Category Archives: Equipment

About the bicycle radar reflector Kickstarter campaign

This is commentary about a Kickstarter campaign for a radar retroreflector integrated into a bicycle taillight assembly.

An image from the Web site:

Image from Ilumaware Web site

Image from Ilumaware Web site



One nice thing I can say about the product is that it is quite inexpensive, so I’ll say that first. The reason is that this is not a high-tech product. This is a low-tech component of a system whose high-tech component is in cars.

Retroreflectors work by concentrating light (or in the case of a radar reflector, radar signals) back toward the source. The product is a single cube-corner retroreflector. Optical retroreflectors are the insect’s eye version, with multiple smaller reflective elements, so they work at the much shorter wavelengths of visible light. The technology is described on another Web page.

Retroreflectors have been around for a long time, but the the product Web site repeatedly uses the term “OTR technology”, without ever spelling out the meaning of the acronym . I couldn’t find a definition anywhere online, either. This term makes the product appear more high-tech than it is. Indeed, the site claims:

Stealth techniques use radar reflection to make an object less visible and/or “invisible” to radar. We have reverse engineered this technique into a product used by a cyclist to make you more visible to a car. This is a revolutionary application of radar technology.

Reverse engineering is correctly defined as analysis of an undocumented product to develop specifications for a duplicate or similar product. Examples are the Wright brothers’ reverse engineering the flight characterisics of birds to design aircraft, and Linus Torvald’s reverse engineering the proprietary Unix computer operating system to construct the Linux operating system. The Kickstarter campaign uses the words “reverse engineered” inaccurately, so as to mislead people who do not understand it, as if to mean design of a product to have the opposite effect of an existing product. And when that product is a stealth bomber — wow, now the new product must be extremely high-tech! Again, the product is a simple cube-corner radar retroreflector, as has been used in boating for decades. The designers describe design and optimization of their product, but this is plain vanilla engineering, not reverse engineering.

As to the effectiveness of this product, I have no doubt that it improves the visibility of a bicycle to radar — but…

A radar retroreflector which works in all directions is more desirable, (though it still will not always work, even if a car has radar, because the radar beam may not be aimed in its direction, and there may be a line-of-sight obstruction).

Radar alone as a robotic aid to a human driver is possible, but not very practical. Only a small percentage of cars have radar as of yet. A human driver uses visual cues. A fully-robotic car also must, because not every potential obstacle will be as large or reflect radar signals as well as a bicycle — think potholes, cats and dogs, etc.

The product, as shown on the Web site, includes an active taillight, but no optical retroreflector — though installed in the same location on the seatpost which is usual for one — following in the long tradition of new products promoted as a panacea for cyclists’ conspicuity problems while ignoring basic legal and functional requirements. Most states require a retroreflector or taillight, but any taillight can go out without the bicyclist’s being aware of that, and so any bicyclist who rides after dark should have a rear-facing retroreflector, not only a taillight.

The online promotion entirely fails to mention the need for a headlight, or the legal requirement for one. The Web site shows a bicycle with no headlight.

A bicyclist must always use a headlight at night, because an optical forward-facing reflector does not alert pedestrians or drivers who do not have headlights aimed at the bicycle (cars backing out of driveways, at stop signs in side streets, other bicyclists without headlights, etc.) Still, unlike the optical retroreflectors on bicycles, a forward-facing radar retroreflector is likely to be effective, because a car’s radar is likely to scan in more directions and its pulsed output is immune to interference from other sources. But the retroreflector here is only rearward-facing.

The online promotion also makes a number of inaccurate statements.

 Riding with a tail light [sic] is important regardless of the time of day.

While a very bright taillight can help to alert drivers — human or robotic —  during daytime, reducing the probability of a collision somewhat, there is no law requiring a taillight (or rear-facing optical retroreflector) when riding during daytime.

* “In 2015, more than 35,000+ collisions occurred between cars and cyclists in the U.S. Approximately every 3 minutes, world-wide, 6 people die and nearly 285 people are injured in collisions involving cars and bicycles. The majority of these accidents are from behind because drivers didn’t see the rider and it is NOT because they did not have a tail light.”

