Besides voltage, batteries are rated by amp hours (AH). Although voltage seems to get the most attention, the amp hour rating of the battery is just as important. It is the measure of a battery’s capacity and provides a good indication of the range you can expect from an electric bike. Although lots of factors come into play in determining range (ie: rider weight, terrain, input, efficiency, etc.), a good rule of thumb is range is equal to AH. So under normal conditions, an average rider can expect 10 miles out of a 10AH battery (with no pedaling). With rider input, this number can be dramatically increased, so most 10AH batteries are rated “up to 20 miles” by the manufacturer which assumes pedaling. On pedal-assist bikes (which require pedaling), the range ratings are much higher because the rider is constantly assisting the motor and reducing the current draw.
The basic shape and configuration of a typical upright or "safety bicycle", has changed little since the first chain-driven model was developed around 1885.[7][8][9] However, many details have been improved, especially since the advent of modern materials and computer-aided design. These have allowed for a proliferation of specialized designs for many types of cycling.
In 2012, two e-bike advocates completed the first 4,000-mile (6,400 km) transcontinental e-bike tour from New York to San Francisco to advocate for e-bikes in major cities across the U.S.[81] Pedego Electric Bikes is the best selling brand in the U.S. Many e-bikes in the United States are standard bicycles converted using a kit. In general, the kits include the motor (the majority of which are hub motors built into the front or rear wheel), a speed controller, throttle (usually twist-grip or thumb throttle), necessary wiring and connectors, and a battery. Several U.S. companies offer conversion kits which also offer advanced lithium battery packs. Major manufacturers also offer complete e-bikes. Trek offers a line of e-bikes using the Bionx system in which the rider programs the controller to determine how much effort the motor will give in response to rider effort, from 25% up to 200% of the rider's power. This system ensures a minimum level of rider participation and is also used to comply with many European laws mandating partial human effort before the motor engages.
The body is made from light and durable aluminum. The handlebar comes with simple controls to let you accelerate, brake, monitor battery life, operate headlights and of course…sound the horn. There’s even an USB point that will let you charge your iPhone or Android on the go. The bike can reach a top speed of 10mph. Feel the wind in your hair as you zoom up and down hills and past all that city traffic…
If you have dynamo-powered bicycle lights, you already own an electric-powered bicycle! Consider: as you pump your legs up and down on the pedals, you make the wheels rotate. A small dynamo (generator) mounted on the rear wheel produces a tiny current of electricity that keeps your back safety lamp lit in the dark. Now suppose you could run this process backward. What if you removed the lamp and replaced it with a large battery. The battery would kick out a steady electric current, driving the dynamo in reverse so that it spun around like an electric motor. As the dynamo/motor turned, it would rotate the tire and make the bike go along without any help from your pedaling. Hey presto: an electric bike! It may sound a bit far-fetched, but this is more or less exactly how electric bikes work.
During testing—and unlike some of the other bikes I’ve tried—this range held true, with the Rad Wagon handling a 20-plus mile round trip with ease. This is helped by a regenerative braking system that automatically charges the battery whenever you engage the brake levels. It’s also relatively quick to charge back up—taking around four hours in my garage—although Rad Power reports that average time is five to six hours.
An electric bicycle is a bicycle with an electric motor used to power the vehicle, or to assist with pedaling. In many parts of the world, electric bicycles are classified as bicycles rather than motor vehicles, so they are not subject to the same laws as motor vehicles. Electric bicycles are one type of motorized bicycle. However, electric bicycles are defined separately and treated as a specific vehicle type in many areas of legal jurisdiction.
European Union directive 2002/24/EC exempts vehicles with the following definition from type approval: "Cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25 kW, of which the output is progressively reduced and finally cut off as the vehicle reaches a speed of 25km/h (15.5mph) or if the cyclist stops pedaling." This is the de facto definition of an electrically assisted pedal cycle in the EU. As with all EU directives, individual member countries of the EU are left to implement the requirements in national legislation.
We rode the Vado through the gauntlet, including some of the steepest hills in Palo Alto, and it easily handled everything we threw at it, maintaining a steady 20 miles per hour even on the most daunting of ascents. The bike also handles well on downhills and is both nimble and quick on city streets and paved trails. It’s even comfortable to ride for extended distances, which is vitally important for any bike built for urban settings.

