Low Observability Motorized Bicycle

Discussion in 'Laws, Legislation & Emissions' started by whodathunkit, Nov 3, 2008.

  1. whodathunkit

    whodathunkit New Member

    I live in a state (PA) that requires motorized bikes ("Mopeds") to be titled, registered, and insured, even though no special operator's license is required and there are no inspection requirements. This would be a nuisance that I would put up with, except it seems to be virtually impossible to get a homemade bike registered & titled (see other posts in this forum).

    The reason I'm building my bike is to have some simple 'pedal assist' when I go out on my weekend motorhome trips in the mountains and back country of PA. I just want to use the engine when necesary, pedal the rest of the time, and 'stay off the radar screen'.

    For this reason, I'm wondering if anyone out there has put any thought into 'low observability' installations that aren't eye-popping obvious to the casual drive-by observer (aka 'Police'). I think there are a number of measures that could be taken, starting with the style of bike frame, then what the gas tank looks like and where it's placed, where the muffler is mounted and how loud it is (very important), and even some sort of shrouding that obscures the engine.

    Is anyone doing this, and would you care to discuss?


  2. Mountainman

    Mountainman Active Member

    yes -- if you look around on this site -- you will find what you need

    I have seen rack engines hidden in milk crates

    and as you mention -- keeping the noise down -- I think -- most important

    you might want to go into the legal threads and just download some of the laws
    that you like
    if you have a drivers license and are not riding crazy
    it would be an up tight pooolice that would give you a ticket
    and with gas prices being the way they are
    the judge will probably throw the ticket out

    a kid down the mountain just went to court the other day
    driving a MB without a license and a couple of other things
    judge dropped all -- our time may be a coming !!!

    ride that thing
    Last edited: Nov 3, 2008
  3. xPosTech

    xPosTech Member

    MM is right about the milk crate. It hides a lot.

    A pusher trailer is another solution.

    With anything you come up with, aside from hiding it visually, sound control (to Major Tom :rolleyes:) should be near the top of your list of objectives.

  4. Underhill

    Underhill New Member

    I've thought about this with my recumbent. If you've seen a recumbent with a tailbox... something like that over my subaru. It could be insulated and I even drew up some air intakes to keep it running cool.

    So far I haven't had any problems with police but I haven't really ridden that much. I can't see the local cop giving me trouble as I've known him for 20 years. But the state troopers seem to have a bug up their rear about almost everything.
  5. benjy6

    benjy6 Member

    i am in philadelphia pa and i have no problems with the police
    i ride by them everyday on my MB
  6. RLK

    RLK Guest

    Stealthiness is the reason I built an electric MB. I'm not getting the 20 miles per charge as advertised but I do make the 8 hilly and part dirt path miles with charge to spare. I'm on my 3rd controller and second set of batteries in almost two years of daily service.
  7. RLK

    RLK Guest

    I like the idea of a rack mount gasser in something like a motorcycle trunk but you'd have to figure out how to get enough air moving around it. A milk crate would work but I personally would want to paint the motor and everything black. Maybe black nylon on the sides and rear but leave it open on the front, top and bottom would work to ventilate and hide the motor.
  8. AlphaGeek

    AlphaGeek Member

    The Tanaka motors have an integral centrifugal fan which pulls air across the cooling fins on the cylinder head. Muffler wrap (or similar insulating treatment) applied to the muffler would also help ensure that heat is expelled in the exhaust gases instead of transferring through the muffler casing.

    Assuming a milk-crate-based stealthing approach, it would also be a good idea to have some form of exhaust redirector/diffuser to get those hot gases out of the crate. One of the objectives of my GEBE motor/mount customization program is to get the exhaust soundwaves emanating straight down towards the ground to make the noise output a bit less directional. Seems to me like this would also be a good goal for any stealthing project.

  9. whodathunkit

    whodathunkit New Member

    Rack-mount vs frame-mount is probably an ideoogical debate all by itself. For my money, I like the idea of putting the motor weight down low on the frame.
    However, as I said in my original post, and others have agreed, noise is the key. There are some good threads on 'dampening' the noise that comes right out of the engine/gearbox housing, but muffler improvements seem to be more elusive. Can anyone point us to a description, and possibly a video/sound clip of some dramatic noise improvements? Can we make these little engines just whine like some high-end scooters?
  10. HoughMade

    HoughMade Guest

    Harder to hide the engine in the frame. Also, tougher to make the frame mount engine quiet if for no other reason than the stock muffler on engines usually used on racks is usually very quiet. The exception would be something like a frame mount Honda, but take it from me- it's bigger yet and harder to hide.
  11. seanhan

    seanhan Member

    Low Observability That's Stealth technology at it's finest.
    Just cover that bike with some R.A.M. ( radar absorbing material )
    And It will be stealth and the radar gun will say your going 2MPH when your going 25mph
    Last edited: Nov 5, 2008
  12. SirJakesus

