Code Break - The Harmonics of Smooth Riding

By Keith Code, Photography by Andrea Wilson

Every control input you make has a resonant effect on your bike. Some echo of your original action occurs each time you twist the gas, pull the brakes, steer the bike and so on. It is an effect similar to a musical note that's prolonged, increased or allowed to decay. A twist of your wrist pumps in more gas and air, which revs up the engine.

Held steady it holds the note; rolled off it decreases it.

In music, the note played opens your ear for the next one and maintains continuity in the melody of the tune. So it is with your control inputs. All smooth transitions from one to the next require listening to or feeling the bike's resonance from the earlier inputs; each must provide a clean acceptance for the next one for smooth to occur. When downshifting, the resonance of the throttle blip, the momentary increase in rpm, smoothes out the gear change by providing a matching harmony between engine rpm and road speed. Left too long, that rpm "note" decays, its resonance is lost and the downshift is rough. Upshifting is similar: If done too lazily, the rpm decays and the gear change isn't clean.

Braking resonates into other systems as well. Aside from slowing the bike, braking creates heat at the discs and shifts the bike's weight bias toward the front. As the suspension compresses in front and extends at the rear, changes occur in the rake, trail and wheelbase. Suspension compliance is significantly altered, directly affecting traction handling and overall feel.

Steering inputs follow suit. As you apply pressure through the bars, the bike leans over and changes direction. The resonance is cornering load, weight transfer and suspension movement along with friction, heat and distortion of the tires. There are similar resonant effects created from forces generated with the clutch, the gear-change process, rear brake and all throttle actions. As you can see, harmonics keeps the band very busy.

Based on their resonant effects, the key control actions of braking, accelerating and steering immediately limit each other based on the intensity with which they're used. Braking limits steering inputs and rules out throttle use; acceleration alters and limits steering as well. Attempting a quick flick while hard on the brakes can make you crash. Its opposite, quick flicking under hard acceleration, requires considerably more rider effort. There is proportion and balance to consider in everything you command the bike to do based on how that control resonates. It's either helping or hurting the engagement of your next control input. Coming into the gas after turning the bike also illustrates that. Too late and you've missed the beat; too abruptly and it clashes.

A rider with a lot of front brake and an abrupt release at his turn-in creates a rough entry. The transition phase of coming off the brake contributes to that. As the momentum of the bike decays, the slowing effect, for that same amount of lever pressure, increases. An unskilled rider can become confused by this increase in stopping force and release too quickly. Disharmony is the result.

Slides produce a lot of negative resonance if the throttle is chopped closed. The tire grabs the pavement too quickly, creating a harsh note. In this case, many of the same resonant changes occur as when you pull on the brakes. The real problem is the bike has three rotations going at once: roll, pitch and yaw. The whole band is playing, but no one is playing the same tune. Not to say that good throttle control (e.g. rolling off) can always save it, but it does help enormously to get everything back into alignment, back to playing the same tune.

Use of the controls is the mechanical aspect of both riding and racing. Having them all in sequence and correctly timed must be accompanied by getting the amount you use them just right and in proportion with one another. Each action creates force and all forces have some resonant effect on one another. Create harmony with your controls. Smooth is all about catching the resonant wave from your last input.

By Keith Code
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