harnois

Yep! If the bike is working properly, new tires, good geometry and all that, and you aren't doing anything to mess it up, the front will naturally steer into the turn exactly the amount it needs to in order to maintain its present lean angle. Thank you modern motorcycles with this "neutral" steering! And so when you countersteer you are pushing the bars to left or right of that neutral steering position, not necessarily to the left or right of center.

Nice drawing. I do understand the concept. Your drawing is similar to the one posted here that I mentioned earlier. http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=312 I don't dispute that the difference exist, I was just saying it's not enough difference to be worth mentioning. In your drawing, it appears to me that you dramatically exaggerated the difference in tire width and CoG location, which is fine because it makes the concept more clear. But in reality, the difference in CoG and tire width between a sportbike and an adventure bike is not that great. I own one of each. Yeah my KLR looks tall when jacked up on it's center stand, but after the suspension sags 3 or 4 inches under its own weight and my weight, it's not that much higher than the sportbike. I would bet at most 2 to 4 inches difference in CoG between the 2 bikes, but I have no way to measure it. But I did measure the tires, and there's only like about a 25-35% difference in how far the contact is offset from the center line at 45 degrees. Your drawing shows like a 100% difference. If you redrew your drawing to scale it would probably be hard to even see the difference in the angle of the thick line. If comparing a low-rided cruiser with one of those 300mm rear tires vs Dakar racing bike, then maybe it'd be enough to matter.

Just because A happens at the same time as B, doesn't mean that A caused B. The superbike school would no doubt help your brother fix his front wheel sliding issue. I have never had front wheel sliding issues except when off-throttle or on the brakes. I'll tell ya story bout my own brother... I was riding in front on a 2-lane backroad, mov'n at a pretty fun pace, as I crested a hill I see an unexpected left curve with a big swath of gravel all over it. So I brake before the turn, lean in quickly, get on the throttle early and kept it on throughout the turn - basically the same way I take any turn. The wheels slid somewhat on the gravel but from experience I knew it would work out fine, and the bike stayed stable through the whole thing. My brother on the other hand, equally surprised by this predicament no doubt, but less experienced, rolled over the gravel off-throttle, his front end stepped out, his SR's fired off and he ran into the ditch, totalled his bike, and spent 3 days in the hospital with a deflated lung, broken shoulder, and bruises all over. Another incedent, all my own, on the track, heavy down pour, I was just trying to get back to the pits but it was dumping like mad. In a downhill section I was off-throttle leaned over, not even trying to go fast, hit a dip and a slick spot of rubber on the track, next thing I know I'm trying to figure out why I am looking at my own bike sliding across the pavement, and then realizing that I was sliding the across the pavement too! Hey Wait! Am I crashing? When did this start? Reacting to this slide was out of the question. Now I think I get the gist of what you are saying, that your method of braking into the turn isn't that dangerous for you because you know what you are doing. Like you said, after 30 years you are still here, and that can't be just luck. And yeah, with good pavement and good tires and smooth riding, of course you can get away with it. And yeah, with your experience you can usually adjust to the things that would make you crash if you see them ahead of time. And yeah, those invisible slick spots are rare and most won't be big enough to make you crash. But despite your 30 years of experience, and my 200,000 miles of experience, either one of us could make a mistake or just have some bad luck and bite the bullet on our next ride. Keeping the bike stable throughout the turn is just sensible risk management, and for most people I think, it also improves the fun of riding.

The Wikipedia article seems not to agree with this: (my bold) Good point. But the often perpetuated myth is that THE reason countersteering works is because of the gyro effect. Case in point, stevo brought it up without even mentioning the out-tracking. It seems that new riders find that answer first and stop looking. While the gyro effect *might* be a minor convenient benefit, it is not THE reason that countersteering works. If the gyro effect did not exist, countersteering would still work just fine. Besides that, while I'm glad to see the wiki article mention actual tests and math, I don't see how the out-tracking "builds up more slowly." And I generally think their math example fails to take into account the whole picture, causing them to give the gyro effect way more credit than it deserves. For example there is no mention of the heavier spinning rear wheel which I would think would cancel out more than half of the front wheels gyroscopic precession effect. I think I recall years ago reading that Keith Code did a test where they balanced a bike up on a jack, so the wheels were off the ground and it could easily lean one way or the other, then they spun the front wheel up to like 40mph with a drill, then turned the steering, and basically nothing happened, and that was without the rear wheel stability. The gyro thing is just altogether a pointless distraction for someone trying to understand why and how countersteering works.

