How to climb big hills with original GEBE kit?

Discussion in 'Rack Mounted Engines' started by MtnGoat, Oct 24, 2007.

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  1. MtnGoat

    MtnGoat Guest

    I posted the whole story in the introduction forum, here:

    This post by uncle punk13 really intrigues me as a solution:
    The gist is "For multi-speed gearing you could have a three speed hub laced onto your rear hoop, and mount the shifter on the handlebars."

    I've thought about this, but can think of no practical way to do this.Any ideas on this or on other ways to get up the mountain with GEBE?

  2. OldPete

    OldPete Guest

    Cutting right to the chase...

    Sell your current kit, might sell fast if left on the bike for "testing".
    Buy the GEBE Tanaka 33cc kit with the 12 tooth drive gear, it normally comes with the 13. Return to 26" wheels. I geared my Robin/Subaru 33.5cc kitted bicycle to have a top gear of 46/11, seems to work for me but I have yet to pull long, big hills with my 60yo legs. If you are worried about spoke breakage, buy the $109 rear 26" wheel from GEBE that is laced up with 12g spokes.

    bamabikeguy will prolly offer you something. He has ridden cross country and has encountered a hill or two.

    David Staton is testing this hub but here in Ca. it moves the pedal assisted bicycle into mo-ped territory. It will pull all the way down to 6 mph.

    Read more in the rack mount forum because every new member seems to want a full tutorial then never returns to "give back" anything except complaints because of thier own ineptitude. :cool: Or so it seems. Bwahaha!
  3. larymor

    larymor Guest

    Some people need to be friendlier to the new guys.
  4. MtnGoat

    MtnGoat Guest

    Perhaps the 33 Tanaka would do it, but I would want a strong "yes it does" from someone with experience climbing long severe grades before trying another version of the GEBE. I can't tell you how many times Dennis at GEBE told me that what I have should climb these 20% grades no problem. Every fix he suggested made no or only very minor improvements. Eventually I just threw in the towel.

    I've looked into the NuVinci hub, but decided it was too expensive. Didn't know that would turn a bicycle into a moped in CA. Multi geared I suppose. But I would think that if the motor uses the existing gearing of the bicycle, that would make it gray enough to get by. And hard to spot as well.

    That would be another reason to use the bicycle gears to get multiple gearing, like through an internal rear wheel 3 speed (or more) type hub.

    One thing that bothers me about the the Staton gear box is that he states on his web page: "The Robin - Subaru, Honda, Mitsubishi & Tanaka engines last about 8,000 miles before the clutch shoes wear out with our gear & chain drive kits, then they will run another 2,000 to 5,000 miles more before the engine needs replaced." Maybe he's just being honest and it's the same for all kits, but 10,000 miles doesn't seem like that much, especially considering the long 2000 mile break in of these high performance 2 cycles. Made me wonder whether the gear box design is a contributing factor. I read somewhere in these forums that he is designing a lighter duty gear box specifically for bicycles.
  5. DougC

    DougC Guest

    I do not understand how you could easily adapt any regular bicycle geared hub to "the GEBE drive ring", as bicycle hubs have their drive sprockets on the opposite sides that the GEBE ring fits on.

    ...And for that matter--the bicycle hub sprockets are on the opposite side that most motor-bicycle engine kits drive the rear wheel on. Not just GEBE.

    The only way you could do this is if you modified the engine's drive setup to run on the RIGHT side of the bike--but then, it's been commented that a 1 HP engine will put out at least TWICE the power continuously that most casual riders can manage to put out for even 5 minutes. Bicycle hubs aren't engineered to be strong enough to be driven by a motor, 1 HP is about 750 watts and an average casual rider might be able to cruise with their legs putting out 150-200 watts.
    Last edited by a moderator: Oct 24, 2007
  6. OldPete

    OldPete Guest

    You will have to contact Mr. Staton about his up n' coming smaller gear box(I posted what he told me via phone several months ago). His current box is bullet proof and his system will deal easily with the rip-roaring hp of a Tanaka 47R. One of his HD wheels MUST be used however.
    Clutch life is dependent on break in and the amount of pedal power used for launch/hill pulling. Engine life is dependent on very clean air. The Tanakas and Robins should see 15k miles...or so I have read. Oil gets changed quite often in my Robin.