This is wildly inaccurate. While rural car-overtaking-bike collisions are disproportionately serious and fatal, only approximately 7% of car-bicycle collisions in the USA toare car-overtaking-bike collisions. A very large percentage of these occurs to cyclists riding at night without a taillight! In urban areas, most of the serious and fatal collisions involve turning and crossing movements. No rear-facing conspicuity equipment —  optical or radar retroreflector, or taillight, will prevent most of these. Sure, many if not most car-overtaking bike crashes could be avoided, day and night, by use of a radar reflector, if cars have radar connected to a robotic crash avoidance system — but again, as of yet, only a very small percentage of cars is so equipped. Which takes me to my next quote:

* “In 2016 … there are 470 out of 566 unique car models sold in the U.S. equipped with radar (83%).”

This is very seriously overstated. Saying that a model is equipped with radar is not the same as saying that radar is standard. Adaptive cruise control is still often an expensive option. Only some adaptive cruise control systems include automatic crash avoidance. Some systems use laser ranging rather than radar. The fleet of motor vehicles turns over slowly. More even-handed estimates are found in this article in the Detroit News. Quote from that article:

IHS Automotive forecasts 7.2 percent of vehicles produced globally by 2020 will feature adaptive cruise control, up from 2.2 percent in 2014.

More details and a list of vehicles are on Wikipedia.

Why do promotions like this occur? Fundamentally, because regulation of bicycle equipment in the USA at the Federal level, where equipment standards are set, is a Wild West situation, harkening to the interests of the bicycle industry. That is another story, too big to cover here.








Support for the Allies in WWII, wrapped around a bicycle sprocket

I wrote to Sturmey-Archer’s European office a few months ago concerning the Swiss-made Vibo three-speed hub described on the Sturmey-Archer Heritage Web site. The Web page about this hub indicates that a scrap of paper which enclosed the sprocket in the shipping box shows German troops marching into Paris. It doesn’t. The page hasn’t been corrected, so I’ll make a correction here.

Here’s the scrap of paper. You can click on the image to enlarge it, and read the caption if you happen to read French.

The scrap of paper which wrapped the Vibo hub

The scrap of paper which wrapped the Vibo hub

Here’s translation from the French on the scrap of paper.

Underground mobilization
in the Paris sewers and catacombs

(continued from no. 29)

A city full of passion and hope

Since the start of the invasion, German illustrated newspapers have ostentatiously been publishing images of Paris which the propaganda agencies accompany with strange commentaries. Here is an example: it is supposed to prove that Paris is hostile to the Anglo-Saxon invaders and that it openly supports the acts and cause of its oppressors. While the tank battle rages in Normandy, German power is being asserted in the French capital through the organization of large demonstrations by reserve troops along the avenues and boulevards. The Germans do not seem to be troubled by the developments alongside and below them, appearing to be content to drown out the muffled rumblings of the partisan army in the underground city with the sound of boots on the Champs Elysées. The Germans are surrounded by large crowds which “applaud spontaneously, clap their hands and throw flowers.” But who, then, has checked whether these are Parisians? There are two hundred thousand German civilians in Paris, to whom might be added, as in any large city, a certain number of women of easy virtue. Let us recall 1870 and the well-known heroines of Maupassant’s stories. There is nothing mysterious about this image. The Champs-Elysées? Yes. But Paris? No!

This establishes a few things:

  • The hub was shipped no earlier than the weeks in 1944 after the D-Day invasion but before the liberation of Paris — not when “German troops were marching into Paris,” as indicated on the Sturmey-Archer Web page.
  • Therefore, any lawsuit to stop production of this apparently unauthroized copy of the Sturmey-Archer AW hub did not succeed till after that time (and I suspect, wouldn’t get much attention while the war was raging).
  • As Switzerland was neutral, the hub could have been exported to Germany or a German-dominated country — including French-speaking countries — and so the message might have been chosen intentionally as an indication of support for the Allies against Nazi Germany. Note how neatly the paper is torn to preserve the image and caption!

