Stopping Power

Research dispels some of the myths about effective braking

Motorcyclists have no shortage of opinions about how to use their brakes. Get a group of riders talking about how to make a hard emergency stop and you’ll hear all sorts of opinions:

“I never use the back brake. It doesn’t do anything anyway.”

“You need to go out in a clear parking lot and practice.”

“Sportbikes can stop in much less distance than a big, heavy cruiser.”

“Antilock braking is okay for beginners, but an experienced rider can stop much better with conventional brakes.”

“I never use the front brake. It’ll make you crash.”

Hopefully, deliberate avoidance of the front brake is limited to a few dinosaurs (who are likely to be extinct rather quickly). However, the don’t-use-the-front-brake concept shares one thing with all those other braking theories: It’s wrong.

I’ll admit to believing that sportbikes, with their lighter weights and stickier tires, would devastate a cruiser in a braking contest. But that belief didn’t stand up to actual science. It turns out that measured stops with expert riders from 100 km/h (just over 60 mph) required an average of just 7 inches more on a Honda GL1500 Valkyrie than on Honda CBR929RR. Of course, that assumes you use proper technique. Proper technique involves using both brakes quickly and effectively.

This and other results of research and testing conducted by the Promocycle Foundation of Quebec were presented at the International Motorcycle Safety Conference in March. They made more than 800 measured stops on instrumented motorcycles. Here are some of the highlights of Promocycle’s findings and advice on how to perform the most effective emergency stops.

Braking, brakes, stops, street survival
Busting the myths of braking.Illustration by John Breakey

The rear brake is important:Even if you ride a sportbike that transfers most of its weight to the front wheel, during that first half-second or so, while the rear wheel is still weighted, any braking you perform will have the greatest effect, since you are moving faster than when the weight has been transferred. Most riders can begin to apply the rear brake slightly sooner and harder than the front. Of course, on a cruiser, the rear wheel continues to carry substantial weight and the rear brake continues to be effective right through the stop. Finally, the rear brake also applies some stabilizing effect, so the back wheel won't try to pass the front. One of the test riders was in the habit of not using the rear brake, but even his braking improved noticeably when he was instructed to use it.

Which is your more important brake? We hope that everyone knows that the front brake provides most of your motorcycle's stopping power. Testers using both brakes on conventional braking systems made stops with a mean deceleration of .776 G. With just the front brake, that dropped to .711 G. But if they used only the rear brake, their stops developed a mere .425 G. That even applied to bikes with linked braking systems (LBS), which typically apply both brakes when the foot pedal is pressed. Using the pedal only developed .583 G, but using both controls brought braking force to .74 G. However, using just the front brake control on an LBS bike made only .44 G. So no matter what you ride, you should apply both brakes using both controls.

Pull in the clutch, but don't downshift: The study found that downshifting added about 10 feet to stopping distances, compared to not shifting and pulling in the clutch. Pulling in the clutch improved stopping performance compared to leaving it engaged and not shifting.

Practice, practice, practice: The researchers recommend practicing long and hard, so that you can immediately and automatically apply maximum braking in an emergency situation. This means making stops from highway speeds, not from 20 mph in a parking lot, where the braking cycle doesn't last long enough for you to thoroughly adjust to the motorcycle's changing weight bias and the pressures on your body. Of course, they were using bikes with outriggers, so over-braking didn't have disastrous results.

A rider practicing stops from 60 mph risks crashing if he locks the front wheel.

Basically, there are two major components of a typical hard, short stop: quick and effective initial braking and then modulating pressure as the bike's weight shifts and speed decreases

ABS is better: The eight experienced riders, who spent days doing hundreds of stops on motorcycles protected from crashes by outriggers, made their hardest stops using antilock braking systems (ABS). And that was on clean, dry, consistent pavement, where the advantages of ABS are minimized. Stops improved from .776 G with conventional brakes to .866 G with ABS. That's a substantial difference and reflects how much better ABS is at modulating braking pressure for changing conditions than our minds, which are still mulling over how hot that girl on the bicycle looked. With ABS, you make very aggressive initial braking inputs without having to "feel" for traction. In a panic stop on wet, slippery or dirty pavement, the ABS would be even more effective. Once you use ABS, especially in a hairy situation, it's easy to love it, which makes you wonder why we have exactly zero 2006 cruiser models offering this life-saving feature. (Actually, we know the answer swirls around cost and the legal repercussions of putting a $2000 system on more expensive bikes, where its cost can be absorbed, but not on smaller bikes ridden by beginners who probably need it most.) And, ABS enables you to practice straight-ahead high-speed panic stops in relative safety, since the risk of a lockup-induced crash is eliminated.

Handle the pressure: Maximum braking loads your body tremendously, throwing you and your passenger forward and putting lots of pressure on your arms and upper body. The researchers said that the pressure was equal to what you'd feel if the bike was angled 64 degrees nose-down. The pressure on your body also makes tall handlebars very awkward as you try to hold your position under full-force stops. The researchers also pointed out that once you are on the brakes, you become "a prisoner of pressure." The forces effectively lock you into a single posture until the brakes are released. You can't even change the number of fingers on the brake lever, so your practice needs to condition you to wrap the right number of fingers (usually all of them) around the lever. Of course, once you're braking this hard, you are committed to going straight; there is no traction reserve for swerving, and releasing the brakes to change direction uses up a lot of time and distance.

For best results: Basically, there are two major components of a typical hard, short stop: quick and effective initial braking and then modulating pressure as the bike's weight shifts and speed decreases. The researchers offer this sequence: 1) Close the throttle and apply the rear brake; 2) Straighten the motorcycle and adjust your posture and hand position; 3) Apply the front brake and declutch; 4) Adjust brake pressure. The initial weight transfer takes about .6 second, and the whole stop from 60 mph requires about 3 seconds from initial brake application.

That’s not a lot of time, of course. However, immediate and effective braking may be enough to avoid the impact and, if not, it will certainly lower the speed at which you make contact.

So when was the last time you practiced braking from high speeds?