belt slipping on gebe, I cant find what the problem is!

Discussion in 'Rack Mounted Engines' started by errolprowse, Mar 31, 2009.

  1. errolprowse

    errolprowse New Member

    hi everyone,
    i have 1900 miles on my gebe robin suburau 35cc motored bike. Its been a good ride but i have broken the lower mount strap, gone through 3 wheels, and a ton of other stuff.

    My problem that has just come up is that when i take off the cover, and just let my bicycle coast, the tension spring will "pop up" for a split second, as if the belt slipped on the gear. When i press the throttle too hard while riding, it does slip as well, same goes for going up steep hills. I can kind of feel it and hear it slipping.

    I have looked it over and cant find why it would slip considering it hasnt slipped before like this.

    I have just bought a new belt before this all started happening as well. Could it be the gear being worn out? how long till i need to replace it? Could it be the drive ring that needs to be replaced?

    any help?

  2. bamabikeguy

    bamabikeguy Active Member

    Hi Errol,

    In this thread, Bumwaiter tried to fix his tension lever by tightening that nut too much:

    The issue might be the same, as to too much bounce on the tension lever, and I'm presuming you haven't switched to a heavier gauge of spokes.

    (I'll just copy paste)
  3. errolprowse

    errolprowse New Member

    well, i did use to have larger guage spokes in the wheel i was using before compared to the one i have now. I usually hear it sqeaking whenever i move the bicycle because the drive ring moves around on the spokes. I guess this is my problem. I do put epoxy and super glue in the notches all the time but it never seems to hold for more than a week.
  4. bamabikeguy

    bamabikeguy Active Member

    Okay, here is how I do it, on 12 g. spokes....

    No zip ties on the spokes until AFTER the ring is on....

    You move the ring around the spokes, 1 position at a time, until you have it where it looks to be the BEST fit.

    Put the soap in the notches.

    There will be ONE spoke a little bit out of alignment, that spoke becomes 6 o'clock.

    Snap 12 and 6, then measure the gap....

    Snap 3 and 9, measure again....

    Then snap around until you have them all on there snug.

    You have to look in those notches, to make sure they are in there all the way.

    Then zip tie the intersections.

    Then put the drop of superglue in them.

    (to melt the superglue, a drop of gas will do it, to unsnap the ring put soap in the notch, and take it off in the same 12,6,3,9 o'clock method)

    edit: did you frame mount the kit, or are you axle mounting the engine?
    Last edited: Apr 1, 2009
  5. errolprowse

    errolprowse New Member

    theres also a ton of epoxy on both sides of each notch but the spoke just slides around through the epoxy and super glue

    I have the engine mounted to the axle

    i did ziptie them afterwards and i also used the 12,6,3,9 oclock method

    still though when i move the bicycle, the ring moves around. The rim is somewhat bent as well, will that cause it to slip too?
  6. bamabikeguy

    bamabikeguy Active Member

    As I understand it, you have changed the wheel more than twice, but are using the same original spoke ring that came with the kit.

    If that is the case, the notches have been "stretched/bored out/grooved to" whatever size those biggest spokes were.

    Switching to a lesser gauge would be the same as stripping out the threads on a bolt, you can't expect it to hold.

    I looked back on some of your posts, and this rear wheel has been a problem since the beginning, and I think we can get it running right if we erase the board and start back from scratch.

    There are two parts of the benefit to frame mounting the engine, a fix that costs about $15 and takes an hour or two :

    1. The distance from the bottom of the engine mount to the axle is constant (357mm in my case).

    2. You can work on wheel adjustments (axle washers/brakes/up-down in the slot/change a flat) without fiddling with engine removal.


    Once you get the engine mount stationary, so that part (the belt drive gear) never moves, then you need to get a 12 gauge wheel with spoke ring as perfectly centered as possible.

    If you've stretched the grooves on your present ring too much, there are 2 choices....get a new spoke ring from GEBE or switch to 10 gauge (which has a different set of issues).

