A number of factors to consider below. Looks like a 7 speed, 9-11 is ideal. Battery and motor dpends on your use case and range reqs. Look at the bikes full specs to find BB diameter or ask the manufacturer.

Factors and Questions to consider for Ebike conversion:

Please answer the relevant questions when asking for help on a new build in the forum.

1. What are your use case and range requirements?

-Preferred terrain - hill climbing or flat, mostly smooth hard ground or sand / snow / mud (latter ideally suited for fat tires)

-How much range do you want on a charge? - This determines what motor power and battery capacity youll want.

Multiply Volts x AmpHrs = WattHours ie my 52v 20Ah battery yields 1040 WattHours, or about 30-50 miles of range on a charge depending on how high PAS levels or throttle I use

2. What is your Bike Frame Model - Does it fit you properly? Is it full suspension or hard-tail (latter preferable for ebike due to ease of conversion). Is it quality enough to be worthy of an ebike conversion? (avoid putting high end ebike kit on a low end frame). Make sure you double check the battery dimensions that it will fit on your bike frame properly...(full susp frames often have a hard time fitting). Do you need folding, or other features? A hardtail with good front suspension fork and a suspension seatpost will perform well in terms of comfort vs a full suspension bike, and is easier for ebike conversions. Keep in mind fat tires ebikes are more suited for sand, snow, mud, roadways, while narrow tires are better in mountains, trails, forests, for agility, and need better suspension due to less tire cushioning.

3. Do you need more torque for climbing steep hills or more top end speed for flatter terrain? This relates to your ideal cassette / chainrings / drivetrain setup. Ideally you want at least 7-11 speeds/gears on rear cassette for ebike conversion, 10 speed is a great choice. Mine for example is 10 speed 11-36T cassette. Shimano Deore / SLX derailleur. Front chainrings/derailleur will be replaced with one ebike chainring up front. Find the best chainring for your use case. 42T using a BBSHD tends to the be sweet spot for me for steep hills / climbing - just enough to not be too torquey, popping wheelies too easily even while climbing steep inclines its a bit uncomfortable! I reach 50-60 kph on flats with just the motor, plenty fast. If you dont have too much steep terrain, more gradual hills and flatter terrain, a 46T stock ring may be the sweet spot for you, or up to 52T for more speed (higher Tooth count = lower torque and higher top end speed, lower tooth count = higher low end torque for climbing, lower top speed). Lekkie blingrings perform better at gripping the chain if you have chain jumping issues. Front chainring just want a slight gap off the chainstay, 1/8 to 1/4 inch, use motor spacers if needed.

3. Whats your budget? - Again ideally dont put a 1k+ ebike kit on a cheap 400$ frame…youll likely end up with a subpar ebike. Why bother on a walmart bike with no suspension youre butt will be sore! Better to match a budget bike with a similar value ebike kit. You can move the kit to a new bike also later. High end frames are more suited for a better ebike kit.

4. Do you have all the necessary tools, parts, bike accessories for the conversion? Are you sure youve done the research on your desired bike, made sure it fits you and is compatible with the ebike kit you want to install? This is to ensure no buyers remorse. Have you watched the conversion install video guides for bafang kits, and how to carefully program the controller post install, so you are fully ready to convert the bike? Its all pretty straightforward with a lot of resources out there though it may seem intimidating at first - actually finding my ideal MTB frame and converting it was a ton easier than sifting through hundreds of pre made ebike models…custom ebikes are the way to go!… You can see my completed build and links to controller programming guides are there. Good luck, feel free to ask for help.

https://www.johnnynerdout.com/forum/general-ebike-forum/victory-best-performance-e-mtn-bike-best-decision-ever