The Toecutter
Power poster
- Joined
- Feb 8, 2015
- Messages
- 1,676
My parts to convert a trike into a quad arrived over a week ago.
I really like the KMX as a build platform. I've made an EV out of one already and would like to keep it operational. I have a kit that would allow for me to convert it into a quad, but I'd rather build another one than change a good, functional one thus removing it from use for an indeterminate period(I have limited time to work on it, yet use it regularly for transportation and thus want to avoid taking it apart).
My overall plans for this quad are as follows,
AWD streamliner with the seat reclined as far back and as low as possible while still being able to see over any bodywork that would be around my pedaling area is the goal. With the seat reclined far back, it will force my boom in as far as it will go, as if I was a very short rider. I'd need short 110mm crankarms that allow fast cadence to assure proper ground clearance for my heels over the road(I want at least 5"). I'm thinking I will have the top of my helmet somewhere around 800mm off the ground, which will keep this very low with a racecar-like center of gravity, and keep the frontal area low in spite of being a quad. The goal is a weight distribution somewhere around 45F/55R.
Regarding shape, it will be much like an Auto Union Type C streamliner viewed from the top and front, except with a big front bulge in the center of the front to accommodate my pedaling. Unlike the Type C, the front wheels will likely be fared on top and exposed for the bottom 2/3 of the wheel(think 1953 Alfa Romeo Disco Volante Coupe), since I need to be able to turn. The rear wheels are going to be fully faired on the outside and mostly fared inside(inside, there will be clearances cut to allow differential and subframe assembly to move up and down with the rear suspension, and spandex boots will be made to maintain aero while allowing movement). The rear of the vehicle will be a downforce increasing Venturi tunnel doubling as a rear diffuser(see 2025 Renault Folante concept for what this could look like from behind), which accepts air from the vent holes in the rider cabin, air initially entering the vehicle through the stagnation point air intake used to cool the rider as well as any open windows or raised windscreen. Part of the plan would include a full rollcage and a gullwing door, with crumple zones. 16x1.5" DOT rims and 16x2.25" Mitas MC2 tires all around.
Gearing will be a 11-34T DNP Epoch in the back with a Schlumpf HS triple up front, with a cadence sensor for PAS. The limited required chainwrap capacity should allow for me to get away with using a short cage rear derailleur in order to minimize ground clearance issues while retaining a wide gearing range.
I'm considering making a rack-and-pinion steering for it, where I can turn the wheels maybe 20-30 degrees in each direction with a 50-70 degree turn of the steering wheel in either direction, using a butterfly steering setup, with brake levers and trigger shifters placed on this system. This will facilitate allowing most or all of the front wheels to remain fared by the shell design while keeping frontal area low, at the expense of having a larger turning radius.
The EV system would be a 6kW Cyclone middrive running 10kW peak driving the rear wheels, with Grin All-Axle 3T wind front hub motors at 6kW peak in each front wheel. This would be powered initially by a Phaserunner for each motor at reduced power(maybe 4 kW each, 90A to rear motor, 45A to each front motor) and later by an ASI bac2000 for each motor at full power, the three controllers all run by a CA3 with a high current shunt. The battery would be a 20S6P pack of Molicel P50b or whatever are the most energy dense cells I can find that make the requisite power by the time I am ready to make the pack.
Solar panels would cover as much of the body as possible. Maybe up to 400W worth of them.
Since KMX are no longer being made, and since the spindle is the weakest mechanical part of the design, I am heavily considering an alternative front suspension to the one I used and Adam Roy designed:
UTCustom KMX Front Suspension Upgrade
UTCustom Ackerman Compensator Steering Upgrade
UTCustom Revolution EC34/30 Headset for Sunseeker Trikes (each)
This alternative design uses spindles from a Sunseeker, which are readily available. Only 1.25 inches travel, not as wide of a front track(advantageous in my case for aero, since by going quad I don't need a massively wide front track to corner at high Gs), but unfortunately they are not gas shocks ad I will lose the 3 degrees negative camber.
I think they are still compatible with these brakes, however:
https://kmxsuspension.epizy.com/Trike Twin hydraulic disc brake.html
And I'd install a gas shock in the rear also, so that I have a full-suspension quad.
All I have to do is find another KMX to butcher.
It will cost me about $5k all in just to build the functional but unmotorized quad, and $7k to complete it to the aforementioned specs.
I'd prefer to have replacement OEM 3rd gen KMX spindles and Adam Roy's front gas suspension, but it doesn't look possible to obtain spindles at the moment. If I can find a KMX with the proper spindles, find a source for the right kind of spindle, or find someone who can make replicas of the spindles I have in my possession, I will go this route instead of the Sunseeker suspension. No matter which I choose, front track will be wider than rear track, which will help facilitate a more teardrop-shaped shell.
In either case I'll keep my existing 3-wheeled KMX with full suspension, 3rd gen spindles, hydraulic front brakes, AVID bb7 rear brake, and 10kW to the rear Leafbike 1500W 3T motor as it is, and pursue no AWD upgrade for it. I'd rather have AWD in a quad if having to choose between the two. The trike will then be my RWD machine.
