Motorcycles and vibrations

I remember my first time soloing on the freeway on my BMW F650St motorcycle: the open air, the speed,... the vibrations. Everything felt normal driving wise as if I was in my car except for the high level of vibration that I thought was curious, only to be told later by my more experienced brother that I shouldn't worry about it because that's normal at high speeds. He also added, "...be prepared for numb butts and fatigue."

Until I've been on a two wheel motorbike I, probably like everyone elso who have not experienced motorcycles before, really took automobile for granted. The comfort and the insulation from the world outside. We believe that we're in own our little world that nothing can touch us. We don't hear or sense the horrendous wind buffeting nor noise, the wind chill in the winter time nor the skin drying heated airstream in the summer, nor the incessant vibration. In a car we're literally separated from the engine via a separate compartment, but not so with a motorcycle. When riding, the rider straddles the engine.

Vibration from riding a motorcycle can lead to discomfort such as in your numbed buttocks or hands and feet. It also makes you tire over long durations. It could also lead to loosened nuts and bolts which could conveniently dropped from your motorcycle and become lost. Which leads me to this anecdote.

Last October (2009) while on the touring trip to Arizona we traversed a stretch of old Route 66 in California that resembled the moon, well, maybe more akin to something that was left over when the US Air Force jets' use runway cratering munitions. The resulting vibration and potholes broke my F650GS fork seal. But little did I know that there was another little surprise.



Ever since that trip in October, the F650ST motorcycle that my girlfriend was riding has been sitting in storage connected to a battery tender. So one day I decided to exercise the bike and took it home from my studio where it is stored. As usual I oiled the chain, make sure the tires were properly inflated and tried to take note on anything that's unusual.

Not barely half a mile out I heard strange noises coming from underneath me. Sort of an irregular clack, clack, clack. So I immediately pulled over to check. After 3 to 4 minutes of examination I couldn't find anything odd so got back on the bike and continue to ride home. Not too far from that spot the clacking sound started again I was worried and a bit annoyed but pressed on.

Once I pulled into the garage and parked, I went immediately to scrutinize it. What I found was a loose drive chain that was literally slapping the frame. "How did that come about?" Then I remembered back to Route 66. Yup! That road not only broke my F650GS fork seal but was also the cause for the loosening and shifting rear axle nut for the F650ST, making its drive chain come loose. It wasn't a big problem but could have easily become catastrophic one if the the chain was thrown off the pinion and freeze the rear wheel... Ooh, that would've been pretty!



The next day I went to my brother and got a torque wrench to re-tighten the nut. In the course of adjusting the chain I found that both left and right chain tension screws had also come loose. Furthermore, one of the screws for the pinion cover was gone and the rest of the cover screws had loosened and were about to fall out!





I usually try to be thorough after a big trip, especially the arduous ones, and check my mount before taking it back on the road. But my complacency this time almost propagated to something bad. So if you ride lots, don't forget to locktite or use a proper torque wrench with the correct torque value to keep vibration from shaking those nuts and screws loose.