My first ebike build: custom-built KMX-based electric velomobile

[The Toecutter]

I use a $10 flip phone. It's my only camera.

 

[amberwolf]

If you want a better camera, I have a few here I don't use anymore, so I could send you one for the cost of shipping from Phoenix, AZ. If it turns out to be cheap enough to ship, I could cover that, too.

I think they all use memory cards of one kind or another, so if you have a card reader on the computer you can read them from that; if not they may be readable via USB cable--I can check that to see if it works on Windows10 or Windows Vista or Linux (I forget which version) (the only three working computers I have at the moment).

 

[The Toecutter]

Thank you. I'm generally averse to buying newly manufactured things, but would gladly take a used but working item. As long as the shipping is reasonable, I'll take one.

 

[amberwolf]

Once I pack it up and verify shipping cost I'll letcha know. Best guess is still around $10 or so.

I also tend to get used stuff instead of new, I guess it's the Haibane in me.

 

[uPET]

I've seen steering dampers being sold by several sellers in China for the KMX. Do you think they are any use, or just extra dead weight?

 

[ZeroEm]

Debated on a damper for my trike, have tuned the front end where don't really need one. It would not hurt my trike outside of adding something else and more weight. If you have issues then it would not hurt.

 

[The Toecutter]

I've seen steering dampers being sold by several sellers in China for the KMX. Do you think they are any use, or just extra dead weight?

Without adam333's front suspension, at anything over 20 mph it handles very twitchy. A damper would probably help here.

With front suspension, the trike is a lot less nervous and I've noticed it is stable at 60+ mph speeding down a hill, and I don't have a steering damper.

In either case, make sure you have a very slight toe-in. No more than 1/8" is needed.

 

[ZeroEm]

The Toecutter where did you get your frame or was it a full trike?

 

[The Toecutter]

The Toecutter where did you get your frame or was it a full trike?

I bought a framekit from Utah Trikes in 2016. They no longer offer it. It was only $650. You had to provide the crank, rear wheel, rear freewheel or cassette, tires, tubes, shifters, front/rear deralleurs, brakes, cables, and levers. The stock front wheels it came with were not well built and kept breaking spokes, so I had a bike shop rebuild them on some Velocity rims.

 

[ZeroEm]

Have been hunting a frame for couple of years. Guess the only way is get a full trike and rebuild it.
Could just find another robust frame. Love my trike but don't think it would handle more weight and speed, would like to keep it the same. Then there is these Titanium frame. Don't like how high but may make a good peddle car frame.

 

[The Toecutter]

You're going to need suspension, at least front or rear suspension, but preferably full suspension, if you want it to handle more weight and speed. The ones you linked will have center of gravity issues which adversely effect the vehicle dynamics. Going to a smaller rear wheel coupled with extending the wheelbase by adding a rear suspension on my KMX was perhaps one of the best things I did for its cornering capabilities. No longer can I easily make it go up on two wheels by cornering hard at speed, as now it wants to slide instead of tip, which is exactly what I'm after. More lateral Gs and less risk of roll over. Sure, I'm a few inches lower, and harder to see, but the fact that other people choose to waste their money on oversized gas guzzling vehicles and the fact that the auto industry deliberately builds them bigger and taller is not in my control. THEY are the safety risk, and not me. Which is why I'm building a roll cage.

Have been hunting a frame for couple of years. Guess the only way is get a full trike and rebuild it.
Could just find another robust frame. Love my trike but don't think it would handle more weight and speed, would like to keep it the same. Then there is these Titanium frame. Don't like how high but may make a good peddle car frame.

 

[ZeroEm]

I agree with all your points of view. This is why i'm looking for a frame or used trike but it needs to be sturdy. Full suspension is a must. Looking forward and wanting to get away from cars, even EV's. Want something with maybe two seats (inline not side by side) to go 5-10 miles at no more than 28 mph. Need room for hauling stuff. Want it covered. Live a Pebl.

My trike slides the front wheels, have never been on two wheels. Have rear suspension and wanting front. It's 4" off the ground and my battery is mounted between the front wheels under my legs. Don't think the ICE trike front suspension is enough. Like Addams, think it can be adapted to other trikes. like that it's makes the track wider.

