Swytch has a 25 mile conversion kit for $299. The ebike will have a 15mph limit for EU or 20mph for USA. The 25 miles is approximately how far the bike will go on a single charge. The Swytch conversion kit will work on any style bike: mountain bike, road bike, beach cruiser or any other bike type. The conversion kit contains the following: 250W motor wheel in ANY size. Swytch power pack 25 mile, quick connect handlebar bracket, 36V 180Wh Li-Ion battery, pedal sensor, two brake sensors and a charger. Swytch also offers a twist or thumb throttle for an additional $15. Swytch also offers a 50 mile kit for $350. Swytch estimates time to install the conversion kit on your bike is 2-5 minutes. The kit can also be removed from your bike to convert back from an ebike to a regular bike. Estimated delivery is currently April 2018. Swytch is a designed, manufactured and shipped from UK.
EAZY Bike is another ebike conversion kit manufacturer out of Sweden. The EAZY bike also rides up to 20 mph (15 mph EU). The current special is $159 for the EU kit and $169 for the US kit. The kit contains one 250W or 350W motor (depending on EU or US version), one 36V 216 Wh battery and one charger. The conversion kit allows you to go full electric or use pedal assist. When pedaling the motor will either engage to assist or drive the bike forward. Stop pedaling and the motor turns off. The total weight added to the bike is 4.5 lbs or just under 2 kg.
Dillenger is another company that offers ebike kits. These kits are manufactured and ship from US. The kits range from $629-$2299 in price. Dillenger offers street legal, off road and mid drive kits. They do also offer a high voltage conversion kit but that is not suitable for most bikes. The street legal kit contains the following: 36V 470Wh Li-Ion battery, 250W or 350W motor (depending on country), LCD handlebar controller, 1 Rim with motor, charger, throttle pin cable, pedal assist sensor, brake sensor, and brake sensor cable. The total weight 17 lbs (9.9 lbs without battery, 7.1 lbs battery weight).
There are other ebike kits out there. The above are the three most popular, as of today, on the market. EAZY bike has the most simplified install with the fewest parts. However, EAZY bike is a very new company and cannot be installed on all types of bikes. Swytch is also a new company. Swytch advertises that their conversion kit can be mounted on ANY bike. However, Swytch has a long lead time to ship product.
Dillenger is a more established company that can ship quicker. However Dillenger conversion kits are more complicated and more expensive. Once the Dillenger kit is installed on your bike it is not as easy to remove and go back to your regular bike. Any of the three may be a good option. Make sure you look at what your priorities are with installing an ebike kit. If you want to be able to go back and forth between an ebike and regular bike the Swytch or EAZY bike kits may be your best bet. They are also the most affordable options.