SHOCK ABSORBERS

If the readers here do not mind, I would like to post an article that talks of shock absorbers in an effort to remove any mystery about what they do and how they work. Safety issues are often merely technology issues - once you understand the technology.

To begin with, they do not absorb shocks - your springs do that.

When your bike hits a bump in the road your wheels can do nothing but follow the curve of that bump. Your tires compress fractionally, but not enough to make a meaningful difference in the effects that bump will have on the rest of the bike, and you. If the wheels of your bike were connected directly to the frame, without springs and shocks, the bike would rise at least as high as the bump, almost instantly. The effect, of course, is that, if severe enough, when the bike came back down you would be left in the air. Your hands would probably not be jerked off the grips, so they would be pulled forward with the rest of the bike while the rest of you was still in the air - and then, worse, you would come down.

Obviously, the fix to that problem is to keep as much of the bike other than the wheels from rising in reaction to that bump (i.e., make as much of the bike as possible 'sprung weight'.) There is a tremendous amount of kinetic energy imparted to the wheels when they hit that bump. That energy must be captured before it is transferred to the bike's frame. And that is exactly what the springs do. By compressing, the springs absorb the energy from the wheels.

Remember pogo sticks? If all you had between the wheels and the frame of your bike were springs, then the only difference the springs would make would be a short delay before the bike was tossed into the air after hitting the bump. That is, once compressed the only thing the springs can do is decompress (that's the law). The energy the springs will exert during decompression is almost equal to the energy that went into compressing them in the first place. (A token amount of the kinetic energy will be converted to heat to make up the difference.)

Now we can understand what the shocks do. They DRAMATICALLY slow down the decompression of your springs (and in the process they convert much more than a token of the total kinetic energy stored in those springs into heat.)

A shock absorber consists of a tube filled with oil, which acts as a hydraulic fluid, and a piston (which is not physically connected to any part of the tube) that slides up and down within that tube, pushing its way through the oil. The piston is connected to one end of the shock absorber via a steel rod, the tube is connected to the other. One end of the shock absorber is connected to the frame of the bike while the other end is connected to the wheel hub (or to a swing arm that is connected to the hub.) Thus, when the wheel moves up towards the rest of the bike the piston is pushed thru the oil. The oil provides resistance to the movement of the piston which slows it down. In the process kinetic energy is converted to heat. (This is why you must change your shock absorber oil regularly - the heat breaks it down.) The oil in these tubes would totally stop the movement of the piston were it not for the existence of a valve in the piston that allowed the fluid to pass thru it. This is because, like water, the oil cannot itself be compressed. That valve can be made to allow fluids to flow faster in one direction than the other. For example, you would probably want your springs to compress faster than they are allowed to decompress. Without that valve your springs would not compress at all, leaving you as bad off as if the wheels were directly connected to the frame. Similarly, if the springs are too strong for the load they are carrying, too much of the kinetic energy will be conveyed directly to the frame of the bike, because they will compress too slowly, if at all.

But just as slowing the compression rate of the springs too much results in ineffective control of bumps, allowing their decompression to happen too quickly is just as bad. Were that to happen you would have 'pogo stick' reactions to bumps. So, it is essential that the design of the springs and shocks on your bike take into account how heavy the bike is and what kind of riding you do. But all such designs are compromises, and you can do things to totally frustrate the designers intentions - and end up hurt or worse as a result.

For example, when you put a passenger or heavy luggage on your bike you should increase the tension of the springs surrounding your shocks. Failing to do that can overload the system and get you close to the 'pogo stick' level of responses from them. Taking a street machine into the country, off road, and pretending it's a motocross machine can do the same.

But even assuming you don't do anything that extreme you will find that the design of your shocks is not perfect. (If it was, you would never feel a bump in the road.) The fact is, sometimes the road surface changes from perfectly level to bumpy. And some of those bumps (and potholes) can be awesome. This is where a few dollars can make a difference. You can replace the springs that come stock on your bike with a set that are called 'progressives'. These provide a normal soft ride until they are confronted with an unusually severe bump, at which point they get harder and harder to compress. And while the oil in the shocks cannot be compressed, air can be. So some shocks (aren't GoldWings wonderful?) are 'air assisted' - in addition to the oil they have a small amount of air in the tubes. These 'air assisted' shock systems are sometimes attached to an onboard compressor that can be used to increase or decrease the pressure of the air, thus making the shocks either harder or softer without having to change the compression of the springs when your load weight or the road surface changes substantially. (Also, of course, you can increase the weight of the oil in the shocks to slow them down.)

