Is 250/500W + 36V 16ah battery enough?

[Dalberts]

Hi all, I'm looking to purchase a mid drive conversion kit to get me back into MTB after a few years out, particularly back into trail riding. I have a great condition Cube Attention 2016 for my donor bike.

I see the Befang BBS02 750W kits are raved about but I can't find anywhere that sells them on a cycle to work scheme which I would like to take advantage of (42% discount!). So I have found this 250W/500W dual motor kit from Cyclotricity: https://pedalandchain.co.uk/collections/cyclotricity/products/cyclotricity-250-500w-mid-drive-e-bike-conversion

My question is whether the 250W motor will be powerful enough to get me up hills at trail centres, or if I am going to burn it out trying. I should mention the battery is 36V 16ah, however I'm a complete novice so I don't really understand if that affects the motor performance or not.

Alternatively there is a 250W/1000W rear drive kit from the same manufacturer: https://pedalandchain.co.uk/products/cyclotricity-250-1000w-rear-drive-e-bike-conversion?_pos=10&_sid=6c88b7384&_ss=r. Although I am planning on taking my 20 month old out riding in a rear seat, so I'd be concerned there would be too much weight at the back of the bike, plus I think the mid drive is a better MTB trail solution. Don't worry, she won't be riding on the trails - I've seen people do it with kids and it looks horrendous for all involved!

Thanks in advance!

 

[soundwave]

hub motors are a no go for trail centers down red and black trails will just destroy the rims and spokes in no time.

my 250w bosch motor gets me up pretty much everything but have a 12spd cassette.

 

[matthewslack]

Hi all, I'm looking to purchase a mid drive conversion kit to get me back into MTB after a few years out, particularly back into trail riding. I have a great condition Cube Attention 2016 for my donor bike.

I see the Befang BBS02 750W kits are raved about but I can't find anywhere that sells them on a cycle to work scheme which I would like to take advantage of (42% discount!). So I have found this 250W/500W dual motor kit from Cyclotricity: https://pedalandchain.co.uk/collections/cyclotricity/products/cyclotricity-250-500w-mid-drive-e-bike-conversion

My question is whether the 250W motor will be powerful enough to get me up hills at trail centres, or if I am going to burn it out trying. I should mention the battery is 36V 16ah, however I'm a complete novice so I don't really understand if that affects the motor performance or not.

Alternatively there is a 250W/1000W rear drive kit from the same manufacturer: https://pedalandchain.co.uk/products/cyclotricity-250-1000w-rear-drive-e-bike-conversion?_pos=10&_sid=6c88b7384&_ss=r. Although I am planning on taking my 20 month old out riding in a rear seat, so I'd be concerned there would be too much weight at the back of the bike, plus I think the mid drive is a better MTB trail solution. Don't worry, she won't be riding on the trails - I've seen people do it with kids and it looks horrendous for all involved!

Thanks in advance!

Cycle to work scheme done properly does not cover things outside legal restrictions, so BBS02 is unlikely to be found. A conversion saves you so much that's perhaps not too much of an issue.

Performance of a nominally 250W mid-drive motor is only limited by the gearing, so think maybe 50T rear cassette, at least 10spd to keep ratios fairly close for off road, so new shifter and derailleur to suit, and check out how small a front chain ring will fit. Varies with the Bafang model.

16Ah battery is OK capacity wise, but it comes down to quality as well. Don't expect long life from a cheap battery if you push the limits of the motor all the time.

 

[guerney]

My Bafang 250W bbs01b mid drive with 19.2ah battery manages to push my 8 speed folding bike up steep hills fine, even with a 52T chainring to 32T rear cassette. Mind you, I don't weigh much these days and my converted bike weighs a not overly hefty 22.41kg. Now that my legs are stronger, I don't even use the lowest gear anymore on steep hills I previously couldn't manage without 32T. Also, I've set the firmware for 100% PAS "Keep current" at 15A... I doubt that factory settings would make steep hills as easy to deal with. Voltage sag using small batteries could be a problem when tackling long steep hills, causing PAS cutoff - I experience the same when running very low on charge.

 

[Dalberts]

Thanks for your replies, it's much appreciated.

My donor bike has a 10 speed 35T rear cassette and 40T crank cassette. The Cyclotricity kit will increase the crank to 42T - is that a massive difference?

I will look into smaller cassettes but there isn't much information available online, so worst case scenario I would have to use the 42T. Although Cyclotricity say their design is based on Befang's so in that respect there may be a glimmer of hope.

The bike should weigh in at just under 22kg with the motor and battery, and I'm 86kg. Is there a way to tell if the motor/battery combo will be too weak for me?

Thanks

 

[guerney]

I weigh 63.5kg but I've carried an additional 22.6kg up a steep hill with my 250W bbs01b conversion, but I did have to use the 52T>32T. Still was very easy.

The big advantage of the BBSXX series is their programmability. I changed firmware parameters because I was instantly dissatisfied with how the kit performed as bought, it was pretty much unrideable and I was considering returning it. When I got a USB programming cable and looked at how the seller had set the firmware, it made no sense to me at all. It's a joy to ride now. I flew 12.6 miles home yesterday up hills and down dales with zero effort.

I believe there are smaller chainrings than 42T available for Bafangs, but in my experience the 42T which arrived with my kit was too slow going and twitchy uphill 42T>32T on my 20" wheeled bike, which has a shorter chain and wheelbase than an MTB.

 

[matthewslack]

Thanks for your replies, it's much appreciated.

My donor bike has a 10 speed 35T rear cassette and 40T crank cassette. The Cyclotricity kit will increase the crank to 42T - is that a massive difference?

I will look into smaller cassettes but there isn't much information available online, so worst case scenario I would have to use the 42T. Although Cyclotricity say their design is based on Befang's so in that respect there may be a glimmer of hope.

The bike should weigh in at just under 22kg with the motor and battery, and I'm 86kg. Is there a way to tell if the motor/battery combo will be too weak for me?

Thanks

If the original is 1 x 10 and 40T chain ring to 11-35 cassette, then it should be fine ON THE SAME HILLS as you previously rode unassisted. The 42 instead of 40T makes the gearing 5% higher, which can be overcome by increasing the 35T lowest cassette gear by 5%, I.e. 37 or more. So an 11-40 cassette with 42T chainring would be fine.

What it will not necessarily do is get you up the steepest hills that you could not climb before! You won't know the limit until you try it out, and it can be changed by changing the gearing.

All up weight is fine, I'm more than that when coming home with panniers full of shopping, with a short 1 in 6 just before I get home.

Edit:
Stay with the big battery, don't shrink that to save weight.

 

[jimriley]

I have a hybrid 29er, 42t front with 13/34 t rear block, 250w Bafang bbs01b, keep current set to 100%, 15ah to stay legal. Of course these settings can be adjusted when you are riding in the grounds of your mansion, 18ah gives 350w, settings can be changed with the android Speeed app and suitable cable. Top speed can be changed on the standard control panel.
It would be hard to tell without connecting the bike to a laptop or phone with the software.
I have no trouble with the tracks and steep bridleways around here.