This is really what started my inquiry. A claim was made, connected to a specific speed even, that in my personal experience is incorrect.
I’m not a MechE, I don’t have much experience in vehicle dynamics. So the difference in opinion on this is fascinating to me and I’m just trying my best to keep up here. I appreciate the effort put in here, and I’m simply curious to better understand the differences
‘High speed’ is going to be relative to everyone unless we quantify it. My own experience as well as numerous other riders shows that channel truck configurations are easily stable up to 35-40mph. I cannot speak to anything beyond that, but I can say that when I reached my own top speed I backed off more to my lack of massive gonads than from concerns over stability.
I would love to explore what the real world limitations/ceiling of these are. I’ve seen radial steering stabilizers added to the rear trucks on 3 different carver builds at this point, which is exactly the type of modifications I would expect on a racing build.
They may not be best suited for high speed on-road racing, but they’re also better suited for off-road and there’s still merit in exploring what the upper limits are, yeah?
I just see a lot of: “doesn’t work well for high speed”
I understand the points made about caster angle in the other thread, but obviously there are other mechanical differences between these boards than that.
I guess we have to define high speed then. Because 30-40 is already done on most common builds that run dampeners.
@Kaly would you like to weigh in on your experience? You’ve probably put more Esk8 miles on channel trucks than almost anyone at this point.
I feel like 35-40mph is pretty fast for a board that you ride with traffic & in bike Lanes.
But on a closed road, racing from point A to point B… Under 40mph won’t put you in first.
I think someone’s ego was injured by your build results. Of course it is always difficult to “eat crow” but the whole strawman argument and then the fact that someone blamed channel trucks for the death of a friend was a little surprising for everyone. I think everyone here knows skateboarding is inherently dangerous, we do not need senior members blaming manufacturers for an accident that could have been avoided had the rider been wearing appropriate safety equipment.
Fact remains that I would feel more comfortable on rkp’s on street but your results have me excited for an upcoming offroad build I have in my shop.
Not really. I felt it coming. Only reason i didn’t eat shit.
Was my first esk8 purchase before i found this place. At least it was under $600.
The trucks mounts & pullys i have on there now are worth more than the rest of the parts lol
Still can’t believe how far this thing has gone. Interesting info and well worth the read.
I will say though. If rkp and tkp trucks did not exist then we would all be screaming round on channels at 45+mph. We would have got used to it and would know how.
When you spend 30 years riding traditional trucks, channels are a learning curve. Different style of riding which I’m sure is the only reason why there is such a passionate argument happening here.
So much muscle memory that we forget how hard it actually is to ride anything at 45+mph
In my experience the channel are pretty stable if the system is properly configure, this trucks are different and ride a bit higher that other trucks.
The stability issues are not due to the truck shape or kingpin position, mostly is a combination of factors that contribute to this, specially this 3 :
1- Rider:
The more experienced a rider is on regular trucks the more subconscious habits his body has and at higher speed this tendencies are what control your behavior. So before gunning it on channel truck try to practice, practice.
2 - Suspension:
The spring damper combination is it crucial since here is where any starting vibrations will get amplify or neutralize, personally I use softer springs and softer vertically hollowed damper for a stable ride at high speed and proper turning at low speed.
3 - Bearing seat and axles tolerances:
This is where the 90% of the bulk of issues and bad Rep for the channel truck originates.
The channel truck is most widely use on big pneumatic tires with a radius ranging from 3.25 inches to 4inches this wheels are unbalanced from factory, add to this the following bearing and axle issues:
Too big of a gap between axle and inside diameter of the bearing.
Inside the ball bearings tracks with too much play.
Too big of a gap between Hub and the bearing outside diameter.
All this contributes to a crazy vibration at the center and the pneumatic wheel will amplify the vibration that then will travel to the springs causing this to fall into a chaotic vibrating state.
At the end it does not matter which truck you are using if your wheels are wobbling too much.
@Deckoz Try not to immediately discount our understanding. I’m an engineer with over a decade of experience in robotics, but I’ve been pretty forthright in my gaps in knowledge or experience and will always try to be. You are probably my single most bookmarked poster on these forums, so please don’t think that I discount what you’re saying. We’re all trying to learn here.
I can comfortably break 35+ on my current channel truck setup, without any concerns of stability. I’m not saying the same setup can go 50+. I don’t even want to go that fast. I’m just curious what it would take to do so.
We still haven’t even defined what ‘high speed’ is.
@deckoz here is a pretty picture to help you understand where the pivot axis is in relation to the truck axle. And in case you are wondering almost everyone with a decent setup is going to have some positive rake on the front and rear of their board. You would need a neg rake to have any of the caster effect you seem to think is taking place.
I’m a heavy guy with a 17 Ply trampa, top speed of board is 30 mph. Had one serious crash due to wobble when going down hill. The road was concave/gravel. After the crash noticed general instability with bumbs and finally figured out the riding characteristics changed drastically compared to when I first used the board. Needed to tighten the springs (and thus dampers) 5 turns to get the original stiffness. Lesson learned, stuff softens up.
Other than things softening up, the deck indeed acts like a loaded spring if you ride it incorrectly. More like snowboarding after fresh snow with tons of little hills, gotto ride low & absorb all bumps with your legs or it will start bouncing / you loose control.
I think that’s the most important statement in your post. BUT I think you’re ignoring one very important thing.
Wheel size will greatly affect castor. The larger your wheels, the greater the effective axle offset. Because any side loads aren’t at the wheel center, but are instead at when wheel edge.
While I agree that castor effects the ride control, I don’t think that a SINGLE esk8 has negative castor right now.
The contact patch of the wheel should line up with the pivot axis (0 castor), or it should be behind the pivot axis (negative castor). This allows the truck to move purely from rider input. It will not move at all from side loads like carving hard.
Our standard trucks will try to continue turning when the rider attempts to turn due to the sideways friction of the wheels. It requires the rider to “fight” the turn, or at least put in minimal effort into turning while in high speed. That fighting is what causes speed wobbles, hence instability.
With a 0 castor or positive castor truck you’d have no additional forces adding to the turn, or even forces fighting your turn. Which for high speed would help significantly.
Go ahead and try it, hold your board and push sideways on the contact patch. It’s gonna turn the truck in the direction that would cause additional sideways friction from a harder carve.
All of the above is just a personal anecdote, but I’m going to have to agree with @Deckoz here.
EDIT: I just found the design for channel trucks. I can see exactly why these would be inherently unstable. You definitely need dampening for oscillations as side loads will simply cause constructive interference.
Not sure if you are special or just don’t like being wrong, I like to think it is the latter. It does not really matter where the king pin is along the pivot axis. The only real difference is the amount of rake on channel trucks. You continue to misunderstand how trucks function and seem to think a caster effect is desirable. To be honest a lot of us are really surprised by your comments.
And again you are confusing truck walk with caster effect.
100% layout and description. @deckoz very few people close their eyes and see complicated applied vehicle dynamic forces at work, glad to know you. The current channel design is flawed, needs redone and tailored to compliment a driven axel. What’s out there is not great, but it could be. Build it and “Bring it to the HILL”
I guess @kaly and his crew are freaking magicians. You two really need to open your eyes, people are regularly pushing speeds above 40 mph on channel trucks.
