Superbikes of Supercross
RACE WATCH
SUPERBIKES OF SUPERCROSS
Every weekend, race fans pack sports stadiums to watch top stars leap man-made dirt obstacles. But much of what makes that performance possible isn’t engine power. It’s the interface between man and machine.
KEVIN CAMERON
WHEN MY EDITOR CALLED AND GAVE ME THE STORY TITLE, “Superbikes of Supercross,” my mind immediately filled with visions of bikes soaring high over triples, propelled by radical engines filled with fascinating technologies. Yum!
Instead, when I began to talk with people in the field, they downplayed engine work. Kawasaki’s Dan Fahie said, “The engine people are very conservative. They don’t take risks, so we don’t do a ton of stuff. We tried some changes to cam phase but haven’t really got anywhere.”
Dave Osterman of Two Two Motorsports said of the current, premier-class 450cc engines, “They’re pretty brutal out of the box. We’re really looking for quality, durability, manipulating it to survive.”
“We spend more of our time to make the bike right for our rider—higher, lower, footpegs, whether he likes an engine with top-end or bottom-end power,” said Fahie. “Our job is helping the rider. In motocross now, suspension is our big push. There’s also a lot in the frame—how they flex, how they feel.”
Fahie used two-time AMA Supercross Champion Ryan Villopoto as an example. "In 2011, Ryan would come in, saying the bike was harsh," he said. "We were trying different swingarms, suspension and bars, all with no success.
“Kawasaki sent over a 2012 frame. We went to Glen Helen, and he tried the baseline [existing bike]. Then, they built up the new frame. Ryan just rode from the truck to the track and said, ‘This bike is so much better.’ He didn’t even have to take it on the track to know.
“He said it was not nearly as harsh and had better grip. That was a very important lesson for us. Everything else had to catch up to the frame. It was groundbreaking.”
Fahie then explained that the real limiting factor in performance is not engine power or any of the usual and measurable factors. It is the point where the rider hits harshness. Machine harshness sets the limit. Therefore, what has to be “super” in this sport is the quality of partnership between the rider and the machine.
Villopoto’s mechanic, Mike Williamson, said, “The old bike was really rigid for him. At about the 20-to25-minute mark, it would just wear him out. When we switched to the 2012 frame, it seemed to take up a lot of the small chop, and it was more forgiving.”
So what is “harshness”? Human muscles seem to have this in common with tires: They are most durable when loaded smoothly, rather than when subjected to sharp peak loads. Highfrequency vibrations are also perceived as harshness. This brings us to the always-hot aluminum-versus-steel argument. Many riders equate a steeltube chassis with good “feel,” and they say aluminum transmits, rather than absorbs, vibration. This comes down to how the metals are used. Aluminum can save weight, but only if it is used in larger diameters and thinner wall. Such larger tubes are very stiff and transmit vibration that a less-rigid steel tube could not. It would flex.
Some observers say, “Watch your rider’s head movements [as the bike deals with terrain]. If you see his head move more than six inches, suspect harshness.”
There has been a lot written on muscle fatigue and controlled movement, as affected by shock and vibration. More muscle fibers are activated when motion occurs in the presence of vibration than in normal muscle contraction. When this happens, fatigue will occur sooner.
Another way to get at the idea of harshness is to say it is any change of motion too rapid for the rider to smoothly adapt to. Harshness is not something that can be overcome by harder training; it is a shortcoming of the man/machine system.
Many years ago, I was given a wonderful insight by Gary Mathers, who was then doing 39 “away weekends” a year as Kawasaki’s racing manager—roadrace and MX. He said that as suspension travel was increased from the three inches of the old twinshock era, riders could jump farther and land harder. This is because the energy absorption of suspension is proportional to travel, squared. Double the travel and you get four times the energy absorption. Naturally, softer springs and damping were initially chosen. But as the riders went faster with this new capability, they tended to increase those numbers back to the old values. This reveals that riders go faster until harshness stops further progress.
When you read MX suspension literature, you see many references to things like “a mid-travel step” in damping force. Much work has gone into removing anything like a step or spike in damping force because the resulting sudden shock occurs faster than the rider can adapt to it.
