Introduction: DIY Electric Bike!
I live in Eugene, Oregon, one of the most bicycle friendly small cities around, and I really like making use of the many, many bike paths and bike lanes that thread throughout the town and out into the surrounding natural areas. As long as you can handle the rain, this place is a fantastic area for bicyclists!
On my travels I’ve encountered a lot of different types of bikes, but I’ve always been intrigued by the occasional electric bike I’ve seen. It seems like a great way to commute! Recently I’ve had some problems with my back and foot, and that’s left me stuck to car commuting to and from work. Gas is crazy expensive, and I’ve considered more than once looking into an electric bike as an alternative to my current situation, but it’s all seemed a bit out of my price range.
As fortune would have it, I was contacted a few weeks ago by thediyoutlet.com, interested in having me review one of the many tools and gadgets they carry. I jumped at the chance, and they sent me this awesome DIY electric bike conversion kit! Now I finally get to try of these things!
Of course, this is just the start. This instructable will cover the basics of installing, using, and customizing the kit, as well as my review of the overall experience. Down the road, I’ve got bigger and better (and more LED filled!) ideas about what to do with this thing next!
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Step 1: Gather Materials
As I mentioned, I got the conversion kit from thediyoutlet.com. They’ve got a variety of kits, but I went with one for the front wheel of your bicycle. Originally I wanted to go with the back wheel version with the pedal assist system, but I’m thinking that for future hacking and modifying of the basic kit, the front wheel version will be easier to migrate to a different platform. I went with the 48 volt / 1000 watt system, as I’m a pretty big guy and I didn’t want to get the 36 volt system installed only to find out it didn’t have enough kick to pull all 300 pounds of depotdevoid around town.
The next thing you’ll need is batteries. This is the biggest expenditure aside from the kit itself, and probably the biggest ongoing expense in owning an electric bike. The cheapest option is a sealed lead-acid battery, or SLA. There are certainly other less bulky options available, but for someone trying to get onto an electric bike without breaking the bank, this is the way to go. Furthermore, the charger that comes with the kit is designed for this type of battery, so there’s no need to convert that particular piece of hardware.
The kit recommends four twelve volt batteries, with a minimum of 17 amps each. I found these 18 amp batteries at Amazon. Most sources I read say this sort of battery will be good for about two years before you need to replace it, so with a price tag of about $160 for all four, you’re looking at a yearly operating cost of around $80, plus electricity, repairs, and maintenance. If you’re using this to commute, that’s waaaay less than driving or even busing will cost you!
The last thing is a bike. “Great!” I thought to myself, “I’ve already got one of those!” Of course, this kit is designed for what most adult bikes in the US have, a 26″ wheel. I’d forgotten that my bike has a goofy 700mm European size wheel. I ended up going to the local St. Vincent de Paul’s and picking up a halfway decent and mostly rust-free used bicycle for about $20. Turned out the brakes were bad, and I ended up blowing another $60 to have the pros at a local bike shop install and adjust a new set. I figured this was a pittance to pay, after my second ride on the completed bike ended up with me coasting in terror down the sidewalk with the sudden realization that the brakes I’d spent the last three hours adjusting didn’t work at all!
Step 2: Install the Motorized Wheel
This kit uses a motor on the front wheel, so you don’t have to mess around with the gearing and the chain. You’ll still be able to pedal as well, which is useful for getting going or just to reduce the strain on the motor and driver–more about that in step 8.
The motor should be installed with the cable on the left side of the bike. For now, just leave it loose, but later on you’ll run the cable along the bike frame. Make sure you tighten the nuts securely.
It’s worth noting at this point that when I had the brakes fixed, the guys at the bike shop mentioned that they’d seen a similar front wheel motor, that a customer had been using for his day-to-day transport for about a year. It had done some damage to the fork itself. I’m not sure if this was a problem with the bike or just that the fork isn’t designed to take force in that area, but it might be useful to install some sort of torque arm or otherwise reinforce this area if you plan on using your electric bike a lot.
Step 3: Install the End Bracket and Carrying Case
The bulk of the weight involved in this conversion comes from the batteries, and these, along with the motor driver, will be installed on a cargo bracket above the rear wheel of your bike, in a fabric carrying bag–I have some problems with the bag, more about that in step 9.
The bracket is designed to fit with most standard bicycles, at the clamp that fixes the seat height. Remove the bolt here and put the bracket on the bolt. At the other end, remove the nuts holding your back wheel in place so the bracket can slide into place along the axle, then tighten everything back up.
The last thing to remember to do is remove the rear reflector and place it on the end of the bracket.
Step 4: Install New Brake Levers and Throttle
This kit comes with new handlebar grips, which is good as I destroyed my old ones when I removed them!
Remove all the hardware (grips, shifters, brake levers) from your handlebars. Fit the new brake levers on first, then the throttle control, then your shifters. Don’t tighten anything up too much, you’ll probably want to adjust everything after your first ride. New grips go on last.
Switching out the ends of the brake cables from your old levers to the new ones is pretty easy, just loosen the appropriate screws, remove the cable, and reinstall. The new brake levers both actuate your brakes and cut power to the motor. I had trouble adjusting them though, and messed around with the brakes for hours and hours. Eventually I took the bike into a local shop and had new brakes professionally installed (after discovering that my own attempts had resulted in no ability to brake whatsoever). Turned out the old ones on this crappy second hand bike weren’t very good!
