A Primer On Bike-To-Bike Communication

Can You Hear Me Now?

In this day of instant messaging, tweets and 24/7 availability, going for a ride incommunicado can have a certain appeal. In fact, that singular solitude is what drew many of us to motorcycling in the first place. But how many times have you had to pull over during a group ride to wonder, What happened to Dave? Is Fred having mechanical problems or did he just stop to adjust his helmet strap? There are times when Bike-To-Bike (BTB) communication comes in handy, even if all you want to do is tell your buddies, “Hey guys, I’m tired, let’s take a break,” with the press of a key.

In this two-part review, we’ll examine the available technologies and categories for BTB communications. In Part I we look at the different options available and try to strip away some of the mystery, confusion and technical mumbo-jumbo. Part II (to run in the following issue), will dive deeper into options for actual products across the categories, the pros and cons of each product class, and will look at installation of the input/output—that is, the speaker and microphone. We’ll finish it off with an Editor’s rating of the options.

So, BTB communications: What is it? Pretty simply, it’s being able to talk to your buddies along on the ride and allowing them to talk back to you. This means that, somewhere on your person or bike, you need a 2-way radio, hands-free speaker(s) and microphone, and a method to transmit and receive wirelessly. That’s it! Options include CB, its more modern cousins, FRS/GMRS, and Bluetooth. There are other more obscure and proprietary options out there that operate on other frequency bands, but the chances of you running into another rider with one of these products are slim, so we’ll just focus on the mainstream ones here.

**“Hello, this is 1958 calling…” **

Citizen Band Radio (CB) is the granddaddy of them all. Established, pretty much in its current form, in 1958, it operates 40 channels in the 27 MHz frequency band. Actually, each of the 40 channels has its own unique frequency between 26.965 MHz and 27.404 MHz; but we’ll keep it simple. Initially, the FCC required a purchased license but abandoned this strategy when millions of applications flooded in every month in the CB heyday of the 70s (remember Smokey and the Bandit?). Today, no license is required and anyone can buy and use CBs on any of the authorized channels, with the understanding that Channel 9 is reserved for emergency and roadside assistance. Often CBs add the capability to receive NOAA Weather Radio, a network of radio stations broadcasting continuous weather information directly from the National Weather Service, but this is not part of the CB standard.

Let’s get technical for a moment. CBs transmit an analog signal at a frequency of 27 MHz (See: Sidebar on Radio Frequency). A useful fact to remember for parties is that the Wavelength (in feet) = 984 / frequency (in megahertz), so 27 MHz is a relatively long wavelength, as communications travel at over 36 feet. The optimum antenna is a fraction of the wavelength, so a quarter-wave for CB equates to roughly 9 feet. Since it’s a bit cumbersome to have a 9 foot wire on your bike, they usually put a load coil somewhere in the antenna to shorten the physical length but allow the antenna to function as if it was longer. This need for a long antenna is one of the reasons handheld CB radios are all but gone from the market, and you typically see those giant whips on semi trucks.

So you have a CB on your bike with your long antenna whipping around. What’s it all mean? Well, you have a system that is regulated to have no more than 4 watts transmit power; you have single duplex capability, which is a fancy way of saying you can either talk or listen, but not both at the same time; and you have line-of-sight signal capability, which translates to about 1–3 miles of range (see the sidebar on Line of Sight). You also have a radio that is operating in the same general frequency band that’s used for RC toys, cordless phones, baby monitors and countless other items, so you often get interference; you have the whole world talking on your channels because you can’t set up any kind of privacy capability for just your group. On the positive side, you get really simple operation (just pick your channel and press the button to talk) and an installed base of about a gazillion other CB units out there, not to mention the 30+ years of CB being the preferred BTB communication method of choice on motorcycles. The simplicity and installed base are the reasons CBs continue to sell as the preferred BTB communication by the manufacturers. There are multiple options for adding a CB to your bike, but we’ll cover that in Part II of this article.

