6.5HP Bicycle Pusher Trailer

ZnsaneRyder

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Joined
Jun 19, 2008
Messages
808
I just got my bicycle trailer running. The trailer is built from a handtruck, and It's powered by a 6.5HP 196cc Horizontal-Shaft 4-stroke engine.

The Drivetrain uses a centrifugal clutch with a pulley, driving a belt going to a larger pulley and a tensioner. It has small 10 inch wheels and It's a rather tall ratio of 2:1 to the wheels. Despite the tall ratio, it has PLENTY of torque and spins the tires when pushing the bicycle. The small wheels don't require as low of a ratio to work.

After breaking a few parts and a few adjustments, I took it out on the road for a test drive. It goes very fast, and you feel the wind on you. I'm not sure how fast, but it felt like I was going over 30 easy. I can go half throttle and get the engine fairly quiet and keep a constant high speed.

So far so good, but a I have a few problems. Main issue is axle friction. The handtruck has small metal sleeves for the axle to ride in, but after a long ride, the metal is wearing pretty badly and squeaks. I'm lubricating it to keep it quiet, but I can see the metal is wearing, and when I get more $$$ I want to change to ball bearings for the axle, and make a way to mount them. I'm afraid the metal won't last long the way it is now.

Other issue is the wheels are pressed-steel and after a few rides, the center hub spins inside the rim where they are pressed together. I NEED to weld them to fix that.

Once I get the weak-links figured out, I plan on using this to commute around on backroads and the side of country highways to get to work, and ONLY pedal in the city and busy roads, and just save the gas for the long parts of my trips.

Any suggestions on how to improve this for long term use?
 

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skyl4rk

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Thats great, how about some pics of the belt side. What do you control on the motor, just the throttle? You have no problems with the clutch disengaging when you throttle down?
 

ZnsaneRyder

Member
Joined
Jun 19, 2008
Messages
808
Thats great, how about some pics of the belt side. What do you control on the motor, just the throttle? You have no problems with the clutch disengaging when you throttle down?
Sure, here's some pics of the belt side, the clutch, tension pulley, and axle pulley. The belt is Kevlar 41 inch belt for lawnmowers.

The throttle is what controls the engine. The rotary clutch engages when I give it throttle, and disengages fine when I bring it down to idle. To coast, I idle it down, then I give it throttle to accelerate again.

It seems to operate best when traveling at speed, it's quietest, and the clutch makes less noise when you are going, then if you are accelerating. This thing is silly fast when riding on the side of the highway.
 

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SimpleSimon

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Apr 18, 2008
Messages
1,181
Man, all I can say is - were you a fighter pilot previously?

That thing looks truly dangerous. Fun, but an invitation to disaster. Get to Harbor Freight or some similar supplier, and replace those wheels/axle with better quality (bearings, definitely bearings) ASAP. While you are at it, set it up so that you can easily pull the erngine/drive gear, and use the handtruck as a handtruck - I rather suspect at some point you are going to need it.
 

Bikeuser

Member
Joined
Jun 4, 2008
Messages
60
man do you love danger. as an engineer how do you account for the side loads as you turn. It looks like your dolly will break in half. As a MB owner I don't believe you when you say you wont drive this on the streets. the dark side is too tempting.
 

ZnsaneRyder

Member
Joined
Jun 19, 2008
Messages
808
Determined top speed, and more testing and improvement!

I got some MUCH better wheels that were pre-welded from another Hand Truck, of nearly the same size, and these were much better Carlisle tires, and the tread didn't wear on these, and these rolled much better at high speeds.

After installing these better wheels, I took it with a test drive on the road with my brother, and he followed along in his Geo Tracker. I accelerated easy for a moment, then gave it full throttle and let it wind up!

My brother pulled up next to me to note my speed on his speedometer, then we pulled over.

:devilish: I got much more speed then expected, it topped out at 52mph!. :devilish: Insane for a bicycle for sure!

We took turns riding it, and IT WAS SO MUCH FUN! My brother was doing an avg of 35-40mph on it, and I kept it around that speed most of the time, with an occasional full throttle run :D 50mph is more than enough, and I don't plan on driving that kind of speed very often!

We also discovered a flaw that will be fixed. The metal that holds the axle supports bent when my bro went way too fast on a bumpy curve, and it put more stress on one side and bent it. We bent it back some and kept riding. I bent it again later, and the belt wouldn't stay on, and I had to pedal back home. I plan on rebuilding that part with tube steel and supporting ball bearings with that for more strength and less friction. Other than that, it seems good, and everything else seems strong enough for the motor.

It was great when I went to the gas station with it and I topped off the fuel with only $2.00 :D I pulled next to the fuel pump, and put the nozzle in the fuel fill, just like a car, but I had to fill SLOWLY.

For the majority of use, I plan on keeping the throttle low for about 25-35mph average. The engine runs nice and quiet at those speeds, and runs a lower RPM. I hope that will extend my MPG.
 
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TWalker

Guest
At first I thought it was a joke all I thought I saw was motor sitting on a handtruck and bungeed to a bicycle, then I saw the drive pics. Reminds me of a barstool racer....52 mph with a handtruck?

Im uh uh........... speechless
 
Joined
Jun 10, 2008
Messages
34
you dear sir are an abomination on the sanity of society! I must say I like that about you, but for now I'm off to get a hand truck.
 

starkm32

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Joined
Jun 1, 2008
Messages
133
Hope we dont have to visit you in hospital, its an eyepopper, and possibly an accident waiting to.....
 
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