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John Swanson
WTF? That and Hesjedal's crash seal it for me. Hub motors are a thing.LaFlorecita said:
John Swanson
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This is like the third time we've seen his rear wheel do crazy things. Sure, the first time it could be explained by some unlikely physics, the second time... well let's give him the benefit of doubt, but a third time... come onScienceIsCool said:
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I like how he accelerates past the guy while braking and holding onto a full drift...LaFlorecita said:
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The terrain has a slight gradient to the left (from front view) and van Aert leaves the contour line, taking an angle towards the gradient and pushes hard in an attempt to overtake the rider in front of him. The rear wheel sliding away sidewards on a muddy spot is not something very surprising to me under the mentioned conditions (given the angles in play).
Right after that his front wheel hits a hole or a bump and the bike jumps as a consequence. The jump brings the bike immediately back onto the straight racing line.
The rider in front of him is considerably slower to begin with. I can't see it in this gif but from the looks I guess they're approaching a turn and the other rider is slowing down to prepare for it while van Aert accelerates to overtake. And as soon as they are touching one another the other rider seems to be heavy on his brakes instinctively because he gets pushed into the barriers. At least it looks as if they had similar speed when going side-by-side for a moment and then van Aert passes the other rider because he quickly decelerates.
Do you think that he didn't lose enough momentum in this incident or what's the killer argument?
Looks very strange indeed. But may somebody point out to me what exactly makes it so completely obvious? I feel that I have missed the deciding factor.ScienceIsCool said:
The terrain has a slight gradient to the left (from front view) and van Aert leaves the contour line, taking an angle towards the gradient and pushes hard in an attempt to overtake the rider in front of him. The rear wheel sliding away sidewards on a muddy spot is not something very surprising to me under the mentioned conditions (given the angles in play).
Right after that his front wheel hits a hole or a bump and the bike jumps as a consequence. The jump brings the bike immediately back onto the straight racing line.
The rider in front of him is considerably slower to begin with. I can't see it in this gif but from the looks I guess they're approaching a turn and the other rider is slowing down to prepare for it while van Aert accelerates to overtake. And as soon as they are touching one another the other rider seems to be heavy on his brakes instinctively because he gets pushed into the barriers. At least it looks as if they had similar speed when going side-by-side for a moment and then van Aert passes the other rider because he quickly decelerates.
Do you think that he didn't lose enough momentum in this incident or what's the killer argument?
It looks like power oversteer even when he stops pedalling.
The bike could be correcting itself because the motor shuts off when he stops pedalling with a small delay. In that case its not a bumb in the road but just the rear wheel finding grip again.
In cyclocross you need some sort of auto stop start function to prevent your wheel from spinning if you carry your bike. The video from Italy looks like his motor kicking in after his crank turns a bit because it hit the ground.
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It's probably better suited to dissect than the gif on twitter.
Here is the whole sequence in a youtube video: https://youtu.be/2VGrJ6M6VGY?t=103 (start at 1:42)LaFlorecita said:
It's probably better suited to dissect than the gif on twitter.
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I'm not so sure about this.Tienus said:
I have to admit that the more I look at it the more my first excitement ("yay, motor"
) gets toned down.The Hesjedal case is still quite a bit more suspicious in my book at this point in time.
I'm not exactly sure what you mean. Let's assume that there's indeed a motor that shuts off when he stops pedalling. How does this influence the bike correcting itself?Tienus said:
At some point he has lost control over the bike and it slides. Then the front wheel very clearly hits a bump and the bike goes in the air, especially the rear wheel. The correction that took place is that his wheels ended up more or less aligned with the direction of his momentum after the jump. Without this jump he probably would have gone down or rammed the other rider straight into the barriers. I guess the fact that he perfectly lands on the right line again is due to a bit of luck, a bit of skill/balance and the other rider being there to "lean on".
I guess you're talking about this scene? I don't buy it. The pedal is in a vertical position, forcefully hits the ground and therefore gets pushed into a horizontal position. The wheel starts spinning. It completely matches my expectation on how it should look like if no motor is involved as it looked natural. If you push a pedal the wheel starts spinning, right? Or what would you have expected to happen in this situation if no motor was involved?Tienus said:
It would have been suspicious if the wheel visibly kept accelerating even after the impact. Or if the wheel lost traction on the ground while he still was pushing the bike and we'd see a wheel spin. I can't recognize any of the two.
@Tom
I'm pretty sure its a saved highsider and thats why the rear wheel lifts off.
https://en.wikipedia.org/wiki/Highsider
The fact that he is only making a very gentle turn makes power oversteer the most likely option for losing the rear end. When I play the video slowly it looks like the rear wheel is still turning when he stops pedalling and the tire is still in contact with the ground. The motor stopping / the wheel slowing down ending the power oversteer is the most likely cause for the highsider.
A highsider is not that difficult to save on a bicycle if you are lucky enough not to get thrown over the handlebars or end up in a position that makes it too difficult to steer the bike where you want to go.
Some highsider examples to show you dont need a bump to get rear wheel lift off.
https://www.youtube.com/watch?v=lM3J4YfBj24
I see now how my previous post sounded like I'm convinced thats what happened. I tried to explain that the motor could start and stop after he starts or stops pedalling. I actually think both motor or no motor are plausible in the Italy incident.
I'm pretty sure its a saved highsider and thats why the rear wheel lifts off.
https://en.wikipedia.org/wiki/Highsider
The fact that he is only making a very gentle turn makes power oversteer the most likely option for losing the rear end. When I play the video slowly it looks like the rear wheel is still turning when he stops pedalling and the tire is still in contact with the ground. The motor stopping / the wheel slowing down ending the power oversteer is the most likely cause for the highsider.
