harrier6

For the past decade or so I've had a cheap Nashbar saddle on my road bike. It has a flexible plastic shell, so occasionally I'll hit a big pothole and bottom the thing out against the rails/seatpost. It seems odd to me that in this era of suspension stems and seatposts that we ride carbon-shelled saddles designed to be as stiff as possible. A saddle designed to offer a bit of compliance seems like low-hanging fruit to me. Maybe a leather saddle does this a little bit, but not much. Am I missing something?

GhostRider62

Yes, Brooks leather saddles can have a lot of flex but can also be quite hard.

Sy Reene

hmm.. laterally stiff but vertically compliant. So they could make a carbon shelled version of this (to minimize weight of course )

wheelreason

They are to varying degrees.

SJX426 

I find this saddle to be very comfortable, once my backside is broken in.
P1040421 on Flickr

This one is from 1972 and disappears when riding.
PXL_20230406_110514222~2 on Flickr

jadmt

brooks C17 flexes.

chaadster

You set a couple of incorrect premises here, namely that current/new/modern saddles aren’t designed to flex and that carbon fiber use in shells is proof of it.

Here’s the descriptive text from the current Fizik site about their Aliante Aliante R3:

Aliante R3 Kium is light, flexible and agile, enabling you to perform at your best. It features a composite fiberglass co-injected Nylon shell for support with optimized stiffness to-weight construction – with Twin Flex technology which combines a strong, stiff carbon layer with a flexible, comfortable carbon layer – and an alloy K:ium rail for light weight and strength.

It’s a description of design, function, and materials use that’s completely 180° from the scenario you laid out.

That said, there are stiff carbon saddles, e.g. the SMP Carbon, about which on their site they say:

Light weight carbon fiber for cyclists with narrow pelvises who love hard seats.

It seems, from these two examples, that at least two approaches to saddle design exist, suggesting generalizations about how saddles are nowadays are not really useful. That’s not to say that saddles couldn’t be designed for even more flex, so that’s something which could be discussed.

freeranger

Your better saddles will be supportive but will have some "give" built into them. Should not have so much give that the base bottoms out on the rails on a hard bump. Some saddles may even have a cutout in the base with firm foam or gel above it. Others may have a solid shell that is designed to have some give. Road bike saddles don't have to absorb harsh bumps nearly as often (if at all) than a saddle designed for off road riding, so they will tend to be more rigid than mtn.bike saddles. But none should bottom out on the rails.

Iride01 

Learning how to un-weight your butt from the saddle as you go over bumps helps a lot. Similarly holding the bars, drops or hoods with your fingers only as you go over those bumps helps keep you from getting numb hands or sore shoulders.

I bet that even the most firmest feeling plastic saddles have some flex to them when supporting the rider weight and encountering a bump.

jonathanf2

I've gone all in with carbon 3D printed saddles. The carbon shells are stiff, but the 3D printed mesh keeps it cushion/shape on long rides, they stays cool even in 100 degree temps and have very minimal friction especially when adjusting saddle position. Plus I find tire profile to make the biggest difference in comfort on rough terrain. There's no way I'd go back to a standard saddle again.

mstateglfr 

As mentioned, the Brooks Cambium series flexes. Its a rubber shell, so it definitely flexes. C13, C15, C17, C19- all flex.

aliasfox

I thought one of the reasons saddles were mounted on rails was to allow the seat to flex between the rail mounting points? Otherwise we'd just bolt the post directly into the bottom of the seat, I imagine.

rsbob 

I just hate it when someone makes an incorrect blanket statement which gets disproved in four posts. So sad.

RCMoeur 

A lot of riders apparently experience discomfort if a saddle is too cushy or flexy. (Note: I am not one of them).

There is a big range of power outputs by riders, with a corresponding reduction in weight transfer through the saddle vs. through the pedals. Riding position can have a big effect, as a more-upright position can shift weight support from the hands and arms to the saddle. I've heard reports that saddles with too much padding allow pressure outside the sit bones and instead in other areas, such as the, well, other areas. This can cause chafing, numbness, discomfort, or dysfunction.

Back in the day, it seemed very few saddles were designed to flex, except for Brooks leather, or Unicanitor / Freccia d'Oro / Avocet plastic saddles. It seemed most others were a hard plastic or metal pan with a bit o' padding. If one hammered all day and used the saddle mostly for stability instead of support, it might be OK, but if not, that piece of, um, plastic was at best described with terms such as "butt-hatchet".

Back in my racing days, I did fine with a Unicanitor with a thin Grab-On pad. It flexed just enough to be comfy for a long race / century or so, and all was well. I also weighed... a bit less than now.

About 25 years ago, saddles with springs or a flexing membrane in the shell began to hit the market, and began to provide greater comfort with good support. I've used a few of these and been pleased with the results. In fact, all my bikes, except for the two intended for speed riding, have double-sprung cushy saddles, and I'm happy with them, with few ill effects even after 100 miles.

The problem is there are so many saddles out there with unforgiving hard plastic shells under a thick (or thin) pad, and they look just like the ones with the flexible membranes. You have to look at the underside or specifications as closely as the top & shape.

