That is like in F1. Revolution started when motor block was part of frame. That was great idea.
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Our deck and enclosure together weigh under 2kg without the aluminium brackets, and with them the total weight is about 3kg for a board that comfortably fits 12S6P 2170. We’ve done our best to reduce weight without compromising performance and we certainly could have made a lighter deck, but in the early days we decided to trade weight for the suspension system as it’d be worth the tradeoff. In design there is always tradeoffs you have to make. If you go to heaps of effort to make a board lighter it doesn’t necessarily mean you’ll end up with one that is better overall. Something that we are really focusing on which we do have more control over is where the weight is located. We are really focused on making lighter wheels and motor mounts to reduce inertia on the part of the board that moves the most, as well as keeping the battery centralised down the middle of the deck close to its pivot axis to reduce inertia there as well. If you place weight carefully you can minimise its effect on handling
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When are your deck and enclosure going to be available?
Around end of this year
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One of the things that motivated me to start this thread was seeing a person moving around a 30lb board in an out of a car. I wondered how much easier it would be if the same board weighted 20lbs.
I think this point is a really important and under considered in most builds.
When looking at trucks, the hanger move about the pivot axis. Reducing the weights of the wheels and hanger means that the whole assembly has less inertia and can respond/conform better to the ground giving more grip.
On the rear hanger this is also true of drives and motors. Reducing weight of the entire drive assembly improves truck response.
Additionally moving as much weight to the center of the board as possible will reduce rotational inertia making jumps and 180’s much easier.
Last summer I built a 4wd with a strong focus on keeping things light and pulling all weight towards the center for reduced inertia.
Went as far as centralising both esc’s in a single case in the center. Also mounted the drives vertically to pull the motor weighs closer in to the feet.
Managed to get this board down to 15kg plus battery which is crazy for a 4wd board. I have a 12s3p race battery which can be fitted bringing the total weight to 18kg.
But I know that there’s still much further this concept could be taken if I did things again. Moving to a bro deck would drop +1kg straight away. Swapping the older 3dSAS trucks for airs would drop another 300g per truck. There are lighter drive options now and I’m sure another spin of the ESC enclosure could shave some more off.
All in I think a V2 of this build could easily come in at under 13kg. Couple that with some small lipos and you could have a race ready 4wd for under 15kg all in.
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Most important. Hanger, motor, drive and wheel weight.
Weight placed on a hanger increases “Wob” recovery time.
The wider a hanger is the less force it takes applied to the hanger tip to overcome mechanical input.
The static weight doesn’t mean as much till you go to carry the board or apply lateral forces.
A drive cable like the ones used in racing for remote mechanically driven pumps could be an answer for removing parasitic hanger weight.
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Can you elaborate on that please?
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Well mate, like me, many people here are fat cunts. So going on a diet would help my board tremendously.
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Forgive me If I mention lot of allready mentioned things. The stuff I’m mentioning is for generic regular boards.
1.If you have TB110’s or any other big PU wheels, throw them in bin and get something lighter (afaik total weight of all for those pure urethane wheels was 2.4kg’s). I have no info how much tr4mpa’s gummies stuff weighs.
2.Nothing much you can save up in trucks department. Most are 400-800 grams, maybe SRB ones are lighter.
3.Running smaller motors that fit the spec. 2x6074 motors add quite a lot of weight. Smaller racestars or even running direct drives/hubs is a good option if done right and high performance is not top priority.
̶4̶.̶R̶u̶n̶n̶i̶n̶g̶ ̶l̶i̶-̶p̶o̶s̶ ̶i̶n̶s̶t̶e̶a̶d̶ ̶o̶f̶ ̶l̶i̶t̶ ̶I̶i̶-̶i̶o̶n̶ ̶c̶e̶l̶l̶s̶.̶ ̶W̶h̶e̶n̶ ̶i̶t̶ ̶c̶o̶m̶e̶s̶ ̶t̶o̶ ̶w̶h̶/̶k̶g̶ ̶l̶i̶p̶o̶’̶s̶ ̶w̶i̶n̶ ̶e̶v̶e̶r̶y̶ ̶t̶i̶m̶e̶.̶ ̶H̶o̶w̶e̶v̶e̶r̶ ̶y̶o̶u̶ ̶w̶i̶l̶l̶ ̶h̶a̶v̶e̶ ̶t̶o̶ ̶d̶e̶a̶l̶ ̶w̶i̶t̶h̶ ̶a̶l̶l̶ ̶t̶h̶e̶ ̶d̶r̶a̶w̶b̶a̶c̶k̶s̶ ̶L̶i̶-̶p̶o̶s̶ ̶h̶a̶v̶e̶ ̶l̶i̶k̶e̶ ̶s̶h̶o̶r̶t̶e̶r̶ ̶l̶i̶f̶e̶s̶p̶a̶n̶ ̶h̶i̶g̶h̶e̶r̶ ̶p̶r̶i̶c̶e̶ ̶a̶n̶d̶ ̶h̶i̶g̶h̶e̶r̶ ̶v̶o̶l̶a̶t̶i̶l̶i̶t̶y̶ ̶i̶f̶ ̶n̶o̶t̶ ̶t̶a̶k̶e̶n̶ ̶c̶a̶r̶e̶ ̶o̶f̶.̶
False, check couple of posts below with correct info.
5.Lighter motor mounts. I run 7mm steel mounts on my setup and it adds good 700 grams to entire build. Thinner ones made from other metals are a lot better option for light riding.
