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  1. R

    Converting a hubmotor to a middrivemotor

    :roll: It is hard to get a handle on all the forces that are caused by a mid drive mounted on the chain stays, as it is in mr.electrics bike. I have found it is best to think of torques and linear forces separately. The torque generated by the hub motor is converted a linear force by the chain...
  2. R

    Letting the cat out of the bag...........

    Me smells an Astro with a lower Kv, Har, Har, Har!
  3. R

    On Designing And Using RC Drives

    Adam Thanks for your input. "As I have found when using a standard RC style ESC and a servo throttle input, that the throttle does control motor speed, not power." I use a Castle 80 HV (old style), at 24 volts, driven by an Astro servo tester board, connected to the throttle. I ran some...
  4. R

    On Designing And Using RC Drives

    Looks like the same overall function. Two freewheels back to back, connected by an intermediate floating shaft. The freewheel positions are reversed from the ones in my system. When you get the bike, maybe more pictures and a description. Strange crank setup.
  5. R

    1000 Watt Mid Drive with True Double Freewheel

    I forgot to mention that motor phase current control, as in my 500 watt mid drive, is not necessary or implemented, on the 1000 watt mid drive, or 750 watt chain puller. The Neugart PLE 60 is rugged enough to handle the torque.
  6. R

    On Designing And Using RC Drives

    I actually tried motor current control, with the throttle, on my 500 watt mid drive bike which measured motor phase current. As it turned out, because the control loop was local (tech talk), and because it was controlling motor phase current, it was very precise, with no perceivable delay. It...
  7. R

    1000 Watt Mid Drive with True Double Freewheel

    The coupler to inner freewheel joint is a light interference fit used along with a special bonding agent, waterproof, and oil proof, made especially for applications like this. For torque, that's a long bond line. I asked Josh to try and break the joint. He is a large, strong guy, who is an...
  8. R

    1000 Watt Mid Drive with True Double Freewheel

    The mid drive weight is just under 8.2 pounds. Here is a picture of the coupling between the two freewheels. The next pictures shows the gearbox to motor adapter. The inner holes are for the motor mount screws, the outer holes are for the gearbox mounting screws. The outer holes are tapped...
  9. R

    On Designing And Using RC Drives

    When using designing and using RC motors bike drives, it is important to understand what the throttle does, and how power is controlled. First the throttle. I always thought the throttle controlled motor voltage. Experience has taught me otherwise. An example: Where I live there is a 3 mile...
  10. R

    1000 Watt Mid Drive with True Double Freewheel

    24 volts.
  11. R

    1000 Watt Mid Drive with True Double Freewheel

    The list price of a two stage PLE 60 precision planetary gearbox is $465 as of a few months ago. I am charging $1500 for the drive, minus electronics. The gearbox is the same gearbox that successfully climbed Pikes Peak powering a bike and rider that weighted well over 300 pounds. Keep in...
  12. R

    1000 Watt Mid Drive with True Double Freewheel

    The very first system I designed, was a 1000 watt mid drive. It had one belt stage, and one planetary gearbox stage. I gave up on it, because was kludgy, and it ate roller clutch double freewheels for lunch (the roller clutch was overloaded in the engaged direction). Also because the two...
  13. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    I have been absent from the forum for awhile. I have been waiting for Astro 3205 motors, which are now here, and I have been getting a 1000 watt midrive, with a true double freewheel, into production. The 1000 watt midrive is out of the machine shop and in assembly. I will publish that drive...
  14. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    Now includes video. http://www.youtube.com/watch?v=ytYuosP2Blg
  15. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    The cranks shown are Vision IPS freewheeling cranks. A freewheeling crank is necessary to prevent the pedals from spinning when under motor power (bruised and broken ankles). The freewheel in this application is lightly loaded due the fact that the motor pulls one direction and the bike chain...
  16. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    I have been testing the system for about two weeks, and need to say something about performance. The test bike is an Electra Townie with Nexus 8-speed IGH. The gearbox output rpm is 300. The max motor driven cadence is 100 rpm (13/39). and the secondary drive is 46/19). The starting gear is...
  17. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    The weight of the 3205 motor with 6 inches leads that are terminated with CC 5.5mm male bullet connectors is 688 grams or 1.51 lbs. The total drive system mechanics, including primary chain, but not including crank chain wheel, is 3181 grams or 7.0 lbs.
  18. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    The primary reason for using half-link chain is to facilitate primary chain tension adjustment, and to eliminate the need for a chain tensioner. Only a 1/4 inch adjustment is necessary. I use KHE chain, which has a cut-away on each link. I believe this eliminates the slapping of the chain...
  19. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    I apologize for the SPAM post. It was late, I was tired, and frankly overwhelmed by the response. The projected price for the complete system is $1700. I am working to reduce that. This includes a complete system, ready to bolt on and go. The only other requirement is a bottom bracket...
  20. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    I don't want to turn this thread into SPAM. Pm me and I will provide information as to availability of parts and pieces.
  21. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    Initial answers to questions. It floats on ball bearings. Provide a rider (I'm 66), and a videographer on the east coast, and we'll talk. Simply turn the motor gearbox system around (It's symetrical, only four screws), and drive the left side of the rear wheel. The freewheel has an...
  22. R

    750 W Chain Puller; Fits Most Bikes (+Video)

    http://www.youtube.com/watch?v=ytYuosP2Blg Since I started developing drive systems 3 or 4 years ago, I have had as a goal, a chain puller that would fit nearly any bike. Finally! Shown below is a 750 Watt Drive Kit that mounts on a standard, slightly modified, bottom bracket. The only...
  23. R

    500 Watt Mid-Drive

    The precision planetary gear box is rated at 20000 hours at full load. My daughter has used my first prototype nearly every day, to "walk her dog", for the last three years. If you ride 5000 miles at 10 MPH, thats 500 hours. These gearboxes use staight cut gears, but because they are...
  24. R

    500 Watt Mid-Drive

    Shown is the circuit that provides the motor current control function, with interfaces to the current sensor and the throttle. I tried to draw this on a drawing program, but it takes too long, with learning curve. This circuit requires an unipolar sensor. The current sensor is an Allegro...
  25. R

    500 Watt Mid-Drive

    Liveforphysics is exactly right in his description of the motor current control loop. The problem is I did not exactly do it that way. I use an Allegro Microsystems active current sensor in one phase wire. Unfortunately, it is a unipolar sensor whose output goes to a single rectifying diode...
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