My Yuba Mundo M-Drive Electric Bike Conversion Kit

I have finally built my mid drive conversion kit for the Yuba Mundo V3.3 - V4. It is mounted in frame using my patented hub motor mount. The system is independent of the pedals, so when you throttle up, your pedals will not turn with the motor. You can coast with just the motor for as long as you like. The motor's gear is connected to a single cog freewheel mounted on a jackshaft then turns a fixed gear on the same shaft to drive the rear freewheel cogs. The front cranks are also connected to a single cog freewheel on the main jackshaft. You can still use all three chainrings in the front cranks. I installed a chain tensioner to address the chain growth issues when dropping down to the smallest chainring. I have been riding and testing the system for 2 months now, out in our mountain bike trails in Santa Clarita Valley. This thing can really haul up the steeps without stalling. You may find it weird that I am testing it off road, but to me it's logical that way. It's only out in the mountains where I can test on really steep hills. Maybe, in a month or two, I will make a trip up to San Francisco to test in the really steep ascents around the city. One of the advantages of the conversion kit is that the gear ratio can be tuned to work in different road / trail conditions. If you live in a hilly area and carry heavy cargo on your bike, you can gear the system to be at it's most efficient setting by just swapping out a drive gear on the shaft. The conversion kit is a direct bolt on to the Mundo frame. No need for modifications, maybe except for 1 part where in I had to drill out and widen one of the holes for the side loader mount in the frame. I found out that there were some quality control issues in the frames because I saw this problem in some of the bikes I sold. The holes don't line up properly, so you need to enlarge the hole a bit so the bolt holding the mount can go through and be installed properly. Other than that issue, all went smoothly. I am using an Aotema Direct Drive rear hub motor. Top speed is 21 to 22mph. Battery I used to test are cheap 36V 12A Sealed Lead Acid Batteries that weigh a ton! I wish I had some lightweight Lithium batteries at my disposal, I could have gone faster, farther than what I got on the heavy batteries I used. I was able to travel 22 miles around our trails with a mix of pedal assist and just pedaling alone.

My goal for this project was to make an efficient conversion kit that can really climb hills without draining excessive juices from your power pack. To be able to climb longer and travel longer distances with cargo. To be able to have the drive system independent from the front crankset. I believe that I was able to achieve all goals. I have a Happy Mundo now.

I will be testing it one more month, and if budget permitting, send out some kits to friends to test and get feedback.