The ti's would need to be reworked, suspension, batteries mounted below the frame with some type of skid plates and the seat is two up right for me. More my back than areo. Have been leaning towards 24" or 22" wheels will do 20's but hard to spoke wheels unless find a solid wheel or maybe go to moped or motorcycle wheel.
Quit using gas over 3 yrs ago. My lawnmower is electric too.

by The Toecutter » Dec 23 2022 9:33am

You're going to need suspension, at least front or rear suspension, but preferably full suspension, if you want it to handle more weight and speed. The ones you linked will have center of gravity issues which adversely effect the vehicle dynamics. Going to a smaller rear wheel coupled with extending the wheelbase by adding a rear suspension on my KMX was perhaps one of the best things I did for its cornering capabilities. No longer can I easily make it go up on two wheels by cornering hard at speed, as now it wants to slide instead of tip, which is exactly what I'm after. More lateral Gs and less risk of roll over. Sure, I'm a few inches lower, and harder to see, but the fact that other people choose to waste their money on oversized gas guzzling vehicles and the fact that the auto industry deliberately builds them bigger and taller is not in my control. THEY are the safety risk, and not me. Which is why I'm building a roll cage.

 

[uPET]

I agree with all your points of view. This is why i'm looking for a frame or used trike but it needs to be sturdy. Full suspension is a must. Looking forward and wanting to get away from cars, even EV's. Want something with maybe two seats (inline not side by side) to go 5-10 miles at no more than 28 mph. Need room for hauling stuff. Want it covered. Live a Pebl.

My trike slides the front wheels, have never been on two wheels. Have rear suspension and wanting front. It's 4" off the ground and my battery is mounted between the front wheels under my legs. Don't think the ICE trike front suspension is enough. Like Addams, think it can be adapted to other trikes. like that it's makes the track wider.

The ti's would need to be reworked, suspension, batteries mounted below the frame with some type of skid plates and the seat is two up right for me. More my back than areo. Have been leaning towards 24" or 22" wheels will do 20's but hard to spoke wheels unless find a solid wheel or maybe go to moped or motorcycle wheel.
Quit using gas over 3 yrs ago. My lawnmower is electric too.

What are your thoughts on not having a frame at all, but having a monocoque body which everything bolts to? If you are going to have a protective body anyway, would it end up being lighter?

 

[ZeroEm]

by uPET » Dec 25 2022 2:40pm

ZeroEm wrote: ↑Dec 23 2022 9:54am
I agree with all your points of view. This is why i'm looking for a frame or used trike but it needs to be sturdy. Full suspension is a must. Looking forward and wanting to get away from cars, even EV's. Want something with maybe two seats (inline not side by side) to go 5-10 miles at no more than 28 mph. Need room for hauling stuff. Want it covered. Live a Pebl.

My trike slides the front wheels, have never been on two wheels. Have rear suspension and wanting front. It's 4" off the ground and my battery is mounted between the front wheels under my legs. Don't think the ICE trike front suspension is enough. Like Addams, think it can be adapted to other trikes. like that it's makes the track wider.

The ti's would need to be reworked, suspension, batteries mounted below the frame with some type of skid plates and the seat is two up right for me. More my back than areo. Have been leaning towards 24" or 22" wheels will do 20's but hard to spoke wheels unless find a solid wheel or maybe go to moped or motorcycle wheel.
Quit using gas over 3 yrs ago. My lawnmower is electric too.

What are your thoughts on not having a frame at all, but having a monocoque body which everything bolts to? If you are going to have a protective body anyway, would it end up being lighter?

Like the idea but i'm limited on what I could do. Could start with this.

 

[The Toecutter]

Monocoques are a lot of work and you have to be very careful to design it to where you will not have packaging or clearance issues. If you screw it up, you might have wasted thousands of hours of work.

I'm sticking with body on frame designs for the near future just to get all the dimensions sorted out. THEN I can build a monocoque based off of that when I know precisely where everything is going to fit.

A monocoque is extremely strong and I could lose 10-20 lbs over a comparably sized body-on-frame trike, while increasing torsional rigidity. This is 10-20 lbs more features the bike can fit without going over that 100 lb weight limit I imposed.

 

[uPET]

I see your point. I have gone around in circles for years trying to decide what to do and in the end not built anything. Having a shell on a frame gives excellent flexibility, but I worry how easy it is to keep the weight under control. So many of these designs I've seen have rapidly ended up at 70Kg or more.

I suppose another option as a kind of half way house would be the space frame, but would that give any benefit?

 

[ZeroEm]

My main goal supporting weight then weather. I'm close to 300lbs now so 70kg while supporting up to 250kg of total weight would be ok. Don't really plan on doing 60kph or faster. Have a Titanium frame back in my head again. Don't see any KMX kits around and if going to buy a complete trike might as well be a Ti trike but they need a lot of mods. Suspension would be first thing.

 

[The Toecutter]

I see your point. I have gone around in circles for years trying to decide what to do and in the end not built anything. Having a shell on a frame gives excellent flexibility, but I worry how easy it is to keep the weight under control. So many of these designs I've seen have rapidly ended up at 70Kg or more.

