Archived: the OG noob question thread! 😀

How-Tos & Esk8 mechanics Esk8 Mechanics
#12378

You could also put the entire rim in the oven if you’re still having issues.

Heating just the hole will actually result in shrinkage of the hole… cuz science.

If you have to go that far though, you’re probably better off sanding with a bit of emery cloth…

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#12379

Yup. Much easier to embiggen an hole than to ensmallen it.

5 Likes
#12380

everything was like it should. I disassembled both wheels, put the left belt to the right and vice versa, spun it and put it back like it was. Problem solved :thinking:

#12381

Hi Everyone,

New here and I can’t seem to create a new topic so I am posting here as per the topic (Noob question thread).

I’m exploring the idea of DIY as I have some experience from building drones and have some basic equipment available.

Goals:

  • To build a board that’s able to reach 40mph for a 170lb rider.
  • Amazing acceleration, more important than top speed.
  • Safe, reliable & relatively budget conscious as compared to high end boardss.
  • Primarily used for on-road, perhaps light gravel from time to time.

Previous experience/expectations with boards

  • Only a Ownboard Carbon AT/GT set-up
  • 10S4p Sanyo GA 18650 cells with 6368 170kv motors & Hobbywing ESC.
  • With 120mm wheels it has decent power, but I am now looking for more acceleration and speed overall for a 170lb rider.

A few questions if anyone is able to offer an opinion:

  1. Currently looking at this motor/esc/remote combo: https://flipsky.net/collections/groups/products/group-d13-electric-skateboard-kit-includes-dual-fsesc6-plus-and-dc-motor-8085

Thought I would start with picking the electronics based on what power/acceleration/speed I am looking to achieve. Understand the vesc6.6 is limited to 12S - will this limit the motor? Am I better off with a 63** series for the motor?

  1. Based on the above combo, is there a recommended battery pack?

Initial ideas are to go with 20700 Sanyo NCR, perhaps 12S5P? Any suggestions would be welcome.

Thanks in advance!

#12382

daily random stupid questions:

considering to try out pneumies, i was thinking to get the metroboard 155mm tires, because i got them recommended as the smallest possible tire for superstar hubs - if anyone knows alternatives in the eu they’d be gladly welcome

is 155mm the number i enter into the calculator for wheel dimension or does that change when inflated ?
how often do you guys replace the tires / tubes usually ? what kind of wear do i have to expect?

anything else i should be aware of beforehand ?

2 Likes
#12383

An excellent first step in planning a build is to go here and plug in all the numbers you’ve decided on, and then play with all the others until the results (range, speed) look like what you want.

Weight isn’t a significant factor in determining your top speed, only your acceleration. The most significant factor in top speed is wind resistance.

40mph is pretty fast - And as a result, you’ll need a lot of power to overcome the aerodynamic drag - You’re gonna need roughly 2.8 horsepower, or over 2000 watts, just to overcome the aerodynamic drag of your body at that speed. That’s a lot of power, so your range will be terrible at that speed unless you have an enormous battery. Since drag is based on the speed cubed, reducing your speed to 30mph (still plenty fast for something with no handlebars to hold onto) will drop your top-speed power consumption by over 55 percent, down to just ~900 watts.

Those motors are pretty large and have shafts extending from both sides, so fitting them both onto a single truck will be… challenging.

12s5p of Sanyo 20700B cells are very high capacity, but not great for power density. For the given amount of power, you could have a pack made of 30Qs or VTC6s that is approximately half the weight and size. Since you want extreme acceleration, you want the lightest board with the highest power density - That means either LiFePO4, RC lipo cells, or high-discharge cylindrical cells, and the 20700B don’t fall into any of those categories.

2 Likes
#12384

What kind of budget are we talking about here?

#12385

I was thinking under USD2,000 give or take, preferably closer to USD1,500 if possible.

1 Like
#12386

Ok that sounds quite reasonable for what you’re trying to achieve.

The calculator that @MysticalDork linked will give you a good understanding of what kind of speeds to expect so I’d start there. 190kv motors on 12S will get you to 40mph without sacrificing too much torque with thane wheels.

1 Like
#12387

Thanks so much for the insight! Totally overlooked the extending shaft of those motors.

Your calculation sounds consistent with what I calculated since my current board at peak is around 1600W last time I computed the numbers.

I think I would be happy with 35mph if the acceleration is good enough. I do intend to use pneumatics at 6 to 7 inches (understand that these will be bigger than my current 120mm ones and so the new setup will require more torque).

