Want to motorize a bike - what bike should I get to motorize?
 

What would be a good frame to use if I wanted to motorize a bike? Does it matter for gas vs. electric?

I have a raleigh mountain bike with road tires and an extended seat. Is that a bad one to use? What is better?

I would want my motorized to still have gears and I would still want to be able to pedal it.

I just want to learn this mechanical skill and I got to start somewhere.

They make electric bikes and they make motorcycles pick one and enjoy. Regular bikes aren't designed for being e-bikes so you can have issues. Slapping a gas motor on it is even worse.

The 2 stroke China Girl (HT) engines are very simple. If you want to learn to tinker with engines, its a great place to start.
-There are a few states with very restrictive laws on motorized bicycles. Most states are more motor bike friendly..
-To me, electric kits have one really big advantage - You can get away with riding sidewalks and multi-use paths on them (at reasonable speeds).
-I like steel beach cruisers when it comes to adding a gas engine. They are comfortable and absorb engine vibration well.
-Your Raleigh MTB is well suited to an e-bike kit.
-Electric bikes are more reliable than gas bikes. The gas powered bike really requires that you enjoy a little tinkering.

A steel hardtail makes a good donor bike for road and light trail riding. Those with 68 mm bottom brackets accept front or rear hub systems (read the tutorials at ebikesca) or mid-drives (read about them at Luna Cycle). A front hub conversion is a good place to start since they're easy to convert (with a steel fork and torque arm) and fun to ride. Mid-80's to mid-90's MTB's are good prospects unless you want full suspension. I've never had any problems using bicycles for conversions. They were overbuilt IMO and make very functional systems. Below is one that had a sidecar, designed to accommodate a wheelchair, added. Had a rear hub motor, but is being changed to a dual motor "bike".
https://cimg2.ibsrv.net/gimg/bikefor...9705b97510.jpg

Starting with the bike you already own is a good place. Hub drive kits can be had for under $500. I put a $1500 mid drive kit on an old Cannondale mountain bike. Shifts, pedals and rides like a normal bike when unpowered, but can either go all day or flat out fly as desired.

https://cimg5.ibsrv.net/gimg/bikefor...620295c286.jpg

I bought a used Currie kit (with lead acid batteries) and installed it on a 1995ish Univega MTB. Disappointing performance. I added a bigger drive cog but
was still unhappy with it. I split an old gasoline tank and stored the controller and main switch in it.
https://cimg2.ibsrv.net/gimg/bikefor...40ad20e590.jpg
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Here are the gas powered bikes I built with 49cc China Girl (HS) engines. The beach cruiser was much more comfortable.
https://cimg0.ibsrv.net/gimg/bikefor...2df0cd553a.jpg
https://cimg9.ibsrv.net/gimg/bikefor...b7b6c1f87a.jpg

A steel frame is the best. Keep it simple for your 1st build!

A front hub is the cheapest and easiest, then rear drive hub. A geared hub is best for stop start commuting, direct drive hub best for constant high speed. Mid drive is the most expensive, and the best off road.

https://cimg0.ibsrv.net/gimg/bikefor...b14d3d6ad2.jpg

This is an alloy frame Schwinn SC2000 I got for free. It has a $250 500W motor kit in back, with a $400 48V battery, I upgraded to a disk brake up front and took off the twist shifters for trigger shifters. Still has rim brakes in the rear.
https://cimg2.ibsrv.net/gimg/bikefor...29ba53ed76.jpg

This one is a steel frame Trek 800, It feels more responsive than the Schwinn, The motor kit was $220, same 500W geared motor as above. Added the front shocks. Normally have a downtube battery like the above bike, but in this photo using some cheap batteries in the bag,
https://cimg6.ibsrv.net/gimg/bikefor...75a08b6bb4.jpg

Doc what brand of hub motor is that and where did you get it, link?

TIA

Pre-covid prices. 500W ebike kit, LED display, from ebikeling. On both amazon and ebay. I picked him originally because he ships out of a warehouse in Illinois,

Your first step would be to research your state laws and decide if you want a motorized bicycle or an e-bike. In most states, they are different things. Then you need to research licensing requirements.

For example, while I ride an e-bike to work, I had the idea to go for higher power, mostly just to do it. I then saw that going for a higher power unit moved me into the motorized bicycle class. After speaking to the state police vehicle inspector I came to the realization that it was next to impossible to do. That was not a big problem for me, I have plenty of bad ideas that I don't act on.

Back to the point, step one is to checks the laws where you live. Generally, e-bikes, motorized bicycles, motor-driven cycles, mopeds, and motorcycles are all different types of vehicles and clearly defined in the law. Don't take the word of a person on the internet who is trying to play cute word games, check the laws where you live.


. . . and this is what I commute on, an e-bike:
https://cimg2.ibsrv.net/gimg/bikefor...107b2faad7.jpg

For e-bikes, there is usually a 750w max for street legality without a tag and insurance. If you ride safe, law enforcement will take no interest in you.
-I wouldn't get a motor smaller than 36v 500w.
-Gas assisted bikes are cheaper but require more maintenance. General rule is that you need a 48cc engine or smaller to avoid the need for tag and insurance.
Some states ban gas assisted bikes altogether, like Ohio.
Some states require a tag, no matter how small your engine is, like California and Florida.
-An electric assisted bike is the better bet, if you can afford a good one.

I would look for something that seems over engineered, most frames could but shouldn’t handle the stresses produced by the motor, an mtb frame sounds about right
I would like steel or titanium because steel is more predictable than aluminum and titanium is more durable, i would probably steer clear from carbon because they are engineered for certain stresses and the tubes get subjected to new stresses.
If i choose steel i wouldn’t look for a high end steel frame because they are a little less predictable because they are hardened more
(but they might prove to be a better choice)

Choose a frame that hasn’t been used much so you know it has some life left, metal fatigue is a thing

https://www.bikeforums.net/g/album/20465304

https://cimg5.ibsrv.net/gimg/bikefor...dfdc47f1cb.jpg

If you are just tinkering then any bike can usually be converted. If you start with a junk bike, you end up with motorized junk. You can always change the bike out latter after a learning curve.

I personally would never even consider a gasoline ICE setup (internal combustion engine). The power curves for an ICE are backwards from an electric setup. With an electric setup, maximum torque is at zero speed. On an ICE maximum torque is somewhere higher than 50% output. Torque is important for climbing and stop/start/low speed work. The ICE/gear changing setup is very difficult to integrate smoothly and always results in some serious compromises unless you are very good with designing and building electronic integration setups. Geared hubs are better but still compromised. . ICE engines are also not included in bicycle laws in most jurisdictions and will not pass muster on anything but the roadways..

presumably a motorised bike is totally illegal on the roads? an overpowered ebike is less likely to attract attention