Got a new truck concept which I think might be a good match for E-skate. Some Qs

ESK8 Mechanics
#1

First off, don’t want to be giving the impression that I’m going to start producing trucks or something. I’m just goofing off with junk in my shop, so take this as largely hypothetical/theoretical.

Given that, what I’ve got is an idea of a truck that more or less has leaf springs, and I think might be able to pull off a suspension travel of… Optimistically 3/4 of an inch. Not a Baja Board, but better than Avenue Trucks, and certainly better than Ronins or MBS Channel Trucks.

My main question would be, if I had to either optimize for hub motors or a pully system and it was going to be fairly mutually exclusive, which of those options would be most suitable for it?

Are current hub motors options good enough that getting rid of the harsh ride with suspension makes them a winner in this scenario?

If you had a chance to make a custom truck for your Eskate, what would you be looking for thats different from your run of the mill caliber?

For the trucks itself, I’m afraid there’s not much to share ATM. I’ll have a video I’m sure if I get something made ( and working ) Its looking like it could be a fairly compact design with lots of room for stuff. Potentially really low loss of turning to slop. And maybe I might be able to pull off Other Planet-esque raising center of gravity to make them really stable.

One cool idea I have for it is I could use tube stock steel for the hanger construction and if you’re using generic hub motors like this:

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( Far as I can tell virtually all sub $600 pre-builts use these motors )

You just feed the wires down the tube out the center of the hanger, and the motor mounts slide in the tube and fix with some loktite and a couple of bolts, and you’re set.

Tubing is really nice because its strong and lightweight. Not so good if you’re planning to grind at the skate park, but I think its got an application here.

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#2

It’s “cheap” versus “good”

If you are designing for the “cheap” market, don’t even bother — because off-brand regular trucks will be far cheaper and people buying hub motors instead of longboard wheels obviously aren’t buying for performance but rather for price & availability and maybe looks/stealth. It doesn’t sound like these trucks would be best for any of those 3 markets.

If you are designing for the “good” market, designing for for belt drive, gear drive, or direct drive (Carvon-style) would probably cover the biggest cross-section of users.

There would be 2 options – a reverse-kingpin truck with a TB 218 hanger (except with with long 10mm - 8mm stepped axle) but a Caliber2 baseplate, and a double-kingpin truck with long 10mm - 8mm stepped axle that’s not made by Evolve. {both with 20mm of 10mm axle and then 37mm of 8mm axle (last 10mm threaded)}

The idea is the reverse-kingpin trucks are stable at high speeds ( >30mph) and the double kingpin trucks are super-carvy but top-out around 27mph -ish before they become unstable.

#3

Well, I’m cheap. So I guess that makes this more of a question of if I’m making this for myself, or for other people :stuck_out_tongue:

Here’s a different question, Why such an emphasis on wide hangers around here? I really dislike having wheels stick out much further than the width of the board, but here people seem to crave that extra width.

I suppose with a good setup you’re not bothering much to push by foot much.

Is it just about the space to fit everything?

#4

People really like having two motors mounted and they are usually 74mm or 84mm long motors. (plus 10mm for motor mount, twice, and 15mm for belt, twice) A 305mm axle will fit dual 74mm motors next to each other. That’s opposed to mounting one motor on the front truck and one on the back truck, or mounting one motor in front of the back truck and one motor in back of back truck, which doesn’t work if you have a tail

Also I can confirm, pushing and hitting the rear wheels repeatedly by accident sucks. But if you’re doing all that pushing, there is another separate problem.

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#5

I’m all about having two motors.

So, for fun, lets assume I’ve got a suspension truck working and I’ve decided to go with a satellite motor with pulleys because thats cool and we’ve got deep pockets.

Here’s a dumb conundrum. Suspension works best when the movement you’re isolating weighs the least amount possible. So what you’d really want for the best functioning suspension is to not be suspending the weight of the motors at all, and to only be suspending the weight of the hanger/wheels.

So that would mean somehow not mounting the motors to the hanger, but instead on the deck, or something like that, and having the belts running from there to the hanger.

I suppose if there were any reasonable way to make that work, people wouldn’t be bothering to mount their motors to the hangers in the first place, right?

#6

That’s not easily possible as the hangers must be able to pivot individually from the board when you turn

#7

Is it the axle twisting thats the issue, or is it axle the travel distance?

Normally you mount the pulleys near the ends of the axle by the wheels where there’s lots of travel. But if you were to mount the pulleys in the center of the hanger where the travel is very very small, and run axles out from there you’d only have to deal with twisting.

With suspension, there’s also suspension travel and this doesn’t address that. But its a start.

#8

Yes you would have to have them in the centre or you could a rod on the board attached to another rod that mimicks the truck movement that way the pulleys would stay the same length apart

#9

I don’t know any easy way to get the motors off the unsprung weight portion, but I would look to the BMW Streetcarver longboard for inspiration. As long as you keep the belt lined-up and the center-to-center pulley distance constant, it should work. Though if it changes wheel camber then longboard wheels won’t work with just their inner or outer edge on the street…

The alternative is to make fixed drive wheels in the back that do not turn.

I can assure you that if getting the motor off the hanger was easy, we wouldn’t be putting motors on truck hangers.

#10

I actually really like you’re intial proposition of designing a decent truck to accept hub motors, but I wouldn’t be pitching it at the e-longboard community I’d be designing them for the e-mountainboard guys as there’s very little in the market at the moment - literally only one seller I can find that I can’t get hold of to buy a sample and I really think that in a few years we’ll be swithcing completely over to hubs and if you can create a decent product now you’ll stand a good chance of succeding in that market.

