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.
     

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  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.
     
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