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From: Frank Krygowski <frkrygow@sbcglobal.net>
Newsgroups: rec.bicycles.tech
Subject: Re: Suspension losses
Date: Fri, 3 Jan 2025 11:44:17 -0500
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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