It is also understandable that a Swiss company would take up manufacture of a copy of a Sturmey-Archer hub during the war. There was no way to get the real thing in Switzerland, which was surrounded by Axis and Axis-dominated countries. Also, production of bicycle components — especially for export — in both Allied and Axis nations was limited by the war. The threat of a lawsuit from England would be much less of a concern than action — legal and diplomatic — by the neighboring Germans; the Swiss manufacturer and/or employees clearly were more sympathetic to the Allied cause, and might also expect customers to be. Therefore, a copy of a British hub would probably be better received than a copy of a German one, even though illegal.

Some Commie Kitsch

Commie Kitsch from Dero Racks

Commie Kitsch from Dero Racks

This bright red shirt — with a design like a poster in “Soviet Realism” style, a mock Soviet propaganda message, “Ride Your Bike for the People!” in fake Cyrillic type, and a portrait of Vladimir Lenin himself — was a giveaway from the Dero company, which makes bicycle racks. I picked up the shirt at a National Bicycle Summit — in 2007 or 2008, I think. The Summit is a national conference and lobbying event organized by the League of American Bicyclists. The event is funded by the rather high admission fee and a substantial grant from the bicycle industry’s lobbying arm, Bikes Belong.

The logic, and for that matter the question of good taste, with the Commie kitsch on this shirt baffle me. The JFK Library here in the Boston area is about to hold a panel discussion on the 50th Anniversary of Cuban Missle Crisis. Living in a world that included the Union of Soviet Socialist Republics was scary —

— while Dero is very squarely situated within the seriously capitalistic U.S. bicycle industry.

The bicycle industry has more recently inverted the Bikes for the People slogan with its PeopleforBikes campaign, but that’s another story. I certainly can be thankful, though, that here in the USA, I can comment about “People’s” movements which actually serve some other constituency, without being hauled away in the middle of the night to some Gulag, or worse.

Anyway, I have adopted the appropriate stern expression and raised fist for the photo, in keeping with the spirit of the shirt.

Electric bicycle legal hodgepdge

A task force under the auspices of the National Committee on Uniform Traffic Control Devices (NCUTCD) is currently reviewing parts of the Uniform Vehicle Code (UVC), the national model traffic law in the USA. The NCUTCD has taken on this task because the National Committee for Uniform Traffic Laws and Ordinances (NCUTLO), which maintained the Uniform Vehicle Code, unfortunately ceased operations about 10 years ago.

I am the bicyclist representative on the NCUTCD task force. Electrically-assisted bicycles are one of the hot-button issues I will have to address.

Due to the novelty of electrically-assisted bicycles, the lack of guidance in the UVC and the lack of a user constituency — bicycling advocacy organizations having largely ignored or disparaged this increasing trend — electrically-assisted bicycles are not being addressed in a consistent or logical way under the law. In some places, electrically-assisted bicycles fall under laws that apply to gasoline-powered motorized bicycles; in others, not. We are seeing a tug of war between manufacturers’ self-interest and well-intentioned but poorly-thought-out restrictions imposed by legislators concerned about safety — as with Segways, but a bigger problem than with Segways, which have never been very common.

In my opinion, vehicles defined as electrically-assisted bicycles should be permitted wherever bicycles are permitted, but should not be capable of more than 20 mph under motor power. They shouldn’t be hard-limited to that speed, because higher speed is often possible downhill — for bicycles without electrical assist too — and is advantageous to the rider, and because speed limits are reasonably imposed locally based on conditions rather than globally based on vehicle type. These opinions are consistent with the product definition and regulation promulgated by the U.S. Consumer Product Safety Commission.

The situation with state laws is more confused. I live in Massachusetts, so let’s take the Massachusetts laws as an example. They are a mess:


Link to Massachusetts General Laws, Chapter 90, Section1: Definitions

The definition for “motorized scooter” in Massachusetts law includes gasoline OR electrically-powered ones, stand-up or sit-down, including those also propelled by human power. An electrically-assisted bicycle, then, is identified as a “motorized scooter”. The definition for “motorized bicycle”, on the other hand, applies only to those with a gasoline motor. The definitions overlap awkwardly.

