I beliven the higher KV motor will actually draw more power because brushless motor efficiemcy goes up as motor speed goes up. The higher KV motor will be at a less efficient rpm for its KV.
But at 25+ you have wind drag so even if the higher kv might have a sweet spot in the 40 mph range it would lose a lot of that efficiency to wind.
What are we doing for front truck with the XL? TB218?
The Evolve supercarve axle length is also 305mm but it’s a double kingpin instead of a reverse kingpin
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Another pair of XL’s!
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That option has not been totally discounted, though with the kv change it’s much less likely now that I will go that route
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haha what was I thinking! 
But I can’t 4wd my daily ride, I have a mixed commute and my tiny nerd arms cry at the thought of 30lb.
Maybe surfrodz tkp, that was available as bunde on carvon’s site, and psychtiller lists longer ones. Don’t know how I feel tkp though
Ha ha ha, you too?
Are any other axles 305mm (besides Carvon SD XL and Evole Supercarve) or are we talking about mismatches here?
Correct. What may be happening though is that the power/torque/rpm condition to push you at said speed is not within the optimal range
I meant it as the power required to push you will always be the same. AKA the power output from the motor. My bad.
I kind of agree. If you lower the kV too much then the internal resistance rises and you’ll be producing lots of heat.
You lose that efficiency regardless of the motor. All that really matters is the torque/rpm condition. D = 1/2 * rho * v^2 * cd *A Rho = Air density V = velocity Cd = coefficient of drag which is roughly 1.3 for a human in a stand up position. A = frontal area.
As I said there are a lot of variables so to find the most efficient setup, we would need to dyno the motors and get some torque/rpm curves
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What? Are you sure the xl is using V2.5 motors? I thought the V2.5 motor was 149kv and not 85kv.
Yes …v2.5 are 85kv . V2 are older and had higher KV.
Sounds right. I’ve been getting 36 actual on a very regular basis on RWD belts at 90mm in a 16/32. torque on the top end is likely roughly similar between a belt rwd and a direct awd and wind resistance as you approach the “sound barrier” (what we’ve been calling 40mph for esk8) gets real stupid. took a belt awd on superflys to get a 220 pound dude with a 15 pound backpack over 37mph casually.
We usually have to tuck to get over 40, and of course there’s jake’s loaded up tronix sled which is running 13S right now on focboxes and broke 41 last night on shaved MBS wheels.
Anyway my point is you’ll definitely see between 35 and 39 on that which is mad respectable for a board anyone can own.
The issue being that you’re basically never in the efficiency zone when you want to be. yeah that’s an issue with hubs and directs. I think directs have a much clearer path of evolution for moving past that issue obviously than hubs do and i think throwing more iron at the problem is the best way to go for the moment. External motors can shrug off more heat much easier so efficiency effectively moves from being cake, as it is in a hub where the heat has no where to go, to be an icing when the heat can just flow off into the air or the hanger and not cause so many issues.
I’m always going on and on about belts but the truth is i want direct drives to not only succeed but take over. Mad respect for the work Jerry is doing here and has been for a number of years now.
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Yep!
Agreed. That seems to be everyone’s solution right now. Not enough power? BIGGER MOTOR/BIGGER BATTERY It’s stupid simple and way less time consuming.
What would be cool to see is motor size calculators like the ones they have for RC airplanes. It is much easier to characterize the power required from a propeller cutting through air than that of a human being riding on a plank at 40mph though… Probably not actually but I’m not about to do the math hahaha.
Yeah, the only problem I see with direct drives is the inability to quickly change your setup from a speed drive to a torque drive without having to get a second set of motors.
Having wheel pulleys of different sizes for different riding styles is too easy!
also being able to deliberately set your efficiency zone to a commuting speed of say 25mph is a win for range enthusiasts. That’s right around where my sensored 6355s start to sing.
That sort of thing shouldn’t be a problem for hubs or directs, just set your KV. The conflict comes when you want that AND you want to be able to start fast from a standstill and race hard and defeat wind resistance at the top end or a number of other conflicting agendas. that’s when you just start throwing more copper and iron at it until it works well and doesn’t pop chips anymore.
Beltd have a whole different set of issues just past the sound barrier. We’re already seeing the diminutive returns of larger wheels and smaller pulleys. You lose the torque you need to overcome the wind, and if you change it up you loose the speed. This is where direct drives could really shine.
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107mm Superfly’s =speed …5 mins later…83mm Flywheels=Torque
Yes! Dual V3–>Quad V3–>Quad V4XL
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Isnt the min wheel size 90mm?
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Well per Jerry’s recommendations yes, 90mm is the smallest you should use, but I have 83mm fllywheels and they work awesome on smooth roads with no debris. The torque and acceleration increase compared to the 107’s is huge.
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16/32 on kegels or popocas seems pretty idea for most cases. i feel like anything over 90 starts to feel tuned more for high end and less for general haul-assery. 97s are ok, 100mm MBS are ok if you mind the ratios but the superflys… man… they’re almost too damned big in my opinion. I don’t know.
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