6.Scaling down battery and rearranging battery layout. Even though must run 12s, 10s is also a good option for sub 50km/h build. If your priority is range, make less series groups and instead focus on parallel groups.
I personally wouldn’t bother much with CF decks as in grand scheme of things it doesn’t change much weight wise. Also the deck is the thing you usually build your board around so compromising on it is essentially building race board at that point. But if we do go that route, thinner deck and using 4 layers of fiberglass instead of 6 on battery case can make the difference. If you want harder decks, get shorter ones to compensate for extra wood on Z axis.
Can we do database of weight of things. Honestly I don’t know if GD’s weigh less or not than a belt setup. Maybe there is one already?
Another idea: if vesc field weakening actually works, then smaller motors with higher gearing could be used to shed some weight and gain that extra top speed with it.
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There is one iirc
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I’ll echo these points. These are incredibly important to performance, as Moe said, not just board-is-too-heavy-to-carry. Another important point is that this is not at all a novel concept. What we’re talking about is reducing unsprung mass - a pursuit in motorsports as old as time.
Any vehicle with a motor and a suspension system has to figure out this balance.
Unsprung mass (parts not suspended by the suspension - i.e. everything below and partially including the springs/bushings themselves) has an outsized impact on the performance of the vehicle. Weight in general slows a vehicle around a track. A higher power to weight ratio is generally always a good thing. Sprung mass can have some benefits like keeping your ride planted and stable. But we’ve all got plenty of sprung mass above the ankles already. Unsprung mass has no real performance benefits (although it can absorb some road imperfections).
When a heavy wheel goes over a bump in the road, the wheel is (essentially) flung into the air. The suspension has to counteract this movement. The heavier the wheel, the harder it’s flung upward. Physics tells us the inertia of an object is directly proportional to its mass: the more massive it is, the harder one has to push to move it. While your wheel is in midair, it has no grip on the road - no traction, no power. A lighter wheel re-establishes ground contact quicker. This concept applies to all unsprung mass - hubs, tires, fasteners, motors, drives, hanger, etc. It’s all being flung up and down unless you only ride perfectly smooth roads. Less unsprung mass means less for the springs and shocks to control. It means the wheels can respond to the road faster, provide better turning and grip.
At it’s extreme, too much unsprung mass can lead to difficulties in control during aggressive driving/riding:
High unsprung mass also exacerbates wheel control issues under hard acceleration or braking… vertical forces exerted by acceleration or hard braking combined with high unsprung mass can lead to severe wheel hop, compromising traction and steering control.
All of this is even more important for off-roading (eMTB), as you might expect.
And then we get into rotational inertia. The less mass on your wheels, the easier it is for your motors to accelerate them up to speed (or brake) - this means quicker acceleration off the line and shorter braking distances.
It is usually said that 1kg of reduction in unsprung mass is equivalent to 2x - 10x of sprung mass reduction. The exact multiplier depends on the system, but it’s important to note the impact it has on the system.
It’ll be really interested when we start getting drives that are no longer directly/rigidly driven - that are mounted to the deck or truck baseplate / bracket and have CV shafts to decouple them from the wheels. Like an AWD Tesla
(CV joint)
Propel X4S with half shafts (you can see the ribbed rubber boots over the u/cv joints) and center mounted motors
Bajaboard G4X drive shafts
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Great points on most everything. However, hard disagree on pt 4
I did the math (Reducing weight in ESK8 - #48 by sleepless) on Wh/kg aka energy density for a bunch of setups. Some lipos come close (like SMC Extreme Graphene at 196 Wh/kg) but most lipos are around 150-180 Wh/kg while the favorite P42A 21700 cells are at 200-230 Wh/kg. P26A are listed at 190Wh/kg, Lishen LR2170SF say 230 Wh/kg. (This calc does not take into account wiring harness, which would be difficult to nail down a weight on. It also doesn’t touch voltage curves.) Lipos have much better power density, generally worse energy density.
If weight is your only consideration, lipos appear to be a worse choice.
Also deck weights vary pretty widely. Agreed no one should be compromising on structural stability, but it’s relatively easy to check the weight of various quality options and choose the lighter one. The Haero Bro for example is 1.1kg lighter than the Trampa HolyPro BigBoi 35. The Prototipo is even lighter.
I bet @MoeStooge tube frames are pretty light - ever weighed them?
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To be clear on this, Li-ion packs usually have higher energy density than li-po and can contain up to double the wh/kg. This is why almost all bigger EV use li-ion cells.
Li-po’s are usually more POWER dense, meaning you can get more instantaneous W/kg. But this is not Wh/kg.
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Bloody hell. So you’d probably need inrunners mounted under the deck (at the expense of battery capacity) with the cables criss-crossing out to the opposite wheels. But surely those cables will restrict the truck’s dynamics more than a set of mounted motors would? …or am I looking at this all wrong?
How much torque per length can those cables handle anyway?
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Ok, I shat the bed with that info. Will be more careful next time. Also edited post accordingly. 
My point was there is no point of sacrificing weight on deck for the regular board as that is the part of the board that people build around it and choose based on their preferences, also wooden decks don’t weigh much on grand scheme of thing. But good point, there is plenty of room for optimization by choosing similar design deck made out of lighter materials.
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My way of weight reduction is reducing my own weight rather than focusing on the board. Its easier too.
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I wish it was that easy, but some of us are already wraiths and can’t afford to lose body weight so we have to focus on gear weighing less
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