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From: Zen Cycle <funkmaster@hotmail.com>
Newsgroups: rec.bicycles.tech
Subject: Re: Getting old is not for sissies
Date: Mon, 3 Mar 2025 11:59:38 -0500
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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:
>>>> On 3/2/2025 7:17 AM, Roger Merriman wrote:
>>>>> Frank Krygowski <frkrygow@sbcglobal.net> wrote:
>>>>>> On 3/1/2025 12:53 PM, Roger Merriman wrote:
>>>>>>> Frank Krygowski <frkrygow@sbcglobal.net> wrote:
>>>>>>>>
>>>>>>>> I'm puzzled by the video's advice to avoid pulling up on the pedals "as
>>>>>>>> it's bad technique." I'm pretty sure I do pull up when jumping the bike.
>>>>>>>> What's bad about it?
>>>>>>>>
>>>>>>>> And more on that video. In slow motion as they showed, the physics is
>>>>>>>> pretty obvious. The rider gets his body mass moving upwards, then
>>>>>>>> essentially pulls the bike up with him. That's where I think I pull up
>>>>>>>> using the pedals.
>>>>>>>>
>>>>>>> In theory it’s better to have the bike rider spring up, than being pulled
>>>>>>> up by foot attachments also slight risk of unclipping.
>>>>>>
>>>>>> I'm not sure I understand your phrasing. 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.
>>>>>>
>>>>>>>
>>>>>>>> What's less obvious, I think, is how a skateboarder with zero foot
>>>>>>>> attachment can bunny hop a skateboard. It's interesting to think about.
>>>>>>>>
>>>>>>>>
>>>>>>> Lot of folks who jump is a focus do run flats so aren’t pulling up.
>>>>>>
>>>>>> I run flat pedals on my mountain bike and my about-town 3 speed. Yes, I
>>>>>> can jump them, but not as high. On the other bikes, I think the toe
>>>>>> clips help.
>>>>>>
>>>>> I’d refer you to the Don who is a ex downhill racer, and rather technical,
>>>>> to explain why!
>>>>>
>>>>> <https://youtu.be/F7LO1qnm0Xs?si=0p3ONupQJCKONsR4>
>>>>>
>>>>> But certainly all of the sane advice for bunny hops are not to being
>>>>> pulling up with your feet, it can be done but it’s poor technique and will
>>>>> limit how much you can do.
>>>>>
>>>>>> As with the skateboard "ollie" (linked in another post) getting the
>>>>>> rider's mass up high is easy and obvious, by jumping. Making the bike or
>>>>>> skateboard levitate is what's tricky.
>>>>>>
>>>>>> I think the physics goes this way: You lift the front of the machine,
>>>>>> raising the machine's center of mass. On the bike, that's by pulling up
>>>>>> on the handlebars. On the board, that's by kicking down on the tail.
>>>>>>
>>>>>> Once the machine center of mass is elevated, then rotate the machine
>>>>>> about its center of mass. That's  by pushing down on the handlebars or
>>>>>> by kicking down on the nose of the board.
>>>>>>
>>>>>> That rotational action about the center of mass is what causes the rear
>>>>>> wheel(s) to lift into the air.
>>>>>>
>>>>>>
>>>>> You shouldn’t be lifting either the bar or pedals, it’s about as with all
>>>>> MTBing weight positions and movement and timing ie push hips back so your
>>>>> arse is almost brushing the rear tyres.
>>>>>
>>>>> And the front will come up, scooping the weight forward to drop the front
>>>>> down and the rear up.
>>>>
>>>> I can accept that the extreme body motions he's describing are needed to
>>>> get more than, say, a foot into the air. They may or may not have helped
>>>> the guys who's crashes he shows from 5:34 - 5:45 in the video.
>>>>
>>>> And as your man says at 5:49 "... well, it does work, it's not as good."
>>>
>>>>
>>>> I'm not trying for "big air," as they say. I'm on a road bike, and my
>>>> objective has been to clear big potholes, railroad tracks or speed
>>>> bumps. For that I don't think there's a problem with moving one's body
>>>> straight up then pulling the bike up using handlebars and pedal
>>>> attachments.
>>>
>>> Kinda depends on your aim, if one wants to learn how to bunny hop for what
>>> ever reason, it’s a better form and more reliable granted needs practice,
>>> your method is cheap and dirty hence folks use it, but it inherently has
>>> limits.
>>>>
>>>> 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, but it’ much like the Don’s advice movement and timing that is
> doing this.
> 
> Which is different to what you’re describing.

I'm not so sure about that, but it's really hard to tell without a good 
slo-mo breakdown. It looks to me like he might have actually pitched the 
front of the bike down before he crossed the median, but my 
bunny-hopping skills are notoriously bad.

> 
> I’d also suggest that it’s a bold move to compare to Sagan who while like
> most isn’t perfect he definitely fluffed up the XC Olympics few years back,
> by being too aggressive aka didn’t nurse the tyres over the technical bits,
> but he’s definitely is rather God tier in terms of bike handling.

Which brings this to mind

https://www.youtube.com/watch?v=bM9Eh2uQ7Ek

For me though, one of the more impressive displays was Andre Tchmil 
winning the '94 Paris Roubaix. He won in a solo breakaway, at one point 
he approached a small-ish roundabout where he simple rode straight 
across it. It was so completely effortless and smooth - mind you, this 
was over 5 hours into the race in off/on rainy conditions after fighting 
the dozens of kilometers of mud covered cobbles.

I dug around a bit and found an old video.

https://www.youtube.com/watch?v=xci1GIwLNoo

The stunt is at 1:08:25. Even Phil Ligget was impressed with the move. 
FWIW - it's worth watching a few bits earlier in the video where some 
cobbled sections are covered in 2 inches of mud.


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