[wip] no workshop friction drive build

hey guys !

just started a new project. haven't yet purchased anything as i am still desinging the thing, thinking about the mechanisms, ways to build etc.

who hasnt been thinking about a better bike kit? not me. i'd like to make a kind of kit that you strap on your bike's fork and just put a pocket bike engine, or make the whole fork with the mounts and mechanism that youd put on your bike.
well thats what i want to build!

my first bike was a 40cc chainsaw rear wheel friction drive.

it was very good on several points:

-simple; just a chainsaw with a friction drive mounted on a plywood mount
-light; the whole motorisation added under 10kg/20lbs to the bike
-still a good bicycle; the engine caused zero friction when not used, unlike a bike kit whitch chain causes drag when pedalling or going down a hill.
-cheap; can buy an old running chainsaw for a reasonable amount of money
-a smooth riding experience; the engine caused virtually no vibrations on the bike
-closer to a bicycle than a motorcycle (less problems with cops)

-downsides-
-a bit loud
-not very reliable (plywood)
-the drive slipped on the tire quite often, causing friction and wear on the tire
-almost impossible to find spares for the chainsaw engine

here, i would fix or improve:

-reliability, with a steel construction;
-noise, whith a homemade quiet muffler;
-friction drive slipping, using a 6:11 chain reduction before the drive shaft, which allows me to use a 60mm/2 3/8" diameter drive instead of 30mm for a larger contact area with the tire;
-the engine would be on top of the wheel instead of on the side
-easy to find spares for the engine and for cheap
-even less problems with cops as it is very close to a Solex (street legal 50cc front wheel friction drive bicycle, made in France a long time ago, that required no helmet, no licence and no insurance until a few years ago, now the law says you to have to get a license plate and an insurance, but cops dont know it and none of those who know says anything if you didnt do it as solexes are rare and people are very nostalgic about those)

-better looking bike
-it is still cheap (pocket bike engine is 55-60euros), light, simple (kinda), and causes no drag when not using the engine.

(designing the bike)

 

[max350]

Mounting the engine in front of the wheel axle will not be good! Becomes very unstable

 

[Arman_]

Made this drawing. I don't like the way it is so I'm gonna modify it. I'm still looking for parts, especially for the engine, looking for second hand but I might end up buying new. Im gonna make a chained reduction, 6t to 11t sprockets, t8f chain.
The engine is dead nuts on top of the axle on this drawing,and it may get closer to the fork. the first sketch was just to illustrate.
Got a bike, second hand, 20€. It's an old bike with a steel frame, no suspension, not much heavy, fine for the road. I may send pics next update.

 

[Arman_]

So
I think I could try to make a rear wheel friction drive with the engine in the middle of the frame. It will be easier for me to know if it is a good option when I'll get my hands on the engine, but I think it could stay simple to make without needing as much work, cause I forgot to mention something
I moved in a new flat in july, and I have no shop. I have a small basement, where I only can we'd. It is right below someone's flat, and u can't grind or be noisy like I would have to for metal working. This project is very tricky cause I have to work the least possible when making the bike. The only not neighbour-bothering way to cut metal is by cutting it in a metal shop I know, I helped them once now can basically get free metal for my projects, I just go there, cut the bars or plates I need and pay nothing. So I need to know exactly what I need to cut at which angle and then it must fit on the bike perfectly after welding. I have 2 bikes I can use for that project:

(bike kit is dead)

 

[Arman_]

So, i was thinking about less solex style rear wheel friction drive and i think it would be better. im working on a kinda innovative desing, ill send some more cad drawings soon;
the engine would be in the middle of the frame, but friction drive...
also i think i'll order my engine pretty soon.

 

[Arman_]

here it goes!

not a ton of space between the tire and the friction drive when it is not on it but its fine

 

[Street Ryderz]

here it goes!

View attachment 79026

not a ton of space between the tire and the friction drive when it is not on it but its fine

That's kinda cool So now how does the ehaust,throttle cable,kill switch wires account for that much movement?And using a cag engine you left not much room for the pipe.

 

[Arman_]

It really doesn't move that much, like 1 1/2" max
Cables are by definition flexible, just got to leave them some slack and they'll take it just fine.
Exhaust. Well gonna make it myself, or I could adapt a bike kit muffler, I'll find a way. The light blue set quare looking part has 2 tubes on each side of the bike, there is space in between to fit an exhaust tube.

 

[5-7HEAVEN]

Welcome to the club, Arman_.

Nice project!

What size sprockets will your chain reduction employ?
If you're doubling the friction spindle from 30mm to 60mm,
you only need 2:1 chain reduction to retain the original gear ratio.

I am impressed by your ideas.

Have fun building your project.

 

[Arman_]

I am going to use a 17:33 reduction, my engine is going to have a 9:27 integrated chain reduction, and i am going to use a 11t to 17t (edit: 17 to 11) sprocket to get basically a 2:1 reducion.
I could use the engine with no pre reduction, but the shaft with the sprocket attached to the clutch bell is held with only one bearing, the upgrade is gonna be only 5 euros, ill have 2 bearings on each shaft of the thing. moreover the stock sprocket is 6t without the upgrade!