    Those two choices would keep the fix under $75-100.

    A third choice is to get Dennis at GEBE to mount a new ring on his .105 gauge wheel, which means you will be perfectly centered....and IF you do that fix, then of course you'll frame mount the engine while you wait for the wheel to arrive.

    Attached Files:

    Last edited: Apr 2, 2009
  7. errolprowse

    errolprowse New Member

    i see

    i like the idea of getting a brand new wheel and spoke ring considering this wheel also has a bent rim on top of this issue with the present spoke ring.

    The number one concern i have before ordering that wheel is that there being something else wrong, like maybe the gear was worn away and causing it to slip or something like that. As long as i know it will fix it i will spend quit a bit of money for something that will last the longest considering i use my bike every single day for school and work.

    so my last question, is there a chance this could happen for any other reasons?
  8. bamabikeguy

    bamabikeguy Active Member

    A belt that shows threads raveling on one side is a sign that the belt is not centered on the upper small gear, or touching the sidewall of the tire as it passes. The fix is adding/subtracting axle washers to move it right or left.

    A belt that is "jumping" and "skipping" and getting unnatural wear on the inside ridges is a sign that the spoke ring is off center, and maybe the wheel is not up in the best axle slot position.

    If your tension lever-the little black ball, jumps back and forth more than an inch as you cruise along, or if you measure that gap between the ring and the rim, and it is over a 1/8-1/4" off in one spot, the fix is resnap the ring.

    Again, frame mounting allows you to suspend the rear wheel in the air and check the performance, then make the fix without having to remove the whole engine assembly.

    What bike are you using, and do you have a picture of the rear wheel area?
  9. errolprowse

    errolprowse New Member

    i did put a new wheel and ring on it with a new belt and gear, seemed to need all of it after i called up julia at gebe.

    ive noticed for some reason that the tension is different too, the belt doesnt go nearly as far around the gear as before. but anyways, it works great, thanks for the help

    i dont have any places to frame mount and my bike used to be disk brake so it doesnt have the lugs in the back anyways.

    thanks for all the help!
  10. I've noticed that after a few hundred miles, the belt will stretch. This also adds to slippage, because the teeth on the belt no longer line up with the notches in the gear(s), perfectly. Even a mm is enough to cause this problem. I've tried everything suggested, but after nearly three years, came to the same conclusion. I weigh in at over 300 lbs There are many ways to "extend" the life of the belt, but I would boast that belt death is the biggest drawback to GEBE. If you search the forum, you'll find much lighter riders with the same problem. It would be nice if the belts went for $10.00, but they're $30.00 a pop. Besides breaking spokes, (which 10 guage spokes installed by "The Wheelmaster" remedied), the belt replacements have been my only issues. A lot of it is when the rider gets "lazy" and doesn't pedal enough. Remember, the GEBE is an "assist" engine, and is not intended to be the primary drive source of the bike.
  11. augidog

    augidog New Member

    we've been kicking this around in ocean park, too...we have a few full-time riders and a few hobbyists, all on gebe's. lots of great comparisons to observe. some guys get thousands of miles, some guys get mere hundreds...BUT, some guys pedal ALL the way up to the belt's capacity to take over, and some guys ride 8 miles along the beach to get home "because the tide was right"..hehe.

    alignment is extremely critical, but we've gotten very casual about it, large channellocks, a twist this way, a tug that way, roll it, good. depending on how you ride, that should do it for a while. keep an eye on it.

    believe it or don't: while i mechanically prefer using tabs welded to the frame, a mounting strap (properly) bolted directly to the axle makes for the best alignment of wheel/ring/gear, and holds it longer.

    new gear/belt combos rock! either component will last longer if you never let the other wear too far. a quick rinse gets rid of the mini-abrasives that prematurely "sharpen" your drivegear.

    rotate the soon as the teeth are starting to show "direction" and before the crest of the teeth get fuzzy, flip it around, it'll feel like brand new.

