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GOING THE DISTANCE

"REV-MATCHING"

by GENGHIS

Photo by Genghis

THE ART OF THE DOWNSHIFT: Rev-matching is critical, and probably ignored by most bikers.


WILLIE NG ON FACEBOOK:

"Scott, you know we still have to get together 'cause I have something of yours I've been meaning to return for over 45 years."

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He walked into my office in the Village, after I hadn't seen Willie for over 40 years. Even after shedding over forty pounds, he looked as solid as the Rock of Gibralter. That much hadn't changed. Willie weighed in at 220 or 230, depending, back in the day. He used to rumble along Northern Boulevard in Queens like Bruno Sammartino's younger brother, but without the Italian accent, commanding furtive glances by passersby. Now he looked absolutely svelte, like a well-conditioned Olympic wrestler. Oh, and there's the matter of his hair. There was none when he strolled into my office. He'd been shaving his head for years. Even at his present age, you wouldn't want to run into Willie in a dark alley if you had bad intentions. HIs face was considerably thinner than when I knew him at his heaviest almost a half century ago. It was the loss of weight in his face that rendered him almost unrecognizable to me. Adding to this phenomenon, was the fixed image I had of Willie in my mind from when we were young. I've actually known Willie since we were about 8 years old.

I said to him, "Hello, young man." After the customary ".... how good to see ya, ya look good, man...." reacquaintance-type comments, I said to Willie, "So, what have ya got of mine that you've held for 45 years?" He took two books out of a shopping bag and said, "Do you remember these?" He handed me two books. They were, "The Technique of Motor Racing" by Piero Taruffi and "Sports Car and Competition Driving" by Paul Frere. The former was copyrighted in 1959, and the latter in 1963. These were books that I loaned Willie around 1966 when I taught Willie how to drive a stick shift in my '64 Corvette Sting Ray. I did not immediately remember these books. However, after perusing them, they came back to me. These were excellent books on driving technique. More germainely, car driving techniques I learned in books like these, transferred nicely over to motorcycle riding technique in terms of manual shifting, as the basic principles apply to both shifting a manual transmission in a car, and shifting a motorcycle transmission.

Some of the more advanced cars on the market today, have a feature called automated "rev-matching," where a computer accomplishes automatically, what a driver would normally do manually with the clutch and throttle. This obviates the necessity of acquiring and honing the skill required to rev-match manually. I feel that this is a shame, because it dumbs down the level of skill required to drive properly. The forthcoming 2014 Corvette Stingray (the "C7" model, connoting that this is the seventh interation of the Chevrolet Corvette since the Vette's 1953 inception) comes with an automatic rev-matching feature with its 7-speed transmission, that can be turned off if the driver wants to "rev-match" the old fashioned way. Rev-matching is a driving technique (or riding technique) whereby the engines revs are raised when the clutch is disengaged while downshifting. This is necessary because the engine at a given road speed, will be turning at higher revs in a lower gear, than the higher gear that the transmission is being shifted from.

For example, at a road speed of 30 mph, a car's engine speed in second gear will be turning at a slower rate than in first gear at the same road speed of 30 mph. One would have to raise the motor's RPMs before making the transition into the lower gear. Using the example of downshifting from second to first gear, it is desirable to raise the engine revs to the appropriate engine speed for first gear, by blipping the throttle after the clutch is disengaged, before shifting from second to first gear. If rev-matching is not performed by raising the revs when downshifting, the trauma transmitted to the drivetrain after the clutch is released will be attested to, by the accompanying violent jerk of the vehicle, and "chirp" complaint from the rear tires. In a car, this not good for the engine, transmission, driveshaft and rear end. In a motorcycle, this is not good for the motor, tranny, primary chain and drive chain. It takes practice and experience to know how many revs to raise by blipping the throttle for downshifting, but required experience in order to avoid the bad effect from not rev-matching. The same bad effect takes place when omitting rev-matching in either cars or motorcycles. Rev-matching is not required when upshifting. When one releases the clutch when upshifting, the elapsed time it takes to move the stick-shift in a car, or the shift lever on a bike from the lower gear to the higher gear is enough time for the motor revs to fall the appropriate amount for a smooth re-engagement when the clutch is released.

