I don't think it has as much to do with the center of mass as it does the mobility from standing. When standing you are able to shift your weight to the opposite direction of an obstacle give you greater stability when going over it.

 

Well, personally I think 10W-40 synthetic motor oil is the way to go, and what it does to improve your center-of-gravity is amazing.

But seriously, the discussion about COG and motorcycle operation is full of variables, and you really have to qualify every aspect of how the bike is being used and under what conditions. I'll believe that standing on the pegs is the "best" way to lower your total COG when I see road racers standing up while going through corners. Dirt riding has another set of handling variables where lower speed, technical riding and handling is improved by the proper movement of the rider on the bike...many/most of those situations improved by standing. More than anything, standing on a motorcycle's pegs is more beneficial because of the ability to dramatically move the whole package's COG...rider/bike combination...very quickly and very effectively in a full 360 degree plane. Still, this is usually reserved for lower speeds and/or technical terrain. But, you see more road racers performing more aggressive body movement on high speed road racers on the track than in the past. Riders sticking out their legs MX-style as they approach corners, sitting up and leaning their upper body in turns more aggressively for more than just wind resistance, etc. Still, I don't think we'll be seeing road racers standing up on the pegs in corners any time soon.

 

Nope, nor will we be seeing Sportsters with 24" seat heights (and possibly the lowest COM of any bike) off-road any time soon either!

 

I'd agree with you, but I would still contend that the higher COM produced by standing is important in providing the overall system of rider & bike with more 'leverage' if you think about it as an inverted pendulum.
If you read Davis' article that TNC posted a link to, you'll see he points out an added benefit of standing is that the rider's weight becomes 'double sprung'.

 

SuperMoto is a fascinating genre to observe this 2-way transference of technology & technique between pavement & dirt! Things that would have been considered 'mistakes' 10 years ago are now standard practice!

 

Let me try again (disclaimer, this is just my opinion, I am no expert………at anything)


When standing and leaning the center of gravity is maintained over the tire contact patch. Sitting moves it out left or right depending on which way you are turning. This works best when riding slower. Riding fast and there is a burm, sitting and applying your weight over the outer foot peg moves the weight over the tire contact patch. (Basically you are standing on the outside foot peg. Your butt just happens to be on the seat). By moving your inner foot forward moves the C of G Forward towards the front tire for better turning grip.

It is not all about center of gravity up and down but also left, right, forward and back. See my crude drawing…LOL!

 

I think of it as a difference in leverage. You know, "give me a long enough lever and I can move the world". Anyway, your 180 lbs. on a peg is a lot shorter lever trying to upset the balance of the bike than your 180 lbs. higher up on the seat.

Whatever, but I've always taught a new dirt rider that he is less likely to fall if he keeps his feet, (and weight), on the pegs. Racing, of course, whether road racing or flat track, is an entirely different animal bringing speed and traction more into the equation.

Norm

 

That guy in the sketches needs to look where he's going

Interesting subject.
As some one who has come from MTBing to this, I find that weight transfer makes much less difference on a heavy motorcycle than it does on a bicycle. In addition, on the MTB the CoG is much higher - it's a lot easier to go OTB!! - but it's also much more maneuverable. My conclusion is that it is all about keeping the CoG above/in-line with the point where the machine is going.

I noticed a difference in riding style when I went out with the local newbies ride. Surprisingly, I stayed in the seat a lot more than the guys with a history of road MCs (they were also quite keen to use excessive power on their CRF250Xs etc in innapropriate situations and thereby ending up on the deck - with a very low CoG).

 

By standing you've replaced a "fixed 1 piece mass" with a "hinged 2 piece mass".

The movement of piece 2 (rider) with respect to piece 1 (bike) allows for much better control of piece 1 with respect to any stationary object (ground).

Youve also introduced 2 fantastic shock absorbers known as legs into the system.

The combined center of gravity/mass is actually higher when standing.

This was a project of mine in mechanics/dynamics (can't remember which one) back at Ga Tech in the 70s.

 

I noticed that too after I already posted. Fixed!