Phil Posted August 17, 2005 Report Share Posted August 17, 2005 I don't want to highjack this thread, so if you would like to discuss this topic as it relates to snowboarding go here: http://www.bomberonline.com/VBulletin/showthread.php?p=53637#post53637 Quote Link to comment Share on other sites More sharing options...
NateW Posted August 17, 2005 Report Share Posted August 17, 2005 400 pound bike + 200 pound rider = 600 pounds At 30 pounds per square inch, the contact patches total 20 square inches. Figure each tire has about a 3" x 3" patch? Seems about right to my intuition. It surely provides far more traction than any street cyclist could hope to enjoy in the corners. Quote Link to comment Share on other sites More sharing options...
Jack M Posted August 17, 2005 Report Share Posted August 17, 2005 At 30 pounds per square inch, the contact patches total 20 square inches. Figure each tire has about a 3" x 3" patch? Sounds reasonable. But, what about the fact that the tire "grows" as speed increases, thereby reducing the size of the patch? Quote Link to comment Share on other sites More sharing options...
mirror70 Posted August 17, 2005 Report Share Posted August 17, 2005 Sounds reasonable. But, what about the fact that the tire "grows" as speed increases, thereby reducing the size of the patch? The patch doesn't shrink, it just changes shape (longer and narrower). The only way to change patch area is to change tire pressure. Quote Link to comment Share on other sites More sharing options...
NateW Posted August 18, 2005 Report Share Posted August 18, 2005 My initial reaction to that was exactly the same as Mirror70's, but on second thought I'm not so sure. Does the deformation of the tire correspond to a change in volume, and thus a change in pressure? Does the deformation make the tire stiffer? I dunno... It's probably been studied, but I'm too lazy to go search for it. Quote Link to comment Share on other sites More sharing options...
NateW Posted August 18, 2005 Report Share Posted August 18, 2005 And another thing. You can steer a bicycle without putting any force on the handlebars. I did it on the way home from work yesterday, and nobody is gonna convince me otherwise! :) I don't see why motorcycle would be significantly different. Sure it would take more weight shift, but wouldn't it all just scale up? I don't see why you can't ride a motorcycle no-handed as well. Or is there some factor that scales up nonlinearly and requires not just 10x the wieght shift but 1000x? I don't get it. Quote Link to comment Share on other sites More sharing options...
Jack M Posted August 18, 2005 Report Share Posted August 18, 2005 And another thing. You can steer a bicycle without putting any force on the handlebars. I did it on the way home from work yesterday, and nobody is gonna convince me otherwise! :)I don't see why motorcycle would be significantly different. I agree. I think what the Kieth Code experiment is trying to prove is that you can't turn a motorcycle without bar input in a reasonable amount of time when the bike is traveling over a certain speed. Presumably, this is due to the gyroscopic effect of the wheel resisting the imbalance from you hanging off to one side. But I really doubt the gyro effect could keep the bike upright forever. Eventually the bike will turn. I think. Quote Link to comment Share on other sites More sharing options...
Phil Posted August 18, 2005 Report Share Posted August 18, 2005 And another thing. You can steer a bicycle without putting any force on the handlebars. I did it on the way home from work yesterday, and nobody is gonna convince me otherwise! :) This is a great point. One thing that bikes and snowboards have in common is that you have to consider where your center of mass is over the tool that you are using. This is why I started the snowboard turning thread. In order to make a bike/SB turn, you must get it to counter steer just enough so that you can lean your center of mass off of the side of the bike/SB that you are trying to turn. An easy way to think of it is to watch a child with training wheels who is new to riding a bike. They will turn the handlebars the way they want to go and/or lean the direction that they want to go. You cannot do this without training wheels because, as the child will demonstrate, the bike will lean to the outside of the turn. In order to get the bike to lean to the inside of the turn, you must counter steer (or counter lean) for the split second that it takes to get your center of mass inside the turn from the bike. This is not something that you would really teach in order for someone to ride a bike - it comes naturally to most. At a high level of riding or coaching for most disciplines, it is important to measure each movement, and therefore becomes important to understand the extent of counter steer/counter lean involved in a turn. Now, back to the no hands on the bar - this is a great way to illustrate how steering IS involved. Simply watch your bars next time you ride with no hands. Due to the rake of the fork (trail of the tire) and the head angle of your bike, the handlebars and front wheel naturally turn when you lean the bike. Furthermore, in order to turn without using your hands, you must do a carefully timed counter lean to get your CM on the side of the bike that you need it. This would be different if balancing on two wheels was not involved - say on a four wheeler or if you had training wheels. The fact that you are on two wheels, even with the gyroscopic effect, means that you have to take these steps to make a turn. Quote Link to comment Share on other sites More sharing options...
