Motorized Bicycle Kit Installation

Our motorized bicycle kit installation takes typically anywhere from 30 minutes to an hour and a half. In 2004 Popular Mechanics wrote a feature article about How To Install A Motor on a Bicycle, they were able to install the GEBE motorized bicycle kit in 30 minutes.

Complete Bicycle Assist Engine Kit
with all mount parts

A. Drive Ring
B. Belt
C. Lower Mount Strap
D. Safety Cover
E. Front Mount Strap
F. Engine w/mount bracket & drive assembly
G. Trigger Throttle, cable attached
H. Kill Button, wire attached
I. Oil – for 2-strokes only
J. 4-in-1 Ring/Spoke/Gear Key
K. Nuts, bolts, washers, Clutch Knob & Zip-Ties
  1. Turn your bike upside-down and remove the rear wheel.
  2. Place wheel on the ground or work bench, sprocket/gear side down.
  3. TIP* Put liquid soap (Q-tips work great) on slots before installing the drive ring to avoid possible damage to slots or spokes.
    Fig. A (a) – Rotate the Ring over the wheel until all spokes line up with slots before beginning ring installation. There is a leading and a trailing spoke on a bicycle wheel, the spacing is slightly different, the ring is tooled to allow for this difference, check for correct alignment.
    Fig. A (b) – Place the 4N1 key, as shown, against the Outside edge of the ring (on the inside could cause damage to the belt track of the ring), hook the spoke with the slot of the 4N1 key.
    Fig. A (c) – Insert screwdriver thru hole on the tool, from the Outside of the ring, place a small piece of cardboard or rubber between the tip of the screwdriver and the ring, and lift on the handle to pull spoke into slot of the ring.
    After 1st spoke is attached, it’s best to attach the spoke on the opposite side of the wheel next (180 degrees from the 1st). Work your way back and forth around the wheel attaching spokes. (i.e. if the wheel were a clock, it would be – 12 o’clock, 6 o’clock, 3, 9, etc…until all spokes are attached.) Don’t forget to hose soap off after installation.
4. Fig. B – Place the belt in the belt track of the drive ring and re-mount wheel on bike. Snug axle nuts and turn bike right side up.
5. Fig. C – Attach front and lower mount straps to the engine bracket with the three bolts and washers (provided), Tighten bolts Securely!
6. Fig. D – Lift belt from belt track on drive ring, loosen axle nuts, slide rear mount strap under belt and onto axle. Snug, don’t tighten, axle nuts.Lower mount strap is installed on the outside of the rear forks, resting On the axle for proper belt tension.

When you slide lower mount strap onto axle, if derailleur nut prevents lower mount strap from sliding down completely onto the axle it may be necessary to grind or file a little off rear corner of the lower mount strap where the strap hits nut.If bike frame has large tubing on seat/chain stays that prevent proper positioning of engine – either for caliper brake clearance or for convenient fueling/oiling  – it may be necessary to space lower mount strap out with a couple of washers and/or nut to allow proper clearances.  Both sides Need to be spaced Equally – same size spacer on Both sides to keep engine mount centered on wheel.The closer to the saddle the engine can be positioned, the better the engine performs.

7. Fig. E(a) – Lower mount strap is installed on the outside of the rear forks, resting on the axel for proper belt tension.

Fig. E(b) – Proper belt routing – run belt around gear on engine’s drive shaft, between gear and tension arm bearing. Install belt on drive ring – with tension lever in OFF position, hold belt on left side of drive ring as you guide belt into the belt track of drive ring.

Fig E(c) – Front mount strap attaches where rear brake or fender tab bolts on. Front strap is malleable – you can bend it to fit your bike, BUT do not bend strap on bolt holes OR crease too sharply, positioning engine so that belt does not rub against brakes. Tighten axle nuts And nuts on Front & Lower mount Securely!

8. Fig. F – Proper installation of safety cover w/wing nut and knob on the tension arm. Tighten wing nut & Knob Securely! The tension arm has two positions: Forward/ON position is for proper belt tension when engine is in use; Rear/OFF position allows less tension for easy pedaling when engine is not in use.

9. Run the throttle cable and kill button wire along the bike frame, away from any moving parts. Make sure not to Kink (bend Sharply) cable or attach too tight, may loose ‘freeplay’ and cause engine to rev.

10. Fig. G – Trigger throttle just clips onto the right handlebar, in front of the handle grips. You can position the trigger throttle for use with either finger or thumb, whichever is more comfortable for you.

11. Fig. H – nstall Kill Button – remove screw from clamp, attach to left handlebar and return screw to clamp, tighten. Leave enough slack in the wire to be able to turn handlebars Sharply to right and left – if Too tight wire will be stretched from under insulator, causing Short. If your handle bars have a plastic coating, you may need to twist button a couple of times to break coating before kill button can make the proper contact with the metal. Press red button to turn engine off.




We recommend dual brakes and that they be in good condition, replace pads if needed.



**April 2009**
New 76/78mm clutch housing/bell assembly:
Includes new tool for gear changes:
Housing is not metal, now has ground wire (green), to allow proper Kill Button function. Rugged plastic housing reduced weight of unit; has cooling vents in housing and bell, allowing engine to run cooler (increasing engine life).

Changing Gears

Fig. J – Gear wrench slides behind gear (between two upper bolts on engine bracket) turn the drive shaft if necessary, wrench will slide over nut on drive shaft.

Fig. K(a) – Hold tool while you turn the nut on gear with 4n1 tool (second tool included with unit). Left to loosen – right to tighten. Tighten Securely!!

Fig K(b) Nut connecting lever to engine bracket is Only nut of entire unit that should Never be TIGHT! Arm should swing freely, easily flipping from On to Off positions.

Fig. L – GZ25N ONLY – Use screwdriver that fits slot on driveshaft, hold screwdriver Firmly remover gear Not spacer washer – this Always stays on driveshaft behind gear

52/54mm and Pre 2009 76/78mm and clutch mounts: – use Allen(provided).
With 4N1 key (provided) turn gear/nut NOT driveshaft – replace with desired gear and Tighten. Standard, Trail or Highway gear can be used without any belt adjustment.

Fig. M – (for GZ25N only) If gear has been over-tightened and is not possible to remove – remove safety cover, loosen engine lock bolt (located on top of clutch housing/snout and under the safety cover). Rocking engine back and forth, remove engine from mount – drive shaft extends out from engine mount bracket.

Avoid damage to drive shaft, put a small piece of cardboard between shaft and pliers, hold shaft with pliers, use a 3/8″ wrench or 4N1 key and turn gear (left to loosen, right to tighten), should be easy to remove. DO NOT over-tighten changed gear, next gear change can be done without having to remove the engine. Re-install engine on drive shaft, BE SURE to push engine back COMPLETELY ON DRIVE SHAFT! **Tighten engine lock bolt firmly.

any changes will effect performance and/or operation