Body position in corners
September 30, 2009 at 3:36 pm #3474
Came across this image in another forum and I thought it one of the best I had seen at explaining body positioning in a corner.September 30, 2009 at 4:28 pm #22608WeaponZeroParticipant
The right side got cut off. Wish I could see what it says.September 30, 2009 at 5:57 pm #22609briderdtParticipant
Look where the person’s HEAD is relative to the bike centerline, and the resulting center-of-gravity position.
There’s a lot of criticism of people hanigng their butt off the seat in a corner and thinking they’re doing a lot of good. Pic 4 shows exactly why this is like tilting at windmills — it’s activity, but does no good at all. Lean your head (and upper body tends to follow) to get the CG lower into the corner, and keep the bike itself more upright.
BUT… (and this is a big but) Is this really necessary on the street? In 99.9% of situations on public roads, I say no. In fact, it’s probably even a bad idea. Gravel, sand, water, traffic… Even if you know the road, some one could have gone onto the shoulder and sprayed gravel into the turn. It’s not a swept track. Sure, having the skill so you can adjust mid-corner if needed can come in handy. I just don’t think it’s a good practice on public roadways.October 1, 2009 at 5:00 am #22617
Sorry about the image being cut off, I tried to resize it but was not able to. You can view the image directly here http://i30.photobucket.com/albums/c304/plasticweld/46139713-O.jpg
Briderdt, the last pic is being presented as the best setup, pic5. In this one he is raising his center of gravity which allows for less lean, which is the important thing. And is this necessary on public roadways? Absolutely I say. It is not about maximizing your speed through the corner, its maximization the traction you have available to you. And it is on public roads you need the skill to adjust mid-corner, due to those unexpected obstacles.October 1, 2009 at 2:06 pm #22618JackTradeParticipant
Great post indeed. Terrific pics, and I love the 5 reasons why you can’t get your knee down. I guessing this came from a foreign magazine…”shite tires” indeed.
I agree that on the street, there’s usually no need for full-on, racetrack hanging off…but shifting your head to the inside of the turn and letting it “pull” your body there does make a difference. Especially at speed, anything that gives you more lean-ability in reserve is a great thing in case of problems.
When spiritiedly tackling the twisties, I move my head about in line with the inside handgrip and shift my body weight to the, er, inside cheek. Still on the seat the entire time, just moving the weight inward. Definitely makes riding more involved, and practically, my Buell’s footpegs are in a straight down standard position, so they scrape pretty easily…so anything that decreases my bike’s lean angle is a good thing.October 1, 2009 at 5:24 pm #22620
I think the first two pictures are particularly instructive. I’m not so onboard with the rest of them. Here’s why:Pic #3: This is not how you hang off. This rider has scooched is bum off of the seat, but otherwise is more or less riding like the rider in picture #1. In fact, Pic #5 is closer to actually hanging off (without hanging off), which is why the lean angle observed is also smaller. Most people are under the misconception that hanging off means putting your butt on the ground. On the contrary, you only move about one cheek off the seat. The REAL gain is that you can then hang your leg and, more importantly, your UPPER body off the side of the bike. Here’s the ol’ Hopkins example:
Notice how much his upper body is pushed into the corner? Yes, he is down low for aerodynamics, something I wouldn’t advise on the street, but he is shifting the combined center of gravity of the bike/rider combination INTO the turn. That is what allows the bike to lean less.
Pic #4 and Pic #5: I would disagree with the caption on #5. I don’t think height is the key component. I think HEIGHT+LEAN is what’s important. Raising your center of gravity isn’t what allows the bike to become more upright. Using your bodyweight as a ballast into the turn allows the bike’s center of gravity to move into the turn. Think of it almost like trying to add an airborne sidecar on the inside of the turn: that inside weight forces the bike upright in order to maintain the same arc. Thus I think what’s happening is that, as a result of sitting up higher AND being leaned into the turn with his upper body, the rider in Pic #5 has a greater effect because he is using leverage to amplify the effect of his weight shift. The rider in Pic #4 isn’t out of line with the centerline of the bike, meaning that he isn’t using his weight effectively to help his bike around the corner.This isn’t a particularly good picture, but I’m having trouble finding the angle I want with google image search, hence we’ll resort to…me.
Notice how the bike isn’t leaned over very much? It is you say? Ok I admit, with the camber of the road, the offset of the photo, and my monkey pose, it might be difficult to see how much the bike is actually leaning. Just imagine drawing the normal (perpendicular line) to the ground at my tire and you’ll see it’s not a very big lean angle at all. It’s about the same as this:Not very much. Now the punchline: I’m going about 90 mph right here, and turning pretty hard. The reason it looks so relaxed is because my bodyweight (1/2 the weight of the bike) is hanging on the inside of the turn. As you approach the limit of your bike/tires, lean angle increases dramatically. Another 5 mph through this turn and my knee wouldn’t be so far out, and it’d still be touching down.
Anyway, I PERSONALLY think that hanging off is overkill on the street, for two reasons. First, you can get pretty firmly locked into the bike while hanging off, but that’s expecting a clear track, a known road, and otherwise predictable surroundings. On the street, you’ll hit bumps, have to suddenly stop for crazy kids throwing themselves in front of you, etc. Two knees slammed into the tank is always a firmer connection than one knee and a bunch of centripetal force. The other reason is that you occupy more horizontal real estate while hanging off than you would otherwise. This isn’t necessarily a benefit when you have limited lane space and the potential off snagging unexpected obstacles with your outstretched knee.
