Line Theory 101
May 26th, 2009 by Leo
So what’s an apex? Where is the “right” turn point? If you drive a car, the answer is “who cares?” Unless you are a racing fanatic you probably wouldn’t have any idea. But the fun thing about motorcycles is that theory and practice are a lot closer, so your ability to find and execute good clean lines makes your riding safer, faster, more predictable and more fun (even if you’ve never been within a hundred miles of a racetrack). So here’s the basic 411 for those who are interested. (All you road riding wizards can chime in and impart your cornering wisdom too in the comments section!)
- A turn-point (or turn-in point) is the spot at which you begin a turn; it’s where you transition from going in a straight line to going in an arc. All your hard braking has to be done before the turn-point; light braking after the turn point is called “trail braking.”
- An apex is usually defined as the point of the turn at which you are closest to the inside edge of the road. It’s also usually the middle point of your turning arc – not the middle point of the turn in the road, but the middle point of the arc you’re drawing with your bike.
- The end of the turn (or exit point) is where the turn ends (duh), where you straighten out the bike. That’s when you’re free to either brake further or really open up the throttle.
You with me so far? The idea is, when you hit your turn point to set your bike at the right trajectory to hit the apex. That’s why the Turn Point is so important… An experienced road racer doesn’t see a road with bends (like you and I might), but a series of turn points and apexes…
So what’s the “right” turning point for a turn? A good turn point and apex means you will be able to [a] maintain the same lean throughout the turn, [b] roll on the throttle lightly to settle the bike in the turn, AND most importantly [c] get to a good exit point for the turn. “Bad” turn-points and apexes, on the other hand, will mean you have to change your speed or lean angle in order to stay on the road after the apex. So the way you figure out what the good turn points and apexes are is by deciding where your exit point or ‘end of turn’ needs to be and work backwards…”where do I have to turn in and where do I have to apex in order to get…there?”
On the street, a good city biker is someone who’s able to figure out where he needs to be at the end of a turn, picks a good line avoiding bad pavement, manhole covers, oil and gravel, and then puts the bike into a single turn (a constant lean angle) to get there… So that’s the theory, now let’s get back to riding. Cheers!
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I want to point out that all of the variables you listed change given different riding environments. For example at a track you are going to have a different turn in then on the street for an identical corner. This is more of a safety issue because of the more variables on the street.
Just a thought.