E-Bike Tech: Currie Electric Bike Conversion Kit
One of the bigger challenges facing many people interested in taking advantage of an electric bike is the price of most electric bikes. No, they aren’t cheap. More to the point, what if you already have a perfectly good bicycle that you like to ride and can convert?
What many people might not know is that besides a growing market of ready-built electric bikes, there is also a variety of retro-fit kits available that allow you to transform your current pedal bike into the pedal-assist bike you’ve been longing for.
Not only did we want to find out how easy it would be to install a kit, but more important, we also wanted to find out how well it worked. With the aid of a Specialized Globe comfort bike that was in great shape, we installed a 500-watt front hub conversion kit from Currie Technologies.
1.) A Complete Package:
The kit is packaged well and includes easy-to-read instructions with exploded views of the job at hand. In addition to a new front wheel with the hub motor laced up, the kit included a beefy (read heavy) steel rack that mounts the controller and the 36-volt, 11.4 amp hour, Li-ion battery cells; all the required wiring; and a thumb throttle with a battery gauge.
2.) The first step is to swap the rim strip,
tube and tire from your bike’s front wheel to the front-drive front wheel from the kit. The kit is compatible with disc brakes if you have them. There are a variety of washers and spacers, and you must arrange those so that the nuts that secure the wheel have a good, flat surface to tighten them against.
3.) Mounting the rack/battery carrier is easier if you remove the battery.
A supplied key retracts a pin through the base plate of the rack, and a firm pull will slide it free. In case your bike doesn’t have the threaded eyelets, the Currie kit includes clamps that can attach the rack to your frame. The installation was easy but a bit time-consuming (just over an hour) since there are so many adjustments to make. Mainly we had to take care with the clearance for the rear brakes. The rack and battery are heavy, so we made sure to mount the rack as close to the rear wheel as possible to limit its effect on the bike’s handling. Make sure there is enough clearance so that the rear brake is still operable.
4.) We used care to tape the two cables together to keep things a little neater.
We couldn’t cable-tie the wires tightly to the frame tubes without compromising the shifter and brake cable performance, so we tied the wiring to the cable lugs. It was hard to keep the install clean while still allowing the slack needed for the front end to have full movement without being inhibited by the wiring.
5.) Currie supplies a molded rubber block that you use to cable-tie the power plug for the front drive to the fork.
We chose to use larger and stronger cable ties than the ones supplied. Ours came from the electrical aisle at the local building supply store. Since our bike has front suspension, we needed enough slack to accommodate the travel without pulling on the power cable. After plugging in the front drive, there is a plastic cap that goes over the end of the axle to protect the cable exiting the hub.
6.) The last thing to do was mount the throttle unit.
With a twist-grip shifter, we had to remove the grip and the shifter. We moved the rear brake lever in as far to the left as possible and mounted the throttle and grip. You must make sure that the throttle has full travel and returns cleanly. Also, you need to be able to reach the brake lever with the throttle mounted between the shifter and brake. Once everything has clearance, snug it all down.
7.) Since this is an aftermarket installation, it does not feature pedal-assist mode.
You can use the throttle to augment pedal power at any time you wish, though like any legal e-bike, there is no assistance after 20 mph. The completed e-bike weighs 61.5 pounds.
HOW DOES IT WORK?
While we admittedly had our doubts about the retrofit idea, we also have to admit how impressed we came away with it after we rode the bike. In a word, the performance is substantial. The motor pulls away from a stop smoothly, and a little pedaling goes a long way. Once the bike gets rolling, it builds speed quickly. We found that we were nearly always in the highest gears (for pedaling) for any sort of commuting or around town riding. Much of our riding was with heavy headwinds, and with an erect riding position, we were like a sail. Only a little pedaling was required to maintain excellent speed. The same is true of climbing. If you don’t pedal, the going is slow and you burn through the battery charge. Pedal, even easily, and the bike climbs very well. The front hub motor has internal gear reduction, so there is no drag when the power is off. You feel the weight, but the bike is easy to pedal without power.
Of course, our biggest preconceived fear all along had been what (negative) effect on the bike’s handling the motorized front wheel would have, but we never noticed any issues. The bike is as comfortable as it ever was, but it is just easier to ride. We recommend this kit for the road with no reservation. You do feel the weight of the rack, and there is added flex in the frame. In stock form we have ridden this bike on dirt paths, but we wouldn’t want to now.
Without too many extreme climbs, we made a few trips ranging from 20 to 30 miles in distance with normal pedaling accompanying throttle assist. On a day we spent riding without pedaling at all, the battery lasted for 17 miles. At $1299, this kit is the most powerful and expensive model that Currie sells. The same Lithium-ion kit with a 250-watt internally geared hub motor is $999. The 500-watt motor is not offered with an SLA battery, but the 250-watt version is, and that drops another $300 in price.
If you already have a good, strong bike with solid handling, you shouldn’t fear attempting a conversion. Very few tools were required, and everything is within the capabilities of any person that is a little handy with tools. We did call a local dealer, and they said they would charge $100-$200 to install the kit. Ultimately, whether or not a retrofit kit is the e-bike answer you’re looking for depends on what bike you already have in the garage. Our Globe had a retail price of $400, so we ended up with an effective pedal-assist bike for $1700, which is right about where many basic e-bikes start off in price.