37 thoughts on “Calculating the speed of your electric skateboard”

  1. Thank you Vitalie!
    This is invaluable as I am trying to mock up my own setup and starting a parts list. Your timing is perfect!
    I am looking at machining my own motor mount similar to Vitalie’s. One concern I have is in leaving room in the design of the motor mount to be able to adjust belt tension? I am thinking of two overlapping brackets joined in the middle with threaded M4 screws to allow a few MM play. Any thoughts?

    1. I might leave this one to Vitalie to comment. However I had a chat to Vitalie and he was talking about a few modifications to his design.

      He used some larger screws and was going to get it welded in place in the end

      He was thinking of move the motor mount to the under neithe the board as when you drop off gutters/footpaths etc theirs a bit of an increased chance of it getting bashed on the way through.

      I getting the belt tighten on my design was a bit of a pain. As you can see I can unscrew the motor when the small cog is in place. So I had to screw the motor in the place I wanted an put the whole small large cog and wheel on at one time. If the motor was in once place then I needed to take it all off again and move it. Not ideal but it worked.

      Check out the youtube clip of this guys mount it might give you some ideas about tensioning: http://endless-sphere.com/forums/viewtopic.php?f=35&t=47176&start=75

  2. Nice, any chance you can convert the spreadsheet to a google doc instead of a download? Getting access to Excel can be an issue, and google docs are very easy to link to. Thanks for the excellent posts.

  3. Thank you that’s great! If it wouldn’t be to much trouble could you also post the part number for the two cogs and belt you bought I want the exact same ones you have they look perfect for the design!

    1. Check out the comments in this post for details of what I order and some recommendations.
      http://howtomakeanelectricskateboard.wordpress.com/2013/04/21/re-working-begins/

      I purchased the HTD belts but the GT2 is probably more appropriate.
      Gates is the company that make these see their product description for more details: http://www.gates.com/brochure.cfm?brochure=7911&location_id=11536

      Also I would recommend something a little wider just for the extra grip if possible. I chose a 9mm belt and thought that maybe a 12mm would be better.

      Also note: The back wheel of my test board is 70mm. The large cog I purchased is too large for the wheel (about 65mm). I should have got something smaller with more clearance.

      http://www.sdp-si.com/ is the company I purchased theme from. They have a good website.

  4. Accounting for belt tension: Beetbox’s motor mount accounts for adjusting belt tension in the fact that the bracket is in two pieces and the holes attaching the two pieces are elongated allowing for adjustment. I am thinking about a straight two piece mount exactly like Vitallie’s but made with two overlapping pieces in the middle that can be bolted together and allow for belt adjustment without removing a cog. I ordered my motor, cogs and belts last night and have an aluminum blank due to arrive any day. My wife thinks I am insane.

    1. Good luck. Be sure to share some pictures or start a thread on the endless-sphere forums.
      PS. Your wife’s probably right but everyone needs a hobby 😉

  5. hey .my weight is 77 kg .
    i am also working on the same projects ,but i dont have any idea about the specification of motor .
    so please guide me .

  6. Hey, I’ve been following your blog for a while and finally put together a list of parts and I was wondering if you and anyone else could check the compatibility of these.

    Feel free to use these parts when you’re building your own board, I recommend reading up about this stuff though cause you learn a lot.

    I also plan on using this as my downhill board when I take the motor and stuff off so you’ll see DH influences here and there. Yeah, the deck isn’t made for it but I’m in Illinois so no worries =P

    Board: Holesom Streetweeper – $100 – I already had this and the holes on the side should help with temporary mounting to test out the setup of the batteries and ESC. Also, large wheel cutouts!

    Wheels: Electric Flywheels – $130 – Why, Ken? Why..? Cause I can, and I plan on using this for years.

    Bearings: Swiss – $50 – I had these, just switching them out. Why? They’re pretty nice bearings. Way above Reds. No point in ceramics since I can’t skate in the rain anyways. Super Sixes would be a nice upgrade though.

    Bushings: Stock – Free – I’ll upgrade later to barrels or eliminators so I don’t wobble.

    Spacers: $2 – I love me some spacers

    Now for the fun stuff!

    Motor: Turnigy SK3 6364 190 – $70 – I don’t know much of RC tech but I just know this is a decent motor. Low kv for high torque. Doesn’t seem to use too much power. 2000+ watts for climbing these awesome hills we have. Actually, I’d go lower wattage and higher kv but I don’t want my belts to be stripped. A high kv motor will be an experiment later on.

    Battery: Turnigy nano-tech 5000mah 10s 25-50C – $120 – High mah = capacity. 10s matches my motor. 25C all we really need. I should do more but I’m already slightly above budget.

