Motorcyclist falls off but bike stays upright

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SUMMARY

The forum discussion centers on a viral video where a motorcyclist releases their bike, which continues to ride upright without a rider. Participants debate the authenticity of the stunt, with some asserting it is staged for an advertisement related to a bike club called "Notorious." Key points include the physics of motorcycle stability, particularly the role of gyroscopic forces that help maintain an upright position. The discussion concludes that while a bike can ghost ride for a short distance, the feasibility of a rider catching up and remounting is highly questionable.

PREREQUISITES
  • Understanding of motorcycle dynamics and gyroscopic effects
  • Familiarity with motorcycle types, specifically sport and downhill (DH) bikes
  • Knowledge of basic physics principles related to stability and motion
  • Experience with motorcycle riding techniques, particularly countersteering
NEXT STEPS
  • Research the physics of gyroscopic stability in motorcycles
  • Explore the design features of downhill bikes that contribute to stability
  • Investigate real-world examples of motorcycles ghost riding
  • Learn about motorcycle safety and recovery techniques in case of loss of control
USEFUL FOR

This discussion is beneficial for motorcycle enthusiasts, stunt riders, physics students, and anyone interested in motorcycle dynamics and safety. It provides insights into the complexities of motorcycle stability and rider recovery techniques.

Hot Rod SS
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There's a video going around on the internet with a motorcyclist coming out of a corner and just letting go of the bike - ghost riding. The bike continues on and wobbles while the rider gets back up and runs and catches the bike. You can find the video (since there's a restriction for posting URL's without meeting a prerequisite) by typing "Biker Loses Bike Then Recovers Amazingly" and either break.com or metacafe will suffice for your viewing pleasure.

there's no question that the video is staged. It's believe to be an ad for whatever this "Notorious" is shown at the end of the video. Best I found on that was a bike club called "Notorious," so there is correlation...

However, beyond that there's much debate whether this is a real stunt or even possible in the physical realm that we occupy. So I present this case before you to confirm or debunk this stunt...

My theory:
I believe this to be a stunt and an actual real event. My reasoning is because the twin gyroscopes spinning on the bike and its natural resistance to angular change - hence the bike's natural position to being upright. To add to it, from my own personal experience riding sport bikes and my understanding of them, the bike will not lean unless you countersteer the front wheel. Which causes an adverse change on the gyroscopes alignment causing the bike to fall over. The wobbling you see after he loses it is the gyroscopes resistance to falling over.

Now I am aware of a threshold revolution speed that the gyroscopes must obtain to counteract any force trying to disrupt their natural course of being upright. I personally contribute the lower revolution speed to being sufficient in keeping the bike upright to the rider's mass not being on the bike...

Anyways, that's my take on it. Hopefully someone that's smarter than me can confirm or debunk this.
 
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You haven't seen a bike continue to go straight for a short time without a rider? Nothing unusual at all.
 
I have been riding bikes and watching bike racing for 40 or more years, i have seen bikes carry on upright for perhaps 1/2 a mile without a rider, i have seen riders hanging on to the handle bars completely unseated, but i have never seen a rider catch an errant bike and get back on,
i think it would be (nearly) impossible, as the bike must have a forward speed greater than the rider can run to stay stay upright, ( and the rider has to recover) so the bike has a head start.
 
wolram said:
...i have seen riders hanging on to the handle bars completely unseated, but i have never seen a rider catch an errant bike and get back on,
i think it would be (nearly) impossible, as the bike must have a forward speed greater than the rider can run to stay stay upright, ( and the rider has to recover) so the bike has a head start.
Yes, that is the critical question -- is there a bike stable enough to remain upright at a speed where a rider can catch it and get back on?
 
I personally don't doubt a bike ghost riding. The big question here is will the bike stand up right on its own accord without high siding when it loses the rider in the corner and come out onto a straight.

I have no question the bike will stay upright on its own, just whether it will in this circumstance. At first I thought it was staged for an ad or something... I've been looking into it the more I do the more I find it might actually have happened at a track day or some minor race event.
 
russ_watters said:
Yes, that is the critical question -- is there a bike stable enough to remain upright at a speed where a rider can catch it and get back on?

I noticed they don't show anything more than the top of the bike and rider, and all the other bikes are zooming past pretty quickly. Can a bike stay upright easily at 15 mph or so? It would have to be going that slow for the rider to catch up (running speed ranges around 15 to 20 mph...maybe faster if he's a trained sprinter). It would have to go slower than that for him to do more than just keep pace behind it. But, since they don't show the wheels, maybe there were some sort of stabilizers installed to help keep it upright at a slower speed.
 
Even if the bike was somehow stabilized, they remembered to wobble it.
 
Bikes are quite surprisingly stable and a slower speed is better. The oscillatory motion of the bike would indicate it was a genuine event.
 
Here it is.

 
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  • #10
Christina, I think that this http://youtube.com/watch?v=n3meOT8jK9M&fmt=18" is the one they're talking about here. Although the one you linked is pretty cool too. We just don't get to find out if the rider catches up and recovers in that one.
 
Last edited by a moderator:
  • #11
~christina~ said:
Here it is.

That is interesting...

Georgina,
yes that is the correct video, thank you for posting it.
 
  • #12
I can do that stunt on my BMX bike. I can take my hands off my motorcycle, and coast almost to a stop before putting down my feet.
 
  • #13
It just doesn't look right, the motorcycle is like shaking left to right quite a lot, and it seem shard to think it wouldn't have fallen over. I may be wrong, as I know nothing about them.
 
  • #15
lol
Where are all the experimenters?

Get out there and give it a try.

You'll learn a lot. Quickly ;)
 
  • #16
I actually race mountainbikes (DH racing) - and I can see from that video (which I've seen elsewhere) that the bike is a DH specific bike (an Iron Horse "Sunday" model) which is noted for having a very low bottom bracket (the part which the crankarms and pedals attach to) which gives it a very low centre of gravity (allowing it to corner very fast). The bike weighs about 40 lbs and the majority of the weight is centred quite low. Also DH bikes have far heavier wheels/tyres than normal bikes. My point is that I'm sure it's far more likely that a bike like that (a DH bike) would be able to roll and keep stable under its own momentum.

Jump off a penny-farthing on that section of the track and see how far it goes!
 
  • #17
DSC_0231.jpg


Me. Testing.
 
  • #18
Alfi said:
lol
Where are all the experimenters?

Get out there and give it a try.

You'll learn a lot. Quickly ;)

Oh if I had a beater bike... I so would ;)
 
  • #19
Lucky that was captured on video, that rider would have a hard time convincing people!
 

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