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 All Forums
 Motorcycle Safety
 Physics and the theoretical
 Lean at slowish speeds vs faster speeds
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mstram
Male New Member
11 Posts


Toronto, Ontario
Canada

(None)

Posted - 08/15/2015 :  2:34 PM                       Like
In this video, the poster goes on and on at how "To do these kind of lean angles at these types of slower speeds is EXTREMELY difficult"

He then states to do the same lean angles at "higher speeds" is relatively easy.

https://www.youtube.com/watch?v=GKDN3okg4ko

From all I've read on this site, I was going to question his statements, but wanted to double check here first.

From the physics and other discussions I've read here, I thought a proportial lean / radius numbers will generate the same forces and have technically the same skill required ? (i.e. 20 mph for 40 ft, 60 mph for 360 feet). (Assuming a hypothetically similar road surface for both turns)

I posted the same video on the ninjette forum and got this response :

What has (lowish) speed got to do with "difficult lean angles / speed" ?


It would be because the centrifugal force is related to the square of velocity. Simplified the faster your moving around the arc of a turn, the greater the force pushing you outward - to combat this, physically you lean the bike at an angle and use this force to drive the contact patch into the surface to create additional friction force for the tire to grip.


He seems to be saying that the "centrifugal force" is NOT = to the lateral acceleration on the lean spreadsheet.

scottrnelson
Advanced Member
6881 Posts
[Mentor]


Pleasanton, CA
USA

KTM

990 Adv, XR650L

Posted - 08/15/2015 :  3:14 PM
I wouldn't trust the "information" from that video. I won't really comment on how easy or difficult it is to lean a bike at a given speed, but the faster you're going, the harder it is to correct a mistake in a corner. If you're going a bit too fast into a 20 mph corner, correcting for it and making the corner is relatively easy because you have more "relative room" to make the correction. Going into an 80 mph corner a bit too fast can easily have you run out of track space before you can correct it.

Centrifugal force is directly related to lean angle, independent of the velocity. If you're leaning at 45 degrees, you're pulling 1G regardless of what the speed it.

Now you see how easy it is to find faulty information on the internet.
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bachman1961
Male Advanced Member
2260 Posts
[Mentor]


colorado springs, co
USA

Honda

CB750 NightHawk

Posted - 08/15/2015 :  6:46 PM
I have no track experience or skills, never rode this type of bike nor ever leaned like that. I can't really offer an opinion based on my experiences, not that experience in itself makes a statement or opinion correct anyways.

Listening to the narrative, the message is as much about how the speaker thinks we should ride and enjoy our bikes as it is his idea of leaning at these lower speeds and thresholds of force. In that respect, he pretty much loses me in terms of credibility.

I can say that my lower speed PLP and maneuvers do incorporate less dramatic inputs or leaning and I find my comfort level (feeling of stability) is directly related to more finesse and tighter control.
I don't know that this relates to that video and type of riding but the effort and concentration involved seemed pretty apparent to me. IOW it did strike me the lower speed maneuvers he was demonstrating were more challenging.

I think it smart to challenge something like this or at least bring it forward as you did here before considering any change in your own riding style or considering anything as 'the gospel'.


Edited by - bachman1961 on 08/15/2015 7:50 PM
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gymnast
Moderator
4260 Posts
[Mentor]


Meridian, Idaho
USA

Harley-Davidson

Sportster Sport

Posted - 08/15/2015 :  7:30 PM
The guy narrating the video is impressed with the skills of the rider however he provides little to no insight as to what those skills are other than "that guy sure can lean".

As indicated by the above posts, the faster you go, the greater the consequence of error. Either your error or the other guys error. I have never found it wise to attempt lean angles as seen in the video on the street for a number of reasons. Available traction and available skill are far more constant on a track than in any on street situation. Besides, on a track everybody is going in the same direction.
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James R. Davis
Male Administrator
17276 Posts
[Mentor]


Houston, TX
USA

Honda

GoldWing 1500

Posted - 08/15/2015 :  8:32 PM Follow poster on Twitter  Join poster on Facebook as Friend  
Some basic knowledge can help understand what the guy is implying.

Slower speeds suggests below counter-steering speeds - or about 10 MPH.

At slower speeds an experienced rider controls his speed (and lean angle) more with his friction zone than his throttle.

At slower speeds when you increase speed the bike stands taller while at higher speeds when you increase speed the bike leans more.
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rkfire
Advanced Member
1688 Posts


Stratford, CT
USA

Suzuki

Bandit

Posted - 08/18/2015 :  10:07 AM   Join poster on Facebook as Friend  
James, I really didn't get the impression at all that this guy in the video was referring to under 10 mph.

The video showed a 250 Ninja navigating a go cart course in race fashion. I'd imagine the slowest he took the tightest of corners was over 20 mph.

His premise (to me) was that it was harder to lean a bike at 20-50 mph on a tight race course, rather than 50-100 mph on a big track.

Which doesn't make a lot of sense to me. Otherwise the little kids riding pocket bikes and small motards around go cart tracks would have to then be the best road racers in the world...lol.
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James R. Davis
Male Administrator
17276 Posts
[Mentor]


Houston, TX
USA

Honda

GoldWing 1500

Posted - 08/18/2015 :  10:13 AM Follow poster on Twitter  Join poster on Facebook as Friend  
Mixed messages - I agree.
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Horse
Senior Member
257 Posts


Newbury, Berkshire
United Kingdom

BMW

R850RT

Posted - 08/18/2015 :  1:04 PM
For amazing tight control skills, Google/youtube GP8 motogymkhana.
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