The chassis must be rigid enough to allow the rider to steer accurately, but rigidity can also transmit shock that might be stopped by a less-rigid structure. All the while, engineers want to be able to measure this mysterious harshness.
Osterman gave insight into what that will mean. “It’s already in golf and baseball,” he said. “It’s called video. In the old days, the coach was the data acquisition. Now, we’re at the forefront of electronics. Digital data acquisition gives real understanding of what’s happening. For me, it’s exciting because that technology is the future.
“Before, we always had the firedrill situation. There’s the rider with a problem, surrounded by five or six of the top tech guys, and they’re all giving different answers. It’s like the old situation with carbureted bikes: Garbs are only so good. EFI completely erased all those problems. I welcome it. It’s going to make the end user’s stuff better.”
Osterman used the starts of rider Chad Reed as an example. The data showed where the problems were, and, being open-minded, Reed used that to make better starts overnight. “Once the rider saw the data, he got it. It’s just like what CNC did for machining: It eliminated trial-and-error. It was expensive at first, but once it was established, it saved money.”
Little imagination is needed to think of putting accelerometers on the handlebar ends and footpegs to record just what the rider is forced to cope with and, perhaps, to quantify harshness. In an earlier era, handling on pavement was pretty much ignored because no one could agree on what it was or how to measure it. Motorcycles of the 1970s were promoted on the basis of easily measured variables like price, quartermile time and top speed. But today, handling is the hot area in roadracing— it is the goal of the whole setup process. On the street, BMW has made a start toward automating setup electronically with the self-adaptive handling of the F1P4 version of its production S1000RR.
Osterman also said some of the things I’ve been hearing from others about fourstroke MXers. “When a four-stroke makes a noise, it’s usually too late. There’s so much going on in them, it’s going to cost you. If you grenade a four-stroke, you might as well buy a new one.”
Four-strokes, which fire only every other revolution, have to make up for this by revving higher. When something goes bad inside, all that extra kinetic energy goes into breaking things. Would some form of electronic early warning be too expensive?
World Superbike tech inspector Steve Whitelock used to manage AMA Supercross. He said MX dads were constantly calling and writing him, urging a return to two-strokes. If a twostroke seizes, you buff the aluminum off the bore, put in a new piston and rings, and you’re running again in 30 minutes. But with a four-stroke, when a valve touches the piston and breaks, it can cascade, wrecking the head, cylinder, crankshaft and crankcase. Just take it to the dealer and write “get running” on the R.O.? How many times can dad’s plumbing business cover that $4000 bill? Some families put hundreds of thousands of dollars into their sons’ riding careers, but in this game, financial sincerity is no guarantee of success.
Another point Osterman emphasized was the importance of understanding what the rider is doing, just as NASA did with its astronauts. Back in 1982, during Honda’s roadrace test in Brazil, Freddie Spencer went equally fast on different setups. Did that mean all were equally good? His tuner, Erv Kanemoto, began to look in Spencer’s helmet after each session. The setup that produced the most sweat would tire him out the quickest in a fulllength GP. MX teams need this kind of insight, too, but in modern form, as heart and breathing rates, and other measurables. If the human rider is the critical limiting factor, we need to know all we can about how best to use his or her abilities.
This sounds expensive because it is. Those MX dads would like to send Moses back up the mountain, hoping he’ll find he’d dropped one stone tablet bearing the commandment, “Thou shalt be rich.” Four-strokes, plus new and unfamiliar data-acquisition systems for all serious competitors? That doesn’t sound like a recipe for a grass-roots sport that any middle-class family can manage.
This is the knotty problem confronting all motorsports. We now know vastly more than we can afford. How do we strike a balance between advancing technology and rising costs? Lots of attempts are being made from Formula 1 and MotoGP down to club racing and local MX. Do we lock competition into a weird kind of vintage racing? Do we let in some technology but just until we need glasses? There may not be a choice. As officials write their rules in the sand, look out to sea at technology’s incoming wave.
