I’m a long-time avid cyclist and was a daily bicycle commuter when I got my Amateur Radio license in 1995. As is often the case with new hams, my first radio was a handheld transceiver (HT). As a technical nerd, it was natural for me to mount it to my bicycle for use during my commute. This old photo shows one of the many variations that I had tried. Most of the other hams on a local “commuter net” were surprised that I could reach the repeater with an HT along my commute. I credit the J-pole antenna that I had taped to a fiberglass safety flagpole. Later, I added a 30-watt amplifier and pair of 6.5-Ah lead acid batteries (heavy!). I even rode that setup on an 1100-mile bicycle tour. Today, my options are both more sophisticated and lighter.
I’ll start by sharing my current radio platform, a 2014 Trek Crossrip LTD. In short, it’s an aluminum utility bike (early “gravel bike?”) with 2×10 mountain gearing, cable-actuated hydraulic disc brakes, and racks for panniers. As a retired(?) randonneur, I’m known for carrying plenty of supplies to keep myself independent on the road. That practice eventually led to the nickname, “Captain Overpacker.” My bike weighs about 30 lbs with racks/fenders, 40 lbs with radio equipment, and up to 80 lbs at full load with panniers (an uncommon occurrence). See my somewhat dormant website at CaptainOverpacker.com for details.
For radios, using an HT is an easy choice for battery conservation, not to mention saving space on the handlebar. I carry an Icom ID-51A dual-band D-STAR radio, which consumes less than 350 mA during receive. It lacks Bluetooth, though; so, I have to use corded microphones. The good news is that it’s not hard to find compact headsets for HTs. I’m currently evaluating an SPM-1430 by Pryme. The bad news is that an HT limits my output power to only five watts. That’s sufficient in areas with good repeater coverage. However, not all of my rides are well covered, especially when I’m on tour.
Let’s face it: 5W leaves much to be desired when operating FM from a bicycle. For additional power, my spare ID-5100A fits perfectly within my large Arkel handlebar bag, shown here. The wiring is a little messy, but I don’t have a lot of free space in this bag to make it tidy. The ID-5100’s most obvious drawback on a bicycle is that it’s larger and heavier than an HT. But an even greater drawback is that it consumes three times more power than an HT during receive. Or does it? My own measurements indicate that it draws ~500 mA unless the fan is running. Still, I think that its benefits outweigh its drawbacks.
For starters, the ID-5100’s screen is HUGE; plus, it’s a touchscreen! Sure, I’ll need to protect it on rainy days, but that’s a cinch with the use of a freezer bag. The large touchscreen, knobs, and familiar interface make operating on the bike very easy, especially since I wear full-fingered gloves. The ID-5100 has 1000 memory channels; so, it’s very easy for me to load the memory banks with repeaters for the area that I plan to ride. It also has Bluetooth, which allows me to use a variety of wireless headsets. An interesting capability afforded by having both an HT and the ID-5100 is that I carry the ability to use my bicycle as a cross-band repeater while walking about with my HT. There’s usually not a spontaneous need for that, but it’s an option!
Selecting a bicycle mobile antenna is easier than most hams believe. Speaking only about the 2m band, some opt for a compact 1/4-wave antenna while others go for a larger 5/8-wave. Both may work, but performance will be compromised since a bicycle offers almost no ground plane. I think most seasoned members of Bicycle Mobile Hams of America agree that a 1/2-wave antenna is the way to go on a bicycle since it works without a ground plane. Sure, it works better with one, but performance is good without. A twin-lead J-pole that’s fastened to a fiberglass safety flagpole is a top performer on 2m (see photo in the album below). However, most opt for a mobile antenna since they’re compact, fast to replace if broken, and easy to mount/dismount. I use a Diamond NR770BNMO, shown above, since I already have one on my car. Selecting an HF antenna for a bicycle is more of a challenge. As with any mobile HF antenna, everything is a compromise, perhaps even more so with a bicycle.
Powering a bicycle mobile radio is much easier today than when I first started. Back in my day [/old man voice], most riders would lug a small lead acid battery since that was what was available. I think mine weighed about six pounds. What I didn’t know in the 1990s is that they’re good for only half of their rated capacity. Today, lithium iron phosphate (LiFePo4) batteries are abundant and affordable. My Bioenno 15-Ah LiFePo4 battery weighs just 4.3 lbs, yet lasts four times longer than my old lead acid battery. Its voltage level stays above 13 volts throughout its discharge cycle, meaning that I can use 50W power for a most of the day. I find that 15W is more than enough most of the time. Best yet, it will last about 2000 charge cycles.
This mobile rig’s shakedown cruise will be in support of a bicycle tour with Magical Mystery Bike Tours (MMBT) in West Virginia. I’m MMBT’s tour mechanic, which is normally done from a truck. However, this tour is on a trail with limited road access and large areas with ZERO cellular coverage. We don’t normally use ham radio support on tour, although I quietly carry an HT in my luggage. However, this is a tour on which my bicycle mobile rig may shine! I have five active repeaters programmed along the 78 mile trail, including two that are part of a linked system. Hopefully, the ride will be uneventful and I won’t need to flex any communications capabilities. Still, it’s good to know that I have the option. I’ll report on the trip later.
Slow Motion Mobile,
Scott
