Stokemonkey human electric hybrid drive
Stokemonkey is an electric motor assist kit exclusively for cargo bikes built to Xtracycle's open source longtail standard. Xtracycle's hitchless trailer concept gives bikes amazing cargo capacity, and Stokemonkey gives you the power to haul it over mountains or swiftly across town.
Most electric bike products are designed for people who don’t, won’t, or can’t ride regular bicycles, even without passengers or cargo. Stokemonkey is different, designed for avid bikers who will continue to ride on their own power most of the time, but want a more capable car alternative some of the time. We don’t believe in replacing human power with electricity; we believe in replacing cars for work that even the strongest cyclists seldom if ever choose to handle without a car. Developed in a car-free household, Stokemonkey is for fellow riders who want to become more completely independent of cars in their daily lives.
- It’s for people who want to transport their spouse, their child, and their camping gear dozens of hilly miles offroad and back. It’s for picking up a friend with two checked bags at the airport. It’s for your knees. And if there are thousands of vertical feet between your farmers’ market and your family kitchen, now you can pedal those couple dozen melons home without qualifying for charitable sponsorship.
- It’s for people who commute twenty-five miles each way, can’t shower at the office, and never want to sit in traffic.
- It’s for people who understand that vehicles heavier than what they carry are inefficient almost by definition; that fiddling with their fuels comes at sustainability problems from the wrong end, and ignores the social and health problems of car dependence in built environments altogether.
How it works
When you want help, you turn a variable throttle on the handlebars to activate the motor. The motor drives the pedals, just like the stoker of a tandem bicycle helps the captain. You cannot use the motor without pedaling, but you can pedal normally without any motor resistance, and coast whenever you let go of the throttle. As you shift gears to maintain normal pedal speeds, you keep the motor operating between its most powerful and efficient speeds, for several times the torque, higher top speeds, and much better range than typical electric bike products lacking variable motor gearing.
A backlit handlebar-mounted display provides system status, including power usage, battery state, efficiency, and typical cyclocomputer functions, in addition to programmable parameters like maximum power and motor speed.
Stokemonkey uses a brushless motor with no internal moving parts other than sealed bearings, for maintenance-free, cool running, virtually silent operation. All drivetrain parts subject to wear are standard bicycle components for decades of service. Stokemonkey is powered by non-proprietary 36-volt rechargeable batteries you carry like any other cargo.
In development since 2003, Stokemonkey is protected by US patent 7,261,175.
Performance
Stokemonkey’s exceptional torque moves heavy loads off the line quickly, helps you walk your grocery-laden bike up stairs, and enables you to haul adult passengers up the very steepest streets. We've managed 480 pounds gross up the steepest block in San Francisco (31.5% grade). This extreme torque capability distinguishes Stokemonkey from electric bike products not designed for cargo applications. Stokemonkey can sustain about 500 watts of assistance, which is comparable to the maximum sustained effort of a world-class bike racer. But Stokemonkey weighs a fraction of what the racer does, your power comes on top, and this full combined power can be applied even at walking speeds: think tugboat or tractor more than scooter.
Powered range is limited only by the amount of battery packs you carry. Experience suggests that your working range will be similar to what it is riding a light, unassisted bike, but that you will carry more, and arrive sooner with much less fatigue. Top assisted speed is limited electronically to 20 MPH to conform to US federal Consumer Product Safety Commission rules, but this speed can be maintained even up modest hills.
Stokemonkey adds 21 pounds to your Xtracycle before batteries, which start at about 12 additional pounds. Gross vehicular weights can start well below 70 pounds, not unlike many loaded touring bikes.
Cost
Complete Stokemonkey kits for your Xtracycle start at $1668.00. The cost before battery and charger system, which you may opt to provide yourself, is $1200. Generally, we don’t sell kit components separately, but you may omit parts for which acceptable substitutes exist. See the Order form for more complete information.
Stokemonkey usually pays for itself every few months when used to replace a typical car. More importantly, you get to ride a bike more often, even when you need to haul your family, groceries, or just your unbearably smug self further or faster than you would on a regular bike.
Guarantee & warranty
Stokemonkey comes with a six-week money-back guarantee, and a two-year warranty against defects in materials and workmanship. Our batteries are warranted separately for six months. We advise you to purchase an Xtracycle, set it up, and become accustomed to it before ordering, so you will have the full guarantee period to install and evaluate Stokemonkey.