Shack to the Rescue…

Not Shaquille, but RadioShack. In 1994, RadioShack proposed a replacement for CB, called Family Radio Service (FRS). It moved things to an ultra high frequency (UHF) band around 467 MHz to avoid some of the interference, and made some other technical improvements like using frequency modulation instead of amplitude modulation that is more noise resistant (but we won’t get into that here). Suffice it to say it’s more advanced, with improvements including the ability to implement privacy codes for filtering out unwanted chatter from other users on the same frequency. Remember the party factoid above on antennas? Well, with 467 MHz, you only need an antenna about 6 inches long to equal the quarter wave-length antenna that was 9 feet with CB. A more sophisticated cousin to FRS is the General Mobile Radio Service (GMRS). GMRS is also a UHF technology and sandwiches its channels within the same frequency bands used by FRS. Many radios these days are combo FRS/GMRS units with channels 1-7 shared between FRS/GMRS, channels 8 – 14 FRS only, and channels 14 – 22 GMRS only—but you don’t need to worry about it, just dial the channel you want and use it. FRS radios were meant primarily for walkie-talkies, have a max power output of 1⁄2 watt and must have an attached antenna. You also don’t need a license for FRS. GMRS, on the other hand, can have a remotely-mounted longer antenna to extend the range, can broadcast at much higher wattage, and requires purchasing a license from the FCC ($85 every 5 years). The FCC has proposed to drop this licensing requirement since they suspect that the vast majority of people purchasing their GMRS walkie-talkies at the local sporting goods store fail to send in the fee anyway. The proposal is pending but expected to be adopted. Meanwhile, read the fine print of any unit you buy; if you are dialing up a GMRS channel today, you need a license.

So what are the advantages of FRS/GMRS? Some include a higher frequency band outside the range of toys and similar interference-generating products, the potentially higher transmission power of GMRS, privacy codes on top of the channels to screen out conversations outside your group, shorter antennas, and newer technology with the ability to pack more into a smaller space. The downsides? A limited installed base, especially in the motorcycle community, means your riding buddies most likely don’t have GMRS. Also, as of today, you can’t purchase a new bike with a preinstalled factory FRS/GMRS radio.

Here come the Swedes...

In 1994 several really smart Swedish engineers invented a radio technology and named it after their 10th century king, called old Bluetooth. It was intended as a replacement for the wires connecting things like phones, headsets, PC keyboards and such. These are short range uses, as Bluetooth is a Personal Area Network (or “PAN”) and is meant for distances less than 50 meters. However. there are parts of the specification that allow the power to be bumped up, and some manufacturers are building BTB radios using Bluetooth with advertised ranges of up to a mile. The principal advantage of being a PAN is the ability to connect to a multitude of devices like MP3 players, cell phones, and GPS units. Also, since Bluetooth operates at 2.4 GHz, the wavelengths are short and the antennas can be very small. The biggest limitation in this class of product is the number in your group that can all be talking to one another at the same time, but we’ll cover the specific pros and cons of this category in Part II of this series.

Keep in mind that almost all of the two-way radios made for use in the United States are generally not meant to be used outside North America, and may or may not be allowed elsewhere. For example, the frequencies used for two-way radios in the United States and Canada were aligned in 2005 to meet the same requirements, but Mexico formally allows only FRS channels. Other countries may use these frequencies for police, military or other applications. Check your local requirements and laws before you buy or use, if outside the US.

Hello, can you hear me now?...

Of course all these radio options are just hunks of plastic and metal unless you have some speakers and a microphone for the input/output. Two things to consider here are comfort and performance.

