How Does the GEBE System Work?

Discussion in 'Rack Mounted Engines' started by smapadatha, Jul 21, 2007.

  1. smapadatha

    smapadatha Guest

    How Does the GEBE System Work?
    (An Introduction for the Curious, the Spurious, and the Furious)

    The purpose of this article is to explain how the GEBE bike engine solution works, for those who have never owned one or seen one.

    Golden Eagle Bicycle Company ( sells gas engines that can be mounted on a standard bicycle, and mounting kits/drive system for getting it on there. The GEBE company doesn't manufacture engines. They re-sell small (about 50cc and under) engines from Tanaka and Robin/Subaru. The quality of these engines is excellent.

    GEBE will sell you:
    1. Just the mounting kit/drive system, if you already have an engine.
    2. The engine and mounting kit/drive system.

    They also have other stuff like spare parts and bicycle wheels (rim, spokes, hub) that are built to take the punishment that an engine dishes out to a bicycle.

    There are several ways to hook a gas engine up to your bicycle. The GEBE company uses a belt system, which many people consider to be the most reliable. (Opinions vary on this topic. Some people prefer a chain system or a friction system, but GEBE doesn't sell those.) The heart of the GEBE system is not the engine, which they only re-sell, but their "drive ring".

    The GEBE drive ring is a molded plastic wheel, 17 inches in diameter (outside diameter) and 1.5 inches wide.


    The drive ring has slots molded into it which allow it to literally snap onto the spokes of your rear wheel, and teeth molded into it so that it grips the toothed belt they give you. It may not look like it from the pictures, but the slots on the ring snap onto 14 gauge spokes VERY securely. It's not easy getting the bleeping ring off, even when you want to. GEBE sells a 32 spoke version and a 36 spoke version of the drive ring.

    In most cases, the GEBE drive ring will go on the left side of your rear wheel; that is, the "left" side if you were sitting normally on your bike. It's possible to mount a GEBE kit on your front wheel, but few people do this or recommend it.


    Note that the drive ring sticks out from the side of the wheel. That's necessary so that the drive belt can slip over the ring and attach to the engine shaft. However, a wheel with a GEBE drive ring on it is so wide that it will not fit on all bike frames. For that reason, it's a lot easier if you buy the engine kit (and even a rear wheel) from GEBE *before* you buy your bike. If you already have a bike, you can measure your frame to see if the drive ring will fit, but it's a lot easier to have the wheel with the drive ring on it beforehand.

    The GEBE mounting kit/drive system has the following main parts:

    1. A heavy steel bracket that attaches the engine to your bike frame.

    Installing a GEBE kit is like putting on a rear bike rack. The weight of the engine rests on a main bracket that attaches to your rear axle, although some people mount the main bracket directly to their frame.


    The kit also comes with a stabilizer bar that prevents the engine from moving forwards or backwards. One end of the stabilizer bar attaches to a bolt on the engine and the other end attaches to your fender mounts or anything else around the back of your bike where you can thread a bolt.


    2. The GEBE drive ring.

    3. A "toothed" kevlar belt. They currently use one made by Gates.


    4. If you buy your engine from GEBE, they will put a small gear on the engine shaft.


    The basic steps for installing a GEBE kit are:

    1. Snap the drive ring onto the spokes of your rear wheel.

    2. Attach the engine to your bike using the main bracket and stabilizer bar.

    3. Loop the kevlar belt around the drive shaft and drive ring.
    3.1. The gear on the engine drive shaft meshes with the kevlar belt.
    3.2. The kevlar belt goes around the drive ring.
    3.3. The drive ring is attached to the spokes of your rear wheel.


    4. Attach the kill switch and the throttle to your bike. If you buy your engine from GEBE, it will come with a nice kill switch and throttle already attached.

    5. Add gas and oil and try not to crash into stuff.

    From the steps above you might assume that installing a GEBE kit is a piece of cake. should be. One the one hand, we aren't building the International Space Station here. On the other hand, a bicycle must meet certain requirements before you can GEBE-ify it. I will cover those in another rant...I mean post.

  2. gone_fishin

    gone_fishin Guest

    absolutely a gem of a post, smapadatha...thanks very much 8)
  3. skyl4rk

    skyl4rk Guest

    Is it possible to use the Gebe system with the motor installed in the frame?
  4. bamabikeguy

    bamabikeguy Active Member

    Excellent platform to build upon Sam

    I just put on 2, the second a lady's coaster brake, which require a tad of "frame squeezing", and want to point out 3 parts for emphasis.

    The key is the spokering, install it in the "clock method", 12-6-3-9 positions, to torque it down and make sure the gap is correct.

    2.125 tires are tricky to work with, the belt can touch the bulge of the tire, and fray. Washers are used on the drivering side of the axle to allow slight changes in centering the belt on the "small gear"/drive gear, and you can adjust the axle slightly to push the tire at clear of the belt.