A couple months ago, on a 12-hour night ride, I was on my racer with the Unicanitor, and I just wasn't happy at all after 50 miles. Apparently I'm now so weak and slow my riding style has changed such that my hiney needs something with a little more cush than my old Italian friend. I swapped bikes for one with a padded saddle with a membrane shell and finished the ride with much less discomfort, and have since retired the Unicanitor for future reassignment / resale.

Everyone is different. A Cat 1 is likely to want a different saddle than a tourist or a casual rider. There are great saddles out there, but there are evil ones that look nearly identical. Caveat buttor.

Edit: An example of my preferred non-speedy saddle is here: https://www.bikeforums.net/22707345-post60.html

RCMoeur 

Which side do you rub the cheese on again?

BCDrums

Which printed saddles do you like? Not like?

delbiker1 

They all flex to some degree. My back end prefers minimal amount of padding and the hammock effect in the central zone. The slight curve of the center and the flex of the saddle are what make it comfortable, IMO. My favorite saddles are Pro Turnix, of which I have two. The older model I have being my all time favorite. No clue how old it is.

PeteHski

Carbon shelled saddles are designed to be as light as possible, not as stiff as possible. They typically still have about the same flex as their plastic equivalents. Obviously some saddles are stiffer than others, regardless of materials.

harrier6

It does appear that manufacturers are conscious of flexibility, but one also has to read through the marketing speak (it's both flexible and stiff at the same time!). While carbon has good strength-to-weight properties, rubber or plastic composite shells probably have better mechanical properties for optimizing elasticity if that's your goal. With some research showing seatpost flex to be a significant source of compliance on thin-tired road bikes, there does seem like there's room to optimize. Not an engineer, but on my saddle the most flexible part is the middle, while you're supposed to put your weight on the wide part in the rear. Having a different rail design that cantilevered the rear out a little bit could be a thing to try for example.

I know there's nothing new under the sun, but sometimes circumstances and trends align to make old ideas relevant again in new combinations

PeteHski

What makes you think modern saddles have not been optimised? The Fizik saddle referenced for example uses multiple materials to achieve a degree of compliance. There are also literally hundreds of saddle choices on the market to suit whatever degree of compliance you prefer.

cyclezen

my view
saddles with a lot of cush, not ridable for more than 10 min...
saddles with a molding cush, too hot and puts all the bits to sleep after 40 min...
saddles without any give, an ass hatchet for rides over 1 hr
saddles with cutouts, holes, embroidery, anything other than a smooth surface in the area where you're actually sitting, are a total NO-GO !
Saddles with a smooth surface need to have enough slide resistance to keep you from sliding around. Sliding which creates too much 'friction' can be disabling.
... if your ride is in frequent and very short, then you can find comfort on a sofa cushion.
If you're riding for 2-3+ hours regularly, your saddle choice is very 'personal' and often more limited.
I'm not disappointed with the saddles I have selected, some are quite 'old school', some with modern design/adaptation, but I'm not disappointed in what I have/use.
Might there be 'better' designs coming? Maybe so, I'm always interested in trying new tech for a better ride. But NO cutouts, holes, indents or vents on the surfaces where the parts will rest.
Ride On
Yuri

chaadster

Well, you said your saddle bottoms out [on the clamp] on hard hits; that’s not good at all, and I’d bet good money it’s not a feature of design.

Similarly, while some seatposts are designed to supply suspension, like the Ergon All Road or Redshift ShockStop, standard seatposts have no way of delivering “significant compliance” outside of the whims of user setups, by which I mean, the amount of seatpost extension above the frame is variable and is the prime determinant of how much the post could possibly flex. Add in seat tube geometry, saddle positioning, and rider positioning as factors in how the post is loaded, and it seems pretty obvious that unless there is an active compliance mechanism, the amount of compliance from post deflection could easily be absolutely zero. That said, for years I was a big proponent of Ti posts and always used either Syncros or USE titanium posts on MTBs precisely for their springy nature, but I also typically rode freakish amounts of post extension due to the frame designs I preferred. Ti posts rarely provided any noticeable flex in traditional road frame designs

Speaking of Ti, with regards to saddles, Ti rails have long been considered to offer smoothing compliance, and continue to be part of, for example, Selle Italia’s most comfort oriented performance saddles. They also anchor them in shock absorbers to isolate vibration from the rails and the shell. You can see this kind of design in their X Cross and TM ranges, e.g. the SLR Boost X-Cross Ti Superflow. As I recall, they pioneered the suspended seat rail design back in the ‘80s with the original Turbomatic.

Other saddles which use elastomers for compliance in different designs are the SQ Lab Active range and the Bike Yoke Sagma line, both of which offer adjustable compliance levels via user selected elastomers. SQ Lab uses the elastomer to control the designed-in flex of the shell at the rear, while the Bike Yoke design actually isolates the rail from the shell both at the front and rear.

There really are tons of options when it comes to compliant saddles, from the aforementioned and newer 3d printed variety to old school solutions like the Tioga Spyder, but I think the rub is that building in significant compliance, especially vertically, is severely limited by the space there is to work in between the rails and shell. You can find crazy, cantilevered rail mounts like the system you mentioned very cheaply on Amazon, for example, but even if your weight matches the amount of spring tension in the rail design, the action is undamped so lots of pogo-ing goes on. Otherwise, one might be too light to compress the saddle to a comfortable angle, or too heavy to let the spring rebound or prevent it from bottoming out.