Welcome to ES****Do this before your first post or now (it's retroactive)*****
This is a worldwide forum, so please go to the User Control Panel, select Profile, and then enter your city, state/province, and country into the Location field (country minimum) and save it. Once done, your location will appear in every post so you won't have people asking where you are ever again. This will help people help you. Example: Wylie, TX, USA. or just USA, but country as a minimum, and country is the most important. There are many cities with the same name all over the world. Without knowing what country you are in it's hard to make any recommendations. Thank you.
To get solid advice on parts to buy, you must provide the following info.
Desired max speed on level ground. mph or kph
Desired max range at what cruising speed. mph or kph
Preferred bike wheel size, or wheel size of bike you want to convert. Most common kits are for 26" wheels.
Brake type of motor wheel. Disc or not.
Terrain. Exp: mostly flat, some short hills under 20% grade, I want to climb mountains, etc., etc.
With the above info, experienced people can make solid recommendations. Without it, well GIGO.
What Bike should I get to convert to an ebike?
A steel frame bike will work best. And these are usually the cheaper ones. Steel dropouts to be specific. They make aluminum frame FS bikes with steel swing arms and these will work just as good as an all steel framed bike. In fact that's what I've been riding the last 3 years and ~12K miles. What you are concerned with is the bike frame, and not so much the components that can easily be replaced. I prefer V brakes, but if you prefer disc, then might have a harder time finding an appropriate bike. And V brakes work a lot better than those little 160mm disc brakes. For a comfortable ride, you may end up replacing the handlebars, seat, and even the stem to get a proper fit. You'll almost certainly want to replace the tires, and possibly even the wheels. If you decide on a bike with aluminum dropouts, you will need 2 torque arms/plates for it. 26" is the most common kit size, so 26" bike has many kits tires , etc. available for it. Other sizes are beginning to become more available, but you won't have a problem finding a kit for a 26" bike.
http://www.walmart.com/ip/26-Huffy-Men- ... e/49058108
https://endless-sphere.com/forums/viewt ... =3&t=80172
Upgrades. If you can't ride a bike because of discomfort, it's worthless to you. Almost all will need to replace the saddle and handlebars.
https://www.zoro.com/worksman-bicycle-s ... /G1116762/
http://www.ebay.com/p/Wald-8038GB-City- ... 1800042090
What motor kit should I get?
For 90% are more people I'd recommend a 48V 1000W rear direct drive kit. Used stock, it should last almost forever. Provide more than enough power and speed for most people. And they are usually the best bang for the buck. And with a controller and battery upgrade, you can get a lot more power and speed out of the motor. I've been running mine on 88.8V 40A for over 3 years now without a problem. Ran on 66.6V before that. Stock top speed with a 48V pack will be 30 mph. Where to buy your kit is up to you, but I find buying from a volume seller within the country you live to be the cheapest option because they buy in bulk and usually offer free shipping within your country or area. In the US, I'd start here.
http://www.ebay.com/sch/i.html?_from=R4 ... nc&LH_FS=1
http://www.ebay.co.uk/sch/i.html?_from= ... 5573.m1684
http://www.ebay.com.au/sch/i.html?_from ... 5573.m1684
What battery pack should I get?
There will be lots of different opinions on this. Personally I prefer rc lipo because its small, light, very powerful, very configurable, and a lot less expensive than other types because of it volume rc use.. But I'd recommend any lithium and no lead. There's just one consideration you need to take into account. The battery pack must be capable of providing the amperage required by the controller. IOW's if you have a max 30A controller, your battery pack should be capable of a 30A continuous output. Motor size doesn't matter. Only the controller, as it's what draws power from the battery pack, not the motor. Most rc lipo is at least 10C, so it won't be a concern, but if you decide to touse 18650 packs, this could be a major problem. For rc lipo, HK is a good source.
http://www.hobbyking.com/hobbyking/stor ... harge.html
For other types, ask or search. There's lots of options.
How much battery do I need?
Watt Hours (wh) required per mile on flat terrain with no wind. MTB
You can cut that in half or more with a recumbent bike/trike. You do the math as to what you need for your mileage.