I also certainly occasionally enjoy the feeling of braking hard into a downhill reducing radius turn, so it's not like I think it's so dangerous that I never do it. Just because we are good enough riders to get away with it does not mean there is no added risk. It is definitely riskier. Aside from the higher likelihood of a traction issues, the technique is pointless unless you are charging into the turn at a fairly high speed, and at that higher entry speed, and already braking, there is less allowance for the unexpected.

Eirik, I think your point about having the brakes preloaded is an interesting one. Although I still think it's obvious that whatever benefit you get from that is offset multiple times over by many other added risks. The general feel I get from your posts at this point is that you agree that the textbook superbike school method (slow in and smooth throttle through the turn) is actually optimal, but you prefer to do it in a less optimal way because you think it is more fun. I can't really relate to that, but to each their own. If you idea of fun is looking for the least optimal way to ride, why not just swerve all over the place all the time for no reason? Or like, aim for cars just to see what happens? Or like, hang way off the wrong side of you bike to see how fast you can wear your foot pegs off. I mean where does that end? This is entertaining. And the point I've tried to make and will make again, is that the only reason you think the less optimal way is more fun is because you haven't given yourself the proper chance and made a proper effort to get comfortable with the most optimal method. When you are flicking from side to side with speed and smoothness and accuracy, and nailing the lines and keeping your bike super stable, you can fly through the turns and practically ignore all the debris and whatever that's on the road, and it's an awesome feeling to get it right. I do understand though what you mean about slow bikes. I have a gsxr750 for the track, but the only street legal bike I have at this point is KLR650. It is by far the slowest bike I've ever owned, and I have knobbies on it which reduce cornering traction on paved roads, so it's a lot easier to challenge myself with it without getting into the "go to jail" portion of the speedometer. But when riding, I'm still challenging myself to find the most optimal way to ride that bike. Riding it on gravel roads, this throttle control thing we are discussing becomes a much bigger deal.

If tyres had zero width, wheel diameter, CoG and wheelbase wouldn't matter. However, since tyres have width, all these things affect how much a bike must lean for a given speed. Wider tyres require more lean than narrower ones. Large diameter wheels require less lean than smaller ones. Long wheelbases require more lean than short wheelbases. And tall bikes (higher CoG) require less lean than lower bikes. There's a thread here discussing this topic, with a nice graphic showing how the tire width affects things: http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=312 The differences caused by the tire width are so minuscule as to be basically academic. In your original post you seemed to be implying that this had something to do with why you were dragging parts and the Africa Twin rider wasn't. This tire width and CoG thing you bring up does not make enough difference to be even worth mentioning. The reason you were dragging parts and he wasn't, is either because your bike does not have good ground clearance, or you have bad body position (leaning the bike more than your body), or you are not on the throttle, or some combination thereof.

Here we go again!.... You do realize this stuff has been hacked at over and over again on a million internet forums already, right? http://en.wikipedia.org/wiki/Countersteering Putting pressure on the handlebars causes them to turn, it's just such a small amount that it is hard to notice. But it is the turning that makes it work. The gyro thing is basically a myth. See the article linked above. Actual testing demonstrated that the gyro effect was only 12% of the cause at 50mph. The primary reason it works is because it drives the tires out from under the bike.

OK, maybe, but you are also going faster to start with, because if you are trail braking, this certainly must mean you have a faster turn entry speed, otherwise what's the point of continuing to brake into the turn? The guy who slows before the turn, then accelerates gradually through most of the turn, he is going slower at the turn entry, has more time to assess the turn, requires less braking to slow for anything unexpected. The trail-braker on the other hand, at the turn entry, is not only going faster but has a less stable bike due to the braking.

Here's the reason why trail braking is dangerous on the street. As I'm sure you know based on your posts and 30 years of riding, if you hit a slippery spot while cornering on the brakes, the front end will step out FAST! You can end up on the pavement before you even knew you were sliding. Now I see in this thread you've addressed that, and say you deal with those issues fine, but what if you don't SEE the slippery spot? I have multiple times had my tires slide out and had no idea what was there to cause it. In some cases I've actually gone back to look at the road to see what it was. Gravel on the road of the same texture and color as the pavement is easy to miss, especially at speed. So lets consider.. Rider #1, who likes to trail brake, he runs over the invisible slippery spot, his front end steps out big time, the bike makes it through the slippery spot still on its wheels and regains traction but the rider is already freaked out, he panics, target fixates on the dump truck in the oncoming lane, game over. Rider #2, also likes to trail brake, but he's more experienced, less prone to target fixation, his front end steps out, but this slippery spot is too big, the bike goes down before it gets back to the better pavement, he slides into the dump truck, game over. Rider #3, hits the slippery spot with no brakes and perfect throttle control. Both the front and rear wheel slip just a tad, but he barely notices, and goes about his day. Which rider do you want to be? Riders 1 and 2 are dead; Rider 3 is a feeling like a bad@ss.