The shock absorber 'system' on your rear wheel tends to have larger springs and have them mounted on the outside of the hydraulic tubes while the one on your front wheel have the springs within the tubes. The ones in the front are contained within the 'forks'. If you take a close look at your shocks you will find that the ones in the rear are typically angled forward from the wheel to the frame of the bike while the ones in the front are angled backwards. These angles tend to be directly in-line with weight shifts resulting from acceleration and braking.

The angle of the front shocks (forks), usually called the bike's 'rake', is essential to maintain! It establishes, along with the front-end 'offset', the bike's 'trail' which determines the bikes handling and steering control. The more extreme the rake is on your bike, the 'slower' your steering will be. (Except at extremely slow speeds - where extreme rakes often result in the wheel 'flopping' over and dumping the bike if you do not have your hands firmly in control of the grips.) If you were, for example, to lower your bike by shortening the front and back shocks, the wheelbase would also be shortened (the distance between the front and back tires). Since your front wheel would touch the ground closer to directly under your handlebars, your steering would 'quicken' as a result. In fact, even shortening the shocks by only one inch could result in steering that was so fast that your steering damper (another small shock absorber) could not safely handle it. The result, known as a 'tank slapper', would be violent swings of the wheel from side to side, and with high probability a dumped bike. (That is an overstatement. If you absorb some of the oscillation into your arms and avoid transferring that into the rest of the bike (through your contact with the seat), or use some braking caused weight transfer to the front of the bike, you can abort the 'harmonic' and probably avoid dumping it.)

Your shock absorber systems make your bike controllable. Make sure they receive factory recommended oil changes, do not modify them, adjust them for major changes in the weight of your vehicle or expected road conditions, and they will do their jobs reliably.

http://motortoyshop.com

www.motortoyshop.com

Yamaha YZ450F: MD First Ride

Sure, other four-stroke motocross bikes existed, but when it comes right down to it, Yamaha revolutionized motocross bikes when it introduced the first YZ400F in the late 1990s. Doug Henry took a version of that bike and won a Supercross main event (in Las Vegas) and an Outdoor National championship . . . proving to the world that four-strokes could work, and work exceptionally well, on a motocross track and a supercross track. You could say that the "beginning of the end" of two-stroke motocross bikes had arrived (although no one knew it at that point).

It took a long time for Yamaha's competitors to fully respond to that ground breaking machine, but eventually they did, and Yamaha found itself knocked out of the top spot in the class. The Honda CRF450R was declared the new king by most motorcycle journalists a couple of years ago -- a crown that Honda has yet to relinquish.

You could even say that the Yamaha YZ450F was getting "old in the tooth". Last year, it was the only 450cc motocross bike produced by any Japanese manufacturer that retained a steel frame (both the Honda and the Suzuki RMZ450 featured aluminum frames). The motor, with various detail changes, had been around for quite a while, as well.

In 2006, Yamaha introduces an all-new YZ450F with the express goal of offering the best motocross weapon in the class straight out of the dealer's showroom floor.

To take back the mantle from Honda, Yamaha began by redesigning the 449cc power plant. Although it is still a DOHC and features five-valves in the head, lots of changes were made to improve the quantity and quality of the power delivered by this light weight package.

No less than the piston, crankshaft, and connecting rods were redesigned inside the engine for increased durability and performance, with Yamaha also directing a spray of oil to the bottom of the piston this year. Still featuring titanium valves, the combustion chamber reaches a compression ratio of 12.3 to 1.

One big change is the addition of an additional gear in the transmission -- the 2006 YZ450F now features a five-speed transmission. Although four-speeds were virtually always enough for a motocross track, the new five-speed answers a call from those riders using their YZ450F for more than motocross, including enduro, cross-country and desert racing. Previously, some of those riders needed to increase the final drive ratio to the point where first gear became overly tall (this is the only way to get enough top speed out of fourth gear in desert racing, for instance). The addition of a fifth gear is a welcome change that should not reduce the effectiveness of the bike on the motocross track.