Motorized-bicycle driving rules:

Link to Massachusetts General Laws, Chapter 90, Section1b: Motorized-bicycle driving rules

These rules apply only with a gasoline motor: 25 mph max speed, 16 year minimum age, driver’s license required (obsolete — now this is the minimum age for a learner’s permit) , carte blanche to overtake on the right, somehow requiring drivers turning and crossing from the left to have X-ray vision to see through other motor vehicles, same as in Massachusetts’s rather unique bicycle laws (!!!!)  Motorized bicycles are permitted in bike lanes, but prohibited on paths: that is sensible because of the noise, pollution and typically higher speed than with bicycles. A helmet is required.

Motorized-scooter driving rules:

Link to Massachusetts General Laws, Chapter 90, Section1e: Motorized-scooter driving rules

Maximum speed 20 mph (regardless of power source –gasoline, electric, human). This law requires “keeping to the right side of the road” — which unreasonably, means not going left of center of the road or crossing a marked centerline to overtake, but can easily be misinterpreted as requiring overtaking on the right. There is no mention of use on paths or bike lanes, despite noise and pollution of gasoline-powered motorized scooters which makes them inappropriate on paths, where electrically-powered ones are more acceptable. A license or learner’s permit is required, as for motorized bicycles, but there is no mention of age; a learner’s permit can be obtained at 16 years of age. There is a totally unreasonable prohibition on use at night. A helmet is required.

The motorized scooter law was passed in a rushed, knee-jerk reaction to the fad of “mini-motorcycles” a couple of years ago.


Placing electrically-assisted bicycles in the same category with gasoline-powered mini-motorcycles and standup scooters doesn’t make much sense from the point of view of where their use would be appropriate. Prohibiting the use of electrically-assisted bicycles at night writes them off as useful transportation.

We need to do better than this. I hope and expect that the Uniform Vehicle code revision will come up with sensible laws to cover this increasingly popular vehicle type, and that Massachusetts will revise its law.

Also please see my post on this blog about electrically-assisted bicycle types and trends.

Bob Mionske on “Driver Sues Family of Deceased Cyclist”

In a Bicycling Magazine blog posting, Bicycling attorney Bob Mionske describes an appalling situation: a motorist driving over 80 mph in a 45 mph zone struck and killed a teenage bicyclist in Connecticut. The bicyclist’s family sued the driver — but then, the driver countersued the family, claiming that the bicyclist was negligent in not wearing a helmet.

Connecticut law excludes such claims. Mionske says that the Connecticut legislature, in its wisdom, excluded the claims because bicycle helmets cannot protect bicyclists in high-speed collisions with motor vehicles.

I seriously question Mionske’s explanation. The same exclusion exists in laws requiring seat belts and automotive child seats, which usually do protect their users in collisions. Also, bicycle helmets do protect bicyclists in many if not most car-bike collisions. Only a small percentage involve high-speed impacts. The bicyclist cut off by a crossing or turning vehicle, or sideswiped, may only be dumped onto the road or onto the hood of a car, and head injury may be survivable or even completely avoided if the bicyclist is wearing a helmet.

Any passive safety equipment — seatbelt, child seat, helmet — can sometimes prevent injury, but cannot prevent a crash. To allow the victim to sue the perpetrator, and to prevent the perpetrator from suing the victim, is a moral issue, not a technical one. This is even more important when a law is poorly understood and weakly enforced, as with bicycle helmet laws. Children often ride bicycles where parents can not monitor them. Distribution of helmets also is an issue, when a helmet can cost as much as a cheap bicycle. In states with contributory negligence statutes, it’s worse yet: a finding of 1% negligence on the part of the victim results in dismissal of a lawsuit against the perpetrator.

To my knowledge, I was first to raise the issue of the liability exclusion. Back in the 1980s, well-meaning safety advocates, most importantly Safe Kids USA, had begun promoting bicycle helmet laws. A law was enacted in Massachusetts, where I live, without a liability exclusion. As a member of the League of American Wheelmen State Legislative Committee, I campaigned for a better law, and it was enacted. The League’s Consumer Affairs Committee, on which I served, publicized the issue of the liability exclusion, and it was written into the laws of many states, including Connecticut.

