ELECTRIC ASSIST AND EXERCISE

Electric assist can greatly reduce the need to pedal.  An athletic human can put out 100 watts of muscle power for several hours, or 300 watts for a few minutes.  Power assists common on the market can provide 200 to 1000 watts, making them often much stronger than the rider.  An electric assist's greater power can be used judiciously to supplement pedaling (especially for climbing hills) or it can totally replace pedaling (at least for the range of the battery.)  You have to be disciplined if you want to get physical exercise with an assisted cycle. 

Our mid-drive setups integrate the motor into the transmission in such a way that the motor doesn't replace the rider's power so much as magnify it.  Such as system helps maintain the incentive to pedal, giving you the best of both worlds.

The beauty of the electric motor/battery assist system is this: when cruising on level ground the energy cost of pedaling a moderate weight system is very low, and, when climbing, the system pushes its own weight as well as that of the bike and rider. 

A possible drawback of electric assist is that, after using it for a while, pedal-only bikes will seem slow.

TYPES OF ELECTRIC ASSIST SYSTEMS ON THE MARKET
 

TRANSMISSION TYPES

Roller-drive type motor systems may be appropriate for the least demanding conditions.  This type of transmission, with the motor spinning a small roller which pushes against the tire tread, may not work well in snow or rain, in sandy and gravelly conditions, nor with knobby or studded tires.  Fenders interfere with the roller. 

Single-speed Chain Drive systems generally use a motor mounted over the rear wheel of a bike, with a chain from the motor to a large sprocket on a specially modified wheel hub.

Multi-speed Chain Drive systems can be shifted down for climbing, or shifted up for faster cruising. Though electric motors have a wide torque band compared to internal combustion engines, they do have limits to how much they can lug down before they "power out" or overheat; the shiftable drive is much more adaptable to varying load and changing terrain.  Shiftable systems also help keep the incentive to pedal high, so that the rider is less tempted to stop pedaling and let the electric do all the work.
 

OTHER IMPORTANT CONSIDERATIONS

Quality varies widely among systems on the market.  More expensive systems usually are more weather-proof, have thermal-overload protection, have better electrical connectors, are more resistant to corrosion, and have better warranties and service.  Poor quality systems may have few safety features and inadequate assembly instructions, leading to dangerous and expensive mis-wiring.

Batteries of Lithium Manganese and Lithium Iron Phosphate, when well made, are presently among the most capable, longest lived, fastest charged, least temperature affected, and most powerful (for their weight) batteries on the market, as well as the most expensive.  Lead acid batteries are tried and true, though heavy, and they are inexpensive.  For proper performance, a battery cannot be so small that it cannot provide sufficient power (amperage) when the motor demands.

Power of the motors used in assist systems typically varies from 200 watts to over 1000.  Some systems, such as the BionX, offer selectable power levels, with levels as low as 75 watts.  75 watts will not push you up a hill by itself, but offers a very noticeable 'tailwind' push on level terrain, rationing power for many hours of riding.  300 watts will push a moderate sized bike and rider up a moderate hill with your pedaling assistance, and can help you hold 20 mph on the level.  700 watts will power almost any single-rider cycle past 25 mph with some pedaling.  1000 watts will power a tandem to 25 mph on the level with some pedaling, and a single rider to 30 mph if gearing allows. 

"Pedelec" features (these 'pedal-electric' features are common on European systems) require that the cycle be moving at several miles per hour before the assist will kick in.  For those operating in a hilly environment, this means that the rider does not have power assist at the moment when it is needed most--starting up from a stop on a hill.  For riders in urban conditions, power is not available for the first few moments of pedaling, as when attempting to accelerate across intersections.  Pedelec systems also are usually speed-limited to 20 mph in the USA, and 20 kph in Europe.

System voltage is usually 12, 24 or 36 volts.  Higher power systems will use 48, 60 or 72 volts.  Low voltage systems are generally safer for the home do-it-myself electrician; higher voltage offers higher efficiency and more power. 

OBTAINING YOUR SYSTEM

In order to improve the affordability of quality electric assist systems for our customers, Lightfoot has chosen to no longer manufacturer or distribute electric assist systems.  Instead we work to give our customers all the information needed to choose and purchase an appropriate system direct from its manufacturer. 

It has long been our goal to make our electric assists both more affordable and easier to maintain.  By removing ourselves as middlemen, and instead helping you to effectively purchase the right system for your application and budget directly from the manufacturer/distributor, we now better achieve both of these critical goals--much improved affordability and better long-term maintainability.

Lightfoot has been putting electric assists on our cycles for over a decade, and we have a lot of experience in what works and what doesn't.   We know that certain sophisticated systems are needed for demanding applications, while simpler and more affordable systems may be adequate for less demanding jobs. 

