Motorised Bicycle Trailer

[Carlman]

Hey guys,

Hope this isn't too offtopic for Spudfiles just want some feedback for my idea from people i know

I have an unused near new Honda GX-160 5.5hp horizontal shaft engine that i was thinking of ways to use it. I had considered a go-kart but decided to build one at a later date with a bike engine and when i have more room. I also considered monstor goped but thought it was pointless doing in suburbia.

And now after many other ideas I settled on a motorized bicycle trailer. Basically a bike trailer (clamps to seat post) with an engine and a wheel to push you along. Genius! a brand spanking new way of making a bike go that little bit faster than pedal power. Little did i know that someone else had already come up with this and made it (see video below)

This did not deter my dreams of a 5.5hp bike trailer!!

Basically how i imagined it is exactly in the video but with my more beefy engine. Great minds think alike, eh?

So what you guys think, worth making?

[youtube][/youtube]

[youtube][/youtube]

[starman]

I thought I was going to fall out of my seat when I saw him "4 wheel" up the hill..

Looks like a worthy add-on and a relatively simple build. Not sure I would be taking it to 41 mph....

[SpudFarm]

that is a hilarious bike

i got a goped and really they are not worth anything

[Carlman]

well i reckon with a motor with as much torque as mine i will gear it high ish to achicve speeds of about 80kph or so...on a bmx

EDIT: and yes i know this guy fails with his "4 wheeling" lol

[SpudFarm]

im not sure if they are safe then, i tire blow out will kill you and that may happend from the gee forces.
it would be cool to gear it really low like a real trial motorcycle. (trust me that IS fun)

[Carlman]

how could a blow out kill me?

there is no twist on the joint just left to right and up and down, so it should just drag..

[SpudFarm]

when the wheels spin that fast they might deg damage and you hit the ground in that speed.
it is bad enough to get a trial bike on your finger but it is even worse to turn into meat sauce on the meat grinding ground

[Carlman]

eh i ride racing bikes at 60-70 downhill so not much difference lol

ill be wearing MTX helmet and padding

EDIT: away from speed/what can go wrong aspect and onto design if ppl wouldnt mind

[SpudFarm]

no offens Carl

don't answer to this since you edited that thing in. the racing bikes has different wheels

[Carlman]

im gonna answer to it to say that my racing bike tyres have a width of about 1.2cm and deflate when punctured badly (blowout) in about a second, now at speed it aint fun so that is why precaution is taked such as kevlar lined tyres and only using tyres for 50% lifespan.

onto anther note, has anyone got experiance in go karts or bikes that can give a ratios for good speed whilst maintaing good accel?

[ramses]

Just make sure that you incorporate a clutch. A centrifugal clutch would be ideal, as it would engage as you hit the gas and disengage on idle. Without one, you can't start the engine, because that would require turning the wheel as well. If you use a centrifugal clutch, make sure that it works with you engine. A big ass chainsaw would have all this rolled into one. Unfortunately they are all 2 stroke. Maybe a 4 stroke weedeater...

[SpudFarm]

well you are talking about a trial bike there, they have three gears at the bottom that is trials gear and is really lame on the speed and the engine runs like it was in netrual. then when you gear up in fourth it just goes. in fourth it has no problem to run at 900rpm and in fivth it is pretty damned strong.
enough useless info, if you search the web about them you might find the gearings in the engine.

it is pretty hard to say something since trial engines are something by themself, totally unique untill you try it you can't understand how high torque they have


Edit: this might be to help. it is gear ratios

http://www.trialspartsusa.com/diagrams/ ... earbox.jpg

taken from http://www.trialspartsusa.com/tech.html here

[Antonio]

onto anther note, has anyone got experiance in go karts or bikes that can give a ratios for good speed whilst maintaing good accel?

Hey Carlman. I made a gokart with a 6.5hp honda engine that goes at 6000rpm (nearly double> so also has about 13hp then) I did calculations before to find the optimal gear ratios. Here is a pic with the torque curve of your engine> its about 10Nm average:

Well k so you know that. If you you have 10 gears on the engine(centrifugal clutch) and 60 at the back you have, 6*10Nm=60Nm torque on the back axle. Now lets say that your tire has a radius of 0.15m you have 60/0.15=400N of force on the road. F=m*a>> a=F/m>>a=400/40kg bike give u 10m/s^2 of acceleration.
a=v/t>> t=v/a (where v is ur change in speed from 0 to max)
If you max speed will be 40km/h=11.1m/s it will take 11.1/10=1.1 second to accelerate to that speed. Thats the way I did it. Ofcourse you have drag etc but like this you can easily find the accel data. Btw keep in mind that the engine normally goes at 3600 rpm>600 at the axle in our case. 600rpm=60revolutions per second>> radius of 0.15> circumference becomes 2*PI*0.15=0.94meters
distance*revs=0.94*60=56m/s......without considiring air resistance.

I think I made a mistake somewhere, so if someone could catch that. Further this is the way to look at it. My kart weighs about 130 including driver and goes to 40km/h in about 4 seconds. Top speed is about 70km/h

[Antonio]

Sorry for double post
I really like this concept as its fairly simple and compact. Btw the guy is using a torque converter(with a belt like in a scooter) so it has better acceleration then on the calcs:)

[Carlman]

hey ant thanks for the reply.i apricite your well writen post.

Myengine will soon do 5800rpm ungovererned from the stock 3600.

the guy used a tourque converter for his first then he took it off, the vids posted are just with your run of the mill kart centrafugal clutch.

I figure my finished project inc rider should also come close to 130 so that makes it easyer lol

I plan on using a wheel round 30cm too like in your calcs lol.

70pkph is plenty for this, so with this in mind i should get quite good acceleration, infact pretty much the same as your kart (minus a second or so to get to 40)

I too love the idea as it cn be moved from bike to bike and when your outa fuel you just tow the engine like a trailer

EDIT: sorry he is using a tourque converter although his engine is a 3.5hp