This piece is provided by our neighbor (back when we had a home) Norm Birndorf who has become a motorbike owner again. After reading our 12 Dolomites II update from 2003 he shared his fascinating insights about the pesky motor bikes that bugged us in the mountains.  Here's what Norm wrote:

 

A 'junior' race-replica bike we spotted in Hungary.

    Those things that look like back braces are actually spine protectors. The most elaborate ones look like a turtle’s bottom shell. The bikes that are terrorizing you are "race replicas" --really common in Norway when we were there. One of the most popular international motor sports in Europe is motorcycle road racing.

   The street bikes are patterned after the racers which force the rider into a crouch to keep their weight forward for balance, steering and wind drag reduction. The street bikes are actually detuned versions of the racers, but still VERY powerful. The average European aboard one of these is emulating a race bike and rider. The loud leather outfits they wear are also patterned after the racers who are their heroes much like Nascar drivers to our southerners.

    We have the same bikes in the USA as well; they are quite cheap. A 120 hp version (Yamaha R1, Honda Firehawk, Ducatti etc.) cost about $10,000. Do zero to sixty in 3 seconds and go 160 mph. They're not as popular here because they are cammed up very high and only produce power at high RPMs. Quite unsuitable for average USA city driving vs Europe with it's mountain pass roads and twisty highways where they can keep their speed and RPMs up to stay on the power band. When they are cutting a line on a twisty road at high speed, stay clear of them. They aren't really racers-just wannabees, and I understand they wipe out frequently. Goes along with your observations that Europeans have the freedom to be quite reckless.

  

     In a follow-up reply Norm corrected my misconception about the stability issues with these race replicas and added technical information suitable for “Nerd News” devotees:


    I have one correction; those race replica bikes don't have stability issues at low speeds, it's just that in order to have fun, those bikes are set up to  have to run very high RPMs to get any power (torque, actually). That's desirable in a road racing bike where the rider is always going at high speeds and is at high RPMs-and why the replica riders like to go fast. But in city traffic where acceleration is needed at slow speeds and low RPMs, it they have to downshift several times to get any power or putt-putt till
their RPMs rise.

   Stability as I'm sure you know is a trade off for controllability in a 2 wheeled vehicle and related to fork rake angle (the angle from vertical of the front fork). Bicycles are exactly the same. The more the rake angle to vertical, the more stable gyroscopically but the harder to turn. Sport bikes have low rake angles and normal "trail" (the distance in inches measured by a plumb dropped from the front wheel hub to the ground to an imaginary line continued from the fork to the ground) and also affects stability.

    Bicycles and motorcycles have exactly the same physics and design. The handlebars totally control turning in a 2 wheeled vehicle. If you didn't know it, you are counter-steering by pushing down on the grip opposite to the turn which turns your wheel OPPOSITE the way you want to turn, leaning the bike into the turn and gyroscopically pulling it around. Have Bill ride toward you and turn and watch his front wheel. It's totally counterintuitive. Someone set up bars on a bike on the frame as well as the fork and defied anyone to use the frame bars to turn while shifting weight. No one could make the bike turn without using the fork connected bars. Just stay out of those biker's way.

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