I feel that some social commentary is necessary here. I frankly have never had another conversation with another biker about rev-matching technique. I believe that this is because the biker subculture is not overly laden with concerns about technology, or technique, unless bikers are talking about repair or customizing technique. I find bikers as a whole, are a machismo-driven group, not given to discussing the minutiae of riding technique. Most bikers may feel that their riding technique is a highly private matter, not to be questioned from within or without, and are not given to rappin' to each other about the technical finesse used in operating their bikes. It's a personal thing, ya know what I mean? Sports cars drivers are a different breed. Sports cars drivers are somewhat obsessed with the finer points of motor vehicular operation, and are more likely to talk about technique than bikers. I admit to being completely ignorant about whether the majority of bikers are cognizant of the necessity of rev-matching when downshifting their Harleys. I will venture a guess, though: Most bikers don't know anything about rev-matching when downshifting. Now, maybe I'm wrong and there may be tons of bikers more talkative than I am, who've discussed rev-matching with other garrulous bikers, and they rev-match like champs when downshifting. I don't know, because I've never heard it discussed among bikers. Where there's no smoke, there's no fire.

I do know this, though: If it weren't for my involvement with sports cars and my reading of books like "The Technique of Motor Racing" and "Sports Car and Competition Driving" I would've been entirely ignorant of rev-matching technique. I suspect that I would've been downshifting my Harleys for the past four decades, with the inevitable jerks of the bikes, and violent protests from Avon rubber. Since no other bikers ever talked to me about rev-matching, I probably would've happily and ingorantly tortured the drivetrains of my Sportster and my Harley 74 without a second thought since 1968, if it weren't for reading these books on driving technique. Another excellent book that taught me proper gear-shifting was Phil Hill's book on driving. Phil Hill was the first American to win a Formula One championship. Another after Phil was Mario Andretti, but Phil was the only American-born Formula One champion (Andretti was born in Italy). I don't believe that in the biker world, there are books on motorcycle riding technique to match the level of detail regarding technique, as these automotive driving books. From Paul Frere's "Sports Car and Competition Driving" check out these passages about rev-matching:

"Changing gear used to be the greatest headache of novice drivers. Modern synchromesh gearboxes, however, have simplified the driver's task to such an extent that anyone is now able to change gear, at least without making horrible noises. Nevertheless, the way in which a gear is changed is executed, easily sorts out the good driver from the indifferent one. The difference lies much more in the way the clutch and accelerator pedals are used than in the way the gearbox itself is handled. It is well known that for a given road speed the engine runs at different speeds according to which gear is in use. Consequently, if a jerk is to be avoided when the driver lets the clutch in, after he has selected a new gear, the engine speed must be adjusted accordingly, before the clutch is re-engaged. This is very easy when selecting a higher gear, for instance changing from third to fourth, as in this case the time necessary to move the lever from one position to the other usually just gives the engine a chance to slow down sufficiently for the drive to be taken up smoothly.

When a downward change is to be made, however, the engine must be accelerated while the change is being performed. Here, quite accurate judgement is necessary, as the engine must be accelerated by exactly the right amount if a jerk is to be avoided when the clutch is re-engaged. Moreover, if the down change is being performed in order to increase acceleration, or for climbing a hill, a smooth take-up can only be achieved if the engine is accelerated again while the drive is being taken up."

Like Frere said, it's judicious and skillful use of the gas and clutch that separate the good drivers from the indifferent drivers. A monkey can be taught to move a stick shift from gear to gear, but not the coordination of the throttle and clutch needed for rev-matching. The same is true of shifting a Harley transmission. It's the skilled use of the throttle and clutch that either makes you a good rider or an indifferent one. I don't recall ever discussing rev-matching techinque with another biker, while I can remember talking about this technqiue to other car drivers over 40 years ago. Wille Ng was one, and Dennis Fanning, another old friend I taught manual transmission shifting, was another. I don't remember ever seeing any articles in motorcycle or biker magazines about rev-matching technique, or any other specific motorcycle operating techniques, for that matter. It just ain't sumpin' that we bikers rap about, ya know what I mean? But there it is, as outlined in "Sports Car and Competition Driving." You just have to substitute "rider" for "driver" in those passages from the book, and it readily applies to operating our Harleys. I have a feeling that most bikers ignore rev-matching, simply because they're unaware of the need for it, and how to perform this fundamental riding technique. Later.



FINITO