Switching the 350w BPM motor on my Big Bear for a 500w one
- Thread starter John_S
- Start date
Thanks for your reply d8veh. I want to increase the torque on my Big Bear. The torque it already has is very good, but in my case I weigh 15 stone and I usually ride with my five year old son on board and often with heavy shopping to carry also, and there are some steep hills around here. I often have to pedal quite hard to get up some of the hills. I have heard that the 500w BPM has better torque on steep hills than the 350w one. This is why I'm considering switching to the 500w version. However, I don't want to do so if it would make my bike illegal.
D
Deleted member 4366
Guest
The 500w version can make a lot of torque if you run it at 30 amps and 36v, but for that you need a new battery, controller and motor.
You can't run that much torque in a front motor, so you'd be better to get the rear version, but then you need a new front wheel too.
My advice would be to sell the Big Bear and get a cheap but robust used MTB and fit a rear 500w BPM with this battery with an included controller:
https://bmsbattery.com/ebike-battery/680-48v116ah-bottle-09-panasonic-battery-pack-battery.html
Make sure you get the right speed (RPM) motor.
You can't run that much torque in a front motor, so you'd be better to get the rear version, but then you need a new front wheel too.
My advice would be to sell the Big Bear and get a cheap but robust used MTB and fit a rear 500w BPM with this battery with an included controller:
https://bmsbattery.com/ebike-battery/680-48v116ah-bottle-09-panasonic-battery-pack-battery.html
Make sure you get the right speed (RPM) motor.
I don't have the technical know-how to be able to put a bike together. It would also cost quite a bit and I have to watch my budget at the moment. I'd prefer to just put a 500w BPM front motor on my existing bike. Would doing so actually improve the torque? I've read that it would.
If I did this, would there be anything else on the bike that would need to be changed? Would it need a new controller?
If I did this, would there be anything else on the bike that would need to be changed? Would it need a new controller?
John the kits are fairly simple. If you get the stuff from one place it should all work. A front motor over 350watts can be dangerous, they can come out or split the forks, not something you want with your son onboard.
D8veh has helped lots of people upgrade the bike. You just have to do as he says and post lots of photos when asked.
D8veh has helped lots of people upgrade the bike. You just have to do as he says and post lots of photos when asked.
Thanks D8ve. I think D8veh is right and it would be better to look into what he suggested if I want a bike with more torque. I wasn't aware that a front motor over 350w can come out or split the forks. That does sound dangerous indeed.
I do like the bike I have, however, and I feel that I'd like to keep it if there is some fairly straightforward way to improve its climbing ability. The only thing I can think of might be to change from the existing code 13 BPM motor to one with a higher code number, preferably code 16 or 17. I'm not sure how easy that would be to obtain though.
I do like the bike I have, however, and I feel that I'd like to keep it if there is some fairly straightforward way to improve its climbing ability. The only thing I can think of might be to change from the existing code 13 BPM motor to one with a higher code number, preferably code 16 or 17. I'm not sure how easy that would be to obtain though.
D
Deleted member 4366
Guest
A 500w motor has the capability to produce more power, but it gets its power from the controller. Without changing the controller, you'd get exactly the same power.
Have a look at the controller to see what's written on it. I believe that early ones were 15 amps and later ones are 20 amps. Your battery is probably on its limit at 20 amps, but the 350w motor is happy with 22 amps, so your motor is not running at its full potential.
If you have the early 15 amp controller, you can upgrade to 20A, which will give 33% more torque. Your forks should be OK at 20A. Even if they did break, you can get cheap steel replacements.
One more option is to chuck the battery and use 12S Multistar lipos, which will give at least 20% more power. Lipos are a bit more complicated than normal batteries, so only do that if you want to embrace the technicalities of using them.
Have a look at the controller to see what's written on it. I believe that early ones were 15 amps and later ones are 20 amps. Your battery is probably on its limit at 20 amps, but the 350w motor is happy with 22 amps, so your motor is not running at its full potential.
If you have the early 15 amp controller, you can upgrade to 20A, which will give 33% more torque. Your forks should be OK at 20A. Even if they did break, you can get cheap steel replacements.
