Archive for June, 2010
KTM 125 EXC
In the previous test carried out in the Suzuki RM 125E, we said that we did not understand the tendency of many users to buy bikes with a lot of power and displacement. After testing the 125 EXC yet we are more convinced of what we discussed in that test, due to the pleasant surprise that this bike has given us.
Most of us end up being faster and safer driving with a bike whose power we are really able to control and fun factor … or talk. We doubt that there is something more fun and exciting to drive to fund a 125 …
As a curious note, we have been struck by the design of brake lever. Just playing, I notice that is different from previous years, and allows less force to press. It has very good touch, and even past the hour, still using one finger. I compare it with the handle of a previous model and discover the secret: the shape is the same but the height profile of the handle is 3 mm lower from the first bend to the ball.
To check if these 3 mm can really change the behavior of the brake, grabbed a handle and the old router with a grinding machine, the hill on a motorbike, 2008 … the feeling was the same as in our test bike. The curious and have something to entertain this weekend.
Suzuki RM 125 E
A few years ago, the capacity of 125 was the school of off road. The natural process of any amateur pilot was going through the 50, where the off road bug caught us after going through the 74 or 80, and reaching 125, which involved displacement and the definitive master aggressive driving technique. After learning of truth with the 125, many decided to stay in that capacity or the most daring move to higher displacements.
These bikes were the real offroad school: their engines with a band of very close, coupled with the constant review of their mechanics, made the young drivers learn the essence of the sport: driving more mechanical.
With the arrival of 4T, and the random displacement rules that were established in the competitions (there are times when I wonder if those thinkers know what a bike, which means a displacement as the 125) we with the paradox that the 125 had to cope with jet with twice the capacity, so that his death at the competition was assured. If to this we add a trend that has been going to fans forget this displacement (the big horse, ride or walk, is the hair), that motorcycles 100% valid for enduro, and must be a must for all kids who want to compete (cost-per school), and all the fans who want to enter the world of enduro, has become something more strange to see that the Iberian lynx. Read the rest of this entry »
HONDA XR
Honda XR has been in the last decade and soul star of many off-road events from simple fan excursion or enduro desert adventures through the world-renowned top competitions in forms as diverse as the rallies, enduro, supermotards, etc. .
The versatility and durability of the concept has not been surpassed XR On no other model and brand. Able to win the Dakar to put in check (Esquirol, Honda XR400) to Peterhansel himself in front of the new Yamaha WR400 unbeatable and in the world enduro Cto. World champion several times in the category with the pilot 250 4t Gian Carlo Rossi. Passing countless victories in national and international Cto different specialties. The first appeared in 1985 Xr 600. It is characterized as a motorcycle with simple lines and compact despite its capacity and cycle, the launch of this bike matches the XL 600 after his first success of the brand harvested in the first Paris-Dakar rallies.
Viscous Hydroplaning
Viscous
The viscous hydroplaning due to the characteristics of the water slimy. A thin film of liquid over a thousandth of an inch in depth is all that is necessary. The tire can not penetrate the liquid and the tire rolls over the movie. This can occur at a rate much lower than the hydroplane dynamic, but requires a temporary flat or smooth surface such as asphalt or a touchdown area covered with rubber accumulated past landings. Such a surface can have the same coefficient of friction than wet ice.
When confronted with the possibility of hydroplaning, the best land in a grooved channel (if available). The touchdown speed must be as slow as possible consistent with safety. After the wheel bow down the runway, braking should be applied moderately. If the deceleration is not detected and hydrofoils is suspected, the nose should be lifted and used aerodynamic drag to decelerate to a point where the brakes become effective.
The Inverted Rubber Hydroplaning
Rubber Invested
Inverted rubber (steam) that hydroplaning occurs during heavy braking which results in a prolonged skid locked-wheel. Only a thin film of water in the channel is required to facilitate this type of hydroplaning. The tire skid generates enough heat to make the rubber in contact with the channel fresh investment to its original. Inverted rubber acts as seal between the tire and the runway, and retards the flow of water in the area of the footprint of the tire. The water heats up and turns to steam which supports the tire of the channel.
The inverted rubber hydroplaning often follows an encounter with dynamic hydroplaning, while the driver can lock the brakes in an attempt to slow the plane. The plane eventually slows enough to where the tires make contact with the surface of the runway and the plane starts to skid. The remedy for this type of seaplane pilot is to throw the brakes and let the wheels do spin up and apply moderate braking. Inverted rubber hydroplaning is insidious in that the pilot may not know when it starts, and may persist groundspeeds very slow (20 knots or less).
Dynamic Hydroplaning Type
Dynamic hydroplaning is a relatively high speed that occurs when a film of water on the runway that is at least one tenth inch deep. As the aircraft speed and depth of water increased, the layer of water builds up an increasing resistance to dislocation, resulting in the formation of a wedge of water under the tire.
At a certain speed, called the hydroplaning speed (VP), the upward force generated by water pressure equals the weight of the aircraft and the tire is removed from the surface of the channel. In this condition, the tires no longer contribute to the directional control and braking action is nothing.
Dynamic hydroplaning is related to the inflation pressure of the tire. The data obtained during hydroplaning tests have shown the minimum dynamic hydroplaning speed (VP) of a tire to be 8.6 times the square root of the tire pressure in pounds per square inch (PSI). For an airplane with a head pressure of 24 PSI tire, the calculated hydroplaning speed would be about 42 knots. It is important to note that the rate referenced above is calculated for the beginning of dynamic hydroplaning. Once hydroplaning has begun, may persist to a significantly reduced rate depending on which is experienced.
Recovery and Prevention of Hydroplaning
Recovery
To recover while traveling in a straight line, the driver should not turn the steering wheel of a car or applying the brakes. Any action could put the car into a skid from which recovery would be difficult or impossible to. Instead, no change in steering input, the driver should gently ease the throttle pressure. The control should then return. If braking is unavoidable, the driver should lightly pump the brakes until hydroplaning has stopped.
Prevention by the driver
The best strategy is to avoid as many contributors to hydroplaning as is possible. Proper tire pressure, narrow tires and not spent, and slow speeds of those deemed suitable will moderate dry mitigate the risk of hydroplaning. Avoidance of standing water is another effective strategy of prevention.
Causes of Hydroplaning on Tires
If multiple hydroplaning tires, the vehicle may lose directional control and slide until it hits an obstacle, or slows enough that one or more tires in contact with the road again and friction is regained.
The likelihood of hydroplaning increases with vehicle speed and water depth. The wear and tread under-inflation also increases the risk for hydroplaning, as well as more wide tires. Narrower tires are less vulnerable to hydroplaning because the vehicle’s weight is distributed over a smaller rubber patch contact, resulting in a greater capacity for water pressure tires on the sides, allowing tire contact with pavement .
The practice of dressing over replacing the size of the original equipment wheel of a vehicle on a wheel of larger diameter and replacing the tire by a tire of the low-aspect-ratio affects the same diameter, some of the performance characteristics of vehicles, and increases the risk of hydroplaning with wider tires.
The Hydroplaning (Tires)
The hydroplaning or aquaplaning by a road vehicle occurs when a water layer structure between the vehicle rubber tire and road surface, leading to loss of traction and thus preventing the vehicle respond to control inputs such as management, slow down or accelerate. It becomes, in effect, an unpowered and unsteered the sled.
Each function of the vehicle changes direction or speed, turning, acceleration, braking, puts an increasing burden on the tires. Control of this load relies on the friction between the contact points of the tire and road surface. More friction makes for greater strength to slip, if the water comes between the tires and the road, the friction can be reduced to the point where the driver can lose control.