d.c. brushless motor

I would assume that at full speed the full 48volts is supplied from battery to motor, therefore your only options are.

1. Higher voltage (more batteries, say 60v).
2. More powerful motor.
3. Alter the gearing, but this may need doing in conjunction with one of the other options.
4. Reduce weight or wind resistance.

Del

Del is, as often is the case, right of course but I would like to add some little thought of my own.

Try to find the performance graphs of the motor that is in your bike and see at what voltage over speed or torque it is currently operating. If you feel that after reading the literature about the motor you could improve the performance, you may decide to alter the motor controls. If however it looks as if the motor is at it's peak performance, which is what i would expect, you are left with replacing the motor for a better one or only riding it down hill.

Mabuchi has a nice website with an interactive display that allows you to change the voltage and get new torque and amp curves.

I just did numerous curves for several of their small DC motors at 12V and 24V voltages.

gears, or probably even better - sprockets! convert an old 10 speed...

You should also consider a legislation related aspect. In Europe electrically assisted pedal bicycles have power supply limited up to 25 km/h. Above, the electrical assistance is off. Now, you may have a pedal assisted electric bicycle which is different and speed limited at the power supply. Try different aerodynamics to see the difference and find out if power at top speed is the limiting factor. (Try standing tall on the pedals or lying down horizontally to see speed differences).

If so, aerodynamics is the easiest way to improve speed, but also range. Work on a tailfin that also serves as luggage compartment or build yourself a recumbent bike.

Tailfins are more effective than front aerodynamics.

It's not a controller problem, it's a result of insufficient power. Stronger motor, higher voltage can help.

Any attempt to alter the Motor Control may

spoil the Vehicle. Your Vehicle is designed for

that speed. If it is necessary better Change the

Motor with High speed one along with the Controller and

Gear Box.

There is no way to say, without knowing the characteristics of the motor, controller and gearing. If the limit is the motor, then changing the controller will simply cause the motor to fail from overloading. If the limit is the controller, then it might be able to be reset for a higher max rpm (higher frequency in your brushless "DC" motor). Alternatively, the controller may already be set for its maximums, and to make a change you would need to change controllers, assuming the motor is not the limiting factor.

If you know the characteristics of all the stuff, then it's simple to make the necessary changes. If you don't, the simplest experiment would be to change the gearing (larger sprocket on the motor, and/or smaller on the wheel). Then see if 1. top speed changes by the anticipated amount, and 2. if the motor or controller overheats. You'd want to do a series of progressively longer test runs, checking temperature of motor and controller, so you don't allow the magic smoke to escape. If the top speed changes by less than the anticipated amount, then the motor might very well be overloaded. If the top speed changes as desired, and the motor and controller do not get too hot, then you may be in luck -- simple change, more speed.

I would try to play around with gearing ratios. If the motor is connected to the wheel by belt try to put a slightly bigger pulley on the motor. Then get a second battery and connect it in parallel to the other battery to increase the amperage.This will make the motor to run with a bit more tourque and longer range. The ratio will increase the speed of the wheel. The volts will have to stay 48V otherwise the motor and controller will burn. Monitor the motor temp before you make any modifications. After the modifications monitor it again and compare. Some multi meters have a tempreature probe. If you find the motor to be overheating you will have to install a second motor or replace the existing one with a stronger motor with a new controller. This might be too expencive. I agree that speed can also increase with better aerodynamics, less weight( go on a diet) , get rid of unneccesery weight on the bike. Good luck and have fun!!

Unnecessary weight....like the second battery?

Only kidding of course, I still feel the answer has already been given and you should first consult the data for that particular setup. If it is already running on best performance you can do nothing.