max safe limit when overvolting/amping a 48v 1000w brushless gearless hub?

[jimmyhackers]

definately a record when the bike was given to me free, even at full price just 4 brand new batteries would of cost me about £120. i have 8 (4 spare)

anyone got 30mph for cheaper than £230?

its a cheap steel framed full suspension mountain bike with 26" rims, unsure of make as it was generic and i removed all the naff looking stickers long ago. ill post a pic up soon.

 

[Deleted member 4366]

ooooo its getting a bit heated, calm down chaps

is counting the windings a case of disassemble and count? the motor has no markings on it and the seller is nigh on useless as a regards to further information :S how usefull would this be in knowing the limit of my motor?

not sure how to tell what amps im actually drawing without an ammeter and a shunt. is there another way?

i have a multimeter so i can check voltages.

only real world figures i have are the 48v (really 54v in sla) and the 32mph flat and 35mph downhill speeds.

the guessed/assumed figures are the 1000w for the controller and subsequently its amp draw.

which gives me an estimate somewhere between 20 - 25 amps draw

my speed is from a bike speedometer and is pretty accurate so the 32 and 35mph figures are real world and not "optimistic" so

dont worry i have good brakes and tyres.

another thing people seem to worry about is my range.... im getting about an hours ride (25miles or so uphill downhill and flats) out of each charge and the battery still shows 2 bars out of the three (bike meter) or a good 52ish volts (mulitimeter) after im done.

this range either mean one of two things. my batteries can output 20ah or im taking a lot less than 20ish amps on avergage

To get the speed of the motor, you put your cycle computer on the motor wheel, lift the wheel off the ground and spin it to maximum with the throttle.

To find the current, look at the controller and see what's written on it. If it's not written on it, only a wattmeter will tell you. It's not that important. It's only for the acedemic excercise of calculating the theoretical maximum speed. If you get 32 mph on the flat already, you'll get about 35 mph at 60v and 25% more midrange power.

 

[trex]

how do you lash the 4 batteries to the bike? they are 7kgs each!

 

[jimmyhackers]

here was the bike with a golf trolley motor on it


here it is now


sorry this pictures a bit sloppy but its dark and wet outside. you get the idea though

 

[Deleted member 4366]

I thought you said that you had good brakes! What do you do - poke a stick through the spokes? The rest of it is pretty cool though - apart from the tyres. I'd go up a couple of sizes to something like 2.3"

 

[jimmyhackers]

the batteries are held on by four identical ruggid plastic golf trolley battery holders bolted to the frame. the batteries are all in padded bags and firmly strapped into holders. they dont budge and the padding makes them suprisingly comfortable to hug with your thighs.

taking off and in motion you dont even notice the weight of the bike. it leans in and out of corners like a dream.

there is still more than enough clearance for the rear suspension to travel freely and its a comforatble ride even on bumpy roads and paths etc

you may notice the rear brake is foot operated (custom bracket cut/welded by myself ) . this keeps my throttle hand doing just throttle and nothing else, making life simpler and safer in my mind.

 

[jimmyhackers]

properly maintained (aligned cleaned and resurfaced) v brakes are good enough for me. i can lock up each wheel independantly and come to a full stop pretty sharpish. i rarely use the rear brake (or feel a need to) as i dont wanna scuff my shiney ehub motor rim :S

i did think about bigger /thicker tyres but im good for grip aswell. i do like the occasional mud path and woodland deviation. so im gonna keep the front tyre mud for that. i may get a bigger slickish rear. will a higher profile tyre will protect my rim from bumps/potholes more so?

 

[Stalkingcat]

So no pedals, digging the foot pegs, must be a crazy riding position. you should stick a banana seat on it (Ebay) and hug those sla's.