I bought this bike from a dealer after extensive research on ebikes. The Elby is on par with European commuter ebikes at a better price point, you get a lot for your $ here. Elby is the complete package commuter: lights & a USB charger (for a phone or whatever) are integrated into the motor’s power supply and wired inside the frame. Rugged fenders have heavy-duty cross braces to attach baskets and whatnot. Thick Continental tires make for a comfy ride. The step-through frame is very convenient, built stout enough to carry me (200#) and two loaded baskets down hills and around curves with perfect stability. The motor on this bike is in the rear hub, and having it behind me makes it virtually soundless. The motor (BionX 500 watt) kicks in as soon as you start pedaling, but there is a


Controllers for brushless motors: E-bikes require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed and angle measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally allow input by means of potentiometer or Hall Effect twist grip (or thumb-operated lever throttle), closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. Bikes with a pedal assist function typically have a disc on the crank shaft featuring a ring of magnets coupled with a Hall sensor giving rise to a series of pulses, the frequency of which is proportional to pedaling speed. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of bicycles limits recovered energy. An implementation is described in an application note for a 200 W, 24 V Brushless DC (BLDC) motor.[43]

It appears Tennessee has not passed any legislation that applies to electric bicycles. Some people think the laws pertaining to a Motorized Bicycle should be used for an electric bicycle. However, a Motorized bicycle would be a gasoline powered device per state law as it is defined as "means a vehicle with two (2) or three (3) wheels, an automatic transmission, and a motor with a cylinder capacity not exceeding fifty cubic centimeters (50cc) which produces no more than two (2) brake horsepower and is capable of propelling the vehicle at a maximum design speed of no more than thirty miles per hour (30 mph) on level ground." [56]


We spent 45 hours on research, videography, and editing, to review the top choices for this wiki. With rechargeable, battery-powered pedaling assistance, electric bicycles offer an increasingly viable alternative to fossil-fueled commuting, and e-bikes enable riders of various abilities to extend their cycling range. But the street legality of these hybrid machines remains a contentious issue, so be sure to check current state and local laws governing their operation before you hit the road. When users buy our independently chosen editorial picks, we may earn commissions to support our work. Skip to the best electric bike on Amazon.
Electric bikes are a green alternative to driving a vehicle. Studies carried out in several towns and cities show that the average car speed in rush hour traffic can dip as low as 18 to 20 mph. Electric bike speed can be as high as 15 mph. With an electric bike, you can reduce pollution, improve fitness, and still arrive at the same time as your car-bound colleagues.

Flyer Vollblut. A new rear motor bike from one of the most reliable E-bike makers. This model doesn't look as "heavy" as most other Flyer models. The Vollblut 500 has the 500W new Panasonic rear motor, front fork suspension, 28 inch wheels. It is in the same price range as the Stöckli and the Stromer. Flyer is known for top service and reliability, but it's a new model with a new motor ....
Not all electric bicycles take the form of conventional push-bikes with an incorporated motor. Some are designed to take the appearance of low capacity motorcycles, but smaller in size and comprising of an electric motor rather than a petrol engine. Bicycles of note include the Sakura electric bicycle, which incorporates a 200W motor found on standard e-bikes, but also includes plastic cladding, front and rear lights, and a speedometer. It is styled as a modern moped, and is often mistaken for one based on its similarity in appearance.