I absolutely encourage leaning with your upper body, however. The effects are dramatic, and as eon has said, it gives you a more upright bike, a larger tire contact patch, more room to turn if you need it, and ultimately more traction.October 1, 2009 at 6:04 pm #22622
I was hoping you would chime in, always interested to hear the opinion of someone who actually does this sort of thing (unlike me who just reads about it). After my last post I got to wondering about the effect of just raising your head. If you assume an average bike weight of 400lbs, how much difference to the center of gravity is raising your head by 1ft going to have? I also noticed in pic 5 his upper body was slightly off to the side compared to pic 4.
I went through a phase awhile back of shifting my butt before corners but I quickly gave up on that as on a scooter, it’s freaking hard to get back on (not having anything for my knees to hold on to). I think I lean my upper body now but I will pay more attention to my form next time I am out.October 1, 2009 at 6:26 pm #22623
Everybody has conflicting opinions, and even at relatively high levels (expert club racers, AMA racers) people will tell you things that are completely in contradiction with the current standards. I have a friend who races who always used to tell me “stick your dick in the tank” (not the most tactful fellow). This is not right at all as it causes you to pivot your hips around the tank when you hang off, leading to “crossed up” body position (where your body is actually facing the wrong way). Yet he’s an expert club racer and pulls MUCH faster times around our local circuits than I do. Probably has something to do with those big ones he carts around
Keith Code is a very successful riding coach, but I find he isn’t the best with words. While he has all the right things to say, he often doesn’t say them very well, leaving you confused. His European disciple, Andy Ibbott, on the other hand, is very clear and concise in his explanations. He runs all of the California Superbike School locations in Europe, and was featured on the UK TV show “Superbike School.” The series itself was actually a waste of time after watching the little teasers on YouTube. All the good info is there. Here’s one on proper body positioning and moving around the bike:
If you’re interested in a layman’s introduction to high-performance riding, including an introduction to the world of racing, this book is fantastic. Great explanations, and lots of awesome and huge color photos. I have the first edition, but an updated second edition is available for pre-order:
Oh, and on the note of “big ones,” one of the funniest things I’ve seen on a forum was over at gsxr.com (a WHOLLY different experience from this lovely establishment…can you say overpopulation of squiddly squid?):
Guy #1 (paraphrased): Hay guyz mai lap times iz slow but I wanna get super fast!!!1 K THX BYE
Guy #2: So what you’re going to want to do is head over to Home Depot and pick yourself up a nice pair of man hands and a sack o’ nuts. Should take care of that for you.October 2, 2009 at 2:36 am #22628owlieParticipant
“Guy #2: So what you’re going to want to do is head over to Home Depot
and pick yourself up a nice pair of man hands and a sack o’ nuts.
Should take care of that for you.”
That was the best laugh I’ve had in a while. I’ll have to file it away for future use…October 3, 2009 at 1:19 am #22648Gary856Participant
This is confusing me:
Picture 4 (rider crouched right down) -> resulting in more bike lean than picture 5.
Picture 5 (rider sitting high) -> resulting in less lean than picture 4.
How can this be right?! Picture 5 (rider sitting high) = top heavy = higher CG, so how can it be more effective in turning than Picture 4 (rider crouched right down) = lower CG?
Do we see racers sitting high like that to reduce lean, increase cornering traction/speed?October 3, 2009 at 4:31 am #22653
Basically the answer is that the advantage doesn’t come from height but rather from upper body position (i.e. the explanation in the pic isn’t quite honest). Rider #5 is shifting the weight of his upper body horizontally: into the turn. Rider #4 is lower, but isn’t leaning into the corner (i.e. body lean, not bike lean) at all. His center of gravity is still over his gas tank. Make sense?October 3, 2009 at 7:17 am #22655Gary856Participant
Eternal05, I re-read your earlier post and saw you touched on the point I raised. That just means the explanation for pictures 4 and 5 are plain wrong, and even the photos are wrong for what they tried to illustrate. Physically, when you sit tall, you cannot be sideways as much. When you crouch low, you can move sideways a lot more, i.e., hanging off -> more body lean -> lower the combined (body+bike) CG -> less bike lean -> better traction. Another point I want to make is hanging off is not just for speed; it’s also used in low traction situation (water, snow, gravel, etc.) to keep the bike as upright as possible to maximize traction.October 4, 2009 at 1:44 am #22675
But remember, to a racer, more traction == more speed. You’re absolutely correct, however. Body position (hanging off, etc.) is much more important in the rain than it is in the dry for the very reason that you are at lower risk of a lowside (or for that matter a rear-spin-induced highside) if the bike is more upright.
Also, I would hope you don’t ride in snow…that’s just a disaster waiting to happen.October 5, 2009 at 9:14 pm #22686motokidParticipant
about this. guy is half right, but gets some things wrong. confuses mass and weight on couple of occasions. Also, it’s pure physics, for every speed and corner radius, there’s only one angle to pass it. Angle being the angle between the line formed by center of gravity and contact patch and flat line. It is irrelevant how high on that line is a center of gravity. So, his idea that tucking itself would decrease the angle is simply wrong.October 5, 2009 at 10:05 pm #22687briderdtParticipant
…but it makes it easier to move the CG away from the bike centerline.
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