    tension needs fine-tuning, tear it down, lightly hammer the arm as flat as your eye will let you, flat-file the underside of the arm and the side of the mount, get the entire area where the 2 surfaces will mate, pay attention to the edges of the metal...a smooth layer of white lith, larger washer, that baby needs to s l i d e back and forth, but with zero-slack on the locknut. get it right and it'll forgive a pretty large drivering "hop."

    keep a spare belt pre-strung by habit, you'll be less stressed about belts :)

    ps-speaking of flat-filing...the top of the strap (where the 2 holes are) & bottom of the mount could use a touch-up, on it until there's no light showing thru, then bolt it down.
    Last edited: May 6, 2009
  12. All good information. At any rate, it is well worth the price of a nice fresh belt, because I know I'll be having a blast with the little Over all I love my GEBE. The Robin Suburu 4 stroker is one amazing little engine. Even with my's barely broken in I think. I have nearly 3000 miles on 'er. All city riding, (another major factor to consider with belt wear), and she purrs like a kitten. :)
  13. Happy Valley

    Happy Valley Active Member

    Good point. And not just for gebe but a reminder what the whole MAB thing is supposed to be about: motor assisted bicycles
  14. Now that's a new one on me Augi......I'm gonna have to try out that rotation thing. Sounds pretty logical, but I'll admit I never thought of that'n. :)
  15. Drive Gear Wear

    After another year and a half, (, Augi is right, another BIG factor in belt slippage is the condition of the drive gear. It seems to me that the drive gears wear out almost as fast as the belts do. Even a new belt will begin to slip when the drive gear shows substantial wear. I went for at least 3 years, replacing belts as often as every 350 miles, ( weigh over 300lbs and ride in the city), when I decided to try a new gear. BINGO! Even some of my old belts worked fine again with the new gear. Sadly, I'm finding out as well that a new gear should be installed with every new belt for optimum belt life. I have over 700 miles on my belt now, and the same with the gear. of the $30 belt replacement, it's $60 for a new belt and gear, which will lasts twice as long. I guess it's as broad as it is long, eh?...hehe.:-/
    Last edited by a moderator: May 30, 2010
  16. augidog

    augidog New Member

    hi roy.

    it always breaks my heart to toss a gear, but like you i learned the hard way...

    i'm hauling 375lbs (est, maybe more) and with the proper philosophy, and a willingness to pedal-off, i'm getting 1000+ out of my belts...those are hard miles, too...see my thread in the "Traveling & Commuting" section.

    that weird "lurch" in the pedals is the indicator the gear is worn...and trust me it won't get better. no need to change both every time, just learn to make yourself do a new gear at 1st sign...before you know it, you'll be spending less overall than when you changed belts only.
    Last edited: May 31, 2010
  17. fm2200

    fm2200 Member

    I'm now thinking how did Bamabikeguy do it, I don't recall him ever complaining about the belts slipping etc. His only remark was that there was two different sizes and the larger one was for the long trips. I have had only the rag joint set up and yet my 12 gauge spokes never broke or warped the rim. I was using a 40T with the bike I bought from Spookytooth, it came with a 44T which was a little to slow for me. I weigh 180 lbs and never tried to haul anything with it, I use a pick-up for carrying things.
  18. augidog

    augidog New Member

    well, the belt's not really "slipping"...the teeth on the drive-gear wear into wedges and too much torque spins the drive-gear instead of it grabbing the cogs on the belt...too much of this will fray the belt prematurely.

    under bama's conditions (light load, steady cruising) this wouldn't have been much of a problem, but with a heavier GVW & stop and go riding, the chances of "wiping" the belt goes up. being aware of this mechanical limitation (after all, the GEBE is an "assist" kit) & pedaling more, and replacing a worn gear at first sign of trouble pretty much makes the situation tolerable, and affordable.
    Last edited: Jun 14, 2010