Anyone build a stealthy motorbike

Discussion in 'General Questions' started by Lee_K, Oct 20, 2012.

  1. Lee_K

    Lee_K Member

    For a while I have been working on concepts for a stealthy bike. And wonder if anyone else had built one. I started thinking in terms of a rack mount, but after reading recent posts with positive things to say about friction drive, I have decided to go that route.

    I just bought an RS 35cc motor for the project. It will have a belt drive to a jackshaft, a second belt drive to the roller. The roller will be 3.75 inch diameter and built around a sturmey archer 3-speed hub.

    I will attempt to build my own muffler to be quieter than the stock box muffler. I also am trying to come up with a pedal start system in place of the pull start.

    I searched the forum for ideas, and found a nifty rack mount setup that used a sturmey archer hub and used a tote box to hide the workings. It was built by a guy in the UK who was concerned about being stopped by the police.

    Here in Wisconsin we have laws that are kind to motor bicycles, but I would still like something that will not attract attention.

    I am still not sure how I would make an enclosure, but the mechanics are taking shape in my mind and my computer.

    Anyone have thoughts or interest in something like this.

  2. grinningremlin

    grinningremlin Active Member

  3. Ludwig II

    Ludwig II Member

    There's another concealed engine bike somewhere in the galleries, a rigid bike box over the back wheel.
  4. grinningremlin

    grinningremlin Active Member

    There was a good pic on the BMP site before he closed shop, an engine in a milk-crate.It was a great poor-man's build good camo but if a cop stopped you, you could easily say "hey if this thing falls over I want the engine protected". I sure wouldn't want to be the guy when pulling the engine for repairs came up, looked like a lot of extra work.
  5. Ludwig II

    Ludwig II Member

  6. Lee_K

    Lee_K Member

    I read through those threads, there were some clever ideas. I liked those that just added a set of bags or simple basket. They seemed to distract attention away from the engine while not trying to totally conceal it. I won’t get a good start on this project until mid December and then it will be a long time before I get to working on a cover.

    Perhaps the more interesting part of this project will be a 3-speed friction drive.

    I have seen friction drives that use a bungie cord to tension the roller. Instead of this method, I plan to compress the roller into the tire to a fixed position so it can’t hop around. Is 1/8 to 1/4 tire deflection about right?
  7. Ludwig II

    Ludwig II Member

    You need to talk to the friction drive section. I'm going all chain, I live in a country liable to unpredictable rain.
  8. professor

    professor Active Member

    Lee, there is one problem with using the SA for a roller- it needs to have oil in it and there is a little oil spout on the diameter of the hub.
    I am using one as a jackshaft and it works well. I try to be careful shifting because the internals are tiny. Every once in a while I shoot some oil in it.
  9. Lee_K

    Lee_K Member

    Ludwig--When I start making parts and building this thing I will start a thread on the friction drive section. I still have some design details to work on before I get to far into making parts.

    Professor--I have used SA hubs as mid drives on my recumbent bikes for a long time with good results. Of course they only saw human power, a motor will increase the power load. The drive roller will be 1/7 the diameter of the tire. So on the plus side, it will be running at 1/7 the torque compared to being used in the wheels hub. On the minus side it will be running at 7 times the speed. So I am sure none of the little parts will break, but will be more likely to wear out. At the higher speeds I think oil would be spun out, I plan to grease it with a light grease and see what happens.