Skike - A eSK8 parts based eBike

I think the first thing that will be broken are the bearings, the can is steel so it should handle a lot without wearing down

I was more worried about where the can bolts to the motor itself.

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So, how do you think a 70kv direct drive or bare hub motor would work? I have a single Carvon V2 and a pair of the infamous, failed Jacob hubs. I was thinking it would be cool to be able to mount just the hanger with the motor to the bike frame on a kingpin bolt somehow and stack bushings/washers (like normal) so it has a slightly dampened mount, and can be swung out of the way also when you’re not using it. :thinking:

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Suggestion. Mount an actual spindle against the tire where where your motor is, pull your motor forward, and then gear the spindle normally with good ol fashioned belts and pulleys. Should help with tire wear and motor heat. Wouldnt be hard to implement with how you have it already.

reading this I just worked out what todo with my old meepo hubs!

I like this idea but don’t like idea of the can taking the strain - I like the idea of that old chunked thane having a new lease of life :smile:

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@Skunk you are right, I have some motors modeled and right bellow the bigger bearing the walls are really thin

I will keep an eye on it, Kepler have been using and selling his kit for a long time and I don’t remember any report of a motor breaking

@Mobutusan it will certainly work, you just have to figure out how to mount it

If you want the motor to disengage look how Kepler does, the motor automatically engage when the motor is assisting, the downside is that you lose regen, since I’m in a hilly city I’m counting that regen will increase the range significantly

@FourteeOZ added this to the list of ideas to try, I would need to go up to 10S and adjust gearing and spindle diameter accordingly

I think your idea is really good for those who want to use more the motor by itself, without pedaling

Let’s see what happens with more current, the downside would be noise of the belts, the motor/tire contact is virtually silent, once I switch to FOC they will be no noise at all

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I was planning on putting something together after our winter and going the spindle route. With a proper tensioner noise can be negated.

Looking forward to see what you come up with, my belt drives were never quiet

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New tire, hopefully the smooth center will make it smoother and allow for lower contact pressure, while the side walls provide at least some grip off road

After searching a lot this was the best tire available around here

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This topic has a different approach, more complex and I didn’t like the added complexity, but someone posted this, and I liked, I will see if I can make it fit

But first I need to calculate the gearing to see if it’s actually better than running the motor directly on the tire

The upside (or downside depending on who you are) is that you have to pedal to use the motor

https://endless-sphere.com/forums/viewtopic.php?f=28&t=96769

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In the last days I’ve sketched a lot of ways of doing the battery/electronics

I think it will be a case mounted where the water bottle would go with a quick connect mechanism, probably will use the connectors friction to hold it in place, there will be a MT60, two XT60, or a XT60 and a XT90S, really overkill for this, but the anti spark will be good since I will remove it every time I park the bike

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Some progress, on the outside a XT60 has to be added, signal connectors, that I just realized I completely forgot and there is not much space, and a rail to hold it in place


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A couple questions on the pack…

from the mini usb, is the esc in the pack? If so, why is there a need for the xt60? It seems like a good way to take everything valuable with you when you lock up.

Are you taking any lateral anti-torque measures beyond the two connectors side by side? Something like the Luna magnetic mount might be nice. A couple key holes might work with the existing bottle cage bolt locations too?

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Yeah, everything is in the pack, the idea is to make it as compact as possible to fit in the water bottle pocked in my backpack, lock the bike, take the pack out every time, only the motor and buttons stay behind

The connector is as follows, the MT60 obviously for the motor, XT90S as a antispark switch, and the XT60 as input for a auxiliary battery, with just the pack I will get at least 30 km, and that was without regen, but even if it gets to 40 km is too little for weekend rides. The plan is to have another battery in a under the seat bag, probably a 6S2P since it’s what I have laying around

The XT60 connects to the main pack via a relay, a Arduino will control it and only close the connection of the voltage of both pack are close to each other

I just added a JST-XH 10 pin, enough for a button to control assist, hall sensor brakes for both brake levers, and Oled display and there is still a few remaining for future ideas

And about the mounting, I’m still deciding what to do, will definitely take a look on how Luna does with magnets, that would be perfect, but I don’t know if it will hold to my riding style, going down stairs, most of the time jumping them entirely, this is one of the reason I didn’t go to hub motors, the would be subject to too much beating, way more expensive to replace than a quick disconnect axle

My idea as of now is to make a rail that locks the battery in place

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@aletheuo Thanks for the Luna suggestion, I will definitely be using magnets, did some calculations and I can get a really strong holding force with some small magnets by playing around with how they are mounted and the steel around them

The issue I see is if I make it too strong it will be a pain to remove

I searched for what I have available locally and the holding force is crazy, will probably go with smaller magnets, make a few mounting positions for them and add them until there is enough force

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Better too strong than too weak!

What about something like a quick release style lever as a cam to give you the initial breakaway force for the magnets? Something like the below, maybe mounted backwards? Using the eccentric pivot to give you the mechanical advantage you need to overcome the first couple mm.

I missed that you had an aux XT connector, but that makes sense as a kill switch.

Secondary advantage of the non-hub execution is the s-count vs the 230 kv motor you have. the 6s2p made me do a double take thinking to typical hubs having an order of magnitude difference in KV and upwards of 20s.

For the range extender pack, if you’re aiming for a 1 way drain, maybe a mosfet would be something you’d want? You’d need to build in a low voltage cutoff for the cell count discrepancy though.

image

That could work, I will probably go ahead and do the magnets as it is, if I don’t do that I will keep changing the design forever, I have some N50 5x5 magnets here that will give a good control of how much force I need. Will keep adding them until it takes too much force to slide the battery out

The MOSFET is a good idea, first I will build without the wiring for the secondary battery, this can be added later

I just installed the motor again with the new tire, all the motor/tire contact noise is gone, you can’t even tell it’s there, together with FOC this will be killer

Unfortunately the new tire has a smaller diameter due to it being narrower (2.35 vs 1.95), some hacking will be needed to get the proper contact pressure

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Well, that was a bit disappointing, only 10% of energy back in the pack, from the simulations I was expecting something around 30%

Also the breaking is nowhere near enough to avoid using the disc brakes, but it can prevent you from speeding up on a moderate hill, if I have the courage I will open my board and take the Metr module from a more detailed analysis

Now I have decent buttons, but having it to lock on assist after a single press is a must, my thumb is numb from holding it all the time

After this result I may pursue again the mount that doesn’t touch the motor all the time, only when throttle is applied

Will try FOC tomorrow to see how quiet it gets, but this new configuration is already really silent

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In case it helps - I’m using a force sensitive resistor module to control my throttle. It turns 0-5kg force directly into the 0-5v ADC signal so no extra wiring. https://www.aliexpress.com/item/32830267123.html?spm=a2g0s.12269583.0.0.1de237a5SDHRKl

You can use it as a button like your existing setup, and can set 1v or so as max throttle in the VESC so you only need to touch it lightly (no sore thumb).

I’ve made a torque sensor for my chain around this module. It floats on the chain and squeezes the resistor module (red line) when you tighten the chain by pedaling. Can’t do that with a mid-drive!

I’ve attached it to my front derailleur with a bit of straight wire so it can float but not move down the chain. It’s surprisingly seamless, but you need to remember not to rest your foot on the pedal at traffic lights! PM me if you want the 3D file.

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