Step 5: Install the Electronics
The bag that comes with the kit has a main section for the batteries, and two side pockets with little wire holes cut into them. I think if you have a front and a rear motor you’re supposed to put one driver in each side pocket, but since I’ve only got the front, I put the charger in the other one.
The kit came mostly wired up, but you’ll have to detach everything to get it into the bag. Most of the connectors are different so there’s little chance of miswiring something, but pay attention to what you’re doing when you hook everything back up. A couple are similar enough that mistakes could be made.
Feed the main power connector from the driver pocket through to the battery pocket. Next, feed the wires from the motor and brake levers through the large grommeted hole in the bag, through the battery compartment and into the driver pocket. Use zip ties to secure the motor and brake cables along the body of the bike. Hook everything back up, and you’re almost done!
Step 6: Install the Batteries
These batteries are bulky and difficult to move around, so I built a little box to keep them all together. It makes removing them from the bag a snap, and I don’t have to worry about accidentally pulling a wire loose.
Using heavy gauge wire (I used the wire from an old computer power cable), wire the batteries in series–positive from one battery to negative of the next. Attach the included connector to the positive lead of the first battery and the negative of the last (see pictures).
The whole kit-and-caboodle goes into the bag! Plug it into the driver, zip things up, and use the long bungee cable to wrap things up tight. You’re ready to ride!
Step 7: ZOOOOOOOOOM!
Wear a helmet! This motor can go scary fast, way faster than I can pedal, and way, way faster than I feel comfortable! It turns out that 45-48 kmph is kind of scary on a bike. The throttle lets you control your speed though, so nothing to worry about. I do find myself overdoing on straightaways, but I usually get nervous and slow down. This thing goes FAST!
Step 8: Pros and Cons
Let’s talk about the good first:
- This motor goes really fast, and has no problem with my weight, the batteries, and my oversize backpack, even pulling me uphill.
- It is really fun!
- The charge lasts a long time, I’ve gone the five miles to and from work four times, and it’s still showing half full.
Now the issues I’ve had:
- The back end of the bike is now really heavy–you feel it when you hit a bump or try to walk the bike. Be aware, because if you lose control and drop the thing, it’s going to smash REALLY HARD into the ground, possibly with you still on it.
- I don’t like the carrying bag. It’s too wobbly, even with the bungee cord strapping it down.
- The driver overheats and shuts off the whole system. I found this out the hard way and thought I’d killed the motor. However, once it’s had a chance to cool down, it will run again.
- The back end of the bike is too heavy now to use the kick stand, I have to find something to lean it against.
All in all, the conversion kit is awesome. I’m in love with it, and have been using it to commute when the weather isn’t too awful. What’s more, I’ve got BIG IDEAS for fun things to do with it!
Step 9: Improvements
Beyond totally taking this conversion kit in a different direction, I have other ideas about ways to improve it. On my maybe someday list are adding a bike light, brake light, and turn signals, replacing the on switch with a key start, and adding an airflow vent on the case to keep the power supply cool. I’d also like to reinforce for forks just in case the bike shop guys were right and this sort of motor can rip them up.
However, by far my biggest complaint about this kit is the carrying case. It’s too wobbly, and the big bungee cord holding it in place is both ridiculous and a pain in the butt. So: time for a trip to the hardware store!
I picked up a medium sized toolbox, and four threaded brackets with hardware. I also had some locking collars to use as spacers, but you can really use anything, from a piece of wood to stacks of washers.
Trace an outline of the end bracket on the bottom of the toolbox, and drill eight holes to line up the brackets. Install on the end brackets, with the threaded ends of the brackets inside the toolbox–no need to worry about them hitting the tire that way.
I had to redo the battery box so it would fit better in the new case, made it more square than rectangular. This actually worked out quite well, leaving lots of room at the back end of the toolbox for the driver and the charger!
The final thing to do was to drill a big hole in the front side of the new case, thread all the wires through, and hook everything up! The result is far better that the original. It’s much more stable, the batteries actually sit closer to the center of the bike (which helps for balance), and the handle on top of the case makes maneuvering the heavy back end way easier. All told, the modification ran about $30.
Step 10: Legal Notes
After an insightful comment by instructables user and fellow Oregonian Jobar007 followed by a trip down the rabbit hole of Oregon’s DMV website, I’ve come to understand that this “bike” is actually a moped! I hadn’t even considered the legal implications of this conversion. Turns out it’s a much more complex grey area than I knew!
If you make a similar conversion, make sure you take a look at state and local laws before you take your new vehicle out on the road!
Step 11: Final Thoughts
I’ve had a lot of fun with this kit, and look forward to making further modifications and new projects with it down the line. It’s a fun and economical ride, and a great way to get into an electric bike without braking the bank. Thanks again to thediyoutlet for providing the hardware!
As always, thanks for stopping by! Please take a moment to favorite, follow, and comment! If you do an electric bike conversion using these instructions, post some pictures below and I’ll send you a digital patch and a three month pro membership!