It SEEMS to show a crash, then a bike that starts rotating around itself seemingly being driven by the rear wheel. I watched it a few times, and it looks to me like the rear wheel stopped spinning during the crash, then started pushing the bike afterwards. I’ve no idea if its a fake video.
This would be very easy to do I expect. With a pound or so of lithium-ion cells stuffed into the seatpost and a high-torque/low rev permanent magnet (Neodymium) motor buried in the rear hub, you could get a system that could add 25-50W for hours. In addition, with every pro crank having a built-in loadcell, I would think it would be relatively easy to have the motor supplement rear wheel torque based on INPUT torque - so if you don’t pedal, it doesn’t push. And the harder you push, the harder it pushes. Great for climbs & sprints…
Real? Fake? Is it time to X-ray hubs at the start line?
I don’t feel an explanation is deserved because the conspiracy theories are too stupid to be taken seriously.
Until they’re proven true, of course. Lance’s comeback was a miracle, at first…
The whiteboard is nice, but doesn’t address this crash. The bike was STOPPED, then processed based on drive coming from the rear wheel. While the conservation of momentum thing is there, it is the energy stored in the spinning rear wheel that would have processed the bike around like that, IF there was enough energy there AND the wheel was still spinning. This has nothing to do with the rider, or his momentum. The calc, to me, would be to calculate the energy stored in the spinning rear wheel based on some assumptions about its rotational inertia, then apply that as a force the mass of the bike (making a further assumption about the time during which the force would be applied) to see what might happen to a bike that could pivot around the bb.
There’s no question to me that the energy to process the bike came from the rear wheel, the question to me is whether it could store that much energy. If the wheel didn’t stop during the crash, I’d GUESS that it might. If the wheel DID stop during the crash, then there’s something rotten in Denmark.
Appears they are descending somewhat and after the crash the bike is simply supported at two points: the rear tire sidewall and most likely a pedal. The bike is just rotating about the point of greater fixity due to gravity.
But it moves FUNNY not like I would expect from my internal bro science physics simulation derived from the video!!
/internet
Appears they are descending somewhat and after the crash the bike is simply supported at two points: the rear tire sidewall and most likely a pedal. The bike is just rotating about the point of greater fixity due to gravity.
If you look at the video, Ryder gives a solid tug on the crank to unclip, which would cause the wheel to spin up again after it had initially slowed.
good point, didn’t notice that.
Also, it would be a bit pointless to have a motor activated on a downhill…
If I were to design such a system (torque based), it wouldn’t have been on either.But a crash could have introduced new loads/commands into the software.
It would be one heck of a stunt to pull it off, and you’d lose any advantage if you took a wheel from neutral support. In addition, at that point you’d have a very risky wheel in someone else’s hands. I think you could hide contacts in the cone nuts & dropouts, but it would really take some effort to make it work AND to make it disappear. However, making it work and be ALMOST transparent would be a (relative) piece of cake. An extra 100W for 40 minutes could take bicycle commuting to new levels.
This would be very easy to do I expect. With** a pound or so** of lithium-ion cells stuffed into the seatpost and a high-torque/low rev permanent magnet (Neodymium) motor buried in the rear hub, you could get a system that could add 25-50W for hours.
50 watts for a single hour would require about 10 iphone batteries. 10 iphone batteries would weight about 3 pounds. How big of battery do you think they would be using?
Here is the question. Which is more likely? You do not understand physics or that there is a motor in the bike. Seriously, which is more likely?
Here is the question. Which is more likely? You do not understand physics or that there is a motor in the bike. Seriously, which is more likely?
The physics was explained, I think, by the pedal release torque. I don’t buy the gravity procession, but I guess it could have contributed. I put this up not because I believed it, but because I wanted to see what others would respond with. Like I said, it would be one hell of a risk - but it would also be a very clever engineering design.
With regard to battery power - I guessed. I had built some lightweight battery packs for a personal project a few years ago using cells from A123 systems, but they were to replace an existing 15-pound lead acid. I remembered wrong; thanks for the correction.