We'll start this off with the latest two Customer Profile videos. In the first one we follow up from the well received Leigh Cross video with a look at his son, Tig Cross. Tig's been refining an original bike concept combining the best parts of an ebike, scooter, and velomobile, and showcases the merits of an electric generator for the human drivertrain.
In the early 1860s, Frenchmen Pierre Michaux and Pierre Lallement took bicycle design in a new direction by adding a mechanical crank drive with pedals on an enlarged front wheel (the velocipede). This was the first in mass production. Another French inventor named Douglas Grasso had a failed prototype of Pierre Lallement's bicycle several years earlier. Several inventions followed using rear-wheel drive, the best known being the rod-driven velocipede by Scotsman Thomas McCall in 1869. In that same year, bicycle wheels with wire spokes were patented by Eugène Meyer of Paris.[22] The French vélocipède, made of iron and wood, developed into the "penny-farthing" (historically known as an "ordinary bicycle", a retronym, since there was then no other kind).[23] It featured a tubular steel frame on which were mounted wire-spoked wheels with solid rubber tires. These bicycles were difficult to ride due to their high seat and poor weight distribution. In 1868 Rowley Turner, a sales agent of the Coventry Sewing Machine Company (which soon became the Coventry Machinists Company), brought a Michaux cycle to Coventry, England. His uncle, Josiah Turner, and business partner James Starley, used this as a basis for the 'Coventry Model' in what became Britain's first cycle factory.[24]
Before you start shopping around for a new e-bike, the first thing you should ask yourself is, “how do I plan on using an electric bicycle?” How far do you plan on traveling? What type of terrain will you be traveling on? How much assistance do you need? Do you plan on pedaling – or do you want the bike to do all the work? Is this bike for daily commuting or casual riding? How fast do you need to go?
"Bicycle" means either of the following: (1) A device having two wheels and having at least one saddle or seat for the use of a rider which is propelled by human power. (2) A device having two or three wheels with fully operable pedals and an electric motor of less than 750 watts (one horsepower), whose maximum speed on a paved level surface, when powered solely by such a motor while ridden, is less than 20 miles per hour.[citation needed],

The recommendation depends a lot on what you plan to use the bike for and how you plan to ride. That said, I would recommend at least a 750 (if not 1,000) watt motor, and, if you want reasonable range, 48 or 52v cells with a minimum rating of 19ah. For shorter rides, you can use a smaller battery. Multiply battery voltage by amp hour rating to get battery watt hours. Divide the watt hours by the motors power rating to get a general idea of how many hours of heavy use you might get. I’d also recommend a mid drive as opposed to a hub drive, or to find a hub drive wheel rated to take your and the bicycle's combined weight.
If you need an ebike that can provide a full-on mountain bike experience, but you are also on a limited budget, this bike is an excellent choice for you. We doubt you can find a double suspension bike, jam-packed with features for a better price. Large wheels and low-rise handlebars provide more control and easier ride, but the powerful 500W brushless motor attached directly to the rear wheel hub will give you plenty of “umph”.
The Consumer Product Safety Commission(CPSC) stipulates that commercially manufactured low-speed electric bicycles, or tricycles, must have fully operable pedals, an electric motor not exceeding 750W of power and a top motor-powered speed not in excess of 20 miles per hour (32 km/h).[22] An electric bike remaining within these specifications will be regarded simply as a bicycle for purposes of safety standards. This supersedes any state law that is more stringent, but only regarding safety equipment required on electric bicycles and the standard of manufacture they must meet.[23]. The legislation enacting this amendment to the CPSC is also known as HR 727[24].
Bicycles can be categorized in many different ways: by function, by number of riders, by general construction, by gearing or by means of propulsion. The more common types include utility bicycles, mountain bicycles, racing bicycles, touring bicycles, hybrid bicycles, cruiser bicycles, and BMX bikes. Less common are tandems, low riders, tall bikes, fixed gear, folding models, amphibious bicycles, cargo bikes, recumbents and electric bicycles.
In the theoretical electric bike we considered up above, we had the dynamo/motor driving the back wheel directly, simply by pressing on the tire. Most electric bikes work a different way. They have compact electric motors built into the hub of the back or front wheel (or mounted in the center of the bike and connected to the pedal sprocket). Take a look at the hub of an electric bike and probably you'll see it's much fatter and bulkier than on a normal bike. You can read more about how these motors work in our main article about hub motors.
In Opinion No. 2007-00602 of the Attorney General, Jim Hood clarified that a "bicycle with a motor attached" does not satisfy the definition of "motor vehicle" under Section 63-3-103. He stated that it is up to the authority creating the bike lane to determine if a bicycle with a motor attached can be ridden in bike lanes. No specifications about the motor were made.
Under New Jersey law a motorized bicycle is "a pedal bicycle having a helper motor characterized in that either the maximum piston displacement is less than 50 cc, the motor is rated at no more than 1.5 brake horsepower, or it is powered by an electric drive motor and the bicycle is capable of a maximum speed of no more than 25 miles per hour on a flat surface."[107] This would include E-bikes, meaning they must be titled and registered. However, only Mopeds approved by Motor Vehicle Services can be titled and registered.
Thanks for your feedback Joe! I personally find black on white to be high contrast and abrasive. Instead, this dark gray scheme is meant to be relaxing… but if it’s uncomfortable to you or difficult to read there are ways to change your browser and even your operating system to be more comfortable using the accessibility options. Here’s a list by device type and for some browsers https://goo.gl/voKTnW hope it helps!
Electric-assist and other "motorized bicycles"[86] do not need to be inspected, do not require a license, and do not require registration. The vehicle must meet all of the following criteria: a post mounted seat for each person it is designed to carry, two or three wheels which contact the ground, fully operative pedals, wheels at least 16 inches in diameter and a motor not capable of propelling the device at more than 20 mph on level ground. The driver does not need a license, but must be at least 16 years old. DC law prohibits motorized bicycles from traveling anywhere on the sidewalk or in the bike lanes. DC Regulation 18-1201.18 provides: "Except as otherwise permitted for a motor vehicle, no person shall operate a motorized bicycle on any sidewalk or any off-street bikepath or bicycle route within the District. This prohibition shall apply even though the motorized bicycle is being operated solely by human power." So, if cars are prohibited in a particular place, motor-assisted bikes are also prohibited.[87]
The environmental effects involved in recharging the batteries can of course be reduced. The small size of the battery pack on an e-bike, relative to the larger pack used in an electric car, makes them very good candidates for charging via solar power or other renewable energy resources. Sanyo capitalized on this benefit when it set up "solar parking lots", in which e-bike riders can charge their vehicles while parked under photovoltaic panels.[66]
During nighttime operation, the bicycle must be equipped with a front headlamp, a rear-facing red reflector, and reflectors on the front and rear of pedals, and the bicycle or rider must have reflective surfaces on each side. Minn. Stat. §169.222, subd. 6. An electric-assisted bicycle can be equipped with a front-facing headlamp that emits a flashing white light, a rear-facing lamp that has a flashing red light, or both. The bicycle can carry studded tires designed for traction (such as in snowy or icy conditions).
There are many possible types of electric motorized bicycles with several technologies available, varying in cost and complexity; direct-drive and geared motor units are both used. An electric power-assist system may be added to almost any pedal cycle using chain drive, belt drive, hub motors or friction drive. The power levels of motors used are influenced by available legal categories and are often limited to under 750 watts.