One more option is to chuck the battery and use 12S Multistar lipos, which will give at least 20% more power. Lipos are a bit more complicated than normal batteries, so only do that if you want to embrace the technicalities of using them.
Last edited by a moderator:
If the controller is 15a rated then a shunt mod might be possible to gain the few extra amps before buying a new one.
My 350w bpm (big bear kit) with upgraded 20a controller from Woosh has very good torque in 700c rim.
My 350w bpm (big bear kit) with upgraded 20a controller from Woosh has very good torque in 700c rim.
Last edited:
Elifbike
48v BPM 350w code 15 205rpm no load spd or 170rpm load spd.
48v BPM 500w code 13 230rpm no load spd or 201rpm load spd.
Rpm/code speeds AFAIK are no load speeds.
Run these @36v for slower wind but torque may not be as efficient.
48v BPM 350w code 15 205rpm no load spd or 170rpm load spd.
48v BPM 500w code 13 230rpm no load spd or 201rpm load spd.
Rpm/code speeds AFAIK are no load speeds.
Run these @36v for slower wind but torque may not be as efficient.
Last edited:
Thanks for your responses guys.
I see that my thread has been moved to this forum. I'm not sure why seeing as I've made it clear that whatever adjustments I make to my bike, I want my bike to remain a legal one.
I looked at my bike and couldn't find the controller. I think it must be hidden somewhere. I bought my bike in May this year and so I would think it probably does have the 20a controller.
I have a quick question: Which will provide better torque going up hills on the Big Bear, using the throttle while pedalling, or pedalling in power assist 5 without the throttle on? My bike does have the 15mph throttle, by the way.
Also, if I am pedalling using the throttle, am I right in saying that it makes no difference which power setting the bike is in while the throttle in on because the throttle will override whichever power setting the bike is in?
I see that my thread has been moved to this forum. I'm not sure why seeing as I've made it clear that whatever adjustments I make to my bike, I want my bike to remain a legal one.
I looked at my bike and couldn't find the controller. I think it must be hidden somewhere. I bought my bike in May this year and so I would think it probably does have the 20a controller.
I have a quick question: Which will provide better torque going up hills on the Big Bear, using the throttle while pedalling, or pedalling in power assist 5 without the throttle on? My bike does have the 15mph throttle, by the way.
Also, if I am pedalling using the throttle, am I right in saying that it makes no difference which power setting the bike is in while the throttle in on because the throttle will override whichever power setting the bike is in?
Last edited:
But the be BB is 350w so is not road legal any motor over 250w and marked as so. Check the hub markings my BB BPM says 350w ( 13). If you want more torque solder 25% of the shunt or try running at 48v to give increase in speed and torque. The controller is mounted in the front of the battery in the black section.
The 350w BPM motor seems to variably be described as 250w. I'm fairly sure I've seen a sticker on my bike also which states that the motor is 250w. I understand that wattage is difficult to measure, and the peak wattage of most e-bikes would be way higher than 250w. I'm not sure how wattage is measured, but perhaps there is some acceptable method of testing whereby it can be argued that the BPM on the Big Bear is a road-legal motor.
I'm not familiar with what it means to solder 25% of the shunt. Would this be an easy modification to do?
I'm not familiar with what it means to solder 25% of the shunt. Would this be an easy modification to do?
John_S, there should be a Bafang label 250W with the motor serial number on it. If it has peeled off or not affixed, contact support@wooshbikes.co.uk, they will send you a replacement. The motor is as powerful as the controller allows it to be. The controller itself is limited by the battery and its BMS. That's 20A for the Big Bear.
Last edited:
D
Deleted member 4366
Guest
Your only option for more power, without spending a lot of money, is if you have the 15A controller, so before asking more questions, find out which one you have. If you have the 15A one, you can probably solder the shunt to convert it to a 20A one, which doesn't cost anything. The controller sits in that compartment on the front of the battery. It's the bit that's left behind when you take the battery out.
It is illegal for use anywhere the public has access.
Cyclotricity won't tell you that, of course.
It's not illegal to sell or possess the bike, so you could buy it and hang it on your wall without breaking any laws.