Jack M Posted August 18, 2005 Report Share Posted August 18, 2005 Are you saying that to turn a bicycle to the right with no hands on the bars, you must first lean to the left slightly? I can't imagine that being true. Quote Link to comment Share on other sites More sharing options...
Phil Posted August 18, 2005 Report Share Posted August 18, 2005 Nothin' to it but to do it. Quote Link to comment Share on other sites More sharing options...
Tommy D Posted August 18, 2005 Author Report Share Posted August 18, 2005 So I'm out riding my bicycle today ... Thinking about this thread ... There might actually be some countersteering going on at higher speeds! I did some very unscientific testing while swerving down the road. Some turns I leaned, and others I intentionally countersteered. These are my results: Intentional countersteering definitely leads to faster turning. It might be my imagination, but it 'felt' like the bike was naturally countersteering when I did naught but lean: In the lean test, I very loosely gripped the bars and felt (I could swear it!) naturally occuring countersteer. Very interesting. Not the direction I expected this thread to go, but it has been informative, and fun. And I learned better cornering! :) I'm surprised I only got one answer to my vacuum question! Quote Link to comment Share on other sites More sharing options...
sic t 2 Posted August 19, 2005 Report Share Posted August 19, 2005 What are the applications for this? None I can think of for the recreational rider, but it is a lot of fun, and a neat trick to have in the bag.What do you think? "Countersteering" is considered a basic street motorcyclist skill. So basic that if you can't perform it, at will, you should not even venture out onto the public roads without your instructor/mentor in tow. Actually, if this were a street motorcycle website then countersteering could be probably be found under a tech article entitled something like "the norm". Not trying to be a wise guy but that's seems about the level this would rate on a website dedicated to street motorcycle riding. And that article would be one of the most important written on that site too (just as "the norm" is here). What gets interesting about countersteering is not what happens when a motorcyclist initiates violent countersteer from a vertical position, but rather the second countersteer from a radically leaned over position. For example; you countersteered violently to miss the leaping deer. And now, from a highly inclined position, you have no choice but to countersteer again in order to miss the telephone pole on the side of the road. This is the one that kills: cause you may fail to countersteer and hit the pole, and/or you countersteer too much and miss the pole but high side your mount down the road (most likely option). Or you thread the needle and live to ride another day! practice practice ! Sic Quote Link to comment Share on other sites More sharing options...
ARCrider Posted August 19, 2005 Report Share Posted August 19, 2005 what will be the effect of adding a second person to the motorcycle or bicycle in regard to steering. or how about a sidecar? I know that my tandem is definately not as nimble as my solo bikes. Quote Link to comment Share on other sites More sharing options...
Baka Dasai Posted August 19, 2005 Report Share Posted August 19, 2005 Hanging off just lowers the COM and allows the rider to keep the bike more upright at a higher speed. This maintains traction. Are you sure it maintains more traction? Jobst says it makes no difference. Why would it make a difference? Quote Link to comment Share on other sites More sharing options...
Speedzilla Posted August 19, 2005 Report Share Posted August 19, 2005 It might be my imagination, but it 'felt' like the bike was naturally countersteering when I did naught but lean: In the lean test, I very loosely gripped the bars and felt (I could swear it!) naturally occuring countersteer. That's my point. Even if you don't think you are countersteering, even if you don't believe in countersteering, even if you think Kieth Code is a loser.....you ARE countersteering when you turn a cycle at speed. Quote Link to comment Share on other sites More sharing options...
