Joe's E-bike build

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I got the disc brake on the front Sunday. I test rode it again and it's pretty fast. It's quieter than I expected with the 530 chain. Not loud at all. Got the belt aligned properly. I had an issue with the rear sprocket. I think I forgot to torque down all the bolts because it developed a wobble and the adapter plate bent. This ultimately led to two of the little m6 bolts pulling the threads out of the hub. So I have to solve that problem next weekend. On one of my runs I used a speedo app on my phone. 42 was as fast as I felt comfortable with although its still pulling hard at that point. The tire rubs the battery under hard braking so when I tear it down for paint I'll have to extend the frame out an inch or two to prevent that. I was worried that might happen which is why I made that corner of the battery box round. The cheap fork performs well, even with so much weight on it. Plenty of damping and with the rebound adjustment set, the front end stays squatted down long enough to maintain traction on the front tire. All in all it's a blast to ride and once I get all the kinks worked out i think it will be reliable. I took a few more pics of the bike out in the daylight.


The rear sags quite a bit when you sit on it. The chain looks super loose in the pic because of the angle of the swingarm when the bike is unweighted. The position of the front sprocket causes the swingarm to push downward when torque is applied. I tried doing a little burnout standing on my feet but the swingarm just pulls down and the seat rises. It won't break traction easily.

Magura MT5 estop
The front brake was a whole ordeal. I ordered a whole assortment of different lines and fittings to get this working. Much of them were not needed in the end but I just wasn't sure how I would connect the mountain bike caliper to the motorcycle brake levers I have on it. I failed to realize that the caliper doesn't come with the M5 banjo bolt needed to attach the fitting. I had these M6 banjo bolts that came with some of the other fittings I ordered to experiment with and I just drilled and tapped the caliper for M6 threads. The gold banjo fitting is a Jagwire quick fit banjo. I drilled that out as well. I used the Jagwire hose which is very nice by the way. I recommend it. It's much more flexible and pliable than the other cheaper hoses I also purchased from Amazon. I did buy the actual Magura banjo fitting too, which fits an M6 bolt however the Jagwire stuff is nicer/more convenient so I opted to drill their fitting for the M6 bolt.

This is the lever end/master cylinder end. The master cylinder uses an M10x1.25 banjo bolt. I got a banjo bolt with a bleeder screw for the rear brake and the bleeder turned out to be M6x1.0 thread so I was able to screw in the small MTB brake line fitting where the bleeder is supposed to go. Basically using the M10 banjo bolt as a thread reducer. This particular MTB fitting was sold described as "for Formula" I'm not too savvy about MTB brakes but I think formula is either a brand or model of bike brake. The fitting just had a straight M6x1.0 threaded end with the correct barb/olive for the Jagwire line(5mm OD). I trimmed the M10 banjo bolt down so that I could thread it into the master further without it interfering with the spring and piston inside. This allowed it to go in past it's banjo hole and seal with the sealing washers. I also faced the head of the M10 bolt with the grinder so that it's flat and provides a good sealing surface for the M6 sealing washer. I trimmed the M6 thread down on the MTB fitting too because it was too long to fit inside the M10 bolt. In the end it all worked out and I'm happy with it. I put DOT 5 brake fluid into the system. This is the silicone based kind. It should be compatible with both the Nitrile/buna n seals in the caliper and the EPDM seals in the master cylinder but we'll see. That's the main obstacle I was facing with this setup. Magura brakes are designed for mineral oil based fluids and the motorcycle stuff is for DOT 3/4/5.1 glycol based fluids. The silicone based fluid should work with both seal types from what I've seen on various chemical supplier and seal manufacturer websites. There is conflicting information about this however. So time will tell. If all else fails I will replace the seals in the caliper with EPDM rubber. I'm running a 2mm thick 203mm diameter rotor which, seems to perform satisfactorily despite the weight. I was easy on it but it did stop me from 40+mph without fade. I'll admit that it seems too small for the bike just looking at it. If I end up overheating this brake frequently I'll probably change the whole fork setup over to motorcycle stuff and take the weight penalty. 230mm rotors are available too so that's another option.

Still wiring to do and I need to make fairings/covers for the controller and set up the cooling system. More updates next weekend.

I want to thank all who have posted here, especially amberwolf for your input about the wheels and forks early on in the build. That really led me in the right direction. I've also been having a great time tinkering with the Lebowski stuff so thank you for turning me on to that. The stuff about crimps was enlightening too and I bought my very first set of crimpers. Very similar to the ones you showed me in your post. I don't know how I lived so long without them honestly. Ive been using them on all the pins and such for the bike. I still solder the crimps afterward but thats just me being paranoid, the crimpers work great! At some point I'd really like to invest in a high quality hydraulic crimper for the larger gauge wires.