Some electric assist systems are available from their manufacturer as kits, and if you have a little mechanical and electric aptitude, can be installed by you.  Other systems demand more knowledge and tools, and can be installed by Lightfoot.   If you already have an electric system, and wish us to install it, you can ship it to us immediately after you order your cycle.  Or, you can follow our instructions to select and purchase a new system, and have it drop-shipped to us while we are preparing your cycle.  We will install and test the system, charging you an installation fee by the hour for the time required.   When your electrified cycle then is shipped to you, it will be ready for you to get on and go.

The list of manufacturers of electric assist systems is at the bottom of this page.  If, after reading through this information, you still have questions about what to order, please call or email us.

USING ELECTRIC ASSIST

OPERATING RANGE

The range provided by electric assist varies, depending upon manner of use, cycle/rider weight, system efficiency and type/capacity of the battery used.

CALCULATING RANGE: Conservatively; each 100 watt-hours of usable battery capacity should provide about 2-3 miles (3-5km) of pure-electric level-road cruising power. 

The number of watt-hours in a battery is calculated by multiplying battery voltage X battery amphour capacity X the percentage of useful capacity (90% for Lithium, 40% for Lead-acid).  Hill climbing uses substantially more power per mile; steep grades can easily triple or quadruple energy consumption.  Coasting on downhills does nothing to regenerate electricity, but serves instead to rest the rider and conserve the remaining stored power.  Regenerative-braking systems (such as in the BionX hub motor) can recapture a small percentage of the energy of momentum normally lost to braking.

USED AS ASSIST: (An example) By using the electric assist 1/3 of the time for moderate hill climbing, by coasting on downhills, and by providing the other 2/3 of power through pedaling, the electric power system can provide an assisted range of 5-9 miles per each 100 watt-hours of battery capacity.  This type of assisted-riding is more feasible if the battery pack is lightweight.

INCREASING CAPACITY: Twice the battery bank will provide twice the range. 

Lightfoot bikes (two-wheelers) comfortably carry one set of batteries, and a dual pair can be supported by a custom-made underseat pannier rack.   Lightfoot road trikes easily carry a single set in the cargo pod, and can add a second set of lightweight batteries with no difficulty.  Large batteries can be supported by custom brackets or cargo boxes.  As a rule of thumb, you should get a larger battery capacity than you will absolutely need.  This is especially important if using lead-acid batteries; they should not be drawn down more than 50% except very infrequently, and should never be deeply drawn down in sub-freezing weather. 

NOTE: Batteries and Chargers usually are designed as matching sets; a charger cannot be changed from one battery bank or system to another.

WEIGHT: Adding extra weight makes hill climbing, acceleration and lifting the bike more difficult.  Unsuspended battery weight is "dead" weight, hammering at the frame and wheel rims when bumps are hit; this is especially an issue with large lead-acid batteries.  Hub motors, being part of the wheel, cannot be suspended from road shock except by high-profile (fat) tires.  Batteries take up room, reducing the amount available for cargo.  Optimal sizing of the battery pack is very important for these reasons.

Weight of batteries varies by type and number.  The 10 apmphour BionX LiMn battery weighs about 8 pounds.  A 20-amphour 36-volt LiFePo4 battery weighs about 14 pounds, not including the weight of its container.  By comparison, a 30-amphour 24-volt (a pair of 12-volt units) lead-acid battery pack would weigh about 45 pounds, though it would only have the same available power as the LiFePo4.  Per unit of stored power; the Lithium battery weighs 1/6 as much and costs 4 times as much.  A heavier battery is also going to require a stouter and heavier and more expensive carrying case/bracket.

COST EFFECTIVENESS

CALCULATING ENERGY COSTS: If we assume that electrical power can be provided at 10 cents per kilowatt hour (this is conservative for Montana residences, which are paying 5-7 cents in mid-2008), and if we assume that the internal efficiency of the charger/battery/motor/transmission is such that 70% of the electricity provided to the battery charger is actually delivered to the drive wheel, and if we further conservatively assume that 40 watt-hours of stored power provides 1 mile of travel when using a chain-drive electric assist on a Lightfoot trike; we can then calculate that the electrical charging needed to travel 1 mile would cost almost exactly 1/2 cent, and thus the electricity to travel 100 miles would be 50 cents. 
This calculation shows that the money needed to buy a single gallon of gas at $4/gallon would buy enough electricity to take a Lightfoot cycle with chain drive electric assist 800 miles (without pedaling); therefore, we are justified in claiming, for illustration's sake, that such an electric motor system at least gets "800 miles per gallon". 

(Lower gas prices at this moment--$3/gallon in the US as of 12-2010--have partially eroded the conservative cushions we used in these calculations, but keep reading.  Recall that gasoline in Europe is generally 2.5X as expensive as in the US, so these numbers still work in many parts of the world where gas is over $7/gallon.)

