RC Brushless Motor Sprockets

[jamesv]

Hi Guys I've been looking into building an electric bike for a while and have decided to go for it, I've settled on this motor http://www.giantshark.co.uk/n637409kv170-outrunner-brushless-motor-p-407738.html
My question is how do I connect a sprocket to the 10mm motor shaft, and where would I source the sprocket from as I live in the UK? I've been thinking about the reduction and I'm going to try and use a jackshaft to gear the motor down to human pedaling speed say 90 rpm, to do this I would need a smaller than 10 tooth sprocket to connect to the motor. I was planning on using a 6mm chain as I already have an 80 tooth sprocket to connect to the jackshaft.
Sorry for the noob question I know pretty much nothing about this! If there is a thread that already answers this could someone please direct me to it.
Thanks
James

 

[gwhy!1]

Hi Guys I've been looking into building an electric bike for a while and have decided to go for it, I've settled on this motor http://www.giantshark.co.uk/n637409kv170-outrunner-brushless-motor-p-407738.html
My question is how do I connect a sprocket to the 10mm motor shaft, and where would I source the sprocket from as I live in the UK? I've been thinking about the reduction and I'm going to try and use a jackshaft to gear the motor down to human pedaling speed say 90 rpm, to do this I would need a smaller than 10 tooth sprocket to connect to the motor. I was planning on using a 6mm chain as I already have an 80 tooth sprocket to connect to the jackshaft.
Sorry for the noob question I know pretty much nothing about this! If there is a thread that already answers this could someone please direct me to it.
Thanks
James

Hi James and welcome, where abouts are you in the uk?
http://www.Technobots.co.uk do 6mm sprockets, you can get then customised with a 10mm bore and a grub screw. hope this helps

edit:.. is the 80t 6mm sprocket a real 6mm or is it #25 the sprockets that TB sells are real 6mm sprockets

 

[jamesv]

Hi, thanks for the welcome That site is perfect! I live in Guernsey, but that shouldn't be a problem even if they will not send it direct as I have relatives in the UK who would send it to me. The 80 tooth is from a Chinese electric scooter so I'm not sure I have always believed it was just 6mm. I'm wandering if it's worth paying the £23.50 and getting their http://www.technobotsonline.com/04b-steel-chain-sprocket-6mm-76t.html sprocket as well as I'm going to have to weld a plate onto the scooter one and then drill a hole for the jackshaft as the current bore is about an inch, it also wont have any set screws so I think I will get their 76. And to secure the sprocket onto the motor would two set screws be adequate?
Thanks for your help
James

 

[gwhy!1]

Hi, thanks for the welcome That site is perfect! I live in Guernsey, but that shouldn't be a problem even if they will not send it direct as I have relatives in the UK who would send it to me. The 80 tooth is from a Chinese electric scooter so I'm not sure I have always believed it was just 6mm. I'm wandering if it's worth paying the £23.50 and getting their http://www.technobotsonline.com/04b-steel-chain-sprocket-6mm-76t.html sprocket as well as I'm going to have to weld a plate onto the scooter one and then drill a hole for the jackshaft as the current bore is about an inch, it also wont have any set screws so I think I will get their 76. And to secure the sprocket onto the motor would two set screws be adequate?
Thanks for your help
James

the chances are that if the 80t is a chinese sprocket is a 98% a #25 so you may be best getting a real 6mm big sprocket from technobots also ( dont forget to also get real 6mm chain ) you can get #25 small sprockets on ebay i.e http://www.ebay.co.uk/itm/Dirve-Sprocket-25H-x-11-Teeth-Single-D-e-scooter-/150654157955?pt=Motorcycles_Parts_Accessories&hash=item2313b00483 the advantage of using #25 is that it is a bit stronger than real 6mm and the chain is a little cheaper. you could try contacting oset http://osetbikes.com/gb/12-5-16-0-parts/drivetrain/ as on there small bikes 12.5 and 16 they use #25 chain and sprockets but im not sure what the internal bore is of there motor sprockets are , With the technobots sprockets I normally fix it to the shaft with one grub screw you will need at least 2mm of matrial in the hub of the sprocket after boringing it out to 10mm so the boss dia needs to be at least 14mm for a 10mm bore , I drill into the motor shaft a 4mm hole about 1-2mm deep for the grub screw to screw into this holds the sprocket very secure.