These bikes that end up so heavy often have heavy battery packs to accommodate a large frontal area and subsequent poor aerodynamics compared to what is typical of a velomobile, and are built for heavier/larger riders, while being very feature-laden and luxury-oriented. And they may even be safer in a collision than many cars of 40+ years ago by being overbuilt.

So much about these vehicles can become extraneous and weight-inducing if one isn't careful in how it is designed.

I suppose another option as a kind of half way house would be the space frame, but would that give any benefit?

If designed correctly, both weight reduction and more stiffness when compared with a body on frame of similar size/application, but not to the extent of the monocque. It should take significantly less design time and impose less design variables than a monocoque, but won't give the full mass and stiffness benefit that a monocoque would.

The Mosquito velomobile appears to be a sort of hybrid between a space-frame and a monocoque and is really neat.

My main goal supporting weight then weather. I'm close to 300lbs now so 70kg while supporting up to 250kg of total weight would be ok. Don't really plan on doing 60kph or faster. Have a Titanium frame back in my head again. Don't see any KMX kits around and if going to buy a complete trike might as well be a Ti trike but they need a lot of mods. Suspension would be first thing.

uPET knows a guy who might be able to sell one to you. But it may not be able to handle your weight. Mine has a rider weight limit of 225 lbs mentioned in the instructions/specs for "offroad" riding, and 300 lbs for on-road riding. The spindles are the weakest part of the chassis. Carrying 45 lbs of suspension/body/EV parts, plus my 150 lbs, plus 15 lbs of tools/food/water, put it close to that limit. I had only 15 lbs to spare before overloading it in the "offroad" spec(which is what I assume is needed due to the condition of the roads where I am located), and did so when I'd make grocery runs or haul heavy items. Even while not exceeding the loading limit, a steering spindle did fail on me at 40 mph due to hitting a deep 7" pothole, albeit that spindle was already cracked from ramping a racoon at 40 mph a month prior that ran out in front of me at night.

The KMX is fairly stout, but it has its limitations. My frame has over 70,000 miles since 2016. It has developed inside surface rust of a small fraction of a millimeter in width that I first discovered after cutting the frame apart to install the rear shock, but looked perfectly fine outside on that section cut, with the paint intact. The KMX frame is repairable with rudimentary steel welding skills. Titanium, OTOH, is a lot more difficult to weld and requires specialized equipment, in the event you ever need to repair it.

 

[ZeroEm]

y The Toecutter » Jan 04 2023 1:36am

ZeroEm wrote: ↑Jan 03 2023 8:00am
My main goal supporting weight then weather. I'm close to 300lbs now so 70kg while supporting up to 250kg of total weight would be ok. Don't really plan on doing 60kph or faster. Have a Titanium frame back in my head again. Don't see any KMX kits around and if going to buy a complete trike might as well be a Ti trike but they need a lot of mods. Suspension would be first thing.

uPET knows a guy who might be able to sell one to you. But it may not be able to handle your weight. Mine has a rider weight limit of 225 lbs mentioned in the instructions/specs for "offroad" riding, and 300 lbs for on-road riding. The spindles are the weakest part of the chassis. Carrying 45 lbs of suspension/body/EV parts, plus my 150 lbs, plus 15 lbs of tools/food/water, put it close to that limit. I had only 15 lbs to spare before overloading it in the "offroad" spec(which is what I assume is needed due to the condition of the roads where I am located), and did so when I'd make grocery runs or haul heavy items. Even while not exceeding the loading limit, a steering spindle did fail on me at 40 mph due to hitting a deep 7" pothole, albeit that spindle was already cracked from ramping a racoon at 40 mph a month prior that ran out in front of me at night.

The KMX is fairly stout, but it has its limitations. My frame has over 70,000 miles since 2016. It has developed inside surface rust of a small fraction of a millimeter in width that I first discovered after cutting the frame apart to install the rear shock, but looked perfectly fine outside on that section cut, with the paint intact. The KMX frame is repairable with rudimentary steel welding skills. Titanium, OTOH, is a lot more difficult to weld and requires specialized equipment, in the event you ever need to repair it.

My welding days are over. Would take it to someone that could do the work. Might just get a Peble or the like, just want something to make store runs. Will keep my 3.5yr old Performer for longer faster rides, if it starts breaking then will get another one. It's only rated for 260lbs. Don't drive off curbs, have hit a few pot holes at 30mph. Well keep reading and studying.

 

[The Toecutter]

You might have difficulty finding someone who can weld titanium, and if you do, you're going to pay very dearly for it.

