Wecome To RVs and OHVs

This blog is all about RVs (recreational vehicles) and OHVs (Off Highway Vehicles), camping, and survival
and how they work together to provide wholesome family fun and great learning opportunities.
Many posts are intended to familiarize novice campers and RVers with RV systems and basic camping and survival
skills. But even experienced RVers and campers will enjoy the anecdotes and may even benefit from a new
perspective. Comments, questions, and suggestions are encouraged.

Tuesday, February 21, 2017

Dirt Bikes

Dirt bikes are off road motorcycles.  They come in all sizes, from little 50 cc machines with training wheels for little kids to giant 650cc dual sport motorcycles for big kids of all ages.   My kids were all experienced riders before they were out of kindergarten.  Some people object to letting little kids anywhere near off road vehicles, but with proper supervision and instruction, they are at least as safe as they are on a public playground.  In fact, my several of my kids were hurt far more seriously on "safe" playground equipment than they ever were on their dirt bikes.

The very first motorcycles were, in a very real way, off road motorcycles.  For one thing, they had to be.  There weren't that many roads!  They had to be able to negotiate  a lot of unpaved and even ungraded routes.  As roads became more prevalent, motorcycles designed specifically for street use became the order of the day for most people.  Bikes began to have more road compatible features and less off-road capabilities.

Modern dirt bikes evolved from custom racing machines usually built by the racers themselves, from Triumph and Rickman street bikes.  As off road racing and trials competition became more popular, international motorcycle companies began taking an interest in manufacturing motorcycles specifically designed for off highway recreation.  One of my riding buddies bought the very second Yamaha IT400 off the boat from Japan in the early 1970s and some years later we bought it from him.  It was a GREAT bike!

The  main differences between a street bike and an off-road bike include tires, suspension, and gearing.  Off-road tires need to be gnarly to get traction in a variety of places.  Street tires are designed for a smooth ride on pavement.  Off-road suspension accommodates huge bumps, often having more than a foot of vertical wheel travel to absorb the impact of going over obstacles.  Street suspension is tuned for a comfortable ride on pavement.  Off-road bikes are usually geared for good low-end performance where traction may be limited.  Street bikes are usually geared for comfortable cruising and high MPG on the highway.  Off-road machines try to keep the weight down, and many don't even have any lights.  Street bikes can handle more weight for accessories for rider comfort.   Some big cruisers even have air conditioning!  When converting street bikes for off-road use, the guys doing the modifications typically changed the tires (and sometimes the wheels), upgraded the suspension, and often stripped off anything they considered unnecessary to get the weight down.  Modern dirt bikes come with knobby tires, tall suspension, and few accessories.  Sometimes they don't even have a kick stand.

Beginner bikes, like the little 50 and 60 cc motorcycles made for small children often use a centrifugal clutch so there is no clutch lever for little novice hands to master.  The clutch engages automatically as the RPMs increase.  Bigger bikes for more sophisticated riders have manual clutches and multi-speed transmissions.  Gear ratios vary depending on the intended purpose for the bike.  Some variations you will see are motocross bikes (designed for racing on motocross tracks), trail bikes (designed for trail riding), and Enduro bikes (designed for specialized off road Enduro races).  Trials bikes are breed all their own, focusing on light weight and maneuverability.  They typically have very narrow, low cut seats, high ground clearance, and fairly low gear ratios.  They are made for crawling over rocks and other obstacles.  A Trials rider is penalized if his foot touches the ground.  Motocross and Enduro bikes, on the other hand, are designed for speed and good handling over rough terrain and you'll often see a rider use a foot as a pivot point when making a sharp turn.

Some beginner bikes come with an exhaust restriction device to limit power until the rider becomes skilled enough to manage a stronger engine.  Removing the exhaust restriction makes a significant difference in the acceleration, power, and top speed of these little bikes.   Bikes with engines as small as 80cc's can be surprisingly powerful.  One of my riding buddies, a former desert racer, bought a Yamaha YZ-80 for his pre-teen son.  He took it out for a spin and was quite pleased with its modest performance.  Then, on his way back he opened it up "to blow it out" before shutting it down and storing it and at somewhere around 11,000 rpm the little bike lurched into its power band, surprising my buddy by delivering an unexpected wheelie!  You definitely want to make sure any rider understands and respects the power of his bike and knows how to ride it safely.  Just because is is only 80ccs doesn't mean you can put a complete novice on it and turn them loose.