With respect to performance, consider what other uses you anticipate. For BTB, you only need to hear others talk, but you might also want to use the speakers to listen to music via FM radio or attached MP3 player. The human voice has a usable frequency range from approximately 300 Hz to 3400 Hz, but once you want to listen to music, the audible range can be 20 to 20,000 Hz; a factor of about 10x higher and lower. Clearly you want a better set of speakers if you plan on enjoying music on the ride. You also don’t want to skimp on quality with the microphone. Look for noise-canceling capability to limit the wind noise being transmitted. Nothing is worse than trying to understand your buddy when he sounds like he has a hairdryer in his mouth. A higher quality mic will also allow your radio to broadcast at its full potential. You might not notice a low quality mic, but your riding buddies will, as your voice will be much fainter than the rest of the group. Convince your buddies to install the best mic they can afford into their helmets since they’re paying for it, not you, and you’ll reap the benefits.

As to comfort, remember two words: Pressure Points. Hold your finger gently against your ear. Not bad; it doesn’t hurt, and is probably not even uncomfortable. But hold it there for 8 hours and you’ll be screaming in agony. Slight pressure for long hours can be excruciating. Don’t underestimate the benefit of comfortable speakers professionally mounted in your helmet.

Summing it all up

CB, FRS/GMRS and Bluetooth are the big three technology platforms. The others tend to be relegated to bit parts. You may run across some that operate at 900 MHz, 49 MHz or claim a better or proprietary technology, but we’ve stuck to the most common product solutions here. Since part of your objective is compatibility with others and the ability to easily add riders to your group, a choice among these three offers you the best bet to achieve that.

In Part II we will take a look at some specific product examples and provide some recommendations and ratings. We'll also look at what's involved and what to consider when mounting speakers and a microphone into your helmet. CR

On Radio Frequency

Radio frequency radiation is measured in Hertz which, contrary to popular belief, has nothing to do with either rental cars or pain. Hertz is a unit of frequency for electromagnetic radiation and is defined in cycles per second. For radio waves it’s the number of cycles, or oscillations, per second of the wave. Think of the letter “S” on its side as a radio wave.

**1 Hertz is 1 cycle of the wave per second.
Kilohertz (or KHz) are thousands of cycles per second.
Megahertz (or MHz) are millions of cycles per second.
Gigahertz (or GHz) are billions of cycles per second. **

AM Radio broadcasts between 520 KHz – 1,610 KHz. FM Radio broadcasts between 87 MHz – 108 MHz. The frequencies around 27 MHz and 49 MHz are filled with inexpensive radio-controlled toys. CB puts 40 channels centered around 27 MHz. VHF and UHF Television signals go out between 56 MHz and 806 MHz. Many garage door openers operate between 300 MHz – 400 MHz. Wi-Fi, Bluetooth and microwave ovens use frequencies in the neighborhood of 2.4 GHz. Cell phones, depending on the type of service, use the frequencies between 800 KHz – 2.6 GHz.

If you’re getting the idea that air waves are crowded, you’re right. Of course, all these devices should be designed to operate only within their well-defined frequency bands as assigned by the FCC, but it’s not a perfect world. Design imperfections, malfunctions, and electromagnetic disturbances can all result in unintended interference. No matter what product or technology you choose, combating interference from other devices is key to a quality signal.

Line Of Sight Communications

Manufacturers provide claims on transmission range of their products, but like EPA mileage estimates, “your mileage may vary.” These claims are based on optimal conditions, which means a clear line of sight between units. What is a clear line of sight? If you are 6 feet tall and standing on the beach, the horizon out to sea is about 3.5 miles away (the point where the earth starts curving away). Get a 6-foot buddy to stand in a boat out at sea and you should both be able to see each other 7 miles apart. You must be able to look each other in the eye without interfering obstacles—that’s your clear line of sight distance. Anything in the way will interfere with the signals to some degree; even your body will absorb some of the signal. Trees, trucks, bridges, buildings, mountains, and rain can all interfere or block your signal. Add in interference from various electronic sources and your real world range will most likely be well short of the manufacturer’s estimate. Realistically, you can expect to achieve about 2 miles of range for CB and FRS/GRMS (give or take), depending on conditions; for Bluetooth, about a mile or less.