    Charger: iCharger 1010Bplus 300W 10s Balance/Charger – $120 – I don’t know why. It was the cheaper charger that did 10s…

    Controller: Turnigy GTX3 – $40 – Big screen! Throttle trim is pretty big for me, and it seems to use a battery pack so I can take it apart and make it smaller if I wanted to.

    ESC: I’m confused here. Mainly cause the choices are fine with me and I can’t really break the tie. Maybe you guys could help a bit.
    1. Turnigy dlux 80A – http://goo.gl/hEKZH
    2. TURNIGY Sentilon100A – http://goo.gl/Ch2uw
    3. TURNIGY K-Force 70A-HV – http://goo.gl/iNJpV

    Drive System: Alien Drive – $250 – I’m only buying this because I don’t have any local machines that can help. Even if I order online, I’d have to make sure it fit a truck perfectly and that’d be difficult. This is also pretty convenient with the custom hub pulley for the Flywheels.

    Total for me (somethings are considered free since I already had them): $812. $12 off budget. Grrr…

    Anyways, I hope this helps some people and maybe some people could help me if they know more about this!

    1. I like the motor selection. The low KV is a good idea. From my experience I don’t know if that much power is needed but why not.
      Speed controller – Still haven’t had time to really look into it. You need a high amps to handle the peak loads. some type of programmable function would be good as the chaep one I purchased doesn’t have the most amount of settings.

      Drive systems $250 – Are you talking about the setup on the Endless sphere forum? I didn’t think it cost that much for one wheel drive? or are you going two?

    2. I still haven’t done enough research in to the ESC. But you want something with enough amps that works will at “low” speeds. Low in a relative to RC or plane rpms.

      As I said the cheap one I purchased doens’t have great programable features and overall my motor, ESC and cog ratios are greared to high so it doesn’t have a very smooth low end.

      Someone recommended this speed control but I haven’t looked at it in details.
      https://www.hobbyking.com/hobbyking/store/__14635__Turnigy_TrackStar_150A_1_8th_Scale_Brushless_Car_ESC.html

      Check out the comments at the end of this page.
      http://howtomakeanelectricskateboard.wordpress.com/2012/10/01/electric-skateboard-component-list-the-electronics/comment-page-1/#comment-256

  7. Guys,

    My ESC 150A died last Saturday. Now I am looking for a better ESC. Has anyone heard or read anything about the mamba monster ESC?

  8. Hi Vitali, that might be that the soft start was not set up in your ESC. That setting makes the ESC slowly increase power to the motor instead just doing a direct proportional load directly from the remote signal.

  9. About ESC from Over and Out previous post … I really like this one :
    https://www.hobbyking.com/hobbyking/store/__14635__Turnigy_TrackStar_150A_1_8th_Scale_Brushless_Car_ESC.html

    Great power but also and especially due to the programing options it got (listed down below) .
    That is a really great to have in order to better tune your board behavior
    according to:

    – Your control system :
    Different radios, remotes, controls will make a small diffierence on the ESC behavior depending on it’s programing options)

    – Load on the board (your mass mostly) and your performance expectations

    Depending on how you electronics are set up and how much load you put on the motor you may burn the system, having some “Soft Start” or “table based load” can be really helpfull for you to set up the board acceleration and power consuption.

    – Help avoid current loads and peaks on the system that can damage it.

    Programming Options (Via Optional programming card)
    Voltage Cut off (depending on how you do this one it helps bateries to have a longer life, but reduces the running time)
    Drag Brake
    Brake Strength
    Punch Control
    Reverse type
    Motor Timing

  10. Nate LeCompte

    Hey man, your blog has completely inspired me to design and build my own. I am just in the planning stage now, and here are a few things I have decided on so far
    -2 wheel drive instead of 1, made possible by adding an axle between the motor and wheels, spreading out the power to both wheels (also making it a triple belt drive instead of a single belt).
    – this motor, I took your advice to use a motor that wasn’t quite as powerful
    http://hobbyking.com/hobbyking/store/__19610__NTM_Prop_Drive_Series_42_58_500kv_1300w.html
    -This battery http://www.hobbyking.com/hobbyking/store/__14070__ZIPPY_Flightmax_4200mAh_4S1P_30C_LiFePo4_Pack.html
    – I believe I have a decent system down for the axle and mounting the gears. I just don’t know what gears and belts to use, I want a teeth ratio between 20-30, and 20-35. Which I have calculated will give me a top speed of around 30mph. I’m going to look into the Gates company you commented about earlier
    – Have you found an ESC that you think would be best? I have no Idea on which one to get and whether it is worth it to go higher or lower quality and price.

