Hyena
10 GW
Hey guys,
After snapping the frame on my kmart dual suspension bike last week I decided to go for something sturdier.
I picked up this Norco Ryde dirt jumper cheap on ebay and bolted on a 1000w rear GM hub.
It's basically a big BMX, which I kinda like and I think I'll fit BMX handlebars for comfortable cruising and to complete the look.
Unfortunately for higher speed ebike use the front crank is a BMX one so it's quite small and looks to be only 22t odd. I can't fit anything much bigger either without making up some sort of spacer or using a longer bottom bracket because as it is the little chainwheel just clears the stays.
I'm using one of the new ecity power / BMS battery 500w 72v 12 fet controller. Because it's rated at 500w it came with a pissy 12a current limit.
Needless to say that wasn't going to cut it so I soldered in a strip of wire along side the existing shunt (about half the strands from a piece of 14ga wire which looked about the same size as the existing shunt.
I strapped on 18S of turnigy 25C lipo (75v hot) and went for a quick test ride. I quickly found that the shunt mod has boosted power significantly - 71 amps and 5200w peak! The fets are only rated at 75v 75a so I don't think they'll last long like this. I think I'll back it off a bit to around 50a - even at that level the torque and acceleration was hugely impressive. I can only imagine how much of a ball tearer methods et al bikes must be with 30% extra voltage and current.
If the fets do blow it'll be a good excuse to throw in some 4110s.
So very impressed I started heading home and then I decided to do something silly. I stopped and gave it full throttle to see if it'd do a wheelie. What it did was rip the axle from the drop outs, rounding them slightly and snapping off the derailleur hanger. DOH! :x
I picked up some 5mm steel plate this afternoon and I'm going to make up torque plates for both sides. I may have to ditch the rear derailleur but I guess I can fit a single speed freewheel if needs be. With the little front chainwheel pedalling will pretty much only be an option for starting off the line or if I have to pedal home with flat batteries. Either way this bike is largely going to be my offroad basher so I'm not too worried.
Updates to follow.
Plans are:
* Make up torque plates
* Fix derailleur if possible and look at options for fitting a larger chain wheel.
* Make box for lipos and neatly house the turnigy watt meter
* Drill hub for air cooling
* Upgrade phase wires to 12ga. I was going to use 2 lots of 14g and do star delta but I don't think I need it now (I may change my mind and want more power after riding it for a week ) The controller ran well sensorless so I can probably do away with the phase wires.
* fit 4110s to controller if the stock fets blow
* cut sick and make a cool video
* maybe paint the frame
After snapping the frame on my kmart dual suspension bike last week I decided to go for something sturdier.
I picked up this Norco Ryde dirt jumper cheap on ebay and bolted on a 1000w rear GM hub.
It's basically a big BMX, which I kinda like and I think I'll fit BMX handlebars for comfortable cruising and to complete the look.
Unfortunately for higher speed ebike use the front crank is a BMX one so it's quite small and looks to be only 22t odd. I can't fit anything much bigger either without making up some sort of spacer or using a longer bottom bracket because as it is the little chainwheel just clears the stays.
I'm using one of the new ecity power / BMS battery 500w 72v 12 fet controller. Because it's rated at 500w it came with a pissy 12a current limit.
Needless to say that wasn't going to cut it so I soldered in a strip of wire along side the existing shunt (about half the strands from a piece of 14ga wire which looked about the same size as the existing shunt.
I strapped on 18S of turnigy 25C lipo (75v hot) and went for a quick test ride. I quickly found that the shunt mod has boosted power significantly - 71 amps and 5200w peak! The fets are only rated at 75v 75a so I don't think they'll last long like this. I think I'll back it off a bit to around 50a - even at that level the torque and acceleration was hugely impressive. I can only imagine how much of a ball tearer methods et al bikes must be with 30% extra voltage and current.
If the fets do blow it'll be a good excuse to throw in some 4110s.
So very impressed I started heading home and then I decided to do something silly. I stopped and gave it full throttle to see if it'd do a wheelie. What it did was rip the axle from the drop outs, rounding them slightly and snapping off the derailleur hanger. DOH! :x
I picked up some 5mm steel plate this afternoon and I'm going to make up torque plates for both sides. I may have to ditch the rear derailleur but I guess I can fit a single speed freewheel if needs be. With the little front chainwheel pedalling will pretty much only be an option for starting off the line or if I have to pedal home with flat batteries. Either way this bike is largely going to be my offroad basher so I'm not too worried.
Updates to follow.
Plans are:
* Make up torque plates
* Fix derailleur if possible and look at options for fitting a larger chain wheel.
* Make box for lipos and neatly house the turnigy watt meter
* Drill hub for air cooling
* Upgrade phase wires to 12ga. I was going to use 2 lots of 14g and do star delta but I don't think I need it now (I may change my mind and want more power after riding it for a week ) The controller ran well sensorless so I can probably do away with the phase wires.
* fit 4110s to controller if the stock fets blow
* cut sick and make a cool video
* maybe paint the frame