For a lot of turns it's a steady speed simply because they are not sharp enough to make me have to slow down for them. I mean, with a speed limit of 55mph, a turn has to be pretty dang sharp to make me have to slow down for it, especially after all the track riding experience. But for the turns where I need to slow down, it's engine braking and/or light braking up to the turn, release the brakes, lean it down, throttle on as soon as possible and slight throttle roll-on throughout the turn. It's the safest way to ride, and it's still fun. A lot of the back roads I ride on are bumpy and sketchy. Being on throttle through the turn keeps the bike super stable so it just sails over all the mess with no fuss.

Eirik, I started riding motorcycles in 1998. By the time I took superbike school in the early 2000's, I had about 80,000 miles of street riding experience. Yeah, I guess I got the bug. I was totally comfortable with riding before I took the school. I didn't really feel like I was missing anything. But the school totally changed my way of riding. In the following 2 or 3 months I remember feeling quite awkward while trying to ride by their suggestions. I felt slow and inaccurate. I was having to think really hard about what I was doing while riding, when before it seemed so natural. But having a good mind for physics, I new their methods made sense, so I forced myself to do it their way, and eventually it started to feel great, better than ever before. Scenarios that used to scare me, didn't scare me anymore, because I knew what to do (or more accurately, what not do do) to keep the bike stable and happy. I was going faster but at the same time safer and more capable of dealing with the unexpected. The process continues constantly today while riding on the track, although in smaller increments. With my adventure bike, I've been learning all kinds of new stuff, standing on the pegs, hopping over big logs, riding up steep embankments, trying different techniques. Since it is all new it feels awkward at first, but I keep doing it until it starts to feel natural. You can't really objectively evaluate the value of a technique until you've done it enough to get beyond the awkward feeling stage. You've been riding for 30 years you say, obviously you are used to doing it a certain way, I can relate. But if you want to get anything out of the suggestions from this forum, or from taking a superbike school, don't you think you'll have to accept that awkward feeling for a while? It seems to me like you are coming up with some kinda bizarre interpretations of the laws of physics in order to justify your current style of riding, rather than making the effort to learn a better way. It's like you are in denial. Maybe you need an intervention.

See this, look at the section called "Leaning." http://en.wikipedia.org/wiki/Bicycle_dynamics#Turning Note in the formula there, the variables are speed, radius, and gravity. The higher CoG of the adventure bike would not cause it to lean less. Now what might be fun to think about, is how would your lean angle or cornering ability be affected if you were riding on other planets with different levels of gravity?

My local tack is Virginia International Raceway. North Course turn 7 is a right-hander with a harsh dip in the middle followed by an off-camber rise in the 2nd half. I have friends who have high-sided there. I've watched one of my friends almost high-side there twice while I was following him. Only a couple of times, in all the 50 or 60 track days I've done there, I had this cool sensation of both front and rear tires drifting equally as I went over that rise. Then I probably got chicken and slowed down and haven't felt it since! I think your idea of keeping the throttle constant as you go over the rise is a good one. It is my natural tendency to flatten out the throttle roll-on in that scenario. It works well for me and I'm not loosing ground on anyone there. Obviously don't chop it off, just slow down the roll-on rate or hold it so you maintain speed rather than speed up. The idea is to equalize the traction demand and load between the front and rear tires, so that if you do slide, everything will stay in line and smooth. If you are on the throttle too much, the rear end will slide, and when the rise ends and the traction level suddenly increases, things could get jerky. If you are off the throttle, the front end is loaded and will be the first to slide. Somewhere in between is the sweet spot. I think the idea of adjusting the line to be straighter is also good. In VIR turn 7 the dip preceding the rise provides a huge amount of traction, which we use to cut hard and straighten out the exit. I say "cut hard," but it's actually something that happens naturally and smoothly.

So you are saying that, now that you are aware of this tip, you can compete with Rossi? The other side of this tip though, is that once you actually go for the pass, you will be at the limit again AND off the ideal line.