 

[ZeroEm]

by The Toecutter » Jan 04 2023 8:34pm

You might have difficulty finding someone who can weld titanium, and if you do, you're going to pay very dearly for it.

Metal shop 5mi from me that sales Titanium, before I commit better see if they know someone.

 

[The Toecutter]

Metal shop 5mi from me that sales Titanium, before I commit better see if they know someone.

I'd love to build my own space frame from titanium. Its strength makes it possible to have a fully-built "glider" with suspension/wheels/tires/axles/brakes/body that are robust enough for triple digit speeds and some minimal collision protection, with everything present except the EV drivetrain/batteries, all weighing in around 65 lbs. That leaves a lot of room for batteries before reaching 100 lbs.

The goal is a miniaturized electric Formula SAE car with velomobile aerodynamics, pretending to be(and also functional as) a "bicycle". The main bottleneck is a lack of modern DD hub motor tech being represented in the hobbyist market, because such a vehicle is just barely possible still using steel, with the tradeoff of going to a smaller battery, but the best hub motor I can find for the application is the Leafbike, limiting my horsepower output. I could use a middrive, but that opens up more unwanted issues of complexity and maintenance that goes against the purpose of this vehicle. A former member of this site built such a vehicle as described but with a 6kW middrive, but I promised I wouldn't share his private videos of its antics.

 

[ZeroEm]

by The Toecutter » Jan 07 2023 1:51pm

ZeroEm wrote: ↑Jan 06 2023 8:13pm
Metal shop 5mi from me that sales Titanium, before I commit better see if they know someone.

I'd love to build my own space frame from titanium. Its strength makes it possible to have a fully-built "glider" with suspension/wheels/tires/axles/brakes/body that are robust enough for triple digit speeds and some minimal collision protection, with everything present except the EV drivetrain/batteries, all weighing in around 65 lbs. That leaves a lot of room for batteries before reaching 100 lbs.

The goal is a miniaturized electric Formula SAE car with velomobile aerodynamics, pretending to be(and also functional as) a "bicycle". The main bottleneck is a lack of modern DD hub motor tech being represented in the hobbyist market, because such a vehicle is just barely possible still using steel, with the tradeoff of going to a smaller battery, but the best hub motor I can find for the application is the Leafbike, limiting my horsepower output. I could use a middrive, but that opens up more unwanted issues of complexity and maintenance that goes against the purpose of this vehicle. A former member of this site built such a vehicle as described but with a 6kW middrive, but I promised I wouldn't share his private videos of its antics.

The formula car aerodynamics is limited by rules. You can make it better. Used to look at TRUBLU Racing trikes down under.


This is on a Spaceframe, like roll cage. Low speed albet.

Don't think the full trike needs titanium, rear forks, suspension and the front suspension, crossbar.

 

[The Toecutter]

The formula car aerodynamics is limited by rules. You can make it better. Used to look at TRUBLU Racing trikes down under.

This is on a Spaceframe, like roll cage. Low speed albet.

Don't think the full trike needs titanium, rear forks, suspension and the front suspension, crossbar.

I only mentioned Formula SAE car as a basis for comparison regarding this vehicle's acceleration and cornering dynamics. It definitely wouldn't be built to Formula SAE specifications or conform to SAE rules. It would simply be a small, go-fast machine that can pass as a "bicycle".

I've seen those TruBlu trikes. They are a partial influence on the concept I've come up with. But they don't have suspension, and for my application, that is an absolute necessity. The strength of its roll cage is "good enough", because when wrapped with a carbon fiber monocoque, the entire structure could be more crashworthy/safe than most 40+ year old cars.

If I can keep it very near or under 100 lbs, then it will be very pedalable on a disabled motor.

Titanium is not a necessity for what I want to do, but it has the potential to free up a lot of extra mass for more batteries and even stronger mechanicals/wheels/tires/axles.

 

[ZeroEm]

It would simply be a small, go-fast machine that can pass as a "bicycle".

Some bicycles here at ES would be hard to pass.
Have become interested in 0-30mph times and how fast is fast.

It may sound like i'm wanting two different things. Have my trike now which will keep it in shape and play with the speed and power and distance. Then want a store runner with weather protection and does not need to be low or reclined for my back. It can be heaver, slower and user friendly. My trike now is not user friendly to most.

Turned up the power and let my brother ride it once, he will not get back on it. Direct steer takes some practice.

My trike is 35lbs have around 35lbs of Ebike mods added on. Figure it's 70-75lbs now. Even with the motor in the rear hub have lifted the rear tire off the ground going down a steep hill with a stop sign at the bottom. Seems the faster you ride the heaver the trike needs to be! Just a thought.