    Search and read my posts. I place helpful information way above being "friendly" to the many that are just passing through. You should do like wise. ;)
  7. OldPete

    OldPete Guest

    Please quote where anyone said the NuVinci hub could be adapted to the GEBE system.
  8. MtnGoat

    MtnGoat Guest

    That's how it appears to me as well. I love the basic idea of using an internal bicycle hub though. Somehow...

    I wonder how much torque Lance A. applies to the gearing when out of the saddle racing up Alps de Huez? Maybe the hubs are stronger than you think, if not abused. And if a competetive cyclist can climb a steep grade outputting say 400 watts, think what a 1 hp motor should be able to do with proper gearing.
  9. DougC

    DougC Guest

    Well maybe you could, but not on the rear wheels axle: such as use a big sprocket on the rear wheel, and use the internally-geared hub as a compound-drive, such as the "middle" pulley on a Whizzer setup. The hub wouldn't be subjected to nearly as much torque that way.
    When I said a "geared" hub, what I meant was an internal-geared hub, like a 3- or 7-speed, which can withstand a lot less torque than the common external gear hubs that most US bicycles use. US bicycles use externally-geared hubs because it's cheaper, but one side-benefit is that they are easier to build stronger.
  10. BTB Wild

    BTB Wild Guest


    Well OLDPETE I ordered both the 11 tooth AND 12 tooth gear for my new Tanaka 33cc. I may hold off until I break in the engine though. I'm in decent shape and can tell you the std gear won't cut it around here. Many hills are steep. Hopefully, I have not damaged the clutch on my maiden voyage as I kept er full throttle up a hill until I came to a stand still. I quickly realized I had to be damaging the clutch. Will the clutch forgive me for this single episode?
    Winter will set in fast so I may not realize a full break-in till spring time. :cry: Dying to try the new gears however.
  11. OldPete

    OldPete Guest

    At the worst you may have to sand the clutch friction material to remove the resin glaze.
    The high torque of the Tanaka 33 may be a bit much for the belt with the #11. Better keep pedaling to assist on hills with the 11. As I recall GEBE recommends the 12 for trail use with the Tanaka 33.
    Do report back with how these drive gears work on the Pa. hills. Pics looking up from the base of the hill would help others to understand.
    I just go deep into the bicycle's lower gearing and pedal up the steep ones. I don't have that many around here. Getting a running start and assisting from the git also helps.
  12. DougC

    DougC Guest

    I'd not really looked at the Staton/NuVinci hub page before (up until a few days ago).

    It's interesting that NuVinci is advocating motorized use of their hub. Other companies will not do that at all, and some even state that you're supposed to use a minimum specific chainring/sprocket combination to avoid putting too much torque on the hub.

    The first bikes that were available to order with the NuVinci were a company making $2000-$3000 custom stretch-cruiser bikes, not exactly the sort of bicycles that see a lot of hard pedaling,,,, so a lot of people on bicycling forums guessed that the hubs wouldn't take a lot of torque well. Having no meshing gears, I'd guess it would just slip if too much torque was applied--but if it slips too much, eventually, something bad has gotta happen......

