Originally Posted by
kracksmith
My exact bike is a 2008 specialized centrum elite that comes with a internal 3spd hub. Looking at the with of the frame, looks like i can get a much wider rim/wheel to use a white industry free wheel cog and hub.
You sound enthusiastic enough but I can tell from you posts that you are going to pay very dearly for your e bike education.
Regardless of what we are all accused of by the purist zealots the real problem with an e bike is the fact that they are bicycles and not motorcycles. Not the other way around. The writers of the USA e bike regs were very clever. 750 watts is really stretching the upper bounds of power to remain safe and have something reliable. Bicycles are engineered for slow reliable low powered transportation. When you want to hang 3000 watts on a bike, you end up with a motorcycle like Sur Ron when you are done. Anything less is dangerous and totally unreliable.
Right away you indicated that you want to save money by piecemealing parts and pieces together instead of building from the ground up.
You mentioned you want to use a 52 volt battery. 52 volts will not support 3000 watts of power. Think 72 volts at 21 amp hours and 15 lb minimum. Even then, you will stress the battery.
Your frame is not strong enough for half that much power let alone that much. Prepare to take a spill when the frame fails.
With a single rear cog driven by a Cyclone you will have one speed only where your cadence is right. Most of the time you will be at lower speeds and inefficient power ranges so you will be over torqueing everything and overheating the motor.
Lifting what you end up with? forget it.
When you get something that stays together and you can live with, your bike will not pass the visual /smell test to ride it on a bike path without scrutiny..
Your biggest expense is likely to be the insurance deductibles. not the broken bike parts.
From your original description a 500 watt bike would suit you fine.
I don't want to throw cold water on your dream here but I have seen this scenario play out many times and the results are always expensive. I have not made these kinds of mistakes but my education has been plenty expensive and not over yet. I keep thinking "one more little fix". When I learn enough, I will start over.