In the year 1885, a British man named J.K. Stanley introduced what can fairly be described as the first modern bicycle. His Rover bike had wheels of equal size in the front and back and used a chain connecting the pedals and the rear wheel as a propulsion system. It was often marketed as a safety bike in contrast with the unstable Penny Farthing, and was a smashing success. The company went on to develop motorcycles and automobiles, remaining in business until the year 2005.
If you’ve got the cash and want to get into ebikes, don’t buy this Rattan. My best advice if you have the money is buy a bike store bike with a Bosch/Brose/Yamaha/Shimano drivetrain. We review lots of them here but I’m currently riding a $2000 Raleigh. If you only have around $1,000+ to spend, head to Luna/Rad/Sondors or at least something from a company you’ve heard of with a Bafang motor.
The Consumer Product Safety Commission(CPSC) stipulates that commercially manufactured low-speed electric bicycles, or tricycles, must have fully operable pedals, an electric motor not exceeding 750W of power and a top motor-powered speed not in excess of 20 miles per hour (32 km/h).[22] An electric bike remaining within these specifications will be regarded simply as a bicycle for purposes of safety standards. This supersedes any state law that is more stringent, but only regarding safety equipment required on electric bicycles and the standard of manufacture they must meet.[23]. The legislation enacting this amendment to the CPSC is also known as HR 727[24].

