Throttle Control

Story by Misti Hurst// Photos by Misti Hurst
March 1 2008

Mention the term “Throttle Control” to any rider and they will nod importantly and say something to the likes of, “Yep, throttle control is pretty important. Gotta have good throttle control when riding a motorcycle.”

Of course you need to have good throttle control when riding a motorcycle, but what exactly is good throttle control? What does it mean?

The throttle is the device that controls the flow of fuel and air into an engine, resulting in more or less power output. Control is the power to influence the course of events. So, throttle control essentially means, how well you influence the course of events on your bike by controlling the flow of fuel to the engine, or controlling the power. That sounds pretty important doesn’t it? That’s because it is.

Throttle control is probably the most important aspect of motorcycling. It affects such things as acceleration, deceleration, traction, and ultimately the stability of the motorcycle. Everyone knows that when you roll on the gas the bike will accelerate, and when you roll off the gas the bike will decelerate. How well you roll on and off the gas will determine not only the amount of traction you have, but also where your bike ends up in the corner. How does the throttle affect traction and line? Let’s look first at what happens to the geometry of a motorcycle when you roll on the gas.

In his book, Twist of the Wrist II, world-renowned motorcycle coach, Keith Code explains, “To determine an ideal scene for traction, machine-wise, we start by simply measuring the contact patches (the actual footprint of the tire where it contacts the road surface) of the tires to discover what the basic distribution of loads should be while cornering. Roughly speaking, those measurements show that 40 percent of the total load should be up front, 60 percent at the rear. The rider’s task is to match the exact load specs of his machine with expert use of the throttle. How do you do that? Considering that most machines in a static or constant speed situation have a 50/50 weight distribution front-to-rear, we begin to calculate the guidelines of correct acceleration through a turn. By the numbers, we want to transfer 10-20 percent of the weight rearwards using the throttle. Technically, this is 0.1 to 0.2 G of acceleration. Simply put, it’s the force generated by a smooth fifth-gear roll-on in the 4000 to 6000 rpm range on pretty much anything over 600 cc’s. That’s not much acceleration, but it does the job.”

So, basically, when you roll on the gas you are transferring weight to the rear wheel to achieve the ideal weight distribution of 40% up front and 60% in the rear.

Motorcycle suspension (shocks and forks) work the best mid-stroke to provide optimum handling and traction. If the suspension is fully extended (topped out) then the front end becomes light and flighty, often resulting in front-end shake or tank slapping. Fully compressed suspension (bottomed out) is heavy and slow to respond and can often push the traction of the front tire beyond its limits. On most bikes you can make suspension adjustments by changing spring rate, compression, damping, rebound and weight bias, but the easiest suspension adjustment you have available to you is your throttle position.

Throttle application gives you a great deal of control over how much weight is on either tire while cornering, and is the key to good suspension set up. With the suspension working the best it can, the bike will feel more stable and will have optimum traction. So, with that in mind, the goal of good throttle control then, is to get on the gas and continue to roll it on through the corner to always maintain the correct weight distribution. Code calls this throttle control rule number one. “Once the throttle is cracked on, it is rolled on evenly, smoothly, and consistently throughout the remainder of the turn.”

He goes on to explain that “this rule rings true for 99% of turns with the rare exception being a long downhill, decreasing radius, off-camber and bumpy-in-the-middle turn but even here you shouldn’t roll off, you should just stop rolling on for a moment.”

So, the next question is, when exactly do you want to get on the gas? Think about it like this, the bike is most stable when you get on the gas. If you wait until the apex or after the apex like a lot of people advocate, then your bike is unstable for over half the turn. The sooner you get on the gas in a corner, the sooner you have the suspension in the right range. Sounds simple enough, right? Well, there are a few things to remember here.