I have mixed feelings about using training wheels on little motorcycles for little riders.  Certainly they can be an aid to keeping the bike right side up until they learn to balance, but they also affect handling and if used off road can get caught on obstacles along the trail.  My solution was to get my kids to master their pedal bikes (with training wheels at first) until they could ride them well without training wheels and then let them try the motorcycle without training wheels.  My youngest son was chomping at the bit to ride during a Spring Break outing when he was only 3 years old.  I diplomatically reminded him that he needed to learn to ride his pedal bike without training wheels before he could ride a motorcycle.  When we got home from that trip he ran into the house, brought his bicycle out, laid it down on the parking strip as we were still unloading, and demanded "Take 'em off!".  He was one very determined little boy.  I took off the training wheels and he immediately went to work on learning to ride without them.  By our next outing on Memorial Day weekend a little over a month later, he rode 13 miles on a poker run on a little 50cc motorcycle and was anxious for more.

These days you have a number of alternate OHV options in addition to dirt bikes, including ATVs and UTVs (side-by-sides) but for many years dirt bikes were the only option for personalized off highway motorized travel.  My family still prefers dirt bikes.  Personally I find them more maneuverable and agile than ATVs.  They are certainly safer riding across hillsides where ATVs have a tendency to roll over and they require a path only a few inches wide.  ATVs are a little more stable and are sometimes easier for novice riders to master quickly.  They are also more capable of hauling cargo and are even sometimes used to transport injured riders or hikers out of remote areas.  However, I fear that the ease of use often lulls new riders into a premature sense of over confidence that I believe is one of the reasons for many ATV accidents among young or novice riders.  UTVs are very easy to drive since the controls are very much like a car.  In most places you must have a valid drivers' license to drive a UTV.  Also, they cannot be easily adapted for diminutive riders to reach the controls.  Let your kids enjoy the ride with  you or another licensed driver at the wheel.

Motocross bikes are very popular among recreational off road riders.   No doubt part of the appeal is mimicking favorite professional riders, who make riding look easy and beautiful.  However,
a motocross bike is not necessarily the best choice for recreational riding.  The gearing of a motocross bike is designed to deliver good performance on groomed tracks.  Trail riding often requires more low end power and better performance at lower speeds.  Some bikes are considered "wide ratio" bikes, meaning there is a wide range of gear ratios available across the several shift positions.  These can be very good in a variety of circumstances and adapt very well to trail riding, since trail riding, by its very nature, consists of many different types of terrain.  Some times  you need a high gear for speed across open spaces.  At other times you a need a low gear for tackling steep grades or tricky, highly technical trails.   A properly designed wide ratio bike will provide a smooth transition from the lowest to the highest gear.

Motocross is a stylized from of dirt biking on a groomed course.  The ultimate motocross race is the Supercross.  You can find amateur motocross races all across the country with many riders of different skill levels.  Supercross is a major, professional level sport where only the best of the best are able to compete.  Supercross tracks often include double and triple jumps where riders and bikes are literally flying hundreds of feet.  Supercross races are extremely exciting to watch, with jumps, sharp turns, whoop-dee-doos, and fast straightaways.  Riders are often competing "bar to bar" in tight packs where a single mistake by just one rider can cause many bikes to crash.  It is definitely not a place for the timid and only the most skilled riders can ever dream of racing Supercross.

That being said, Supercross is still the inspiration for hundreds of recreational riders.  Even if they can't begin to match the extreme stunts by their professional  heroes, dirt bikers still enjoy trying to approximate their behavior as much as they can.  Most of us will never ride a professional Supercross track, but we can have a lot of fun riding trails, which usually include fast straightaways, hill climbs, downhills, whoop-dee-doos, and sometimes even jumps.  Many amateurs can learn to master the art of riding wheelies.  We had a guy in our Desert Rat group in California who rode a custom-made bike that included a very large rear sprocket.  He didn't have a lot of top speed in the open desert, but  he could ride wheelies just about anywhere. I used to tease him that he had an unfair advantage on the trails because he only hit half as many bumps as the the rest of us did -- because he only hit them with one wheel!

To me a dirt bike is the perfect way to ride off road trails.  It is nimble, light weight, goes anywhere, and is pretty much something you have do without any help.

Dirt bikes rock!

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