Hey im Moritz and I am planning to build a more comfortable “electric-inlineskate”-thing. I know that there have been some concepts in the past (like “Thundrblade”) but are pretty high off the ground and use small rubber wheels without dampening for high speeds. My idea is based on a larger wheel diameter with rubber tires or air-filled tires and a lower center of gravity. Thats why I plan to base my prototype on 2-wheeled rollerblades called “Skikes” or “crossskates”.
In the past I really wanted to build my own e-longboard and later an e-bike but never really got to it as I was always told that I had a functioning bike and two working legs :v For some time these plans were forgotten and now that I have to commute to my university this Idea came back. Now this semester I got the chance to “realize my own project” and this will be it! So its a project im planning for my university and I really want to realize a functioning prototype which can also reach speeds of an average biker. For the whole project I got nearly 70 days left and am in kind of new territory.
To get a feeling for how these Skikes feel and handle (also for measurements) I already got me some used off ebay and am now trying to get my electronics set for ordering (and mechanics, depending on the type of motor I use). That is time-critical I think because of the long ordering times I saw from browsing 100 chinese sellers websites for different motor-types… Because I only had to work a little bit with drones and occasionally with electronics/mechanics as a hobby, I would love to get some hints about what to choose for the drivetrain. The wheels are 6 inches outer diameter (150mm) and there could maybe fit 8 inch wheels (200mm) into the wheel mount.
One concept could drive the wheel from the top with a small hub motor pressing onto the wheel. It would be kind of compact and maybe slower+lossy than other methods, also might slip.
Another concept would be a typical brushless motor (with a low kv?) on a mount (i would have to machine) and it would drive the wheel over a gearbox (heavy+complicated) or some sort of belt/chain.
The last option I would take into consideration would be a hub motor directly replacing the 6" wheel. This last option would be the most compact and clean method (I think) so thats why i already searched many parts of the internet for hub motors that would have 6" diameter (~150mm). I know that there are 6" motors with through-axle for scooters but they often say that they are made for 12km/h and also advertise them with details like watts, voltage and max-rpm instead of KV or max-current. So far I have only found this with advertised 400watts (?) and although it says 6 inch it also says it is 170mm in diameter (which should be okay)
I wonder how these handle higher currents or voltages as I imagine the max-rpm is for the highest voltage of the ones they advertise (24/36/48V) how would that scale with higher voltages and how would that translate to the middle 36V for example (10s battery) Another great motor that I found was the
which is really expensive and I dont really know what the 6-Pins of the hal-plug are for (instead of 5-pin standard) and the general pinout is unclear because of lacking documentation about their “proprietary” motor-wheel. Then I found a clone of these wheels that is supposed to deliver similar power:
The last one has 36kv in its description which should be relatively slow (so is it high torque - low rpm?) A candidate with 8" diameter from amazon would be this listing: https://www.amazon.de/Electric-Scooter-24-V36-V48-Brushless-Electric/dp/B078S4268V/ref=pd_rhf_dp_s_pop_multi_lclrrecs_rbr_cn_1_sccl_8/261-4874303-2382661?pd_rd_w=cCGKN&pf_rd_p=9911ab34-8a76-4d9f-914b-338ea24ff951&pf_rd_r=5JJ92YHETTGTQ7GT1EBJ&pd_rd_r=7ff23fdf-a429-4c59-911b-b35ef1c671e1&pd_rd_wg=w2K6F&pd_rd_i=B078S143MR&th=1&psc=1 What confuses me about most of the listings (similar to the last amazon one) is, that they look very similar and state various output powers and max speeds. Are these just picked randomly and it reaches like 18km/h at best, so its claimed speed is reached with 0 load or are these claims about >30km/h realistic. I can imagine that they are again depentent on the voltage but it would be nice to have some sort of max speed on a fixed load Well if any of you have a recommendation or experiences with these sort of motors please let me know! Maybe I will switch back to some other brushless motor and drivetrain if you convince me for one or the other ^^ Another thing for the motor decision would be that the wheel mount of the skike is quite narrow and could need modification to increase width. With a hub motor on top it might require minimal modification and with hub motor inside or belt-drive it would almost certainly need widening/welding. Exept if you know a method of driving a wheel in these narrow spaces (are there slim chains? or thin belts with thin belt-wheels. Or are these maybe too weak/unstable?) This is the top-down view of the stock backwheel:
Depending on the motor I will continue the project with the sourcing of fitting ESCs or VESCs (that many talk about as I have seen recently). Then I will continue my questions about wheter or not I can have two inputs per esc for something like tilt-control on the legs and hand-controller simultaneously (two input methods per foot and each foot as an independent system). Battery is planned to be a 3-D printed quick release 18650 ~10S pack on each foot.
Well I am just posting my project with most of my questions here and I hope that some of you can give me advice or hints on what I am overseeing or doing wrong
Thanks for reading my wall of text and links so far!