On 25/02/2017 15:31, Nick Maclaren wrote:
I should have given some numbers. Mine loses essentially no sideways
stability, no matter how far you lean forward

What a quadruped ladder will do which a tripod will not is to flop
between two stable states. On rough ground with one foot slightly off
the ground these states are scarily close to normal use - it will often
move from one to the other as you climb up. Even if it doesn't go over
this is disconcerting. And as it moves, and you gain momentum it's quite
possible it will go past the other stable state and fall over.

You can get around this by chocking one of the feet every time you move
it. If you are doing a lot of work outside - for example, picking fruit
in an orchard - this is time consuming.

A tripod ladder intended for use in such an environment can afford to
have a wider base which would be impractical in a ladder intended for
use indoors.

Andy