The biggest news for 2006 is the new aluminum frame that combines cast, extruded and forged aluminum tubing to optimize frame rigidity, and that also repositions the engine for better mass centralization and improved handling. Unlike the competition, Yamaha's aluminum frame is not a "perimeter" design. In fact, it appears to mimic, in many respects, the configuration of the old steel frame.

Like its smaller brother, the YZ250F, the 2006 YZ450F features Kayaba suspension components, including a speed-sensitive 48mm fork and a titanium-sprung rear shock (with a 2mm larger shock rod and a friction-reducing coating).

Engine changes are topped off with carburetion and exhaust changes for better breathing and even greater power. The cylinder head angle and the relocation of the dry sump oil tank inside the front of the crank case is said by Yamaha to improve the machine's overall balance and handling (as well as eliminate external oil lines).

Our test rider Russ Somers (a pro-level vet rider who works for Team Simpson) had a chance to test the 2006 YZ450F at Competitive Edge Motocross Park in Hesperia, California. These are our first riding impressions of the new big Yamaha motocross weapon.

To begin with, this is the first track we have tested a 2006 motocross bike on that was not perfectly groomed before we arrived. For our test, the Competitive Edge track was riddled with braking bumps, acceleration bumps and chop. This gave the suspension on the 2006 YZ450F a real test. A test it passed with flying colors.

The revised fork and shock give the new aluminum chassis a very balanced, composed feel. The YZ450F was very stable on the higher speed, choppy straights, but also dropped into corners well and turned predictably. The new YZ450F does pretty much exactly what you ask of it.

The new engine also earned high marks. Very smooth and usable, but very fast, the deceptive power of the YZ450F had Russ overcook more than a few corners with unexpectedly high entry speed. The bike also had plenty of torque, because jumps right out of corners were cleared easily.

When every manufacturer is aiming for a smooth powerband in the 450 class, the new Yamaha YZ450F just might be the smoothest of them all. Vibration levels are low, and there is no hit anywhere to be found.

The new five-speed transmission is outstanding. Russ commented that he never felt unsure of a shift, and never missed one. The bike also shifts well under power. On this particular track, Russ did find himself between second and third gears on some corner exits (he would have preferred either a taller second or a shorter third).

Like the 2006 YZ250F, brake power and feel on the new YZ450F are excellent. The ergonomics of the bike, which features a stock Pro Taper bar this year, worked very well. The bike is slim, and easy to move around on.

The bottom line is that the 2006 YZ450F is "night and day" better than the old YZ450F. Is it better than the competition? That question is impossible to answer after a single day on the bike. It is clearly in the hunt for class leadership, however, and is unlikely to disappoint any buyer shopping for a new 450. It is a very balanced, refined package that reflects Yamaha's unrivaled experience in this category.

U.S. MSRP for the YZ450F is $6,899.00 for the Team Yamaha Blue/White model and $7,099.00 for the 50th Anniversary Yellow/White edition. The 2006 YZ450F will be available later this month in U.S. dealer showrooms

Drunks

"Every year in this country approximately 40,000 people are killed in accidents involving vehicles. Half of these accidents involve drunk drivers.

If America was able to actually rid itself of drunk drivers it would theoretically safe 20,000 lives a year, in addition to eliminating countless injuries, many of which are life altering. But no matter how hard we try, it seems impossible to do this - stop drunk driving.

Several European countries are using a technique which seems to work, very well - a DUI Re-education Camp. Could this work here? In America?

We can't speak for the accuracy of the numbers mentioned, nor if the 'DUI Boot Camps' actually exist. Nevertheless, it is an interesting concept. There must be at least one or two MOfos with comments? C'mon, just a little one? Pretty please?--MO


These are not nice places. They involve a mandatory live-in scenario where anybody caught / convicted of drunk driving lived for two to six weeks, isolated from family, their job, friends, etc. The impact of these camps has been so severe that people actually will NOT drive if they have been drinking, at all. They have no desire to be re-educated (as it were) in such a fashion.