A highsider is not that difficult to save on a bicycle if you are lucky enough not to get thrown over the handlebars or end up in a position that makes it too difficult to steer the bike where you want to go.
Some highsider examples to show you dont need a bump to get rear wheel lift off.
https://www.youtube.com/watch?v=lM3J4YfBj24
Yes.
I see now how my previous post sounded like I'm convinced thats what happened. I tried to explain that the motor could start and stop after he starts or stops pedalling. I actually think both motor or no motor are plausible in the Italy incident.
Meh, I'm not convinced. Hesjedal was 100x more obvious to me. The main problem with this clip is that it's an-almost head on view on a two dimensional screen. It's hard to gauge from this viewpoint. When I saw the GIF, it looked more "motor-like" to me, but watching the YouTube clip on full screen makes me think it's much less apparent. Again, I think the problem is in the camera angle. He's going very fast, but it does not look like it because of the angle. So when the wheel appears to be accelerating out of control, it's likely just the momentum of the speed he was carrying. It's a lot harder to judge these things in CX races due to the nature of the courses and terrain. Even the other clip of Van Aert isn't at all conclusive due to the "bouncing" of the bike and hitting the cranks on the ground.
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https://www.youtube.com/watch?v=R6SbXBb-_Mo
https://www.youtube.com/watch?v=On-yp6w85II
They're not proper high sides unless you're doing in synchronicity (1.05) or getting proper air!Tienus said:
https://www.youtube.com/watch?v=R6SbXBb-_Mo
https://www.youtube.com/watch?v=On-yp6w85II
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I see your point. It's really not easy to see but I feel that (when watching it frame-by-frame) the front wheel kinda falling into a small hole or hitting a small bump leads to this impulse and it therefore is not a clean highsider. I don't think that it's the rear wheel re-gaining traction or anything like it that initiates this jump. But hard to tell.Tienus said:
Why should the wheel stop turning when he stops pedalling? Traction on this mud is small and angular momentum can't suddenly vanish into nowhere.Tienus said:
Don't get me wrong: A hub motor would help a lot to lose the rear wheel in this situation, no doubt about it. I just look at this footage and ask myself: Do we really need a motor to explain what we're seeing? The underground at this spot is very slippery, he chooses a line that is not very smart given the angles of the terrain and he tries to overtake and therefore pushes hard. I feel that, combined, this is enough to lose the rear wheel like he does without external "assistance". But open for debate for sure.Tienus said:
(As a matter of fact I have a considerable scar on my elbow from having done the same mistake on my mountainbike once. Lost the rear wheel after having attacked the terrain on the same bad angles. But that doesn't add any value to this discussion.. :lol: )
No I didn't assume you were convinced. You never jump to conclusions or sell your speculations as facts. So fair game.Tienus said:
Yes, it could be a motor in this Italy incident discussed some time ago. But when I look at that scene I can't recognize anything that requires a motor. It looks completely natural to me. And therefore I prefer to scratch the motor from the explanation as it doesn't add anything.
(When I look at the Hesjadal crash on the other hand and do a couple of calculations on a napkin based on a few assumptions then I figure that this is right on the edge of what could happen naturally. And I mean really on the edge.)
No, this is a quote that already appeared earlier in this story by cyclingtips: https://cyclingtips.com/2016/12/hidden-motor-inventor-varjas-claims-technological-fraud-still-possible-despite-uci-checks/Tienus said:
It's not just about losing the rear wheel though.
The other problem (which most reactions on Twitter seemed to focus on) is his retention of speed after the highsider. As another poster also pointed out it's kinda weird to see him overtake the other guy with such velocity despite not pedalling and having just saved a highsider.
Also, although of less relevance, prior to the highsider it's weird to see him generate so much more speed than his competitors despite a similar looking physical effort and cadence.
The other problem (which most reactions on Twitter seemed to focus on) is his retention of speed after the highsider. As another poster also pointed out it's kinda weird to see him overtake the other guy with such velocity despite not pedalling and having just saved a highsider.
Also, although of less relevance, prior to the highsider it's weird to see him generate so much more speed than his competitors despite a similar looking physical effort and cadence.
The (probably not motor) elephant in the room for me was him looking way off on a tangent, very bizarre but not explained by a motor.
It seems like a classic momentary lapse of concentration, misreading the course ahead of him, with a desperate attempt to correct his path causing the loss of traction. Are finish bottles a thing in cyclocross haha?
I mean seriously look at his eyes, he was (intentionally) riding like a bat out of hell into the rope at the opposite end. If a motor caused this instead his eyes would still along his intended path, perhaps even more intensely so.
It seems like a classic momentary lapse of concentration, misreading the course ahead of him, with a desperate attempt to correct his path causing the loss of traction. Are finish bottles a thing in cyclocross haha?
I mean seriously look at his eyes, he was (intentionally) riding like a bat out of hell into the rope at the opposite end. If a motor caused this instead his eyes would still along his intended path, perhaps even more intensely so.
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People still don't get it.
Yes, theoretically, physics could explain this. Theoretically, physics could also explain the first and second time his wheel went crazy. And that is the issue. Can anyone point to similar crazy wheel behavior in CX? It doesn't happen very often, and curiously it has happened three times in one season to Van Aert. Three times his rear wheel seemed to have a mind of its own. I call BS.
Yes, theoretically, physics could explain this. Theoretically, physics could also explain the first and second time his wheel went crazy. And that is the issue. Can anyone point to similar crazy wheel behavior in CX? It doesn't happen very often, and curiously it has happened three times in one season to Van Aert. Three times his rear wheel seemed to have a mind of its own. I call BS.
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