    SirJakesus Guest

    Rack mount friction drives are the best way to go for a stealth bike. Everything about the bike will look like a normal bicycle, even the rack. Just deck the rack out with panniers and a rigid bag up top and cover the engine with a loose woven cloth and you're done. You can lift the engine when you want to pedal and engage it when you want some power. If you're traveling bicycle speeds and pedaling nobody will EVER suspect you have an engine on it unless you ride right past them and they can hear it. I know Dimension edge even has an engagement lever so you don't have to stop to drop the roller onto the tire.
    I've thought about going this route with my MB's but I happen to enjoy the trouble of wiring up my own electrical system and being recognized as a motor vehicle. The ability to travel 30mph without worries about the po also helps. Plus, I get more experience and skills in case anybody wants to buy one from me. I'm a big fan of the old style mopeds with pedals but all they sell is those lame scooters nowadays.
  13. KilroyCD

    KilroyCD Active Member

    I live in PA as well, and have been frustrated in my attempts to get my builds licensed for the street. PennDot states that anything under 50cc need not be titled, yet two pages later in the same literature packet they state that for anything to be registered it must be titled. I will be working with some PA legislators (now that the elections are over) to try to get the motorized bicycle category defined and MB-friendly laws to be enacted. What I'll be proposing to the lawmakers is not a formal registration (with title), but a "road permit", much like the bicycle licenses of yesteryear. It could be in the form of a plate, or of an official, state issued adhesive sticker (along the lines of the inspection sticker that adorns my Whizzer). Wish me luck, guys!
  14. buck

    buck Member

    We need the Pennsylvania Motor Vehicle Code to be specific that
    under 50cc is to be considered as a bicycle. No more conflicting
    sections of the code. No stickers, plates, or paperwork needed.
    Just gas up and go. Other states have it that way and it works
    for them. Why not the Keystone state? I have over 600 miles
    on my bike this summer. No problems... But i ride it no faster than
    a bicycle. I go slow thru residential neighborhoods and wave at
    everybody that i see. Yes quiet and stealth is the way to go.
    I also ghost pedal when i see somebody looking. I have found one
    common thing with everybody that flags me down when i am riding -
    They all want one of their own!!!
  15. machiasmort

    machiasmort Active Member

    I recently felt like I won tour de france or something on the Buffalo bike path. People linning up to wave. Says something about the law in the state where you live when people go through that much trouble to show support!

    Blue Collar Bob put up an excellent post on quieting Ht's down. Search his name for posts and I'm sure you'll find it.

    I packed my pipe loosely with steel wool (in addition to bob's advice) and turn my idle down real low after the bike is warm. Maximum stealth mode!!! Very quiet until you hammer on it!
  16. loquin

    loquin Active Member

    I would think that some sound deadening material (sound deadening sheets, or, egg-crate/pyramid acoustic foam) lining the enclosure would also help. The same sorts of things that are used in sound studios or auto installations...

    ref Parts-Express
    Last edited: Nov 6, 2008
  17. AlphaGeek

    AlphaGeek Member

    A couple of things to keep in mind regarding use of sound-absorption materials:

    (1) With small motors in general, and two-strokes in particular, an awful lot of motor noise actually comes from the intake. Dampening the sound waves emanating from the intake should be a high priority for any would-be stealth motored biker.

    (2) Practical sound suppression in an open space (as opposed to an enclosed room or container) is the enemy of free airflow. Any sound absorption approach for a small gas motor will have to balance sound suppression against adequate airflow to avoid overheating the motor.

    (3) The lower the frequency, the more omnidirectional the sound and the harder it is to suppress. Getting the high-frequency stuff under control is easier by a very wide margin, so focus on that first.

    For example, since upgrading to a low-restriction K&N-style filter, I've noticed a significant increase in noise on my Tanaka 33cc. After I get the carb and exhaust upgrades fully sorted out, I will be looking at ways to redirect and absorb this noise. Ideas include a 'dome' or 'can' over the filter assembly (but not blocking/touching the actual filter element) lined with rubber sheet and fiberglass.

  18. KilroyCD

    KilroyCD Active Member

    That is the way I'd really like to go, but I'm a realist. As more of these bikes find their way into mainstream use, PennDot is going to look for a way to regulate them. If we begin at a common sense starting point, it might be easier to get MB-friendly legislation enacted. When MBs start showing up on the roads in increasing numbers, it is inevitable that some politicos will try to find a way to turn it into revenue for the state. It could end up being costly for us MB riders, so to try to get a low cost common sense scheme in place now is likely to be to our advantage.
  19. whodathunkit

    whodathunkit New Member

    Good points, all, about fixing the legislation to be more friendly to us. However, the issue of annoyingly loud sound is still an issue that could get the populace up in arms and cause new problems for us.

    I keep thinking about my back-pack 2-cycle leaf blower. It's actually pretty quiet, even when screaming. Two of the things it has going for it is are a complete plastic motor enclousue, and not being hard-mounted to a big steel frame that transmits high-frequency mechanical vibrations. I think this helps with a lot of the mechanically emanating noise. In a frame-mount installation, I think this translates to a shock-absorbing mount, a decent muffler, and a sound-deadening enclosure.

    Anyone done any of this?
  20. loquin

    loquin Active Member

    The sound deadening sheets I was talking about are about a quarter-inch thick, and are self adhesive. You can buy them to cut road noise by placing them on the inside of the doors on your car. In a car, they will cut external noise by about 3 db, which is by 50% They actually absorb sound by converting the molecular motion of sound into heat. If you had a box with an open bottom, lined with this stuff on all the remaining sides, you should get noticeably fewer dBs being released into the wild... :)