If America was to establish a similar scenario the incident of drunk driving would shrink to nearly zero although it might take six months to a year. The savings in life, limb and money would be astounding. There would be serious impact . . . to the drunks.

States or the Federal Government would establish a Marine Corps style basic training camp in a remote area such as Wyoming or Texas. Similar to Marine Corps style boot camp, everybody awakes at 5:00 am, is exercised, fed, given basic training in traffic safety, offered detoxification (for the hard corps drunks) and finally graduation. Not a drop of alcohol will be served and the food offered will be military style.

Anybody caught driving drunk must attend - anybody. It matters not if the violator is a single mother, a politician, a CEO, doctor, lawyer, rich, poor, foreign, domestic - anybody who is caught, goes!

Although expensive to establish the money to do this can come from the attendees. The courts should (and must) force them to pay for it.

The initial suggested time to graduate is six weeks. The camp could (and should) be established by former Marine Corps Drill Instructors -- they have the ability, and attitude to create a thoroughly miserable environment where people can dry out and LEARN that they have done wrong.

If this country has the courage to do this, the prediction is that the horrible impact of this camp will force people to really think before they get behind the wheel after they’ve been drinking. And it just might do the trick.

Twenty-thousand people saved from death per year and hundreds of thousands of fewer injuries. Makes sense, yes?"

Motorcycle review

I drove up to Martin Eurosports in Coopersburg, PA today for their scheduled demo rides. As I mentioned earlier, I was hoping to get a ride on the Sprint ST and the Speed Triple as I’ve not had a chance to try out either of the new models with the 1050cc triple engine.

Well, I got there around 1:00 and all 7 bikes were signed up for both the 1:00 and 2:00 demo rides. The demo collection included 2 Rocket IIIs, one Sprint ST, 2 Daytona 650s, a Speed Triple and a Bonneville America. The last demo ride was going out at 3:00 and the Speed Triple was available so I signed up and took a quick look around the dealership before heading out for lunch to waste some time before I could get my ride on.


Once fed, I returned to the dealership and looked over the Triple for awhile. The paint scheme was the one of kind gold metallic and though quite a headshaker at first glance, I have to admit that the color grew on me more and more as my eyes soaked up the curves. The size of the bike is a shock and what little bodywork there is seems like just enough to get the job done. Everywhere else you look is machinery: the motor, wheels, swingarm and exhaust and it all looks mean and has that trademark Triumph streetfighter DNA through and through.

Once on the bike it completely disappears beneath you, with nothing but the superbike handlebars visible. The pegs are mounted high and rearward compared to every other big Triple which might cramp you up over long distances, but ergonomically the bars and seat fit my 6′2″ frame perfectly. A quick stab on the starter brings that classic roaring growl to life and the engine revs willingly with light pressure on the throttle.

The route we rode in the demo group led first through some choppy, old uphill twisties and then on to clean fresh pavement where the curves started to become tighter and tighter. I was slotted between a Daytona 650 in front and a Rocket III behind me. With the tremendous horsepower of the Triple I was consistently forced to ease off to avoid running up the tail of the Daytona and the only time I saw the Rocket was when he would pull up behind me at stop signs. The engine is smooth as silk and has power absolutely everywhere. Due to the route, I never got out of third, but second is good for anywhere between 35 and 70mph so shifting at legal speeds is altogether optional.

Probably the aspect of the bike that most impressed me was the incredible suspension. It soaked up everything thrown at it, but provided good feedback through the bars and behaved surprisingly well under hard braking. The short wheelbase is a blast, making flicking the bike from corner to corner a sheer joy and lending well to wheelies both intentional and accidental. As with any demo ride, riders are instructed before heading out that wheelies and stoppies are forbidden, but the power got the best of me pulling away from a stop sign midway through the ride and I stood it up momentarily. The bike took it all in stride and did nothing but inspire more confidence in me as it set down easily and begged for some more throttle.

In conclusion, while I’m not ready to get ride of Sprint RS yet, when the time comes, I’ll definitely be in the market for 1-2 year old used Speed Triple. Cycle World rated it their best open class streetbike of the year and if you’ve ridden one, you know why. If you haven’t ridden one, don’t wait any longer, get yourself to a local dealer now for a demo. You won’t stop smiling for the rest of the day.