    The NuVinci raises a lot of questions all on its own.
    I'm not ready to spend the money for one yet but it will be interesting in a few years to see how they hold up.
  13. Jim H

    Jim H Guest

    My area is flatland with slight grades, eastern shore, maryland, delaware, virginia or Delmarva... gebe system is perfect for my terrain but north of me is Pennsylvania with hills and mountains... I'd definitely be considering a bulletproof gearbox and chain setup from Staton. I have a wheel from staton for that setup that I don't use... not sellin, just sayin.
  14. BTB Wild

    BTB Wild Guest


    I don't understand how the drive system ( chain VS belt) has any relationship to hill climbing. Chain or no chain, pedal assist is required in a big way to tackle the hills, the centifugal clutch slips anyhow ( not the belt) and IMO it is the power of the engine and total weight that matters most. And don't forget about the down hill reward.....little or no engine drag.:grin:
    I don't see a chain system as having advantages on hilly terrain. The GEBE system weighs less. There is no pedal drag to speak of. I have yet to try the #11-#12 gears ( with pedal assist of course) but it's so wet and cold here.:cry:
    Maybe I'm missing something ( this is my first MB) but if I want to cruise "pedal free" and tackle all hills I may purchase a TOMOS moped as well. My MB still provides ample exercise and I'm able to ride much further distances before I tucker out.
  15. MtnGoat

    MtnGoat Guest

    By chain vs. belt I assume you mean Staton chain drive vs. GEBE, based on the previous post which I think you are replying to. Chain vs. belt is not the issue. With a single speed system one is relying on the engine torque to define the climbing range, so I agree with you that it is the power of the engine and total weight that matter most. But the total weight includes the rider and bicycle and cargo, so the amount saved by GEBE over Staton is not that significant. OTH I believe with the Staton system one can use a more powerful engine due to the attachment point being a sprocket attached to the hub rather than a spoke ring attached to approximately the mid span weakest point on the spokes.

    Also the range of climbing can be shifted much lower on the Staton than the GEBE. Changing pulley size on GEBE from 13 to 12 changes the total reduction from engine to hub from 20.5 to 1 to 22.2 to 1 with 26" wheels. An 11 tooth may not be practical and appears to be "too much torque" on all but the 25cc Komatsu/Zenoah. I think this means broken spokes, though that is just speculation on my part. The Staton range can be shifted much lower (by choice of sprocket sizes from 28 to 48.) Assuming the takeoff sprocket on the gear box is 28 (I don't know this), this would give a range from 18.7 to 1 to 32.1 to 1. So with GEBE you can lower the gear range by 8.2% versus 42% on the Staton. 42% will allow for some steep grades, without any pedal assist! 8.2% will be just noticeable.

    You should rethink the downhill rewards (and pedaling without motor assistance) as well. Both systems give you the ability to be free of the engine drag. Staton uses a freewheel on the left side of the hub, so cut off or idle the engine and there is no drag, automatically. With GEBE, one must turn off the engine, stop riding and remove the belt.

    I own a GEBE 25cc KomZen, which is not adequate for the grades I encounter. I have no direct experience with the Staton, have just looked at the details on the web page. Obviously I prefer the Staton concept as far as climbing is concerned. I started this thread to see if there was any way I could modify the GEBE system to make it climb better. So far the only advice is get a bigger engine, actually the one you have. I was skeptical whether that would help much, so I'm very interested in your experiences with the kit in regard to climbing.

    I hope it all works out for you. I'm guessing that will depend more on the steepness of the grades you encounter than the choice of pulley size. You seem to be willing to pedal assist, which I think is great. It is a bicycle after all. I'm a very strong climber and like to pedal as well, but the speed is just too slow for me even with pedal assist when the grades get much above 12%. And the engine is working SO HARD. Sometimes I feel I might as well drop the engine and just climb on my own. That's an exageration of course, because my wife can waste me if we ride together and she is on the GEBE bike. But it has been hard to keep the belt from slipping and spokes from breaking, and riding up a mountain with a slipping belt is not enjoyable.