For the 18650 sizes you recommended (30Q & VTC6), what kind of configuration did you have in mind? I am struggling a bit with understanding the amperage draw based on the battery config.

Thanks for pointing out the low weight needed for acceleration (which is one of my goals). I am happy with the current range I am getting which is around 17-20 miles with the way I ride.

#12388

A pretty common configuration for 18650s is 12s4p - With either of those cells, given their 20A-per-cell rating, would give a total of 80A, or 40A per motor. With a 44.4v (12x3.7) nominal battery, that’s 3500W. That configuration would have about 520 watt-hours of energy, and assuming 20wh/mile that should get you about 26 miles. Keep in mind that as your speed increases, your wh/mile energy consumption will increase as well - If you started with a full battery and went flat out at 35mph until you hit empty, I’d expect your wh/mile to be 60 or higher, and thus your range to be less than 10 miles. If, on the other hand, you rode like a granny at 10mph the whole way, you’d probably get better than 40 miles out of that same pack.

If 3500w isn’t enough and you can afford the 25% extra battery size and weight, you could jump up to 12s5p, for 25% more power and range, at ~650 wh and 4400 watts.

#12389

So for Li-Ion, 18650 sizes are most energy dense as compared to larger sizes.

Is there a way to determine the torque from the esk8 calculator? I am trying to understand how it can be manipulated.

I see how the increase in voltage (ceteris paribus) will provide higher top speed. As per my original goal, I want to increase the torque across the whole throttle spectrum. Which statistic(s) will tell me that?

#12390

If you want more info you can use the @3DServisas calculator found here https://calc.3dservisas.eu/

#12391

just found this, is this legit ? evolve 6" on superstars ? this makes my triggerfinger itch uncontrollably

if im not mistaken this would be the smallest possible tire @sesat ?

could alternate those with my gummies without much work too :smiling_face_with_three_hearts:

1 Like
#12392

they are legit

if you’re comparing them with the metroboard and torqueboard tires (which all fit on the same wheel hubs) the evolve has the smallest size printed on the tire. but i understood all three to be very similar in size once inflated.

i would stock up on any of them if they were on sale

the do have to put up with more abuse than 8" tires and tubes though

1 Like
#12393

i see, diddnt expect that :thinking:

got myself 2 sets of tires and tubes, that should last a bit

triggerfinger was too itchy to wait any longer :joy:

1 Like
#12394

small pneummies look soo good

if i had to guess, you’ll go through 6" inner tubes 5x faster and 6" outer tires 33% faster than you would 8" tubes & tires

how i came to that conclusion

it’s been awhile since i did high school math. since you’re a little bit brian, i figure it would be worth playing with pencil and paper

i tried the volume of a taurus thing and it seems to me that an 8" tire has almost five times more volume than a 6" tire in the same 3.75" wheel hub. i don’t have a spare unmounted wheel hub to measure, the math is different if the hub is actually 3.5"

i used these numbers, lord forgive me for using fractions of an inch:
R1 = 31/16"
r1 = 9/16"
R2 = 48/16"
r2 = 17/16"
where V = 2 x pi-squared x R x r-squared
and the 1’s are 6" and 2’s are 8"

furthermore, for a given speed on the road, the 6" tire has to revolve/spin 33% faster than an 8" tire.

i can not guess how much quicker you’ll go through 6" tires and tubes than what you’re already used to, but i hope this gives you a ballpark. i like to imagine that inner tube resilience is proportional to volume, outer tire durability is related to linear distance the tire surface travels

2 Likes
#12395

fancy the math, but overall i cant really debate on this topic at all…

i have zero experience with pneumatic wheels, neither with tube nor tubeless so i cant even estimate how long they would last on average even for the regular sizes like bicycles or similar

i know car tires live for around 50.000km or 3 years on everage, but thats about it :see_no_evil:

i wouldnt mind being educated on this topic tho…

edit: some real life data from someone running bergmeisters would be great, i dont think a comparison to bicycle wheels is legit, but thats the only values i could find easily… which is an average lifespan of 2.500 to 5.000km

1 Like
#12396

Thank you for having a realistic budget. The amount of people who list desired specs like yours without a parts list made up and then set a $700 budget drive me nuts.

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#12397

Its the wheel pulley in my case, i loosened it like @MysticalDork mentioned and it actually worked quite well, i can run the belts really loose without skip and it did eliminate almost all the ticks.

1 Like