Re: Getting old is not for sissies

On 3/3/2025 10:23 AM, Roger Merriman wrote:

Frank Krygowski <frkrygow@sbcglobal.net> wrote:

On 3/2/2025 7:55 PM, Roger Merriman wrote:

Frank Krygowski <frkrygow@sbcglobal.net> wrote:
>

I submit Peter Sagan at about 0:15 in this video:
https://www.youtube.com/watch?v=Viszek1LlpA
>

I’d suggest he probably did more than just pull up, it’s fast ...

>
It helps to slow it down to half speed or slower as you view it.
>

... but looks
like he compresses and then springs up, he’s also someone with some MTB
background and likes to throw the bike about.
>
Ie that doesn’t look like just a cheap and dirty pull on the bars.

>
Reread above, please. What I said is still there:
>
"On my road bikes, I "spring up"- that is, jump my body upward. I then
pull upwards with both hands and feet. Since I use toe clips instead of
clipless, I don't think I've ever unclipped while doing that."
>
If I want to jump a bit higher and if I have time, I think I do
"compress" a bit before I spring up.
>
>

He clearly does compress ie not at all clear that he’s pulling up much if
anything...

Really? Let's think about this in terms of physics - of force, mass and acceleration.
Unlike your mountain biker, Sagan does not use an extreme wheelstand to raise the center of mass of the bike, allowing later rotation around that elevated C. of M.
Instead, after Sagan's body rises, the bike rises in pure translation (as opposed to rotation). Such a motion requires upward force. Without an upward force, a body can't experience an upward translational acceleration.
If Sagan is not pulling up, what would make the bike levitate?
--
- Frank Krygowski