First of all, if you get on the gas while you are still leaning the bike over, it will run wide. So, what that means is that you have to wait until the bike is at the lean angle you want and pointed in the right direction before you start rolling on the gas. As Code puts it, “get on the gas as soon as possible once you have the bike turned. Each moment you hesitate in cracking the gas and getting to the 40/60 weight distribution, reduces your average speed through the turns and lessens control and handling.”

And remember this, if you are too greedy with the throttle and apply too much too fast, then the bike will run wide or risk sliding the rear. If you are lazy with the throttle and only crack it on but don’t continue to roll it on, then the bike will not achieve the correct weight distribution. Or, if you snap off the gas in the middle of a corner it will transfer 70-80% of the weight to the front, which is designed to carry only 35-40% while cornering. Rolling on the gas evens out the weight balance and makes the bike more stable. The most important thing about your throttle control is that it should be smooth and consistently applied.

The way you enter a turn will effect how early and how well you are able to apply the throttle. If you enter a turn too quickly, it is nearly impossible to force your right hand to get on the gas. You end up coasting through the turn, or rolling off mid-turn because you are freaked out that you are going too fast. You now know what affect this has on the bike. It’s better to approach the turn a little slower, roll off the gas, brake, set your speed, get the bike turned and then roll on the gas as soon as possible.

Good throttle control is helpful in dealing with poor surface conditions as well. Take a wet road or a sudden encounter with gravel or a slick surface. If you freak out and chop the gas or apply some brake, you will transfer too much weight to the front, reduce your traction and possibly end up sliding down the road on your butt. Your survival reaction in these situations tells you to roll off the gas, but in reality, you will improve the situation greatly if you roll on the gas. Get the weight to the back of the bike, off the front tire and you have a better chance of staying vertical and making it through the turn. That being said, remember that on a wet or slippery road, it will become even more important to have smooth throttle control.

Good throttle control also helps with maintaining a predictable line. Contrary to what a lot of people think, if you follow Keith Code’s throttle control rule number one, then you will have a predictable, consistent and smooth line through a corner. Rolling on the gas does not make the bike run wide. The bike will only run wide if you apply the gas too much, too early in a corner or before the bike is fully turned. If you made a mistake at the entrance of the turn and feel yourself running wide, the worst thing you can do is roll off the gas, which unfortunately is another one of our survival reactions. Rolling off the gas mid-turn will cause the bike to want to stand up, and essentially run you wide.

If you insist on hauling butt into a turn, braking super deep, and waiting until all the way past the apex before getting on the gas then not only are you putting excess weight on the front tire, but you are risking going through the corner slower than if you had gone in a little more conservatively and got on the gas earlier.

John Parker, Westwood Motorcycle Racing Club’s expert road-racer, and recent student of the California Superbike School level one programme said, “I always used to think that I needed to go as fast as I could into a corner, brake as hard as I could until as late as possible and then pin it coming out. It felt fast and I was skeptical of Code’s throttle control method. I decided to try it though and forced myself to go into the turns off the brakes and get on the gas as soon as possible. What I realized is that the bike feels way better. I can carry more corner speed, I have more control with my line and I can exit faster with less risk of sliding the rear. I was doing it all spastic before and even though it felt fast, I was really going slower mid-corner. Code’s way means I go faster through the entire turn. When I sat in the class and listened to the throttle control lecture I thought, “Ya, I know that man,” but what I realized was that I wasn’t applying it. It was a very cool experience.”

Lastly, there are a few things you can do with your body position to ensure that you are able to achieve good throttle roll-on. Maintain a relaxed position on the bike with your arms bent and wrists relaxed, like wet noodles. Sit back in the seat a little bit and pinch the tank with your knees to reduce any weight you might have on your arms or hands. Any extra pressure on the bars will reduce your effectiveness in feeling the throttle and achieving the perfect roll-on that you need to make it through the corner in the smoothest and safest way possible! MMM

Cheers, Misti

Misti Hurst is a motorcycle racer, an instructor and a freelance writer. Visit her website www.mistihurst.com

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