    Smaller tire sizes do not have this problem, only the fattest standard size.

    Also, the two straps that came with these latest engines had to be reamed slightly to fit onto the engine mounts.


    I usually use either the second or third hole on the strap, you might use the fourth or first, depending on the bike.

    Check the strap out on the mount, see if it will slip on before starting that part of the install. You might have to take a drill bit to the hole, so it will make it fit at a crucial moment.
  5. bamabikeguy

    bamabikeguy Active Member

    Well, the simplicity it that the rack, fit over the axles, makes the belt measure perfectly.

    NO varience on the distance from the axle to the "small gear"-drive gear.

    That couldn't be achieved with all the different bike frames and lengths.

    Installed properly it's pretty flawless, those belts are tough.
  6. Vaughn@Gebe

    Vaughn@Gebe Guest

    Thank you for the wonderful resource, Smapadatha. I direct people to this link at least once a week who have questions about how the kit works.

  7. TheMasterChief

    TheMasterChief New Member

    how long is the belt in inches please?
  8. pumpbuilder

    pumpbuilder Member

    Nice advertisment. I didn't know they allowed that here.
  9. lennyharp

    lennyharp Member

    Not a very dependable looking kit. I got rid of mine as soon as I got it and compared it to other kits. Fortunately advertisements like this help it keep an inflated value so i got rid of mine easily.
  10. shawnshank

    shawnshank Member

    Yeah I looked at their weibsite and they seem awefully expensive when compared to other kits that offer the same perfomance and reliability.
    Nice post though. You made it seem easy to install.
  11. augidog

    augidog Banned

    this was posted by a member, not affiliated and only trying to be helpful to other members.

    what i was always led to believe was that getting in on a topic just to bash is what isn't allowed... i see more double-standard at work here.

    first-hand, experienced, opinions are welcome in the "reviews" area.
    Last edited: Oct 13, 2008
  12. vegaspaddy

    vegaspaddy Member

    wow, for a post that was put up to help newbies, just like me not so long ago, i really appreciated the time smapadatha put into this....

    This post was put on here to help and for that reason only, just like the posts for the happytimes, the titans, the statons,etc.etc.....

    get over it !!!!!!

    I think the moderators should just lock it.
    Last edited: Oct 21, 2008
  13. seanhan

    seanhan Member

    Thats becuse they are worth the money..
    If you want to ride or work on bike all the time is the question.
    I want to ride !!!!!!
  14. TWalker

    TWalker Guest

    How do you disengage the belt, or can you? is there no "free coasting"?

  15. bamabikeguy

    bamabikeguy Active Member

    TW- the tension arm gets pushed back to disengage the belt, though I rarely do. If you were going to pedal with the engine off for more than a half mile, it might be a good idea, if you were going to pedal for an hour or more, you could take the belt loose from the drive ring and tie it out of the way.

    But usually you just keep the tension on at all times, and especially when starting the engine.

    The belt doesn't have much drag on pedaling a 7 or 21 speed.

    Attached Files:

  16. jacliny

    jacliny New Member


    i have over three thousand trouble free miles, on the same bike, same belt, same drive ring and the tanaka 40cc. worth every penny!
  17. TWalker

    TWalker Guest

    Really hard for me to see exactly, you have to get off the bike and adjust tension? Any way to do it on the fly?

  18. augidog

    augidog Banned

    cut the engine, reach back and release the tensioner, on the bama says, tho, there's minimal drag, so you only need to disengage (or remove) the belt for long-distance pedaling.

    never run the engine without the belt engaged!
  19. TWalker

    TWalker Guest

    Ok thanks. Not tryin to be a pain here but say I disengage on the fly, can I then re-engage on the fly easily or should I be off the bike to make sure I get it tensioned properly?

    I understand there is minimal drag while engaged but I don't want to spin the engine for a whole lot if it isnt being lubricated by a pump.

    Also does the belt have a chance of flopping off if I disengage?

    Again, I may seem picky but what I am trying to accomplish is a really superb lightweight pedal mountain bike with motoring capabilities. Pedaling will be a priority on this build.

    Thanks again
  20. bamabikeguy

    bamabikeguy Active Member

    I'd say NO, you wouldn't want to disengage on the fly, besides the ungodly noise of the belt running loosely over the drive gear, there could be a chance of it coming off.

    But most likely it would just rub the belt grooves ineffectively. Where the real noise comes is if you hit the throttle while disengaged, WHHHHHIIIIRRRRRRR.

    You can take your finger off the throttle at any time and coast/peddle all you want....AND since you are talking 21 speeds, 95% of the time, you will be able to peddle and assist the engine.

    In other words, you can nearly ALWAYS go 2-3 mph faster by assisting, except when going down a steep grade full blast, maybe 40-45 mph. If you assume the engine tops out at 35mph, peddling may get you up to 37-38 on a straightaway.

    On level ground and upgrades, you'll always be able to put some pressure on the chain and sprocket.