The League remained neutral on the issue of helmet laws, as its members’ opinion on them was divided — also realizing that fighting helmet laws could look bad and might not succeed; but the League insisted that such laws include the same liability exclusion as other safety-equipment laws. To their credit, safety advocates responded positively, supporting laws with the liability exclusion and innovative penalty structures. Examples:

  • no penalty, but only a warning;
  • penalty waived if the violator purchased a helmet;
  • positive incentive, such as coupon for a free serving at an ice cream shop for a kid seen wearing a helmet.

The safety advocates also initiated helmet distribution campaigns for disadvantaged children. With time, the awareness became widespread that educational and promotional campaigns, more than laws, would be effective in increasing the rate of helmet use in the USA.

Helmets sometimes prevent injury and sometimes don’t — but that wasn’t the issue that propelled the campaign for liability exclusions. That a helmet would not have prevented injury could, quite to the contrary, point out the seriousness of a crash and make a persuasive argument that a bicyclist should recover damages!

About bicycle lighting and onions

A chance meeting can lead to unexpected discoveries.

I met and spoke with Kurt Cibulski following a reading from a new book by its author, a mutual friend. I had arrived at the reading by bicycle; Kurt and I were talking bicycling. Kurt explained that he has a seizure disorder. The bright, rapidly-flashing LED headlights that bicyclists are increasingly using can initiate a seizure for him. “Who’d ‘a’ thunk it.” thought I.

Who? A proper, national standards-setting body, because someone, somewhere, would have brought the issue to its attention. On second thought, it’s obvious. Flashing lights are well-known to trigger seizures.

It’s also a truism that flashing lights draw attention. Many bicyclists ride in urban areas with overhead lighting, and don’t need a steady headlight beam to guide their way. But on the other hand…there’s the seizure problem.

Without careful standards setting, issues like this slip through the cracks. Designs get based on whim, commercial appeal, economies of production and avoidance of liability risk.

In the USA, individual cyclists are held responsible under state laws for using lights at night, but law enforcement is near-nonexistent, and many cyclists don’t use lights. The USA does have a Consumer Product Safety Commission, which, under pressure from the bicycle industry, has set standards — weak standards — only for retroreflectors on bicycles, never for lights. Retroreflectors only work for drivers whose headlights are pointed at them, and do not light up for the pedestrian stepping off the curb, the motorist in the cross street ahead, two bicyclists on a path approaching each other head-on. Bicycle manufacturers can point to Federal regulations and say that they are doing something for nighttime safety, while not being held responsible for these deficiencies.

This situation holds some ironies and unintended consequences beyond the obvious one that cyclists are being injured and killed for want of lights. The lack of standardization in the USA has given lighting manufacturers free rein to innovate, and has led to the availability of some very fine bicycle lighting systems. In the USA, when you see a cyclist with a light, you will probably see that cyclist from a good, long distance, because the light is a very good light.

In Germany, by way of contrast, lights are required on new bicycles. Manufacturer pressure comes to bear in a different way. To keep expense down, most lights only meet the letter of the law and are are less bright, and much less reliable, than the good ones sold in the USA. Bureaucratic inertia has compounded the problem: Germany requires bicycle lights to be powered by a generator. That made sense 40 years ago when battery lights were weak and battery replacement was expensive. Today’s efficient light-emitting diodes and high-capacity rechargeable batteries make battery lights economical and practical.

Generator lights also have improved, thanks to advances in technology and to discerning European cyclists’ demand for better lights that also meet the requirements of their laws — but a good generator lighting system can cost half as much as the bicycle on which it is installed.

A restrictive legal climate leads to this kind of market distortion; contrast this with the wider scope of innovation and slip-through-the-cracks issues in the US market.

I can’t help noticing that kiosk “bike share” (actually rental) bicycles that are becoming popular in American cities all are equipped with LED headlights and taillights, powered by a generator in the front hub. It only makes sense. The rental agencies have a more direct liability exposure than bicycle manufacturers who sell to individuals. But — the lights on the rental bicycles flash, because the generators produce alternating current and the output is not smoothed. Possibly also because flashing lights are popular and nobody though of the seizure-disorder issue.

