Saddle Width
 

So for the last five or six years I've been riding a 143mm wide saddle which I 'thought' was perfect. In comfort stakes and riding all day, no worries, never had pain or saddle sores. What I have had issues with is being too far forward on the bike and using too much quad.
Having recently seen a picture of me on the bike (not a hard effort; just cruising), compared to others whose saddles almost disappear under their butts, it appeared that I have only been using the front two thirds of my saddle and it's a short saddle at that.
So, to prove the point I tried a narrow 130mm saddle and wow! instantly I'm 20 to 30mm further back (where I should be) with plenty of glute engagement.
Now, my question relates to the new sensation that if I wanted to, I could actually slide myself off the back of the saddle. This would have to be a concerted effort, it's not happening naturally; I'm naturally planted right where I should be.
Now, do you think this sensation is simply because I have become accustomed to a too wide saddle or simply a characteristic of saddle shape?
Thanks in advance.

TBH I’ve never thought about trying to force myself off rearwards. Hanging your butt off the rear of the saddle is a very basic MTB riding skill. Not quite as frequently needed during road riding, but coming from MTB, the way to get there is already ”programmed in” so to speak.

I’d assume most of what you’re feeling is merely a response to the change in circumstances.

Where you tend to sit on the saddle can be affected by all sorts of factors. Tilt, reach, your body angle, how much power you put into the cranks and I'd suppose how wide your saddle is.

I wouldn't worry about pushing yourself off the back of the saddle. Why will you want to do that? I can pull myself off the front of the saddle, but I don't.

Might indicate that your body is willing to be stretched out a little more but I don't know from any knowledge, I'm just supposing.

The short, stubby saddles are designed to keep you supported in one position, without accomodating very much movement fore-aft. If it's causing no discomfort, pain or injury, it's doing it's intended job. Longer, more traditionally shaped saddles accomodate more forward-aft movement on the saddle, but I don't know if I would rate the saddle disappearing under you as something desireable, especially from the point of view of comfort over long rides.

I can lift my backside off the saddle and move to the rear when descending super steep stuff, but not quite "slide" behind it.

As for positioning forward and back, I experimented on that by well, moving the saddle. Too far forward and the bike becomes unstable, and taking hands off the bars becomes a chore. Moved back, putting out power while in the drops on the flat becomes weird, although it feels fine on climbs. However, while the feeling is different, I can develop the same power unless the difference in position is dramatic (eg. switching to a TT bike where there's a huge difference in seat tube angle and saddle position vs a road bike plus a big difference in hand position).

that back position is good for seated climbing...

Hey, thanks for the replies.
I've experimented a bit more with some new saddles and concluded that the 143mm was definitely too wide. I can't actually physically pedal when I'm sitting right up on the widest part. My sit bones measure about 90mm which seems to be narrower than most; my position is also fairly aggressive and I have good pelvic rotation so this narrows the measurement further.
I tried a different design of saddle which is 139mm and although much better; I was still a little forward.
I also tried another design at 134mm where the 'wings' of the saddle drop quite steeply down each side; this felt much more sensible and I could really feel my sit-bones right on the most padded section at the back.
I now have a slightly flatter model that is 134mm which so far feels perfect. I think part of the issue is that a lot of the noseless saddles that I like tend to change transition from the narrow nose to the wide rear very quickly (Specialized Power, Fabric S-Line, Pro Stealth). Whereas, the one I'm using now is narrower for the front two thirds and only widens at the rear where you need it; this also means my thighs aren't rubbing anything. So anyway; so far so good!
I'm sure for most people this isn't an issue as given that most saddles tend to be in the 143mm region I have to assume that most have wider sit bones than me.

You might drop in to a Specialized shop and see if you can sit on the saddle width gadget and get their opinion on what width is right. If your sit bones are always supported, that is a real good sign. If you get zero inner leg and perineal chafing, that's also good. On the 143, if you are on the hoods and can lift your hands 1" off the bar without sliding forward and staying relaxed, that's great. If you slide forward your center of gravity is too far forward and you should move the saddle back, maybe ⅛" at a time until you feel in balance with your hands lifted. Then recheck your saddle height, you might need to drop it a little bit. Once you're in balance you can adjust saddle tilt to optimize pressure distribution along your underside. But make one change at a time.

It also depends on how aggressively you lean forward. You could go through the above procedure with both the 143 and the 130. It doesn't take more than a few days riding and then you'll know, and not have to trust a bunch of Internet guys whom you don't know and who might not know any more than you do.

Thanks; my question was quite specifically about saddle width; I've no issues with overall fit.

I'm coming from a time when you only had a choice of a few decent saddles and width was never even mentioned; you just picked one!

It's funny you mention Specialized though; after years of riding on the same saddles I went to a Specialized shop when the power was first released. I got 'measured' and was sold a 143 power. I since purchased 3 of them and have ridden them happily for the last 5 or 6 years. Although the basic shape is OK; what I hadn't realised until recently was that I was only actually utilising the front two thirds of the saddle as they're far too wide. I now believe the sit-bone measurement system is pretty useless if your sit bones fall outside of the range. It also doesn't take into account the fact that the further forward you are, the narrower the measurement (I think a measurement system where you're actually sitting on a saddle would be far more valuable)

The saddle I'm using right now is 139mm but is visibly far narrower over most of it's length than the Power and I can comfortably utilise the whole length so I'm not experiencing the 'quad dominant' sensation I had with the power. It's just a bit different from the power and the saddles of yester year in that I can actually sit anywhere on it.

I can't say much about your points about width. I'm a skeptic about fitting formulas, but Spesh measured me at 143 and that has turned out to be best for the Toupe and old Alias series. But they're not my favorite saddles - that goes the the recent Selle AnAtomica H series (the Clydesdale version). So width is not everything, since the SA width is about 170 mm. But it works when set up right!