The drive side chain is a simple BMX bicycle chain. For extremely high power systems (20kw or more) a trials bike chain is best. But, for this application, a normal BMX (single speed) bicycle chain works great.
280 amps is the peak battery amps the controller is programmed for. With the weight and layout of this bike, I would need to lean over the bars to see more than 200 amps and, even then, it would be a mere fraction of a second until the front end leaps up and the throttle is lowered to keep from flipping over.
The drive system is 6 to 1 ratio from the motor to the jackshaft. The output freewheel on the drive unit is 16 tooth (White Industries) and the rear sprocket is 60 tooth. This should give me a 30mph top speed.
Limiting torque is handled two ways on this bike;
First, the controller is programmed with low throttle response. This effectively gives a throttle ramp up delay, thus softening the throttle "Hit".
Second, there is an adjustable mechanical torque limiter (slipper clutch) inside the large belt pulley on the drive unit. This will be adjusted to slip a small amount under only the harshest conditions. This will protect the driveline.
Setting up a bike with these high output and light weight RC systems is like setting up a Formula-1 car or a factory two stroke dirt bike, if setup right it will run reliably with plenty of power. However, if setup incorrectly, problems will occur.
My black street bike is setup with this same drive unit, same motor, same controller. It runs wonderfully with hundreds of miles problem free. That bike is geard for 37mph and weighs 90 pounds (LOTS of lipo). This bike should be even more reliable because of the lighter weight and lower gearing. That is the hope, anyway.
Oh, my black street bike is running a CA (setup for RC use). This bike will not have the CA for a few reasons;
#1 Complexity. I want this bike as simple as possible.
#2 Throttle response. The CA tends to dampen the throttle response and that affects the "Feel" of the bike. My Motoped had a direct PWM throttle like this new bike will be wetup with (no CA) and I prefered that setup for dirt use. For street use, I prefer the CA.
#3 Ease of build.
#4 Removeability. I want to be able to completely remove all electric components on this bike as quickly as possible so I can transport it on a bike rack on the rear of my car without worrying about rain. I plan on making the entire electric system removeable in less than 10 minutes for easy transport. The CA would increase removal time.
#5 Stealth. I want fewer components on the bars so it looks more like a normal bike (not like the drive unit is not visible
).
#6 Distractions. On a long range street bike, I like being able to monitor amps, volts, battery state of charge, etc. But, on a dirt bike or trail bike, I prefer no distractions to take my eyes off the trail.
I may go with a CA eventually if I find I need it for some reason. But, I would rather go with a smaller motor to reduce power and wheelie tendency (and save weight) than resort to a CA to limit power on this particular build.
Matt
) I wonder did You ever thought about putting a freewheel on Your rear sprocket? I have also a leftside drive and find it sometimes anoying when i am at a certain speed and let loose the trottle , i still hear the chain rolling, instead complete silence.
