why do motorcyles have separate brake controls?

weight transfer under braking is much greater on a bike than in a car so the balance of front to rear braking effort is continually changing & it's simplest to let the skilled rider make the adjustments. Some touring bikes have combined braking where the foot brake brings in the rear & one front disk & the hand lever brings in the other front disk. Also some bikes now fitted with ABS but a skilled rider will still pull up faster without it

For more control over a wide variety of road surface conditions.

On clean dry pavement, the front brake works very well. On slick or sandy surfaces, the rear brake will help you maintain more control.

Bikes are a single track vehicle and the rider has to maintain the balance. The wheels are huge gyroscopes and if the front wheel washes out after it skids, it can throw the bike to the ground so they separate the brakes.

70 percent of your braking comes from the front. Most bikes are equiped with a disk front brake and drum rear brake. I prefer to use only the front brake since it is easier and cheaper to maintain. Other bikers prefer to use only the rear brake because they are ignorant.

in maximum circumstances, the sole difficulty easy between the two is the brake shoes/calipers on the rear drums/rotors. The emergency/parking brake is actuated via a cable. The pedal brake is actuated via hydraulic rigidity on the calipers/wheel cylinders. On some vehicles with rear wheel disc brakes, the parking brake actuates a thoroughly separate friction device on the rotor - it incredibly is all based upon layout. Many, some years in the past, i think it became Chrysler positioned a drum brake on the force shaft making it thoroughly self reliant of the pedal braking gadget. there are various designs for the parking brake gadget.

Boils down to this-

The front brake slows the bike down 'quickly'.

The rear brake is more for just 'slowing-down'.

If you're a "rear-braker" it can cost you a couple of thousand miles in treadlife....even more if you skid the tire and flat spot it. Your hand is a MUCH better regulate of braking pressure....better feel and more dexterous. In addition, with two braking systems, it's highly unlikely thay you'll ever find your totally brakeless as it would take a simultaneous failure of both systems.

its not so bad to lock the back brake,,,

its really bad to lock the front brake.