Standing on the pegs?

you're correct right up until you state it lowers the bikes centre of gravity.

It both doesnt and can't (at least thats the conclusion I've reached, please dont ask me to try to do the math).

Its like the difference between mounting a mast on the roof of a boat or in the bilge, if it's the same height/weight the centre of gravity is the same, it's the ability to shift sideways that moves the centre of gravity to the left or right of where it would be with the rider sat down, which has a similar effect to lowering it in terms of when lean becomes unsustainable but doesnt actually drop it at all.

Standing on the pegs does not lower the centre of gravity of the bike, it is built and does not changa, but does lower the centre of gravity of the package...If you sit on the seat your contribution to the bike's centre of gravity is on the seat (right at the top) where as if you stand on the pegs your contribution to it's centre of gravity is at the footpegs (quite low).

Also standing on the pegs will generally move your weight backwards load the rear tyre more, especially if you stand on your tip toes. The slightest of movement forward and aft can make a huge difference. I've ridden trials for 7 years now, and a competent intermediate rider, and simply by standing on your tip toes instead of the arch of your foot, grip is dramaticly increased. Trials riders stand up because it helps with sideways balance/stability not so much for anything else.

Originally Posted by Cursed

Standing on the pegs does not lower the centre of gravity of the bike, it is built and does not changa, but does lower the centre of gravity of the package...If you sit on the seat your contribution to the bike's centre of gravity is on the seat (right at the top) where as if you stand on the pegs your contribution to it's centre of gravity is at the footpegs (quite low).

when you consider it this doesnt actually make sense because the whole bike is connected to the wheels so that ought to mean the centre of gravity would be in the wheels anyway.

Obviously it isn't.

the weight may be attached at the pegs but that doesnt change the height of the weight, only your body shifting about can do that. An example would be the difference between a 10lb weight on the seat and an 10lb weight suspended just above the seat by a frame connected only to the pegs. COG would be the same for both because they are both the same except the "frame" that holds th seat is part the bike not one you constructed outside it.

I see what you mean, your right. It does let you control where your weight is applied however by moving your body, which as you correctly said will change the CoG.

But only in terms of shifting it sideways or front/back.

In my mind this could act similar to lowering the centre of gravity when it comes to particular maneuvers since your movments could bring it back closer to the wheelbase/contact point.

I feel like I need some drawing skills to try to model it but I'm sadly lacking there.

Originally Posted by Cursed

Standing on the pegs does not lower the centre of gravity of the bike, it is built and does not changa, but does lower the centre of gravity of the package...If you sit on the seat your contribution to the bike's centre of gravity is on the seat (right at the top) where as if you stand on the pegs your contribution to it's centre of gravity is at the footpegs (quite low).

This is going to sound really ***Tish but I cant word it any other way, you're missing the point which is odd because you half state it. Correct the COG of the bike does not alter at any stage, ours however can move dependant on our stance.
Our COG however is not the point at which we're transferring load to another surface it is undefined point at which our average mass is positioned. By standing up you do not and will never transfer your centre of gravity to your feet. By standing up you increase the distance between foot and head, thus elevating your COG.
Wether you've done it for 7years or 70 what you're doing is elevating your body into a position where your mass becomes independent of the bikes and can therefore counter act its lateral movement due to obsticals.
Directly translating that into your trials riding, when you climb an obstacle to its crest then balance before leaning forward just to pop on to the summit you do this is to move your COG forward and use it to load the front of the bike. If your COG was acting through the foot pegs you'd achieve nothing by moving your body.

As you say by standing up you do apply your mass to the bike at a lower point, but COG of the bike itself doesn't alter and the riders does elevate.

The further you get away from the ground, the higher the COG, its that simple.

I think some people are confusing COG with weight distribution.

[ophic]

Without getting into physics, I do it a lot over speed bumps. I find the bike "pivots" around the peg rather than lifting me via my butt. Also, legs are "sprung" like suspension, which is better than padding in either bum or seat.

Originally Posted by specialone

The further you get away from the ground, the higher the COG, its that simple.

I think some people are confusing COG with weight distribution.

I indeed made this mistake.

Originally Posted by Owenski

This is going to sound really ***Tish but I cant word it any other way, you're missing the point which is odd because you half state it. Correct the COG of the bike does not alter at any stage, ours however can move dependant on our stance.
Our COG however is not the point at which we're transferring load to another surface it is undefined point at which our average mass is positioned. By standing up you do not and will never transfer your centre of gravity to your feet. By standing up you increase the distance between foot and head, thus elevating your COG.
Wether you've done it for 7years or 70 what you're doing is elevating your body into a position where your mass becomes independent of the bikes and can therefore counter act its lateral movement due to obsticals.
Directly translating that into your trials riding, when you climb an obstacle to its crest then balance before leaning forward just to pop on to the summit you do this is to move your COG forward and use it to load the front of the bike. If your COG was acting through the foot pegs you'd achieve nothing by moving your body.

As you say by standing up you do apply your mass to the bike at a lower point, but COG of the bike itself doesn't alter and the riders does elevate.

Aye I realised after Spank's comment.

Originally Posted by Spank86

But only in terms of shifting it sideways or front/back.

In my mind this could act similar to lowering the centre of gravity when it comes to particular maneuvers since your movments could bring it back closer to the wheelbase/contact point.

I feel like I need some drawing skills to try to model it but I'm sadly lacking there.

Yeah this is what I was trying to get at, however its not all about CoG position, the way in which you apply force etc to different points can cause the same effect as moving the CoG of your body, for example if you press down on 1 peg your CoG has not moved at all but the bike will move to the side, so has the same effect?

Simplify it by taking gravity and weight out of the equation. If the rider were floating in space, where would the 'centre of mass' of bike and rider be? That has nothing to do with whether or not he is connected to the bike by the footpegs or the seat. It only matters where the greatest mass of the rider is, where greatest mass of the bike is, and their relative positions in the homogenous assembly.