To go further with this comparison, we can justly claim that meeting half of the cycle's power needs by pedaling (burning food calories, which in America are often "excess" calories) and the other half with electric assist, constitutes a vehicle that "gets 1600 mpg".  (It has been calculated that, when one compares the caloric value of gasoline and that of food, the human engine gets 3000 miles per gallon.)  Even with very modest amounts of pedaling, we can easily claim the attainment of 1000 mpg, and this number therefore can serve as a good rule-of-thumb for the efficiency of electrically-assisted Lightfoot cycles.

Case study--calculating energy costs for the BionX assist: The 360 Watt-hour capacity BionX battery can move a heavy rider (who is pedaling) strongly at least 25 miles (as our experience confirms) at almost 20 mph.  At a conservative 10 cents per kwh for electricity, charging the battery once should cost 3.7 cents.  Assuming a 15% charging inefficiency, we can calculate that a single fill-up actually costs 4.3 cents.  This 4.3 cents assists us for 25 miles, as we have shown, or we assist it, since it may be providing the majority of the power used (depending on efficiency, weight and aerodynamics of the cycle being ridden) needed to travel at 20 mph.  If we spend our $4 on electricity instead of a gallon of gas, we can charge the battery 93 times, which is enough to travel 25 assisted miles 93 times, which is to say; 2325 miles for the cost of a gallon of gas. This conclusion more than supports our rule-of-thumb claim of 1000 mpg for our electric assists.

MAINTENANCE

For the most part, electrically assisted cycles are welcomed throughout the US and in most other countries.  We have never had a customer unable to use their electrified Lightfoot cycle.  There are limits on the power of motors, and there are restrictions under certain conditions and in certain areas.

The United States Federal Low-Power Electric Bike Law

HR 727, signed by President Bush on Nov 27 2002, specifies working pedals, one horsepower maximum, and a top speed of 20 mph under electric assist.  There are a few states allowing 1000 watt vs. the 750 watts (750 approximately equals one horsepower), and a few allowing 25mph. However, the majority of states use the 20mph rule to identify a bike or trike under the low powered electric bike rule.  If you max out at 25 mph, in many states that bumps you up to moped classification, requiring more equipment such as turn signals, rear view mirror, horn etc; some may even require registration. This law can be seen in The Federal Register / Vol. 68, No. 29 / Wednesday, February 12, 2003 / Rules and Regulations pages 7072 and 7073.

Excerpt: SECTION 1. CONSUMER PRODUCT SAFETY ACT.

The Consumer Product Safety Act (15 U.S.C. 2051 et seq.) is amended by adding the following:

`LOW-SPEED ELECTRIC BICYCLES'

SEC. 38. (a) Notwithstanding any other provision of law, low-speed electric bicycles are consumer products within the meaning of section 3(a)(1) and shall be subject to the Commission regulations published at section 1500.18(a)(12) and part 1512 of title 16, Code of Federal

Regulations.

(b) For the purpose of this section, the term `low-speed electric bicycle' means a two- or three-wheeled vehicle with fully operable pedals and an electric motor of less than 750 watts (1 h.p.), whose maximum speed on a paved level surface, when powered solely by such a motor while ridden by an operator who weighs 170 pounds, is less than 20 mph.

`(c) To further protect the safety of consumers who ride low-speed electric bicycles, the Commission may promulgate new or amended requirements applicable to such vehicles as necessary and appropriate.

`(d) This section shall supersede any State law or requirement with respect to low-speed electric bicycles to the extent that such State law or requirement is more stringent than the Federal law or requirements referred to in subsection (a).'.

SEC. 2. MOTOR VEHICLE SAFETY STANDARDS.

For purposes of motor vehicle safety standards issued and enforced pursuant to chapter 301 of title 49, United States Code, a low-speed electric bicycle (as defined in section 38(b) of the Consumer Product Safety Act) shall not be considered a motor vehicle as defined by section 30102(6) of title 49, United States Code.
 

State Variations From Federal Law

We do not guarantee that this information is accurate or up to date.  If you know that any information herein is in error, or have knowledge of important details or exceptions to these regulations, please email us at info@lightfootcycles.com.

Motor vehicle license required (most of these states also require a helmet, possibly a motorcycle-rated helmet): Connecticut,  Kentucky,  Louisiana,  Massachusetts, Minnesota, Pennsylvania, Utah.

Minors disallowed: Arkansas (10 years of age minimum), Florida (16), Lousiana (15), Massachusetts (16), Minnesota (16), Tennessee (14), Washington (16).

Electric cycles illegal: Hawaii, New Jersey (on state roads), New York (on state roads).

Miscellaneous Restrictions: Texas (cycle cannot weigh over 100 pounds),  California (1000 watt maximum), Colorado (1000 watt maximum).
 

The Canadian Power-Assisted Bicycle Law