Thanks to Aaron Frank of Motorcyclist magazine for providing valuable input and comments on this article and sharing his electronic-control experiences on the racetrack; and Toph Bocchiaro for additional input and article content. For more on Aaron and electronic engine management, visit motorcyclistonline.com.
New BMW motorcycles have it, as do Harley-Davidson Touring bikes, so do many models of cars and even jet aircraft. What is it? Throttle-, drive-, or fly-by-wire—electronic throttle control (H-D’s official wording) and engine management systems, of course.
To take on the entire concept of how electronic throttle control is used in every type of transportation technology is to exceed the scope of what can be covered here, but there is much that can be discussed about the positives and negatives of using such a system in motorcycles, and to examine the reasons why using electronic throttle control systems in motorcycles should be examined on its own merits as compared to them being used in almost any other mode of transportation.
Throttle-by-wire replaces throttle cables with an electrically wired or electronic position sensor at the throttle handgrip that transmits a signal to a motor controlling the opening and closing of the throttle plate...
As most know, throttle-by-wire replaces throttle cables with an electrically wired or electronic position sensor at the throttle handgrip that transmits a signal to a motor controlling the opening and closing of the throttle plate(s) (butterfly). Some newer and “high-end” motorcycles, such as the new touring BMW 1600GT and GTL, also integrate throttle control with traction control, anti-lock brakes, and many other facets of engine and ride control management.
So to establish why the use of throttle-by-wire (TBW) and ride control systems might be viewed differently when these systems are used on motorcycles, let’s start with the very basic differences between riding a motorcycle and driving an automobile:
- You do not have to balance a car.
- Cars rely very little on the gyroscopic effect of rotating wheels for stability.
- Cars do not lean into turns.
- There is a much greater level of physical protection while driving a car than when riding a motorcycle.
First, it should be established that some electronically controlled systems used in motorcycles are considered worthwhile by most riders and motorcycle authorities. A self-contained ABS system; a system that is limited to preventing wheel lockup in straight-line emergency stopping situations, is a benefit to the vast majority of motorcycle riders. Likewise, fuel injection systems on motorcycles are a great benefit: the fuel is dynamically adjusted for altitude, air pressure, ambient and engine temperature, and results in smoother throttle response, better drivability, and greater fuel efficiency. It also requires the use of a fuel gauge, or at a minimum a low-fuel light, giving the rider an objective indication of when they are low on fuel.
Where potential problems begin is in using a system where dynamic control of the motorcycle (or any vehicle for that matter) can be acted upon by an intermediate controlling system. Some “anomalies” in TBW systems, often in conjunctioin with electronic traction control, have been noted by motorcycle publications. An internet search turns up some very interesting, and potentially alarming, characteristics with these systems. However, some results and the consequesnces are designed into the electronics, depending on the application. For example, here’s the first paragraph of a review of the 2011 BMW S1000RR written by John Acton in February 2010: “Coming out of the long right-hand turn nine at Palm Beach International Raceway, BMW’s new S1000RR did something unexpected. Despite having the throttle pinned wide-open, the bike didn’t want to accelerate. It wasn’t until the lean angle came within 45 degrees from vertical that a blast of horsepower from the Bavarian bullet lifted the front wheel about a foot off the asphalt and hurled the bike down the 0.6-mile straightaway.”