I've got a BBS02 750W since March 2017 (so approx 3 yrs now) and travelled 11300km (7000 miles) to date without faults. My daily commute is about 20km (12 miles) round trip, most of it over flat terrain and in relatively ok weather (Brighton, UK).
My two cents on the motor, cycling style and other ebike stuff:
All motors have two power ratings, the nominal rating and the peak rating. The nominal is the 750W (or 500W, etc. advertised on the product), and the peak rating is the maximum the motor is allowed to produce without undergoing significant damage (ie not overheating too much or causing significant wear) for a particular amount of time.
The peak power output for the BBS02 I belive it's about 1200-1300W. You will be able to achieve this kind power
only when pressing the acceleration button. The power output with pedal assist is limited to the nominal power.
For a long lifespan I would definitely recommend driving it at 750W (or whatever the nominal power of your motor is), or below. You can set the screen to show the power output in the settings.
You most likely won't need to go over the nominal power, unless you want to have some fun. For example, I weigh 100kg (220lbs) and would not feel the slightest effort when
pedalling up very steep hills ( with max pedal assist level), the 750W power is more than enough to push my fat bum up a steep hill.
In the link below you'll see what I mean by steep hills. It's 1km long and 100m change in altitude ( left side of the screen you'll see the details of the route) - pure mental and physical pain for the amateur cyclist.
www.google.com
My other recommendations for a good e bike build are: 1. buy a good battery (samsung or lg cells) and 2. schwalbe marathon plus tires. These are more expensive than the average stuff but in the long run you'll avoid other costs and headaches with breakdowns/repairs.
The lifespan of a battery depends mainly on the quality of the cells, which in turn will give a high cycle ratio. For example, cheap no-name batteries will have 4-500 cycles and the good cells (samsung, lg) can provide 7-800 cycles. A battery cycle is measured in 100% to 0%! power hold, not how many times it's charged. At the end of the day if you still have say 30% power in it, then this would represent 0.7 cycles, 50% power left - 0.5 cycles and so on.
The cycle rating of a battery does not mean that it will stop working when it reaches the number (ie 500 or 800), but that it will start losing hold. For example, I have a 48V 11.4Ah samsung battery and could do 30km at the beginning but now after 3 years I can do about 25km. After a year of two it will drop to 20km, etc. So if you're round trip is say 30km, would be best to buy a battery that would provide 40-45km - ie check a battery with 14Ah capacity. Also, if you're commute is likley to change in the future (ie changing jobs or home) then a bigger battery would come in handy.
The battery capacity also depends on how heavy you are and how you use the bike. I'm 1.9m tall, 2m wide and travel to work mostly with the acc. button (always keeping it below 750W), I don't pedal too much for several reasons, one being to keep a low gear to have the motor spin fast (electric motors love to spin fast) and reduce wear on components.
There's another element that controls the lifespan of a battery and that is called a BMS (battery management system). In short, it ensures that all cells discharge/recharge at an equal rate - all have the same no. of cycles. This BMS is of less importance compared to the battery quality as it's quite cheap compared to batteries and reputable vendors will go for the good BMSs. You want to make sure the battery has a BMS.
The volage of the battery should be as the nominal voltage of the motor - ie for the bafang bbs02 750W 48V, buy a 48V battery; for the bbs02 500W 36V - buy a 36V battery. Some recommend a higher voltage battery (ie a 52V for the 48V motor model) but this will put additional pressure on the motor's 'BMS' (there's something similar in the motor that controls the voltage intake).
Regarding the schwalble tires, I can't recommend them enough, they're quite expensive (£25) but definetly worth it. I've never had a flat in over 10K+ km, and I went over big chunks of broken glass (not on purpose) several times at high speed . These things are unbreakable. From the amount of wear I see on them I think they'll be good until 15k km. If you swap them around, put the rear tire on the front wheel and viceversa, at about 7-8K km I think you'll be able to get 20K km out of them (I know, it's crazy). Best thing is to check them every couple of months and see how much wear is on the rear tire compared to the front one, and if the there's a noticeable difference then swap them around.
About other bafang components, I would suggest buying the largest chainweel available (for the bbs02 I think it's 52T or 56T), if you're planning to use the bike mainly in the city and have long strips of flat road on your commute where you can go fast. For mountain biking buy a small one (ie 36T or smaller). For the bbshd model I think you can find 52T or higher chainweels from other manufacturers and are quite expensive.
If you live in the UK then check out eclipsebikes (UK shop), they don't hold too much stuff on stock but it's the cheapest vendor I could find. Otherwise check EM3ev (based in hong kong or thereabouts) or Luna Cycle (US). FYI if ordering from these last two beware as the taxes on imports are quite big. I bought my bbs02 from em3ev and paid £40 only on import tax (in 2017), a friend bought the bbshd from em3ev last year and paid £120 on import tax - note that this is for air delivery, for shipping there's some other play. Em3ev have great customer support (always replied within 24hrs and I had quite a long correspondence with them) and also a team in London for repairs from what I was told. For batteries em3ev are the best in my opinion, haven't seen anywhere else so much diversity on both battery size and cell quality.
Never ordered anything from Luna Cycle but from online videos they seem to know what they're doing and are passionate about ebikes, have plenty and good videos on youtube.
For further info and videos I recommend Ebikeschool and BrunoPOWEEER - he's crazy but top on bafang motors, also he did a tour of the em3ev battery assemby factory.
All the best,
S
www.pedelecs.co.uk