How do the State Laws relate to the 2001 Federal Law? This is a difficult question to answer and know how they apply to you individually. From the Federal Law, one would hope that your purchased ebike is simply classified as a bicycle, with all the rights and privileges allotted to a normal cyclist. However, State Laws are confusing because they may be more restrictive in parts and add other requirements. About 30 U.S. states still have confusing regulations around them. Either the bikes are technically classified as mopeds or motor vehicles, or they have equipment, licensing or registration requirements that cause problems for riders. Thanks to the People-For-Bikes/Bicycle Product Suppliers Association (BPSA) partnership with local advocacy groups, they have been able to make the case for streamlining state regulations so that e-bikes are essentially treated like regular bicycles.4


This 150mm-travel e-mtb tackles big descents, shines on flowy trails, and provides the boost you need for the trip back. Pedal assist comes from Shimano’s 6.2-pound STePS E8000 motor with a 20mph boost. Shifting is motorized too, with Shimano’s exemplary XT Di2 drivetrain providing the most precise and consistent shifts a mountain bike can have. The fun comes from the E-Core’s 150mm of front and rear travel courtesy of a RockShox Yari fork and Deluxe RT shock. Both can be locked out for long, fire-road type climbs, though on an e-bike that feature feels less necessary.


In conformance with legislation adopted by the U.S. Congress defining this category of electric-power bicycle (15 U.S.C. 2085(b)), CPSC rules stipulate that low speed electric bicycles[64] (to include two- and three-wheel vehicles) are exempt from classification as motor vehicles providing they have fully operable pedals, an electric motor of less than 750W (1 hp), and a top motor-powered speed of less than 20 miles per hour (32 km/h) when operated by a rider weighing 170 pounds.[65] An electric bike remaining within these specifications is subject to the CPSC consumer product regulations for a bicycle. Commercially manufactured e-bikes exceeding these power and speed limits are regulated by the federal DOT and NHTSA as motor vehicles, and must meet additional safety requirements. The legislation enacting this amendment to the CPSC is also known as HR 727.[66] The text of HR 727 includes the statement: "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." (Note that this refers to consumer product regulations enacted under the Consumer Product Safety Act. Preemption of more stringent state consumer product regulations does not limit State authority to regulate the use of electric bicycles, or bicycles in general, under state vehicle codes.)