Jack M Posted August 19, 2005 Report Share Posted August 19, 2005 By hanging off, the bike is a bit more upright and the outward pressure on the tire is reduced allowing for more power or braking. How is the outward pressure reduced? The centripetal force is not reduced if the bike is going at the same speed/radius. There’s a great shot of a guy on an MV Agusta Senna with his elbow and knee on the tarmac. There's a picture of Nicky Hayden doing that, granted his elbow is on the red & white track curbing, which is raised slightly, but yeah it's cool. Also, above you said the center of mass of a bicycle is down very close to the road. I think you meant the roll axis is down near the road? Surely the center of mass of a bicycle can't be any lower than the wheel axles, right? Or higher...? And you also said that due to the castor effect, the front wheel of a moto/bicycle would flip around backwards if it didnt' have the bike behind it. I highly doubt that. Doesn't the trail prevent that? The tire contacts the road behind the pivot point, so it follows or "trails" the pivot and is therefore stable. If the fork had negative trail (which would be "lead" I guess) then it would be unstable and would flip around backwards. otherwise, good points and thanks for the cool diagrams! And I was out on my moto yesterday, weaving back and forth in my lane at about 35mph with no hands on the bars, and it was quite easy to do. I wonder at what speed does throwing your weight around have little effect. Quote Link to comment Share on other sites More sharing options...
NateW Posted August 20, 2005 Report Share Posted August 20, 2005 I believe the part about needing an initial nudge in the "wrong" direction to initiate a turn while riding no-handed. What I don't understand/believe is the part about being unable to turn without applying force to the handlebars. I believe that people failed to turn the bike with the welded handlebars, but I don't see why they failed, and I'm not ready to believe that it isn't possible. Quote Link to comment Share on other sites More sharing options...
philistine Posted August 20, 2005 Report Share Posted August 20, 2005 Alright, I find this thread incredibly insightful and packed full of knowledge. I didn't realize that everyone on Bomber was a genius. I mean really, I need to get alot smarter. Anyways, was I the only one who saw that picture of those guys DRAGGING THEIR FUGGING KNEES ON A HAIRPIN TURN, ON A BIKE!???!! What's the deal with that?!?! What was that?! I LOVED IT! !!!!!...!!!!! I'm speechless! Quote Link to comment Share on other sites More sharing options...
ARCrider Posted August 20, 2005 Report Share Posted August 20, 2005 used to have a weekend job with "Trail tours and dirt bike school" teaching newbies how to handle motorbikes offroad. The style of riding that we were trying to pass on was all about steering with your knees. standing on the pegs with knees slightly bent and pressed to the tank. tight forest trail and running mostly 2nd or 3rd gear on 250/300cc machines. I found the action very similar to skiing and although your hands were on the bars they were there mostly for throttle/brake control. Quote Link to comment Share on other sites More sharing options...
Tommy D Posted August 20, 2005 Author Report Share Posted August 20, 2005 Alright, I find this thread incredibly insightful and packed full of knowledge. I didn't realize that everyone on Bomber was a genius. I mean really, I need to get alot smarter. Anyways, was I the only one who saw that picture of those guys DRAGGING THEIR FUGGING KNEES ON A HAIRPIN TURN, ON A BIKE!???!! What's the deal with that?!?! What was that?! I LOVED IT! !!!!!...!!!!! I'm speechless! Yah! That's awesome! :lol: First time I saw that, I was amazed and inspired. Now I can drag my knees while on my Deere! :D Quote Link to comment Share on other sites More sharing options...
philistine Posted August 21, 2005 Report Share Posted August 21, 2005 Where did it come from? Quote Link to comment Share on other sites More sharing options...
Tommy D Posted September 12, 2005 Author Report Share Posted September 12, 2005 WOW! I am taking the BRC right now, and had my first lesson in countersteer on a mcycle. WILD stuff. Glad I practiced on my road bicycle first. :) It is pretty amazing; I 'feel' like I can turn the bike by leaning over, but without a doubt the bike manouvers much faster using countersteer. Quote Link to comment Share on other sites More sharing options...
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