I really like the KMX as a build platform. I've made an EV out of one already and would like to keep it operational. I have a kit that would allow for me to convert it into a quad, but I'd rather build another one than change a good, functional one thus removing it from use for an indeterminate period(I have limited time to work on it, yet use it regularly for transportation and thus want to avoid taking it apart).
My overall plans for this quad are as follows,
AWD streamliner with the seat reclined as far back and as low as possible while still being able to see over any bodywork that would be around my pedaling area is the goal. With the seat reclined far back, it will force my boom in as far as it will go, as if I was a very short rider. I'd need short 110mm crankarms that allow fast cadence to assure proper ground clearance for my heels over the road(I want at least 5"). I'm thinking I will have the top of my helmet somewhere around 800mm off the ground, which will keep this very low with a racecar-like center of gravity, and keep the frontal area low in spite of being a quad. The goal is a weight distribution somewhere around 45F/55R.
Regarding shape, it will be much like an Auto Union Type C streamliner viewed from the top and front, except with a big front bulge in the center of the front to accommodate my pedaling. Unlike the Type C, the front wheels will likely be fared on top and exposed for the bottom 2/3 of the wheel(think 1953 Alfa Romeo Disco Volante Coupe), since I need to be able to turn. The rear wheels are going to be fully faired on the outside and mostly fared inside(inside, there will be clearances cut to allow differential and subframe assembly to move up and down with the rear suspension, and spandex boots will be made to maintain aero while allowing movement). The rear of the vehicle will be a downforce increasing Venturi tunnel doubling as a rear diffuser(see 2025 Renault Folante concept for what this could look like from behind), which accepts air from the vent holes in the rider cabin, air initially entering the vehicle through the stagnation point air intake used to cool the rider as well as any open windows or raised windscreen. Part of the plan would include a full rollcage and a gullwing door, with crumple zones. 16x1.5" DOT rims and 16x2.25" Mitas MC2 tires all around.
Gearing will be a 11-34T DNP Epoch in the back with a Schlumpf HS triple up front, with a cadence sensor for PAS. The limited required chainwrap capacity should allow for me to get away with using a short cage rear derailleur in order to minimize ground clearance issues while retaining a wide gearing range.
I'm considering making a rack-and-pinion steering for it, where I can turn the wheels maybe 20-30 degrees in each direction with a 50-70 degree turn of the steering wheel in either direction, using a butterfly steering setup, with brake levers and trigger shifters placed on this system. This will facilitate allowing most or all of the front wheels to remain fared by the shell design while keeping frontal area low, at the expense of having a larger turning radius.
The EV system would be a 6kW Cyclone middrive running 10kW peak driving the rear wheels, with Grin All-Axle 3T wind front hub motors at 6kW peak in each front wheel. This would be powered initially by a Phaserunner for each motor at reduced power(maybe 4 kW each, 90A to rear motor, 45A to each front motor) and later by an ASI bac2000 for each motor at full power, the three controllers all run by a CA3 with a high current shunt. The battery would be a 20S6P pack of Molicel P50b or whatever are the most energy dense cells I can find that make the requisite power by the time I am ready to make the pack.
Solar panels would cover as much of the body as possible. Maybe up to 400W worth of them.
Since KMX are no longer being made, and since the spindle is the weakest mechanical part of the design, I am heavily considering an alternative front suspension to the one I used and Adam Roy designed:
UTCustom KMX Front Suspension Upgrade
UTCustom Ackerman Compensator Steering Upgrade
UTCustom Revolution EC34/30 Headset for Sunseeker Trikes (each)
This alternative design uses spindles from a Sunseeker, which are readily available. Only 1.25 inches travel, not as wide of a front track(advantageous in my case for aero, since by going quad I don't need a massively wide front track to corner at high Gs), but unfortunately they are not gas shocks ad I will lose the 3 degrees negative camber.
I think they are still compatible with these brakes, however:
https://kmxsuspension.epizy.com/Trike Twin hydraulic disc brake.html
And I'd install a gas shock in the rear also, so that I have a full-suspension quad.
All I have to do is find another KMX to butcher.
It will cost me about $5k all in just to build the functional but unmotorized quad, and $7k to complete it to the aforementioned specs.
I'd prefer to have replacement OEM 3rd gen KMX spindles and Adam Roy's front gas suspension, but it doesn't look possible to obtain spindles at the moment. If I can find a KMX with the proper spindles, find a source for the right kind of spindle, or find someone who can make replicas of the spindles I have in my possession, I will go this route instead of the Sunseeker suspension. No matter which I choose, front track will be wider than rear track, which will help facilitate a more teardrop-shaped shell.
In either case I'll keep my existing 3-wheeled KMX with full suspension, 3rd gen spindles, hydraulic front brakes, AVID bb7 rear brake, and 10kW to the rear Leafbike 1500W 3T motor as it is, and pursue no AWD upgrade for it. I'd rather have AWD in a quad if having to choose between the two. The trike will then be my RWD machine.
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