Electric cyclekart

[erajomppa]

I have built 2 electric bikes before, but it has always been my dream an electric vehicle, with 4 wheels.
Recently when looking for inspiration I came across with the term "Cyclekart". I suggest you google it for more accurate information, but I'll just say: They look brilliant! Gorgeous, inexpensive, fun, and simple structure. They are off course meant to be built with 200cc petrol engine. They would be perfect in my opinion for a electric conversion!

So I'v decided to base my electric vehicle on a cyclekart design, with a few main differences and similarities.

Similar:
17" wheels (17" rims, with 2.25" tire, the total wheel diameter is 560mm).
Simple frame design. 3" x 1" steel tubes.
Leaf springs front suspension (*)
Single wheel drive and braking (**)

Differences:
Max. width 800mm (instead of the 38" track of the standard cyclekart). more on this later...
Wheelbase will likely be slightly shorter to try and maintain the cyclekart-look.
(*) springs are >150€ shipped from USA, cant find them locally. Might sacrifice suspension...
(**) I will add a mechanism that will mechanically lock the other rear wheel to the axle when needed (drifting on gravel/ice etc).

Dry weight will probably be near 100kg, much is yet undecided. I weight 90kg, thats total of nearly 200kg to pull.

For the electrics:
QSmotor 3000W 138 70H (https://endless-sphere.com/forums/viewtopic.php?f=30&t=93627)
Votol EM-150 controller, probably will buy this together with the motor.
20s10p LiPo batteries (around 2,2 kWh)

I would want to aim for the max speed of no more than 60kmph (37mph). I dont care for super speed, but rather high acceleration and sporty feel at slower speeds. This would require high reduction rate, maybe 1:8 ? I haven't made exact calculations yet. I would prefer to use chain instead of pulleys.

I also want to be able to limit the max power to 1000W so that it can be legally driven on the bicycle lane as a light electric vehicle. (max 1000W, max 25kmph, max 800mm width). But I do WANT to get FULL POWER when I want to go off the main roads.
I might do this be running the throttle input through an arduino and measuring the power from battery and therefore limiting the speed and power with a flip of a switch etc... I doubt there is such functionality in the VOTOL EM-150 controller (prove me wrong please )

I have the most important part already taken care of, which was asking my wife for the permission for the project :wink:
I have not come across any electric conversions of this sort, so with nothing to blatantly copy from I though it best to run my idea through the mind of other EV enthusiasts before I actually start ordering the parts.

Attached are some pics of cyclekart, so you know what sort of vehicle I'm talking about.

 

[pdcm]

Ahh very nice. I've been working on traditional cyclekart on and off for a while, but recently having had solar panels installed on the house I've been thinking about ditching the GX200 ICE engine in favor of trying an electric build, so I'll be watching your progress with interest 8)

 

[erajomppa]

I would want to aim for the max speed of no more than 60kmph (37mph). I dont care for super speed, but rather high acceleration and sporty feel at slower speeds. This would require high reduction rate, maybe 1:8 ?

Hmm. I did the math. Turns out the required reduction would be aproximately 1:10.5
That would require a HUGE rear sprocket and TINY front one. I sent a question to the manufacturer to see how small sprocket they can supply with the motor.

I don't think it would be impossible to have 2-stage gearing reduction, but I'm not a fan of the idea...

Ahh very nice. I've been working on traditional cyclekart on and off for a while, but recently having had solar panels installed on the house I've been thinking about ditching the GX200 ICE engine in favor of trying an electric build, so I'll be watching your progress with interest 8)

Cool to hear. I have no experience in actual cyclekarts, but the concept of them sounds amazing. I doubt there are many (if any...?) here in Finland. I will be using cyclekarts as my main source of inspiration, but the fact that I will want this to be road legal (width < 800mm) will force me to not be truly loyal to the concept.

But if you have some advice about the cyclekarts that would translate to my build as well, I will welcome it with open arms

 

[pdcm]

Cool to hear. I have no experience in actual cyclekarts, but the concept of them sounds amazing. I doubt there are many (if any...?) here in Finland. I will be using cyclekarts as my main source of inspiration, but the fact that I will want this to be road legal (width < 800mm) will force me to not be truly loyal to the concept.

