Picture of 130 MPG BICYCLE

I live about 10 miles away from my job which meant I was using about a gallon of gas a day just to get to and from work. I figured there had to be a better way. I looked at electric bikes and conversion kits but the cost was way more than I wanted to pay. Then there was the 49cc 2-stroke conversion kits. I found these as cheap as $140 but wasn't really sold on the idea of altering the bike so much. Then I remembered the "Stinger" from my childhood. These were friction drives we bolted to the back of our bikes. I started doing a little searching and found friction bikes of all kinds on YouTube. These were various motors mounted to the back of the bike with a peg on the output shaft making constant contact with the tire. This meant that every time you stopped the bike you would have to restart the motor. If something happened to the motor you would have to get off and adjust a turnbuckle to ride the bike normally. I wanted to ride the bike powered or un-powered at any time and not have to restart the motor every time I stopped. So after watching countless videos I came up with my own idea. I would incorporate some kind of clutch system in my friction bike. Presented here is what I came up with. Unfortunately I failed to take pictures during the build so I only have pictures from the finished project. By the time you finish this instructable you should have a good enough understanding of the concept to build one yourself. If you already have a bike and a motor and do some salvaging you should be able to complete this for around $50. Here is what I used:

GMC Denali 700c Road Bike

26cc Weed Wacker Motor

Schwinn Seat Tube Bike Rike

1 x Sunlite ATB Shift/Brake Lever Set - 1 Pair, 3x7-speed, 2 to 1, Black

1 x Tektro RX 4.1 Reverse Brake Levers Black

Bell Shift Cable Kit

1/2" Aluminum "U" Channel

1/8" x 1" Aluminum Flat Bar

Misc. Nuts, Bolts, and Spacer (I used all stainless steel but you can you what you have}

1/2" Plywood (A piece of scrap)


Cable Clamp (Salvaged from another bike)





Tape Measure

Rarnd1 year ago

This is a great little instructable and very clever :) However I have to warn people (for the UK at least but I believe the laws are similar in the USA?)

Any bike that is powered / power assisted with gas/petrol requires you to have a drivers licence (for a motorbike), for you to wear a crash helmet (technically anyway), and to have a licence plate, insurance and tax.

Basically, any conversions that involve high voltage (>250w in eu, >750w in usa) or gas/petrol will be treated as a moped/motorbike, which will increase the costs significantly; and gives the police the right to confiscate your bike on the spot if you cannot produce the relevant documents.

I'm not trying to knock this instructable because it is really really cool, as well as shockingly cheap, I'm just warning people. I'm trying to get an electric bike myself and I've had to do a lot of research into the laws around them. It sucks.

Thank you for sharing this instructable anyway :)

ALTAMIRA Rarnd1 year ago

Sorry to say but I don't know where you got the idea that the laws are similar une UK and US ??

The truth is that the laws in are much more different you might think ! In the US they pretty much can do what they can do in term of custom bikes. Under 49cc, it's considered a moped; no drivers licence, no licence plate, nada !

joshcube ALTAMIRA6 months ago

Depends on the state. Here in California if it's capable of speeds over 20 MPH it is a moped that requires an M2 motorcycle endorsement (vs. an M1 endorsement which is for motorcycles over 150cc) in addition to your regular driver's license. Also here, while bicycles don't require licenses, they are considered vehicles and you are subject to all traffic laws (including DUIs) while riding them.

Rarnd ALTAMIRA1 year ago

When I said that "I believe the laws are similar" I mean't it in the fact that both areas have restrictions on wattage and gas/petrol limits.

If you read my entire comment, you can see that I mention the differences between the EU and USA when it comes to wattage (250 vs 750).

When I say that they have "similar" laws, it means that they both have laws revolving electric bikes, both having restrictions on the same types of things. The severity of the restrictions, however, is dependant on each location. The USA, while having far more loose restrictions on electric bikes, do still have restrictions before they are considered motor-bikes and require driving licences to use. They can not do pretty much anything, they can just do more than the UK/EU, for example.

I hope that clears things up.

ContraptionMaker (author)  Rarnd1 year ago
Thanks Rarnd, and yes, you are right, everyone should check their local laws as they are different depending on where you live. Here in Illinois, USA, you only need to be a licensed automobile driver, the motor must be less than 50cc, cannot reach over 30mph in a one mile stretch, and cannot have a transmission that lets you change gears. No tags or insurance required. There is no helmet laws in IL for motorcycles or bicycles. As far as E-Bikes go, anything goes there. We can have 6000w on our bike, as long as it is electric only and has pedals, there is no restriction, unless of course it is an electric motorcycle then the rules are the same as any other cycle. Again, these are IL laws and yours will probably be different.

And my country has different laws just depending which state you're in.
My state for example:

Riding a power-assisted bicycle

A power assisted bicycle (or power-assisted pedal cycle) is a pedal cycle with a motor attached to assist the rider. The attached motor may provide assistance but the pedals must be the main means of propulsion.

In South Australia, there are two categories of power assisted bicycles that may be used legally on our roads:

  • power assisted bicycles with up to 200 Watts of power (the power is controlled by a throttle or accelerator); or
  • power assisted bicycles with no more than 250 Watts of continuous power which meet the definition of a pedalec (the power is controlled by the ride using the pedals).
What is a pedelec?

In order to be a pedelec (legal for use on our roads), the power assisted bicycle must comply with the European Committee for Standardization EN 15194:2009 or EN 15194:2009+A1:2011 Cycles - Electrically power assisted cycles - EPAC Bicycle ('EN 15194') and this includes the following.