 

[jamesv]

Thanks that has cleared things up a lot. As the bike will soon have to be my main mode of transport to school and back I'm thinking of going with the larger motor (http://www.giantshark.co.uk/c808508-kv170-p-407469.html) and hopefully this will make it much more reliable as I will be running it at about 2800w instead of its rated 6000w. This motor has a 12mm shaft so the smallest motor sprocket would be a 12t. I'm thinking of using a spare wheel hub to act as the pillow block bearings for the jackshaft what do you think of this?
Thanks
James

 

[gwhy!1]

how do you plan on controlling the motor i.e what controller are you going to use and at what voltage? I would stick with the smaller motor it will be more than enough and its a lot easier on controllers than the 8085 also the smaller motor has a better no load current than the 8085. Yes a wheel hub will work well as a jack shaft.

 

[jamesv]

OK thanks I have just welded a plate onto the 80 tooth and drilled a 10mm hole its good but definitely not perfect so it looks like I will be going with the 76T technobots sprocket as well but it will work OK for testing. I plan on using the 190A Hobby King SS speed control (http://www.hobbyking.com/hobbyking/store/__14500__Hobbyking_SS_Series_190_200A_ESC.html) running at 24v (two 12v 12AH lead acid batteries) and then a servo tester, I'm not quite sure how I plan on connecting the servo tester to a throttle but I guess I could just pull the POT out and put it on the bars. The reason why I was going to go for the 8085 is because I don't want to have to buy a HV ESC so the more amps the better! I'm really pleased with how the hub is working though, I plan on welding an old 16T bike sprocket up and giving it a quick test with an old 250w scooter motor just turning it on and off! Is 25mph a realistic expectation with this (not the 250w) setup as that's what I'm setting up the gearing for?
Thanks for all your help I would be lost without it!
James

 

[gwhy!1]

with the 6374 motor http://www.giantshark.co.uk/n637409kv170-outrunner-brushless-motor-p-407738.html I was able to gear it for around 35-40mph pulling around 3.5kw but this was with a 48v e-bike controller and the motor was fitted with hall sensors, 25+mph will be well within reach running on 24v teh trouble with using a rc esc is that they do not have current limiting and this can make the rc controllers go pop very easy as they are not designed for this high initial load that a bike puts on them.

 

[jamesv]

That's impressive I didn't think that was achievable the speed limit here is max 35 so that would be amazing! I really wanted to avoid hell sensors as they seem complicated to a newbie! I plan on still using the gears on the rear cassette so in '1st' gear it would have a max speed of 9mph, I was hoping this would avoid the massive current surge when setting off, the pedals are staying on so I can pedal to set off which I think I have too anyway without sensors. The controller is also 190A but it would be nice having a current limiter is there another way I can achieve this still suing the RC controller?
Thanks
James

 

[gwhy!1]

if you can drive the cranks at a sensible max speed i.e 100rpm and it is possible to do on 24v and if a small bit of pedal input from starting off in first gear then this will work with a cheapo rc controller but there will be no room for error if you tried to give it a handfull of throttle from near zero mph and you happened to be in the wrong gear then the chances are that the controller will go pop, once moving ( pulling away in first gear ) you will need/wantto shift stright up the gears and this makes it a real pain remembering how many gears you need to shift down when slowing dow. I would recommend forgetting about using rc controller without current limiting if you are going to use the bike gears , you can get a sensorless ebike controller that run on 24v the current limit will have to be upped from standard ( these have current limiting, more forgiving ) these controllers are around 25 quid on ebay and in the uk and as long as the motor is running below around 4600rpm max, a sensorless e-bike controller will work.

edit: http://www.ebay.co.uk/itm/ELECTRIC-BIKE-CONTROLLER-250W-24V-10A-SENSORLESS-HALL-SENSOR-COMPATIBLE-/321123530660?pt=UK_Bikes_GL&hash=item4ac47437a4