This year was busy at Haibike’s EUROBIKE stand. The reason: the new FLYON series, which we could only admire behind glass. The new bikes are the spearhead of Haibike’s eMTB development with an exciting and unprecedented level of integration and connectivity. They have a specially developed display, their own remote and, thanks to a 5,000 lumen headlight, are able to turn night into day. To make the rider visible at all times, taillights are neatly integrated into the frame. The bikes also come with the most powerful motor currently available on the market, from TQ Systems. We are sure that many will buy this bike not only for its performance but also as a status symbol.
The oldest patent for an electric bike I've been able to find at the US Patent and Trademark Office is this one, by Ogden Bolton, Jr. of Canton Ohio, which was filed in September 1895 and granted three months later. You can see from these original diagrams that it bears an amazingly close resemblance to modern electric bikes. In the general picture on the left, you can see there's a hub motor on the rear wheel (blue), a battery suspended from the frame (red), and a simple handlebar control to make the thing stop and go. In the more detailed cutaway of the hub motor on the right, you can see there's a six-pole magnet in the center (orange) bolted to the frame and an armature (made from coiled wire, yellow) that rotates around it when the current is switched on. It's quite a hefty motor even by modern standards; Ogdon mentions "a heavy current at low voltage—for instance, to carry one hundred amperes at ten volts." So that's 1000 watts, which is about twice the power of a typical modern bike hub motor.
Electric bicycle usage worldwide has experienced rapid growth since 1998. It is estimated that there were roughly 120 million "ebikes" on the road in China as of early 2010.[1]. The “Electric Bikes Worldwide Reports – 2010 Update”[2] estimates that 1,000,000 electric bicycles will be sold in Europe in 2010. The same report estimates that sales in the USA will reach roughly 300,000 in 2010, doubling the number sold in 2009.
Electric-assisted bicycles are treated as human-powered bicycles, while bicycles capable of propulsion by electric power alone face additional registration and regulatory requirements as mopeds. Requirements include electric power generation by a motor that cannot be easily modified, along with a power assist mechanism that operates safely and smoothly. In December 2008, The assist ratio was updated as follow:
In cities where bicycles are not integrated into the public transportation system, commuters often use bicycles as elements of a mixed-mode commute, where the bike is used to travel to and from train stations or other forms of rapid transit. Some students who commute several miles drive a car from home to a campus parking lot, then ride a bicycle to class. Folding bicycles are useful in these scenarios, as they are less cumbersome when carried aboard. Los Angeles removed a small amount of seating on some trains to make more room for bicycles and wheel chairs.[65]
The European Committee for Standardization (CEN) also has a specific Technical Committee, TC333, that defines European standards for cycles. Their mandate states that EN cycle standards shall harmonize with ISO standards. Some CEN cycle standards were developed before ISO published their standards, leading to strong European influences in this area. European cycle standards tend to describe minimum safety requirements, while ISO standards have historically harmonized parts geometry.[55]
Photo: Zap Electric's power-assist kit turns a conventional bike into an electric one. There's a bolt-on DC electric motor (weighing just over 3kg or 7lb) just above the back wheel, behind the police officer's foot, pressing against the tire and driving it by simple friction. The motor's powered by a compact lead-acid battery (weighing about 5.5 kg or 12 lb) inside a protective nylon bag. This kit adds quite bit of weight to the bike, but gives extra range and speed when needed. Photo taken in Santa Rosa, California by Rick Tang courtesy of US DOE/NREL.
The Espin is powered by a 350-watt motor that’s rated for trips up to 50 miles (depending on the terrain and assist level). Once depleted, the battery fully charges in roughly five hours. Thankfully, Espin makes it easy to remove the battery, allowing you to quickly recharge it at home or in the office between trips. A backlit LCD control hub displays your basic metrics and battery life while in transit and LED headlights add a touch of light when needed.
In general, U.S. and European cycle manufacturers used to assemble cycles from their own frames and components made by other companies, although very large companies (such as Raleigh) used to make almost every part of a bicycle (including bottom brackets, axles, etc.) In recent years, those bicycle makers have greatly changed their methods of production. Now, almost none of them produce their own frames.
The U.S. Consumer Product Safety Act states that electric bicycles and tricycles meeting the definition of low-speed electric bicycles will be considered consumer products. The Consumer Product Safety Commission (CPSC) has regulatory authority to assure, through guidelines and standards, that the public will be protected from unreasonable risks of injury or death associated with the use of electric bicycles.[61][62]
Range is a key consideration with electric bikes, and is affected by factors such as motor efficiency, battery capacity, efficiency of the driving electronics, aerodynamics, hills and weight of the bike and rider. The range of an electric bike is usually stated as somewhere between 7 km (uphill on electric power only) to 70 km (minimum assistance) and is highly dependent on whether or not the bike is tested on flat roads or hills.[14] Some manufacturers, such as the Canadian BionX or American E+ (manufactured by Electric Motion Systems), have the option of using regenerative braking, the motor acts as a generator to slow the bike down prior to the brake pads engaging.[15] This is useful for extending the range and the life of brake pads and wheel rims. There are also experiments using fuel cells. e.g. the PHB. Some experiments have also been undertaken with super capacitors to supplement or replace batteries for cars and some SUVS.

The federal Consumer Product Safety Act defines a "low speed electric bicycle" as a two or three wheeled vehicle with fully operable pedals, a top speed when powered solely by the motor under 20 mph (32 km/h) and an electric motor that produces less than 750 W (1.01 hp). The Act authorizes the Consumer Product Safety Commission to protect people who ride low-speed electric vehicles by issuing necessary safety regulations.[63] The rules for e-bikes on public roads, sidewalks, and pathways are under state jurisdiction, and vary.


My one complaint is the bike’s weight. This sucker is heavy! The aluminum frame looks light, but the the hub motor (4 pounds) and battery (5 pounds) add up. The bike’s total weight is 39 pounds, which is about average for e-bikes but not something you’d want to lug around all day. “This is not a solution for everybody,” Miller admits. “If you live in a fifth floor walkup this is probably not going to work.”
Firstly there's a magnetically-fired locking pin in the rear wheel, triggered by kicking a button on the hub. This is fairly secure in itself and almost impossible to remove without destroying the bike. In London, we'd pair it with a more traditional bike lock so there's a more obvious visual deterrent, though a LED matrix screen on the frame does issue a warning to would-be tea-leafs.
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