  • It must be certified by the manufacturer and labelled as complying with EN 15194. The label must have the manufacturer's name, the motor's cut off speed in km/h and its electric motor motor maximum continuous rated power in Watts. The label is often found on the bicycle's frame immediately adjacent to the crank.
  • The motor must be electric.
  • The maximum continuous power output of the motor cannot exceed 250 watts.
  • The rider must pedal to access the power (the motor may operate without pedalling up to a speed of 6 km/h).
  • The power must cut out when the pedalec reaches 25 km/h or sooner (if the operator stops pedalling).
Road rules for power assisted bicycles

Riders do not require a driver's licence, motor vehicle registration or compulsory third party insurance. Riders are bound by the same rules as for other bicycles, including the need for:

  • the rider to wear a helmet
  • effective brakes
  • a bell, or other audible warning device
  • a rear-facing red reflector at night
  • a white light to the front and a red light to the rear at night (both may flash) clearly visible from at least 200 metres.
Differences between a power assisted bicycle and a motorcycle

A power assisted bicycle is a bicycle with a motor attached to assist the rider. At first glance some motorbikes with pedals look very similar to power assisted bicycle. The main differences are speed, pedal crank spacing, weight, seat position, seat shape and gearing

A good rule of thumb for deciding if the pedals are the main power source is:

  • if the distance between the inner faces of the cranks is less than 180 mm
  • whether it can easily be ridden without power assistance (you should be able to ride it home if the assistance motor fails)

If these apply and the motor output is either 200 Watts (or less) or 250 Watts (and meets the definition of a pedelec), then it is a power assisted bicycle.

If the main source of power is the motor then it is a motor vehicle and operating it requires a driver's licence, registration and compulsory third party insurance. However, few, if any, of these vehicles are able to be registered because they are not capable of meeting registration requirements, such as compliance with the Australian Design Rules. Such vehicles cannot be legally operated on our roads.

Wow, you have some really loose regulations in IL! I wish I lived there.

In the UK, you cannot have a bike that has more than 250w of power, it must have pedals, and it cannot exceed 15.5mph on full-electric.

Anything more than that, or anything with petrol at all, is considered a motorbike and you have to have documentation, helmets, etc. etc.

Talk about fun-police! Thanks for the comment though, always nice to learn about how the laws differ and such :)
ContraptionMaker (author)  Rarnd1 year ago

*always nice to learn about how the laws differ and such*

That's what Instructables is all about, LEARNING! :)

nlane61 year ago

ContraptionMaker, thanks for sharing your creation with us. I've been trying to figure out how to make a similar motor mount. I was thinking the rear support bars would need to be on opposite sides of the wheel, I've been working for weeks on this but it never works (the spindle keeps riding off the wheel). You have brought forth a great new idea, place the mounts only on the left side and have the rear support act as a guide rail for the clutch action. Out of the box thinking for the win!

As for troll-people like solsmac, they do not understand. This guy probably doesn't ride long-distances, and thinks his muscles are made of titanium. You will probably never get to race him and his pedal power, but if you did, my money's on the 2-stroke!

True, this project is not going to change the world. But I'm sure it has already made your life better.

ContraptionMaker (author)  nlane61 year ago

Yes it has. I love to ride but my knees can't take the peddling anymore. I hope you do a structable on your bike. I'm glad I could inspire you.

Interesting, but I bet it's noisy on the road. My ears ring after 20 minutes using the weed eater or chainsaw. Buzzzzzz

david.daines.110 months ago

Rarnd, You only need a drivers license ,license plate... If its above 50cc's, but not sure if you need a helmet i assume it depends on the state you live in.

Just though id clear that up.

This is awesome great clutch design I think I might attempt this

Glad I could inspire you, hope you'll create an Instructable, can't wait to see your progress and what you do with it.

I love that you can just get up and go, you don't have to jump off and mess with a pull cord. (BTW can i say i hate pull cords!)

HaHa! Me too!

loganrt111 year ago
That's pretty awesome
ContraptionMaker (author)  loganrt111 year ago


Like your bike dude. Does it ride smoothly.
ContraptionMaker (author)  chessman1221 year ago

Thanks, glad you like it. It rides very smoothly. It's just like riding the bike without the motor, just faster, and best of all, very little peddling!

amulder11 year ago
love the old solex bikes we have here, rode one a while back. Those are just awesome! Bit odd in the beginning, always riding full throttle and no clutch....
ContraptionMaker (author)  amulder11 year ago

Ya, that sounds a little dangerous...

Wow, super cool! :)

ContraptionMaker (author)  doodlecraft1 year ago

Thank you!

Thats a great project looks like a pile of fun. If you go for the four stroke, the six to one gear box in the photo will bolt straight on to a 35cc Honda.


Screenshot from 2014-07-06 20:48:24.png

Thanks for the info. Think I'm going for a belt drive with the 4-stoke.

You can also convert it to propane. I do all my lawn mower a this way. good plans liked it alot....
TFS Jake1 year ago
http://www.gomeyer.com/rc-cars-scooters/goped-clutch-kit-54mm-p-435.html this is what you want.
Gregbot1 year ago


ContraptionMaker (author)  Gregbot1 year ago

Thanks, glad you like it!

solsmac1 year ago
But it's still cool!
ContraptionMaker (author)  solsmac1 year ago


jleslie481 year ago

wait a minute, how do you start it? my weed whacker and a pull rope to start it and it doesn't look like to me that that is how you are starting your motor. It seem to me you are starting in more like how you would push start a manual car: get the bike up to some kind of speed, "pop the clutch" and the engagement of the clutch wheel against the tire spins the motor and starts it that way. Is that what is happening?

ContraptionMaker (author)  jleslie481 year ago

Yes that is exactly what is happening. I only need to get to about 5 mph. I pull the lever, the motor spins against the wheel, and it starts. No pull start required.