    Thanks for the inspiration, I’m excited to see your final project, and I will keep you updated on my own once I can purchase the parts

    1. Hey Nate,
      Regarding you motor selection your should go for a low kv value in the motor. kv is a measure of rpm. kv x voltage = rpm. mine was 380kv and I should have purchased one with less kv.
      Speed wise you want to aim for 15mph or 25kph top end. Trust me it feels and is very fast. However, the most important thing for an electric skateboard is the smoothness of the 0-5kph range. Your want a smooth low end and this is why you should aim for a low top end (ie chances of you going at 30mph not likely, chance of you travelling between 0-10mph very likely. So its better to be smooth at that end rather than very twitchy). Use the calculator to aim for a lower top speed. But most importantly start with a motor that works at low revolutions or kv.

      Battery – Looks fine. (been thinking about two 3 cell units in series for clearance but haven’t discussed that on the blog or even remotely looked into it. So no advice there.

      Ratio – relook at the motor then look at lessr teeth for the drive cog.

      ESC – still investigating. Something with some type of programability would be good. My selection wasn’t great for the programability about “smooth acceleration” mode. Another reader just blew his 150amp Hobbyking ESC however I don’t know if that was a issue with his individual unit.

      Axle which drives both wheels – check out the legrannge trucks for how they achieve this. (or buy from ebay) link for pictures here

      http://endless-sphere.com/forums/viewtopic.php?f=35&t=47640

      1. Hey O&O, been following your blog for a bit on and off, even more so recently. I am setting up my board at the moment and I will eventually set up a blog/guide for my build.
        Now don’t get me wrong I love the la grange, the company has a web site up and running now redrockboardshop.com and I have been following it a bit now for all the useful info, but it’s not a 2WD truck. I spent a couple of hours on the web trying to figure out how to replicate the design so I could have 2WD and not spend $400 only to find out it is just a ‘floating axle’. Brilliant set up nonetheless, but I am a college student on a budget haha.

    2. PS. Skip to the 2min mark in the legrange video link provided of how scary 28mph looks. (he’s wearing a motor bike helmet and shitting himself)

  11. Nate LeCompte

    haha yeah I can go that fast comfortably, but on a secluded hill. It would feel super fast on flatland and sketchy on the board I plan to use

  12. Great stuff here gang.
    Spent a couple of hours milling my own motor mount the other day with a drill press and band saw from an aluminum blank but not clean enough to mount around the trucks yet.
    I’ve been looking into controller options. Has anyone considered a wired controller? I have found some references to using a cheap servo tester to control an ESC and a motor. http://www.youtube.com/watch?v=7cXiw4P1R2Q
    Anyone considered a bluetooth iphone controller? Here is a kickstarter program that has already reached funding goals putting out a generic RC bluetooth receiver with an iphone application for $55 USD. The project has met its goal and will be funded on May 27.
    http://www.kickstarter.com/projects/1992869862/blue-rx-a-16ch-servo-pwm-bluetooth-40-receiver.

    I have also ordered my electronics:
    NTM propdrive 50-60 270 KV
    Turnigy 5000mAh 6S 25C Long Lipo Pack
    HobbyKing Variable 6S 50W 5A Balancer/Charger w/ accessories
    Turnigy dlux Programming Box w/Data Logging Feature (USA
    Turnigy dlux 100A SBEC Brushless Speed Controller w/Data Logging

    I went with the long Lipo pack as it is much thinner and will conceal nicely under the deck of the board. I went with the turnigy ESC because it had the available programming box and a lot of the comments on the cheaper hobby king ESC’s noted problems with programming. I am hoping the 100A rating will suffice.

    This stuff is getting completely addicting!
    Cheers
    Clem

  13. Pingback: Electric skateboard component list – the electronics | How to make an electric skateboard

  14. About the spreadsheet what is the load factor? And when calculating the top speed you multiply three things and one of them is the motor speed. So with lower rpm doesn’t that mean that you lose speed? Why is it better to have lower rpm in the motor?

    1. Load factor was just a calculation to factor in that it won’t run at top speed given that its got a heavy body on the board. (It’s just an arbitrary figure)

      You want to aim for a low top speed overall as you will spend more time travelling between 0 – 15 kph than over 15 kph. Hence you want smooth acceleration at the low end is more worthwhile than a super fast top end. The fastest I got my board upto is 28kph. It feels very fast and you won’t be doing that speed for long. (it you come off the board at that speed your going to lose lots of skin)

      If you have a motor with a lower kv that is designed to run at those speeds its a better starting point than a motor that was design to run at really fast rpm then only using it a 1/10th throttle

  15. Oskar Harrison Pilkington

    is a 0.5 drive ratio good with a 270kv motor and what does load factor mean?

  16. trying to make one but im having problems with the gearing, not sure which or what specs to choose. help me!
    i have a 230kv motor, 22.2 volts battery, 72mm wheels and i weigh at about 70kgs. im afraid that it may not support my weight!
    is a 6 drive ratio good? any suggestions? im really lost…

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