Re: Suspension losses

On 1/3/2025 10:46 AM, Radey Shouman wrote:

Frank Krygowski <frkrygow@sbcglobal.net> writes:
 

On 1/2/2025 8:45 PM, bp@www.zefox.net wrote:

Frank Krygowski <frkrygow@sbcglobal.net> wrote:

>
One further thought: If we accept (as I do) that jiggling the human
pedaler does cause loss in energy and speed, why aren't we all using
saddles with some sort of damped springing?
>
I know suspension seatposts exist, but even those are not popular on
road bikes.

I'm using a suspension seatpost now, removed from a town bike. It's
slightly more comfortable. No idea if it's more efficient. Certainly
heavier, probably lossy unless I balance pedal effort to keep pressure
on the saddle constant. That difference is small at most.

>
FWIW, when coasting - especially on rough downhills - my habit is to
take some of my weight off the saddle, hoping the "suspension" offered
by my legs causes less jiggling of my body mass, so less energy loss.

 To get back to the question of how this might be modeled, it's really
complicated.  Sometimes all your weight is probably off the saddle,
meaning that any computation would have to figure out when there was
contact, and the forces generated by that contact.
 You can read a whole book about it online, if you're ambitious:
 https://www.yastrebov.fr/LECTURES/Yastrebov_NMCM_Wiley_ISTE.pdf
 Not to mention that there is a poorly understood nonlinear control
mechanism involved, somewhat different for each individual.

Wow. Yes, it's probably good to remind ourselves that whatever topic we tyros discuss here has probably been the life's work of some true expert.
--
- Frank Krygowski