A continuously variable transmission (CVT) is an automatic transmission that can change seamlessly through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant RPM while the vehicle moves at varying speeds.
Brake fluid is one of the most important components in motorcycle operation. The chemical composition of the brake fluid should be of the highest quality, since the operation of the entire brake system depends on it.
Brake fluid is manufactured in all countries of the world according to international standards:
In most cases, the American DOT3 and DOT4 standards are used in the production of brake fluid for private vehicles. Their composition differs in chemical additives that affect the boiling point of the brake fluid when it heats up during braking.
During braking (when the brake lever is pulled), the caliper pistons are pushed out, and the brake pads compress the brake discs. As the brake pads contact the brake disc, heat is generated and transferred to the brake fluid. If the brake fluid is in good condition and the brakes are used correctly, the brake fluid will not boil, and the braking system will work properly.
If a cyclist uses the brakes improperly and thoughtlessly, especially on long downhill slopes, it can cause the brake fluid to get very hot and then boil over. In turn, since brake fluid is hygroscopic and absorbs moisture during use, and contains 0.5-3% water when the brake fluid boils, the water it has also boiled.
When the brake fluid boils, air bubbles appear in the brake fluid. Gradually their number increases, and they increase in size. This is the vapor arising and released from the molecules of boiling water.
Since air has the physical property of being compressed, the brake fluid becomes compressible once it begins to boil. As a result, when the brake lever is pulled, the air in the brake fluid is compressed, but the brakes do not work because the compressed air cannot push down on the brake caliper to give it the necessary force to stop the spinning wheel and brake disc.
This is why disc brakes fail when improperly handled by CVT motorcycles on mountain slopes.
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In order to avoid problems with the braking system, motor bike manufacturers recommend following a number of simple rules:
Thus, we not only follow the recommendations of the motorbike manufacturers, but also do it a little better.
By following these simple rules, we avoid serious problems that threaten the safety of your traffic:
What’s more, you’ll never find an automatic motorcycle with two disc brakes in our fleet. Our CVT motorcycles always have disc + drum brakes.
Because if you’re heading into the mountains and suddenly, due to lack of experience driving an automatic motorcycle on mountain roads, your disc brake fails, you can always use the drum brake to stop the bike completely.
If this article is read by experienced riders who have never used a motorcycle with CVT and do not quite understand the problem of overheating disc brakes, just remember that on a motorcycle with a manual gearbox on mountain slopes, you can put in a lower gear, thereby slowing the motorcycle without using the brakes.
But motorcycles with a CVT do not have a manual transmission and a downshift. A motorcycle with a CVT without using the brakes on a long slope accelerates as fast as possible. Therefore, the motorcyclist is forced to use the brakes at all times. And if the brakes are used inappropriately, this can cause the brake fluid to overheat and boil over, followed by disc brake failure.
What should you do if your disc brake fails on a downhill run?
Cat Motors Team