Longboard Technology Breakdown of Curfboard Trucks.

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Urban Survival - Skate Therapy says:

That was intense, but worthing, your old videos helped me to figured out many things. A few years ago I made my self a three wheel surf trainer (regular truck in the back and single casterwheel in the front) and I used the same principle of this not using springs or bushings (actually I copied the mechanic of a ripstik), a front angled riser that on a regular truck will only change the pivot angle, in this board will increase the resistance on the turn as will lift the board. But what I really like of this mechanic is that give you freedom to change this value on the run. What I mean is that more influence than the height of the lifting is given from how much of your weight you put on this part, in my board if I shift most of my weight on the nose (you can check it on my channel in the english section) it become very hard to turn so I need to rotate (just leaning wouldn’t help) with lot of strenght translating all this power in a much stronger pump, if I keep most of my weight on the back instead become super easy to turn, it will request a lighter pump which will give less spring effect, but will allow you to pump in a steep up hill. Is basically like changing the gear of your mountainbike. When going downhill on this board you want to keep your weight in the front for stability and to give a significant pump to improve speed. When you are performing crazy turns you want to shift the weight more in the back. I really like the idea to get this benefits on a 4 wheel surfskate, as the threewheeler is quite unsafe on high speed, it really train your balance on surf, but if you lose focus and bump in an obstacle you fall easy. I’d like to add for experience that vibrations shouldn’t be significant, a soft riser should absorb them much more than bushings, I know it doesn’t seems right, but it work. About the wearing, you are so right, is a big issue of most of surskates.

KalKyuLayTor says:

I really appreciate your documented exploration.

Hydroman 7 says:

Back again. Just a heads up on the rigidity of a single armature vs. double.
A single knex will have half the rigidity of a double knex. To compare apples with apples you need to make the single out of 2 knex with a single pivot in place of the double.
You have seen my design which is a single arm swivel, it is very strong with less joints than the curfboard.
Having less joints improves the rigidity as it takes slack or play out of the system.
The more joints or mechanical links in a system the less stable it becomes.
Also if you revisit me single pivot point design you will see thatbi have a removable axle assembly. My next STP of development will be to make a can axle similar to the OP but with an elastomer return to centre for stability and resistance.

Hydroman 7 says:

Oh and you are not completely wrong on the bushing and bearing life on the Curfboard. They use a IGUS plastic range of bearings in the linkages. I also use an IGUS SAM10 bearing in my design https://www.youtube.com/watch?v=2N3I8LO6qmc&t=1s. https://www.igus.com/wpck/3753/igubal_sphaerische_Axiallager

These bearing are light weight but take a reasonable load above an 8mm bearing, looking at the Curfboard design I can only assume that they are using a smaller than 8mm bearing of a slightly different design to mine which given the material grades that are available will have a significantly reduced lifespan and especially so with the lever loads applied. https://www.igus.com/iglidur/cylindrical-bearing

Jasper van Loo says:

could you do a test about the gbomb torsion tail?

brandon Mathwig says:

I have found the opposite when I longboard. When I lean back it feels more like a surfboard and when I lean forward I feel stable. And I know this is true for everyone because if you look at the normal tucking position that downhill skaters do, you’ll notice the center of gravity is over the front truck. When they turn they bring their center of gravity backwards on the board. Very good video though. You earned a sub

neonboy22 says:

This is great ! I always only considered the static geometric aspects but your dynamics approach is fantatstic. I’d love to see the otherplanet knex stability too. I expect its very stable at higher speeds but, as you say, nowhere near as “curvy”. Very very cool. Thanks

Krishan de silva says:

that was very informative video.great work .can you tell me what were you using to build the prototype model and where can i buy that small stuff ?

Matthew Barnson says:

Visually explains how trucks get speed wobble. Establishes some ratios at which speeds wobble occurs and goes off the rails. Accidentally demolishes the popular Reddit /r/longboarding myth that speed wobbles are “all about the rider, not the setup.”

Love it!

Hydroman 7 says:

LBT great overview as always, man you guys go to a lot of trouble to show these principals to people. As an engineer I often assume that people have some mechanical understanding.

Anyway I posed a number of questions to the Curfboard designer in the promo vids regarding lack of resistance and issues with stability and drop in etc… you can see discussion here:

https://www.youtube.com/watch?v=3nAgzanaCXA

https://www.youtube.com/watch?v=3w3c5LUbZp8 – This is best for technical discussion on surf skate designs.

And most of what I assumed and deduced about the Curfboard seems to be echoed here:

https://longboardlife.org/2018/01/07/first-impressions-of-the-curfboard/ (hope he doesn’t mind that I linked his site here)

One thing you should remember is that they (Curfboard) are selling a surf emulator and not a longboard. As such you should really be comparing like for like as longboards are different animals than Surfskates.

Mees Deppe says:

the speedwobbles came because of the back truck i think

Hydroman 7 says:

Sorry to keep bombing comments on you.

Regarding centring of the axle and resistance…….

This is my latest design, modelled in CAD and made. Fully tested and rips with a good return to centre idea borrowed from you guys (I’d do a thumbs up thingy but don’t know how).

https://www.tapatalk.com/groups/pavedwave/carving-and-pumping-surf-style-truck-t3754.html

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