Where are we heading with all this? I think that we’re approaching a political tipping point where regulations requiring lights on at least some kinds of new bicycles might be possible in the USA: both because of an increase in interest in utility cycling, and because improving technology had made bicycle lights much less expensive, more reliable and more compact. I mean, if little children can have flashing LEDs in the soles of their shoes, just to look cool, it isn’t much of a leap to think that every new utility bicycle could be equipped with lights.

But we also need to be smart, and look forward as technology improves, so regulations don’t box us in with outdated technology and inferior products, as in Germany.

Now, about those onions:

To give Kurt proper credit in this article, I asked his name and came up with another unexpected discovery. He spelled his name, and then volunteered, “Cibulski means ‘onion man’ in Polish. It’s a pan-European word.” Yes! Again, who’d ‘a’ thunk it? German, Zwiebel. Spanish, cibolla. I looked it up, and found variants in languages as diverse as Basque, Czech, Gaelic, Norwegian, Romanian…

I suppose that there’s another parallel, besides the two unexpected discoveries. Bicycle lighting issues, with all the political and technological complications, peel apart in layers like an onion, too.

Thanks, Kurt!

Tipping point for electric bikes?

I have just returned home from the 2010 Interbike bicycle trade fair in Las Vegas.

This was the year for electrically-assisted bicycles – over 40 booths displayed them. Here are some examples:

Lahaina electric bike, essentially a conventional bicycle with a motor in the front wheel and a battery on the rear rack.

Nirve Lahaina electric bike, essentially a conventional bicycle with a motor in the front hub and a battery on the rear rack.

The Nirve Lahaina electric bike is essentially just a conventional bicycle with add-ons. The front brake is an inexpensive long-reach sidepull, marginal even without the added weight of a motor and battery. The rear wheel has a Shimano three-speed hub with a coaster brake.

Front brake and hub of the Lahaina bike

Front brake and hub of the Lahaina bike

Here’s another example, a Pedego electric bike configured more or less like a conventional bicycle, and with derailleur gears, but with an electric motor in the rear hub, and on its way to be a motorcycle with fat tires that would have unacceptable rolling resistance with pedal power only. The disc brakes should be adequate to their task.

Fat-tire electric bike, with distinct motorcycle tendencies.

Fat-tire electric bike, with distinct motorcycle tendencies.

The e-Solex electric bike shown below is configured more like a motor scooter, with a step-through frame that favors a rider with limited flexibility, or who wears a skirt. The saddle is adjustable upwards, for efficient pedaling. (Note other bike in the background, with raised saddle.) Solex was the classic mid 20th-century French moped add-on, a small gasoline motor that transmitted power through a roller on the front tire of a conventional bicycle. The e-Solex recalls this design, though the motor is actually in the rear hub and the cylinder over the front wheel is a baggage compartment.

An electric bike which is more like a motor scooter

An electric bike which is more like a motor scooter

At the show, there was even one cargo trailer with a motor, that could be hitched onto any bicycle and could help bring home a heavy load.

I didn’t expect to see so many electric bikes at the show. I have thought in the past that adding a motor to a bicycle would inevitably lead to atrophy of the pedals through disuse. Motorcycles began as a subspecies of bicycles in the first decade of the 20th Century. Again, in the mid-20th Century, bicycles with a small gasoline auxiliary motor evolved into mopeds, with vestigial pedals, and into motor scooters, with no pedals at all. Why?

  • The heavier machine with its motor made pedaling ineffective;
  • the motor also made pedaling irrelevant;
  • the motor made higher speed possible, and a larger and more powerful motor, in turn, required a heavier frame;
  • storing a gasoline-powered machine in a living area was not practical.

For these reasons, motorized two-wheelers diverged into entirely different categories from bicycles, with little or no overlap. Electrically-powered two-wheelers never succeeded in the market, as the dead weight of batteries made them more trouble than they were worth – no fun to ride, heavy to carry, with short range.

