how fast can you safely go on a bicycle?

Where are you going to get a battery that will supply that much power and how much do you think it's going to weigh. You will need to supply 438 amps at 48 volts. There is no parts on a bicycle that will handle that much torque.

I would be more worried about the chain and sprockets being damaged by that kind of torque than about what speed is safe. I would also doubt that a motor like that would have the kind of torque needed to get you up to a cruising speed. You need some lower gears to get up to speed in the first place. I wouldn't worry about the motor burning up, I think it just wont do anything.

Now in regards to speed, the pro sprinters are often recorded doing about 50 miles per hour or more in races. The fastest that I have ever ridden was a bit over 40 on a downhill. Because my bike is very stiff, this was bumpy even going down a freshly paved road. This would have felt unsafe if I was not in complete control of my bike. In my opinion handling becomes a problem when dealing with high speeds on a stiff bike. One solution may be to buy larger tires or wider handlebars (i ride a cyclocross bike). I would start off slow to test the theory and work my way up to a higher speed

The fastest I ever went on a bicycle was 32.7 mph and it didn't feel safe at all, of course I was going down hill and on a bumpy road. And it was a mountain bike so it's not exactly built for speed. The thing started shaking and I felt like I was losing control. Good luck.

I tend to cruise at hyper-speed. Some people, however, like to stay at ludicrous speed but that can be dangerous. I do believe though that the physical limit is 88 MPH, but that is just a theory at this point because everyone who has tried it has some how disappeared.

id get a mountain bike because at those speeds you need suspension also you need disc brakes all around you dont see motorcycles with rim brakes do you? on my singlespeed bmx ive gone 30 down hill and it felt fine so probably 40-60 is good anyfaster and itd be way to dangerous and youd get pulled over plus the charge would last for like 2 minutes at those speeds

The limit is going to be your tires. The faster you go, the more friction and heat you generate and alot of bike tires are not designed to handle sustained speeds of 60mph the way motorcycle and car tires are.

How fast are you willing to go before falling off? Answer that and you'll realize you didn't need to waste your time on Yahoo Answers.