But if you have some advice about the cyclekarts that would translate to my build as well, I will welcome it with open arms

Less than 800mm? Interesting. I'm not sure how much help I might provide as there are probably quite a few things you'll have to do differently in order to make it road legal. I'll definitely speak up if I can though.

I was never really intending to participate in any great Cyclekart meetups or racing, I was just doing it for the fun of it and I'm actually straying from the default ideas myself, trying to narrow mine down to under 900mm so it will to fit through a workshop doorway. I still don't have a body concept either, just the frame and some driveline bits.

 

[John in CR]

If you want it peppy to 60, then you need to plan on an actual top speed of at least 70. Acceleration tapers off drastically near the top end, especially with wind resistance increasing geometrically and being a big factor above 30kph.

 

[erajomppa]

If you want it peppy to 60, then you need to plan on an actual top speed of at least 70. Acceleration tapers off drastically near the top end, especially with wind resistance increasing geometrically and being a big factor above 30kph.

Good point, actually I don't care about the top speed at all. What I want is some wheelspin when I punch the pedal on a corner at some loose surface.

Watched one video where they tested the top speed of a cyclekart: 73kmph.
They got 200cc petrol engines, that produce 6kW or something in the ballpark or that.
I don't need to go any faster than those do. You can hurt yourself really bad at those speeds in a homemade vehicle.

I thought that aiming for a gearing reduction that would result in a theoretical top speed of 60kmph SHOULD be okay for my application. But I don't have anything other than my own hunch about that. Any and all thoughts on the subject is appreciated.

 

[Dauntless]

Cyclekarts started with an engine rated at 6.5hp, whether it delivered I wouldn't know, but they claimed the performance you're talking about. So you would think of a 5,000w motor. When you hear of a faster cyclekart they are probably using a more powerful engine, just a 125cc dirt or street motorcycle engine would clobber the traditional Honda engine. I think you're facing some disappointment with a 3,000w motor.

This will be heavier than an electric bike, the performance at 1,000w might be, oh, equivalent to a 200w bike. I think you would be very unpopular out on the road and getting in the way with that thing.

 

[Grantmac]

Keep in mind that the QS3000 peaks at 15kw.

 

[John in CR]

Keep in mind that the QS3000 peaks at 15kw.

That's input, not output, and it's likely to have heat problems with the repeated accelerations on a kart track with a controller setting of 15kw peak input. I do agree though that it's probably a good choice instead of the quite expensive drone motor for this application as long as it's geared down enough and he isn't too big and/or make the kart too heavy.

 

[Grantmac]

Keep in mind that the QS3000 peaks at 15kw.

That's input, not output, and it's likely to have heat problems with the repeated accelerations on a kart track with a controller setting of 15kw peak input. I do agree though that it's probably a good choice instead of the quite expensive drone motor for this application as long as it's geared down enough and he isn't too big and/or make the kart too heavy.

Being both traction limited and not having any major hills to climb should keep things under control. Also limiting power to peak around 5-6kw which should be lots more than the ICE option.

 

[John in CR]

Keep in mind that the QS3000 peaks at 15kw.

That's input, not output, and it's likely to have heat problems with the repeated accelerations on a kart track with a controller setting of 15kw peak input. I do agree though that it's probably a good choice instead of the quite expensive drone motor for this application as long as it's geared down enough and he isn't too big and/or make the kart too heavy.

Being both traction limited and not having any major hills to climb should keep things under control. Also limiting power to peak around 5-6kw which should be lots more than the ICE option.

That would end up at only 4-5kw peak output, which even geared for only 60kph would be too tame for an adult. I'd want to know the motor's phase to phase resistance to determine its current limits. Get controller with plenty of headroom in terms of current. Then if it runs too hot add some ducted fans to the mix to force cool the motor and controller. Karting races are relatively short, so wasting some energy on fans is no big deal, and the added noise might be a plus in terms of cool factor, pun intended.

 

[Hillhater]

^^^John..
This is a “cyclekart”, not a “Go Kart”, and reading between the lines, the OP is not planning on any racing.
60kph in a cyclekart is plenty to get the adrenalin going ! ...the CofG is way too high. :wink:

 

[Grantmac]

Yeah they have purposefully low traction to keep things fun at lower speeds.