Getting Started

Your first ride

Before your first ride, confirm that you aren’t wearing anything that could touch Stokemonkey’s drive chain. You may already be in the habit of protecting your right trouser leg. Get used to protecting both.

Disconnect the battery and ride the bike normally to test brake and shifter function, as these may have changed during the installation. Again make sure that the throttle does not stick or interfere with other bike functions.

Connect the freshly-charged battery and switch on the controller. The switch can be operated through the soft top flap of the controller bag. CycleAnalyst for Stokemonkey (the handlebar display) should power up. CycleAnalyst functions are described in the next section.

The throttle is inactive when no speed is detected; you should pedal normally to start. Once in motion and pedaling, open the throttle. The motor will “catch up” to your pedaling speed to assist. Let go of the throttle to pedal without help, decelerate, etc. Pretty simple! Please use extra caution until you learn to assess safe stopping distances and other handling characteristics of your now heavier, faster bicycle.

About volts, amps, watts, watt-hours, and other matters electrical

Electricity is a complex phenomenon we won’t discuss in a rigorous way here. But you do need a little understanding of some basics to make best use of Stokemonkey, particularly the electrical information that CycleAnalyst reports.

A common way to discuss electrical charge is by analogy with the flow of liquids. Let’s pretend that our liquid is a fuel like gasoline or diesel in its common motor vehicle application.

  • Battery: fuel tank. The capacity of your “tank” is best understood in watt hours (Wh). Multiply the amp-hourage (Ah) by the voltage (V) of any battery to determine its Wh capacity.

    Unfortunately, unlike fuel tanks, batteries don’t have a simple float and gauge to indicate how much charge remains in them. Their useful capacity changes with the rate at which they are emptied, just as the useful capacity of a bottle of beer will be diminished, lost to foam if you pour it too quickly. It also changes with their temperature, how long they have been sitting idle off the charger, and over their service life.

    Instead of a fuel gauge, CycleAnalyst features a watt hour counter showing how much “fuel” you have used since you last reset the counter, and some indicators about how the remaining charge is flowing. From this information you can determine approximately how many watt hours are left, whether you’ll be pedaling home on your own power entirely, or whether you can afford to let Stokemonkey do most of the work.

  • Watts (W): horsepower. On CycleAnalyst’s first display (right) are several power figures, chiefly wattage. You can think of this as the burn rate of your fuel. For reference, 750 watts is 1 horsepower.

    For any given throttle setting, you will notice that watts decrease as your pedal speed increases, either from you pedaling harder to do more of the work, or downshifting to drop speed.

  • Watt hours (Wh): units of fuel used since last reset. To reset CycleAnalyst, hold down the button for 2 seconds. For reference, there are 37,500 watt hours in a gallon of gasoline.

  • Volts (V): fuel line pressure. The voltage drops as the watts increase and as the battery is depleted. Thus the voltage at rest and the way it fluctuates as the motor works is a quick indicator of remaining charge. A fully charged “36V” battery might be 41-43V right off the charger. It might drop or sag to 37V at full throttle. By the time it is 36V at rest, it might sag to 32V at full throttle. When it sags below 30V under load, the controller will cut power to prevent damage to the battery. You’re “out of gas.”

    Resting voltage will drop non-linearly as charge is depleted. An S-shaped discharge curve is common for many battery chemistries. Over time you will develop a feel for what part of the voltage discharge curve you are on, even without referring to the numbers, and what this indicates about remaining charge.

  • Watt hours per mile (wh/m): MPG or metric equivalent. On CycleAnalyst’s second screen (right) is wh/m, a useful measure of efficiency. If you know that your battery capacity is, say, 432Wh, and your journey is, say, 30 miles, divide to determine how many watt hours per mile you can afford so your charge will last. 432/30=14.4. Simply keep an eye on this figure as you go, adjusting your effort and speed to keep on target. If you know that you have hard climbing ahead, you can “bank” watt hours by aiming for a lower wh/m figure in advance.

    Most Stokemonkey users find that wh/mi figures in the 7-9 range are low, just enough to take the sting out of mild hills while maintaining a slightly elevated speed. Wh/mi figures above 15 (or their metric equivalents) suggest hard use, either lots of loaded climbing, higher speeds, minimal rider effort, or some combination of these.

  • Amperes or amps (A): flow, also called current. CycleAnalyst displays power in watts by default, but it can be configured to display amps instead. Amperage is easy to confuse with wattage, but it’s not as complete an account of charge flow. Imagine a very fat (high current or A) pipe in which fuel is flowing at low pressure (V). Now imagine a very skinny (low A) pipe in which fuel is flowing at high pressure (V). Both pipes can deliver a similar rate of fuel (W) over a specific time (Wh). Watts is volts times amps.

Other configuration options are described in Stokemonkey’s Installation documentation.

Keep in mind

We recommend you leave your battery pack attached to the charger in a climate-controlled environment between uses. Most batteries do not benefit from being depleted all the way before recharging. In fact, deep discharges are hard on them. Therefore, ideally you will always connect them to the charger at the end of each day, and leave them connected until next use. If you don’t want to leave them connected, charge them up every 2-3 months of storage in a cool place to preserve service life.

Don’t leave the system powered on when you’re not riding it. You drain the battery all the time it’s on, and a powered system can be hazardous to curious or careless handlers.

Stokemonkey’s drive chain is likely to become loose and possibly derail as the tension cable breaks in after installation. Carry a 10mm wrench to re-tension the chain by sliding the cable yoke down the tension cable spans, then re-tightening. You may need to do this a few times before the tension stabilizes, and at longer intervals as the chain and sprockets wear.


Possible cause Remedy
Motor drive chain comes off in use Chain too loose Increase support cable tension. 2-3 adjustments over the first few hundred miles are a normal break-in phase.
Improper installation Re-adjust mount according to installation instructions. If the problem persists, note whether the chain comes off to the right or to the left of the chainring, and reposition the motor a very short distance in the opposite direction.
Turning throttle does not activate motor even when bike is in motion, or power cuts in and out Loose or faulty connection Confirm that power light is on, check all connections, inspect contacts of connectors for corrosion
CycleAnalyst spoke magnet not being sensed Adjust gap between magnet and sensor on fork.
Internal wire break or failed controller Contact us or your dealer for support
The system is noisy or doesn’t feel smooth Freewheel on motor wearing out Replace freewheel
Drive chain tension too high or misaligned Re-adjust mount according to installation instructions
Electrical malfunction Check all connections, inspect contacts of connectors for corrosion
Range is too low Pedal speed too low Pedal faster. Always start in a low gear and shift up as you gain speed, or refrain from applying full throttle when starting in a high gear. Use throttle less overall; go slower.
Battery capacity insufficient or in poor condition Upgrade battery. Eat better and stay hydrated.
Climbing assistance poor Bicycle gear too low Shift up to bring your pedal speeds down, where Stokemonkey works hardest.
Battery capacity insufficient or in poor condition Upgrade battery.

Leave a Reply