That said, I don’t know how much demand there is for it right now as there are some really fantastic direct drive options available but for me hubs are the future.

Have a read of this thread which includes a few examples of what I’m referring too:

Image for quick ref:

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You wanna make these things industructable though as they’d need to stand up to some seriously heavy impacts.

#11

So actually Flexboardz uses the same mechanics as the BMW Streetcarver.

The motors aren’t in a position where they don’t move at all, but they certainly move a lot less.

This guys been doing electric setups since 2011, its does all the things that my idea has, including suspension and raising center of gravity, but its a pretty complicated way to go about doing it.

Do they have a specific community?

Far as I’ve been able to tell, this place was the best resource for the whole body of DIY e-skate.

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#12

If your designing for the community then I would assume basing it around belt or gear drive would be best. Currently these seen to provide the best performance per cost. The popularity of wide trucks is driven by the need to fit 2 big motors between the wheels.

I think moving power from the board to the Axel will be difficult so it makes sense to mount motors directly from the Axel. And if the wheels have suspension travel belts could still be reliable as long as the suspension arm pivots about the center of the motor, then belt length will remain constant.

#13

Hi there. No same community and you’ll find riders here building all terrain boards using the same technolgy. Search eMTB and you’ll get a lot of examples/use cases.

#14

Ok, here’s what I can actually share.

Its the same type of family of truck as both the old torsion beam style trucks.

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And also the Gbombs Torsion Tail TT-A DX ISO BLACK450x300g

Which is of course also kind of similar to the suspension used in Avenue Trucks

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So its not like a radically new idea, but it does have a lot of limitations, especially if its going to be made to be up to the task of supporting Eskate, and doubly so for what I want, All Terrain Eskate.

If you look at the old torsion beam trucks, they actually work pretty good. But in order to be flexible enough to work in the small space, they’re made of plastic.

Here’s a video that looks at them in more depth.

You can see they’re working pretty well for a dumb little toy skate, but there’s no way anybody could trust that for a legit setup where you’re relying on these things at high speeds or in abusive conditions.

There’s also a huge dilemmas going on where any truck has to make compromises between size and flexibility, endurance, etc. To be a functional truck its got to be able to handle many thousands of cycles without breaking.

The trailer tail compensates by being very long, being made of the highest quality of material, and being very stiff to vertical loads ( AKA, very little suspension travel ). Also being 0 degrees means it doesn’t have to twist as far for the same amount of lean compared with like a 45 deg truck.

Avenue deals with this by not having the leaf spring do any turning at all, but instead sticking a whole truck on top to handle that. And even with that the suspension travel is still really small.

And the torsion beams just accept that they’re going to break and have a short life, so they sell them as super cheap kids products. They also don’t have any suspension travel at all really because the torsion beam has to rest on a support post because its so flexible.

The ideal of what you’d want would be turny trucks that can lean as far as you want, with as much suspension travel as possible, which won’t break, while not being any larger than any normal truck. All of these things work completely against each other.

I did manage to make a small proof of concept prototype and I’m really excited. Its just plastic though but it does look promising :slight_smile:

This isn’t a very developed family of trucks, and I’m sure there’s lots of room for all sorts of other ideas. You can get pretty radical with it too.

This isn’t my current concept, but I’ll share it just to show how crazy you can go with this.

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This would fundamentally be very similar to the torsion beam truck, but it gets around the issues by having a very long spring in a coil. It won’t break because the stress is distributed over such a big area, and it has a lot of travel for both turning and suspension because the spring is so long.

Out of the box solutions like that might open up this family of torsion spring trucks to be more practical.

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#15

How do you control rebound? It looks as though it would be impossible to hold a line going around a corner as the spring would just bounce you back to center and straight off the road? :thinking:

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#16
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#17

I’ve ridden some pretty high rebound trucks and haven’t run into any issues like that. Its no different than a bushing, just with a quicker return. So its not like it builds up energy and then suddenly releases it all on its own.

But if it does end up needing to be dampened thats usually pretty easy. Introducing bushings somewhere would bring in some dampening. Or the springs could be coated in plastic to slow them down a bit. I’d plan on having bushings somewhere anyway if possible just as an extra means of rider customization w/ standard parts.

Other ways to deal with it could be things like running the trucks at a lower angle so the rider has more mechanical advantage. Also changing the ride height as well so the Gs help hold you in a turn a little bit.

Overall though It seems to me as though higher rebound in the trucks return results in better grip, and stronger hookup. Not to say there isn’t such thing as too much, but I think higher rebound is generally desirable.

#18

I also think if the spring pre-loads it will twist & as I asked before if the spring is so strong as to not pre-load (twist) with your static weight but react to aggressive body movements, your inertia will be met by a equal and opposite force springing you back to center.

#19

Wouldn’t it need a sort of dampener as well?

#20

Yeah, I get what you’re saying but in my experience it doesn’t work out like that. You lean, and it responds back with a force equal to that of your lean, and just stays where you put it.

You mean like a suspension dampener?

For Road driving, no I don’t think so. The amplitude you’re dealing with when it comes to road vibrations is so small, that I think you almost need suspension rebound to be as fast as possible, at least if maintaining wheel hookup is your goal.

For AT stuff, I don’t know… Possibly. It might not get enough suspension travel to have any use for it.

Theoretically you could run into resonance problems if the spring rate is too high, but I think its the sort of thing you just have to experiment with to see if its an issue or not.