Folding Triple Motor All-Purpose E-Bike

[Chilekesh]

Hi All,

Wanna share my semi-custom build. Base bike is a Cmacewheel RX20 MAX with 750W Bafang front+rear hub motors and 48V 17ah in-frame battery. Arrived at this after adding Bafang BBSHD, 52V 28.8Ah triangle battery, Eggrider, Lekkie 52T chainring, 203 mm rotors + Shimano 4-piston calipers, Goodtaste levers, Topeak front rack, MIK base plates for front + mid + rear, Rad retro headlight, and a bunch of small accessories like 12V adapter with USB (for continuous GoPro recording), multiple relays for brake cut off and keyed switches, moto horn w alarm, discharge balancer for extra batteries etc.

Also strengthened the folding point with extra bolts to make sure it'll take the additional weight and not lose its rigidity.

Acceleration helps a lot during daily commuting with car traffic, top speed is about 60-65 km/h though I prefer to keep it under 40. It's good for daily commuting, hauling heavy cargo, bike-packing, trail riding, winter conditions etc. Does very well in pretty much any scenario. I also made a 50Ah battery pack that goes on the mid MIK plate and through a balancer against the triangle battery, extending the range to about 400 km full electric or 700-800 km with pedal assist. Potentially could take it further if I were to add batteries to front or rear racks as well. The folding stem enables me to take it in the 1mx1m elevator in my building so I can keep it in my apartment on 10th floor, not worrying about theft all the time.

Lemme know what you think!

 

[calab]

Cool bike, be interested to know how much it all weighs. Were those extra bolts grade 8 bolts?2500wh for 400km, 6-8wh/km is pretty amazing for throttle only, then double that range means your assisted wh/km is 3wh/km.

 

[Chilekesh]

Cool bike, be interested to know how much it all weighs. Were those extra bolts grade 8 bolts?2500wh for 400km, 6-8wh/km is pretty amazing for throttle only, then double that range means your assisted wh/km is 3wh/km.

Bolts are 6mm, 8.8 with hand knobs added later by me to make folding practical. Not that their strength matters much. Even with grade 6 bolts the alu frame would give in before them The tension at the bottom is about 2000N max with road impact. the top bolt is only for when I lift and carry it, other than that that part is always in compression. The bolts are more about rigidity actually. Full suspension is a huge factor in longevity of the frame and components, in addition to riding comfort.

The weight is around 62 kg with full battery pack of 50 + 28.8 + 17 Ah. The total capacity is 28.8x52+50x52+17x48 = 4913.6 Wh, which for 400 km makes about 12.3 Wh/km fully packed and 25-30 km/h speed. I tried 50 km/h constant and made about 260 km before emptying everything, which makes sense. On flat roads wind and road drag is the main obstacle which is proportional to the square of speed.

I have space (MIK plates) ready for 100 Ah more easily, so if I did that I'd weigh 85kg+ with a range of possibly 700 km full electric and 25km/h. I could carry all the gear with me too with side bags in that case. 85-90 kg is ok for me, I'm big enough.

Potential weight is the main reason I went for quad piston calipers and 203mm rotors, stopping power is much more important than speed in my eyes. And brakes and tires are the first (and only) thing I check before riding.

 

[Matchstick Man]

Wow that range is absolutely bonkers. That is the equivalent of πx my 52v 30ah battery. I can't possibly imagine a scenario in which I would need that much range, but that's super cool.

 

[Hwy89]

It would be interesting to know how you regulate the three motors. Are they linked to a single throttle?
I have dual motor Big Dummy cargo bike with a BBS02 mid drive and a geared front hub. I couldn’t get the two motors to play well together using a shared throttle so I set it up to use pedal assist on the mid drive and throttle for the front hub. It actually works quite well with the mid drive doing most of the work and just adding power as needed with the front hub. There is less shifting required because I can get an instant boost for starting and hills with the throttle.

 

[Chilekesh]

It would be interesting to know how you regulate the three motors. Are they linked to a single throttle?
I have dual motor Big Dummy cargo bike with a BBS02 mid drive and a geared front hub. I couldn’t get the two motors to play well together using a shared throttle so I set it up to use pedal assist on the mid drive and throttle for the front hub. It actually works quite well with the mid drive doing most of the work and just adding power as needed with the front hub. There is less shifting required because I can get an instant boost for starting and hills with the throttle.

Take a look at the 5th picture, the half twist controls the mid and the thumb throttle below Eggrider controls hubs. The picture below shows it a little clearer. Hubs have common controller and front hub can be disabled with a switch when not needed, for economy. It is very easy to finely adjust both throttles with one hand simultaneously. For example one cool result is not having to downshift at traffic lights. I can start with hubs and switch to or add mid as I gain speed. I especially wanted the throttles separate because of this. I combine the throttles and assist levels as a habit now according to various scenarios - snowy or rainy road, high gradient uphill, slow sidewalk speeds, long stretches of asphalt, economic speed etc.