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American Rider
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There was something about the 2007 Dyna Super Glide (see 2 Bikes in 1, page 26) that I didn’t mention in the story because I wanted to expand on it: vibration.
Vibration can be objectively measured and analysed with computer programs and techy equipment like oscilloscopes and such, but how does this subjectively affect us as riders? We want a smooth ride, yet we’ll drop a dollar into an airport vibrating lounge chair and pay for a vibrating foot massage, and love it. Proving, I suppose, that all vibration isn’t bad. Thus it is with Harleys that are powered by the inherently imbalance 45-degree V-twin engine.
Vibration comes in many forms. When I started road-testing motorcycles back in the early 1980s, I rode all manner of foreign and domestic motorcycles: GPZ, GSXR, VR, GL, Guzzi, Ducati, Harley XL, FL, FXR, FXD, FLST—everything from 50cc singles to CBX six-cylinders. Believe me, I’ve been vibrated every which way but loose. Some motorcycles emit good vibrations, others offer nothing but torture. For instance, the Kawasaki Eddie Lawson Replica, an in-line four that had a high-frequency/low amplitude vibration—a tingly, buzzy, irritating feeling—turned my hands numb. Then there were Harleys with solid-mount engines like the pre-2004 Sportsters and four-speed FLs that shook like a possessed demon doing the Saint Vidus’ Dance. But the character of those two types of vibrations is dramatically different.
When a Harley sits at idle it can rattle the whole bike, which is not exactly a vibration, it is more like a shaking. Rubber-mounted engine isolation like that on most current-model Harleys allow the engine to jump around of its own accord, which shakes everything from the mirrors to the rider’s eyeballs. I call this shaking as opposed to vibrating. Shaking moves things in a big way, while vibration buzzes and tingles things. To me there is a big difference in the essential nature of these types of vibes, and whether or not it irritates or pleases me.
Getting back to the 2007 Dyna in this issue, its TC96 engine had that idle-shake thing (more so than the TC88), and since it was only when sitting at a stop, I didn’t mind it. Once underway there was nothing to comment on or complain about ... except when decelerating. Passing through the 3,000-to-2,000 rpm range the whole bike shuddered, especially the footpegs, reminiscent of solid-mounts. Depending on what you happen to like, this could be interpreted in several ways: “My God, it’s falling apart and I am going to die,” or “Wow, this feels cool and I want some more.” In this case the vibration period is brief and not really bothersome. The important thing is that although I could feel vibration (or shaking) it didn’t really bother me.
Vibration is not necessarily something bad; it can actually be a pleasant sensation. Yes, the Dyna has moments of shaking and vibrating, but I for one am grateful that the Dyna reminds me it is a motorcycle powered by a mighty internal-combustion engine. In this case it’s all good. U
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