that my beloved Selle SMP Lite 209 is actually too narrow for me where it counts (It tapers too quickly), even though I'm skinny and narrow guy. So I started a quest to find a saddle that is closer to what my butt actually needs. Of course, there's nothing like comparison shopping and daydreaming about stuff to get you into a heap of trouble, but while digging around and looking at saddles that might possibly be more the shape I need (similar width, and big cut out, but a more pear-shaped), I've found an aspect of saddle fit and/or design that doesn't seem to be addressed directly in any discussion I've yet come across: where the rear "Max" line of the rails is relative to the widest part of the saddle.
Even Steve Hogg, in his exhaustive treatise on the SMPs only discusses "effective width"--which actually isn't even accurate in my experience!

My sit bones were measured for a 138mm seat. My Lite 209 is 139mm, but the fact of the matter is that I have a hard time getting my sit bones onto that width, because the rails simply don't go far enough back. On my old giant I used a zero setback post, and it worked well, but still, due to the taper of the SMP, I often found myself perched far enough forward that the seat was pretty much against my tender parts.

So I had some candidates: Selle italia Max Flite gel, Max SLR, SLR superflow 145, Romin Evo, etc. What I did then was download pictures of the saddles taken from the underside and stack them up in photoshop with a picture of the Lite 209, correcting the scale based on rail width. From this I noticed that some of the saddles had the bulk of their width far behind the rail Max line, and that, for me, the usable area would be too narrow. (The Max Flite Gel and the Romin Evo, in particular.) Using this technique I was able to hone my focus down to the SMP Pro, and the Selle Italia Max SLR and Max Gel. (See attached photo. Max line is marked in orange.) Some of the saddles were immediately unsuitable; (The Max Flite Gel, The Fizik "Bull" Saddles, all the Prologos.

So here is my deep thought of the day: it would be really helpful if Manufacturers supplied some sort of "saddle geometry" data, that would give an idea about where the widest part of the saddle falls relative to the Max line on the rails, otherwise width means pretty literally nothing. (Sure, you could buy a zero offset post to allow the saddle to be set further forward, but that often puts the nose of the saddle too close to the bars.) I think this detail is one more contributor to the mystique of finding the right saddle that could be mitigated with this additional data from manufacturers.

Anyway, the three saddles were delivered yesterday, and all three saddles fit me perfectly, as I expected they would from my research with photoshop. And after some preliminary experiments and tweaking, I'm probably going to end up with the SMP Pro. I actually like the Max SLR better because it's lighter, harder, and prettier, and the SMP Pro is big and UGLY UGLY UGLY, but really I prefer more contour to a saddle, and especially a flare on the back.
Saddle Comparo.jpg
Agreed. The SMP is so ugly it belongs on a blind stoker's seat post. U.G.L.Y.

I like the old narrow (131 MM) Flite Gel and I'm riding been riding that saddle for the last...7 or 8 years.

Contour from the plan view and flatness from the side profile AND the rear view really does nose narrowness. At least to me these dimensions do.

Personally, I can not tolerate...or rather my crotch can not tolerate...a saddle with any 'hammock shape' or 'slung' geometry. At all. I need flat-flat-flat in a side profile. A little kick at the problem, although I prefer it to just tail off without a 'spoiler' kick. Personal preferences in saddles has got to be one of the most frustrating attributes of cycling for newbies and old hands, alike. Nailing that home sweet home can be a *****.

Then there's 'roll off' in the rear profile! Does the rider prefer a wide flat with little roll off in the 145 MM or a more narrow flat area with a greater amount of radius roll off on the wings? Totally rounded? Another variable even given a perfect plan view contour.

Trying to relate them to a fore/aft marking on the rails might be really tough and different manufactures offer rails with more or less adjustment range and locate the centerline of that range differently. I do agree that some measurement of taper is needed, but where it happens to set up on a given frame with a given seat post at 'X' extension out of a particular frame...could get a little esoteric. Toss in BB drops, the vast differences in head tub heights, top tube lengths and stem/bar combinations...I might need one of those fancy professional set-up jigs to replace my tape measure, levels and framing square!

The weird thing is that rider 'X' prefers that zero setback post and rider 'Y' thinks his 25 MM setback post really should be 30 MM...both sitting on the same saddle. The last bike I bought came with a lame 8 MM of setback. I had to go with a new post to get the 20 MM minimum I needed ON THAT BIKE. I might have went for more setback on a different frame or less on another...just another variable.