But now electric bikes have improved substantially thanks to lithium-ion batteries and rare-earth magnets. Concerns about air pollution also come to bear. An electrically-assisted bicycle can be stored in a living area. It can go up in an elevator, though it can’t easily be carried over the rider’s shoulder like a pedal bicycle. Electric two-wheelers have become popular in China (though still using lead-acid batteries there), and the corner may be about to turn in other countries as well, including the USA.

At the dirt demo days at Interbike, people on electrically-assisted bicycles were effortlessly cruising up the steep hill to the demo site in the 99-degree heat. Even in the dry, desert heat of southern Nevada anyone who pedaled up the hill would be wearing a coat of sweat-soaked dust before reaching the top.

There was even a sort of John Henry vs. the steam drill uphill race. Everyone was pedaling furiously, so everyone ended up sweaty, I’m sure. One particularly strong cyclist on a racing bike finished near the front, but a small-wheel, fat-tire electric bike was first.

At Interbike, I spoke with my colleague John Schubert, who suggested that electrically-assisted bicycles would be useful:

  • To allow a person incapable of producing enough power to make use of a bicycle for local transportation. This is obvious enough. With the Baby Boom generation aging, this can be a substantial market.
  • To make short “Dutch-style” utility-cycling and commuting trips possible without a person’s having to work up a sweat – important for many people.
  • To make longer “bigger, hillier US city” trips practical for people who would otherwise only consider shorter trips.
  • To allow a bicycle tourist to cover greater distances or keep up with a group of stronger riders. This is, to be sure, only possible where there are places to recharge overnight — but most campgrounds have electrical power. John tells a story of an elderly man who was thrilled to have participated in a multi-day tour which would have been impossible for him otherwise.
  • And entirely eliminating the complications and extra weight of pedal power, that small, electrically-powered motor scooters, would be practical for short-distance urban travel — and they exist, but they do not yet fit into a legal category in many places.

I would add one more point: that electrically-assisted bicycles will be much more appealing in hot climates than in cold ones. This is mostly a question of rider comfort, but also, battery performance decreases appreciably in the coldest weather. In impoverished countries with hot climates, bicycling of the very slow, energy-conserving variety has been a favored mode of transportation, but has given way to gasoline-powered motor scooters as soon as rising income made them affordable.

Whether electrically-assisted bicycles are going to find an important niche in the US market remains to be seen. Certainly, they are less expensive than mopeds or motorcycles; their environmentally-friendly and indoor-storage-friendly characteristics may appeal — but for the foreseeable future, the power-to-weight advantage lies with the internal combustion engine and its fuel tank.

Wherever electric or gasoline-powered two-wheelers steal a substantial part of the market for utility trips away from pedal cycles, expect some serious dislocation in planning. But that’s a topic for another article.

Audible warnings

Some jurisdictions require a bicyclist to have an audible warning device, commonly a bell or horn.

My bicycle has an audible warning device. Well, actually, I have only one warning device which I move to whatever bicycle I happen to be riding: my operatically-trained voice. Though less courteous than a bell or horn to warn pedestrians, my voice can transmit messages, not only a warning — “bicycle behind you”; “passing on your left.” My voice can be modulated from a whisper to a shout, which is more likely to be audible inside motor vehicles than any bell or horn commonly sold for use on a bicycle (except an air horn, which would startle pedestrians right out of their shoes every time). Bells and little squeeze-bulb horns make the most sense on multi-use paths, but they are rather pointless when riding in the street.

My voice also operates without my having to remove a hand from a brake lever.

I live and ride in Massachusetts, USA. which requires an audible warning when overtaking a pedestrian, but doesn’t specify a device. That works for me.

Some bicyclists don’t like to install a bell on their bicycle; one claim is that there is limited “dashboard” space on drop bars.

I think that a more common objection is that these bicyclists don’t want to look geeky or add the horrifying couple of ounces of extra weight. After all, if there’s room for a bicycle computer one side of the handlebar stem, there’s room for a bell on the other side — or on the stem itself.

Bell and horn requirements could possibly be invoked by a police officer with nothing better to do, to cite bicyclists who are not committing any other offenses. If I had to defend myself against this charge in court, I’d bring little ding-ding bell, give a demonstration of it and of my voice, and ask whether the court could tell me seriously that the bell was a more effective warning device.