    Let us know how much difference the trail gear makes.
  16. OldPete

    OldPete Guest

    IIRC, Staton offers a two cog sprocket for their hub. The Staton hub uses spokes that are all the same length...if you are a cyclist you know how strong this makes the rear wheel.
    I think the issue with using #11 with a high torque engine is one of belt life because of the reduced tooth contact.
    I wire tied n' soldered my 14g Wheelsmith spokes and as of yet have not broken one. I laced my Mavic rim to a Staton hub. I weigh 236#, am 5'11", know how to ride motorcycles well and am not afraid to stand on the pedals over rough ground.
  17. MtnGoat

    MtnGoat Guest

    I realized today that I don't understand how Staton goes from 16 tooth left side freewheeling hub drive sprocket (the only choice), to 28-48 sprocket hub size. 16 to 28 would be a be reduction of 1.75, and this range doesn't make sense when applied to the gearbox reduction of 18.75. Apparently the gearbox takeoff is 18 tooth so at the 16t freewheel on the Staton hub the ration is now 16.67.

    I wonder how this converts to the selectable sprocket sizes? I can't find any pictures or descriptions on the web site that show or explain this. It does say to choose between hub sprockets of 28-48 to select gear range.

    Whatever the actual reduction numbers are, it seems the Staton offers a much lower gear for climbing, or higher for top speed than does the GEBE.
  18. BTB Wild

    BTB Wild Guest

    Thanks PETE, I was not aware of the many gearing options offered by Stanton. And I'm not prepared to buy a larger engine at this point. The Tanaka 33CC seems like a fine engine. Robust and quiet... the engine works best when momentum is established via a running start or modest pedal assist. On steep hills I try to match or exceed the engine torque via pedal assist....and the clutch will slip well before the belt would. I certainly will report back with the #11 and #12 gear results.
    I am 6' tall 197 lbs and in good health. I pedal hard where necessary and have to walk the bike on occasion. What I enjoy most is the pedal-free speed I'm able to attain on level/ small slopes etc. Ample time to rest and enjoy the wind, the view etc. before I hit the next hill. I'm concerned the trail gear will greatly diminish this wonderful aspect of's a trade-off I suppose.
    Prior to owning the MB, I would have to transport the bike ( bike rack) to a park or trail to ride. Now I can take off from home and make it back ( barely):eek:
  19. BTB Wild

    BTB Wild Guest

    #12 Gear review + question?

    ( Tanaka 33cc w/ #12 trail gear VS #13 gear)

    #13 pros: speed on flats and good momentum builder to gain a running start on hills. Smooth symmetry between bicycle high gearing, pedal assisting, and engine torque on gradual slopes of varying degrees. Ability to pop the throttle wide open while coasting downhill.
    #13 cons: lower torque that boggs down on rapid inclines or harder pitches
    #12 pros: adequate speed on flats for a bicycle, noticable improvement regarding torque on modest slopes ( with pedal assist) and not much improvement on steeper hills. I prefer the #12 for my style of riding
    #12 cons: Can't pop the throttle wide open during speed coasting. Must slowly add throttle to synchronize engine to wheel speed etc. Springing throttle wide open (if coasting speed exceeds engine top speed) with cause a belt grinding noise! This is where I'm getting belt dust. Allow bike to slow down some, or gradually apply throttle until clutch engages.
    Hopefully, I'll get to try the #11 before winter sets in.:cry:
  20. Hive

    Hive Guest

    I Was Going to Let

    this thread go, but might as well add my experience with GEBE drive.

    As Pete and few others know, I live on hill; am on third bike. First was 4-stroke Honda and it was great but did not do job on cruiser going up the hill.

    Went to a Tanaka 3300 on a bent and then to the Raleigh Gruv 2.

    That little 2-cycle is great. I put the bike in (don't know gearing) small chair ring and smallest rear gear and then pedal with motor and it goes perfect, and even goes well without pedaling for a bit.

    Have not tried other ratios yet, but I suspect it gets easier, with more spinning, and more powerful with higher ratio. Best combo need for more juice.

    BTW, the NuVinci hubs are way spendy. Worth the money and time for a motored bike at this point?
    Last edited by a moderator: Nov 4, 2007