My advice to guys seeking the 'perfect saddle' is to keep trying different ones until you find your match. 10 of the damned things before the manufacturer changes dimensions (Screw you, Selle Italia and you 145 MM Flites!) or discontinues the model all together. 10 saddles should get us through at least 25-50 years! :)

I hope that SLR Max works for you. The SLR models, in general, are IMO great looking saddles and probably on my short list of things go for a long test ride on. In width and type of riding the SLR has replaced the Flite...again just my opinion.
I'm glad you found a good saddle so easily. However I don't understand your argument. On a road bike, you should put your butt in the spot that gives the best fore-and-aft weight balance and adjust reach to suit that butt position. I've never seen a saddle that prevented one from putting one's butt in the right spot for balance, usually with either a straight or set-back post. Looking through my used saddle box, most of them have the "perch" behind the end of the usable portion of the saddle rails. On my bike with a straight post, I have the saddle shoved all the way back. On the bikes with set-back posts, the clamp is about in the middle of the rails.
Seat fitting is flippin' mysterious. I have never understood width measurements, as I just don't seem to sit that far back, but allow that same people may. I think I'd like more to see a cross section for the middle of the saddle (to see what Hogg calls "tumble-home"), or maybe some grading of the transition to the flare from the middle could be useful, like "1-2", where the 1 corresponds to something like "continuous taper from nose," and 2 corresponds to a shallow transition to the flares (or wings). Just something to characterize the shape of the saddle relative to other saddles, because it can be hard to tell just by eye-balling.

Anyway, since my SMP Dynamic fits better than any saddle I've ever used thus far, maybe I should have it 3D scanned, so I can parse its attributes and know better what makes it work for me!
There are a lot of ways to think about saddle selection, adjustment, and fitting. Wheever, many of us have worked out ways that we each think work for us and for when we help others, and some of us agree with each other on how we like to proceed. That doesn't mean your ideas are truly wrong, or that they aren't better than what you've seen here. Beyond the opinions you see here, I'm sure there are many others new and old that can be found on the Intarnetz. I really haven't seen anything like yours before. I'm not sure it would work for me, but I also don't know it well enough to try it.

It's great you found an approach you like. Install your saddles, ride your bike, and see how it feels after a few hundred miles. I found that no matter how exactly I adjust a saddle, I have to fiddle with it on the road as my distance increases.

Speaking of treatises, if you have found some please share the titles and good reference information, so we can read some of them.

Maybe there will be a better consensus as a result.
TLDR but I have a specialzed toupe 143 im looking to unload. Its a wider seat, firm with nice padding. It came on a bike, its too wid for me.
I'd just be happy if the widths claimed for a saddle were the actual width of the flat part of the saddle. I have a 138mm wide saddle that has, at most, 100mm of flat and then the surface drops off pretty quickly. If they can't get agreement on that sort of basic saddle dimension, it is all just down to trial and error.
I've been thinking along these lines too.
Two bikefit calculators used the tip of the saddle as a reference point.
With that, but switching between two saddles, I could feel the fit being way off.
So I taped a piece of string across the saddle, moved it around until I found the line for the sit bones.
Hardly surprising, there was an 1" difference fore-aft between the two saddles.
showthelifesint said:
My sit bones were measured for a 138mm seat. My Lite 209 is 139mm, but the fact of the matter is that I have a hard time getting my sit bones onto that width, because the rails simply don't go far enough back. On my old giant I used a zero setback post, and it worked well, but still, due to the taper of the SMP, I often found myself perched far enough forward that the seat was pretty much against my tender parts.
It sounds like your saddle is set way forward on the rails and you're still sitting on the front part of the saddle so your pelvic bones aren't reaching the widest part of the saddle. Tell me if this impression is wrong.

If this is the case, unless you're a dedicated triathlon rider making do on a road bike, you probably need a fit doctor more than a new saddle. Reasons for sitting too far foward include saddle too high for legs to extend when pelvis is where it should be, handlebar too far forward because the bike is too big or the stem too long, or a pile-driving pedaling style that feels stronger because your center of gravity is over the pedals as they pass the front of the pedaling stroke.

If I've said this once, I've said it a hundred times. Your seat should be low enough for you to exert pedaling force in a full circle; to see what I mean, unclip one foot and pedal for a few hundred years using one leg. Your gearing should be low enough for you to increase your cadence at will, without the sensation of breaking your knees. And your saddle should be set back far enough for you to maintain a neutral hands-on-the-hoods position without supporting your upper body using your hands on the hoods; try doing this on a trainer with your hands clasped behind your back to see what I mean.

This is a problem that would be so much easier to diagnose with a sort video of you on a trainer.