…and hope I didn’t have laryngitis on the trial date.

If I regularly rode where a bell is required by law, I suppose that I would install one. But I’d still use my voice most of the time.

Drive ratios of bicycle hub gears

My examination of drive ratios of the SRAM S7 hub has led to examination of other hub gears. I now have information on a very large number of hubs posted online in a Web version of a Microsoft Excel workbook — which includes a link to the source Excel file too.

The workbook gives exact (fractional) gear ratios as well as decimal approximations, and corrects a number of minor errors in manufacturers’ literature and online gear calculators. For most hubs, the information is calculated directly from gear-tooth counts and an examination of the hubs’ internals. The workbook page about each hub therefore indicates how the hub generates its ratios.

Thanks to the excellent Sturmey-Archer Heritage Web site and to documentation on the site of Tony Hadland, author of the book The Sturmey-Archer Story, I have information on Sturmey-Archer hubs all the way back to the first model sold, in 1902. I also cover most geared hubs from SRAM (and the companies it absorbed) and Shimano, and the Rohloff hub. Please see the acknowledgments page of the workbook for a list of people who have been helpful. Coverage of additional hubs will be added as the information comes to light. If you have information to contribute, please don’t be shy!

Why am I doing this? I’ll admit, I’m a bit of a math nerd. It’s been bothering me for years to see only inexact, and sometimes incorrect, decimal numbers given for the drive ratios. But also, I am writing an article for the technical journal Human Power about trends in the design of internal hub gears. My research toward the article has generated the information on drive ratios.

About the laser bike lane…

Lasers projecting the image of a bike lane from a bicycle onto the street ( Laser — high tech — must be a great idea then? Not really.

Light shining directly from the vehicle toward the viewer is many times more efficient than lighting the road to indicate the position of the vehicle.

A bike lane that moves with the bicycle conflicts with the road markings on the road.

The page: (with the red lines) is a Photoshop job. The beam from the light would have to pass through the rider to illuminate everywhere shown, and there is no pavement texture visible in the lines on the pavement.

The green lines at either side on the page appear to have been generated by a device on the bicycle, but the bicyclist symbol in the middle of the lane looks like a Photoshop job.

The video embedded above and at, [missing from the Web page as of July, 2011] appears indeed to show lines on the roadway projected from a device on the bicycle’s seat post, but not from the device shown on, as the green spots which the light comes from are too far from the centerline of the bicycle. Also, I just gotta love this masterwork of obfuscation:

“Preliminary contextual research shows its performance in real world situations is best when lighting conditions are at their worst, improving safety in the most critical situations.”

That is to say that light output is weak.

Lasers are hugely inefficient, but because they produce a pencil-thin beam, can send all of it into the pupil of an eye and cause retinal burns if bright enough to light the road — especially, green lasers, whose light is absorbed by the red chorion tissue behind the retina. One reflection from a puddle into the pupil of your eye, of a laser above 10 milliwatts in output power, for as little as a few microseconds — boom — retinal burn, if a mechanical scanning device is used to generate a pattern, as is usual, or if the device stops. A hologram might also be used, but it would reduce efficiency. The lines shown do not extend forward of the bicyclist where most conflicts occur. Notice in the picture that the reflective spots on the cyclist’s shoes show brighter than the taillight included in the laser device, when the cyclist is in the car’s headlight beams. To the credit of the promoters, the cyclist is shown using a headlight.

There is only an e-mail address on the Web site for contact information but, judging by the uniquely nonstandard curve-into-curb edge stripes on the roadway, I think this video was shot here in Massachusetts.

And, the bicyclist in the video rides in the door zone and makes a left turn from the right curb on a red light. The car following him also turns left on red. I’m glad I wasn’t sharing the road with these people!

Now, looking at this photo, , I can confirm Massachusetts — the famous Citgo sign near Fenway Park (go, Sox!) is visible in the background.

Right here in Massachusetts! Maybe the perpetrators are associated with a certain educational institution on the Charles River, of which I’m an alumnus! What a thought…