 

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Now THAT'S a pocket rocket! Luke would be proud.

 

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I started making a cover for the controller.
It's made from the drivers side front fender of an 03' LeSabre. Still haven't painted the bike yet. I put a DNM rear shock on it because the other ones were just too soft. The old ones had 250# springs and the new single shock has a 1000# spring. It's stiff but I'll be using this for groceries etc... so the extra weight capacity will be needed. I'm planning on putting bags on the sides of the seat.

I put a big spring inside the fork to stiffen it up. I got the spring from work. It goes into a folding cafeteria table to assist the user in folding it up. It was about 3ft long but I cut it to the right size and it ended up working out. The tire doesn't rub the battery anymore but I'm still going to stretch the frame out about 2" when it comes apart for paint. I need room for a fender and I'd just feel better knowing the tire has plenty of clearance.

I've been riding it on the weekends when I go to the garage to work on it. I ran the battery low one day and pedaled it without the motor about a mile. Even with the gigantic front sprocket the ratio to the wheel is pretty short. I can only go about 10mph with the pedals. It would be better if I had a way to disengage the motor. However, they are usable and its actually quite comfortable to pedal with the pedals being out in front of the rider.


This is a screenshot from the top speed run I did. I only held this speed for a short time. I don't think it's smart to go this fast on the BMX front tire. The sidewall is too soft. The bike was actually very stable at that speed but I'm sketched out by the tire. Had to test it out though now that I'm more confident on it. Overall, it rides pretty good. I sit upright and it's comfortable. The turning radius is wide with so much rake. It has tons of torque even with the small controller. It's a far driver nd72360. 180 line amps and 360 phase amps. I think that's more of a peak rating honestly. It won't wheelie but from about 20mph on up it takes off like a bat out of hell if you give it full throttle. When I chose the pulleys and sprockets I sized them for the peak torque to be in that range. Video coming soon.

 

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No video yet. Planning on ordering a GoPro this week. I have the cooling system set up now.
The water pump is 12v and runs off a buck converter along with the lights. There's no reservoir although I may end up adding one in the future. It seems to work well this way. The square thing with the acrylic sides is a flow meter for PC water cooling. The fitting on the top is a barb with a rubber cap on it. That's where I fill the system. The air bubbles settle in the flow meter and I have enough hose there to move it around and get the bubbles up to that top fitting. It took a couple days before they all worked their way up there.

That's the radiator there on the side below the seat. The pump pulls coolant from the bottom of the radiator pushes it through the flow meter and then through the motor and back to the radiator. I'm planning on making another sheet metal panel with louvers to cover the radiator and help direct air through it. I just have a button to turn the pump on and off. The plan is to add some kind of thermostat to the circuit so that the pump only runs when it's needed but I haven't been able to significantly heat the motor no matter what I do. I don't think the controller is powerful enough to get it to that point. The motor gets warm to the touch but barely. The top speed run was done before I had this set up. It didn't get hot at all even with no water cooling.

I put a shinko 241 2.75x18 on the 22" BMX rim on the front. It's heavier but it's much better. The bike handles better and I don't feel the sidewall folding on sharp corners now. I'm loving that tire! It was a little tough to get it on the rim with the big motorcycle tube in there but I got it on there and the bead seats well.

I also switched out the wheel setup for this pit bike wheel. Same tire from the old wheel. It's a little heavier but not by that much compared to the 20" BMX rim with the moped hub, although that's not taking into consideration the weight of the caliper that will go with it. Originally I planned to use the freewheel on the moped hub for the pedals but my plans changed and I no longer needed it. This disc brake setup should be better than the drum brake on the moped hub. This thing needs all the braking power I can get. I didn't start fabbing the caliper bracket since I was working on that blue f150 in the background this weekend. Ball joints and suspension bushings ate up most of my time. I also switched to a 420 chain since the pit bike sprockets are all 420 or 428. I'm planning to do some experimentation with different sprockets. Originally it had a 22 tooth on the motor, 40 tooth on the input of the jackshaft a 19 tooth on the output of the jackshaft and a 31 tooth on the wheel. Now it's 22,40,18,35. Very close to what it was with the old wheel setup but I have a lot more options now that I don't have to modify sprockets to fit the wheel. The sprocket I modified for the original wheel was slightly off center because I couldn't drill the holes perfectly. The bike feels smoother now and is also quieter. I do miss the look of that giant 530 chain though