Archive for category Recumbent Bicycling
APRS coverage of this part of the Mighty Wappinger Creek Valley isn’t very good, particularly for our bicycle radios (low power, crappy antennas, lousy positions), so I finally got around to setting up a receive-only APRS iGate in the attic.
The whole setup had that lashed-together look:
It’s sitting on the bottom attic stair, at the lower end of a 10 °F/ft gradient, where the Pi 3’s onboard WiFi connects to the router in the basement without any trouble at all.
After about a week of having it work just fine, I printed a case from Thingiverse:
You must solder the TNC-Pi2 a millimeter or two above the feedthrough header to keep the component leads off the USB jacks. The kit includes a single, slightly too short, aluminum standoff that would be perfectly adequate, but I’m that guy: those are four 18 mm lengths of heatshrink tubing to stabilize the TNC, with the obligatory decorative Kapton tape.
The only misadventure during kit assembly came from a somewhat misshapen 100 nF ceramic cap:
Oddly, it measured pretty close to the others in the kit package. I swapped in a 100 nF ceramic cap from my heap and continued the mission.
The threaded brass inserts stand in for tiny 4-40 nuts that I don’t have. The case has standoffs with small holes; I drilled-and-tapped 4-40 threads and it’ll be all good.
The radio, a craptastic Baofeng UV-5R, has a SMA-RP to UHF adapter screwed to the cable from a mobile 2 meter antenna on a random slab of sheet metal on the attic floor. It has Kenwood jack spacing, but, rather than conjure a custom plug, I got a clue and bought a pair of craptastic Baofeng speaker-mics for seven bucks delivered:
For reference, the connections:
Unsoldering the speaker-mic head and replacing it with a DE-9 connector didn’t take long.
The radio sits in the charging cradle, which probably isn’t a good idea for the long term. The available Baofeng “battery eliminators” appear to be even more dangerously craptastic than the radios and speaker-mics; I should just gut the cheapest one and use the shell with a better power supply.
I initially installed Xastir on the Pi, but it’s really too heavyweight for a simple receive-only iGate. APRX omits the fancy map displays and runs perfectly well in a headless installation with a trivial setup configuration.
There are many descriptions of the fiddling required to convert the Pi 3’s serial port device names back to the Pi / Pi 2 “standard”. I did some of that, but in point of fact none’s required for the TNC-Pi2; use the device name
/dev/serial0 and it’s all good:
<interface> serial-device /dev/serial0 19200 8n1 KISS callsign $mycall # callsign defaults to $mycall tx-ok false # transmitter enable defaults to false telem-to-is false # set to 'false' to disable </interface>
Because the radio looks out over an RF desert, digipeating won’t be productive and I’ve disabled the PTT. All the received packets go to the Great APRS Database in the Cloud:
An APRS reception heat map for the last few days in August:
The hot red square to the upper left reveals a peephole through the valley walls toward Mary’s Vassar Farms garden plot, where her bike spends a few hours every day. The other hotspots show where roads overlap the creek valley; the skinny purple region between the red endcaps covers the vacant land around the Dutchess County Airport. The scattered purple blocks come from those weird propagation effects that Just Happen; one of the local APRS gurus suggests reflections from airplane traffic far overhead.
An RPi 3 is way too much computer for an iGate: all four cores run at 0.00 load all day long. On the other paw, it’s $35 and It Just Works.
I didn’t notice this at the time:
The camera runs at 60 frame/s, so the entire show spans a bit more than half a second: zzzzzip!
I think it’s a member of the Yellow Jacket wasp family, noted for their in-your-face attitude and repeat-fire stinger. They’re highly capable flying machines, that’s for sure…
We were pulling out of the local “health food” store with fresh-ground nut butters in the packs, nearing the end of a 17 mile loop on a fine Sunday morning.
This truck’s home base seems to be south of Maloney on Rt 376 and it occasionally passes me on the road:
My eye-blink reaction that it was a junker turns out to be completely wrong, as it sports a really great paint job (vinyl wrap?):
The junker aspect may not be quite what they expected…
I’m not sure that’s skeuomorphic, but I don’t know the proper term.
I generally ride somewhat further into the travel lane than some folks would prefer, but I have good reason for that. Here’s how bicycling along Raymond Avenue at 14 mph = 20 ft/s on a pleasant summer morning works out…
T = 0.000 — Notice anything out of the ordinary?
T = 1.000 — Me, neither:
T = 1.500 — Ah!
T = 2.000 — I’m flinching into the right turn required for a sharp left turn:
Less than half a second reaction time: pretty good, sez me.
T = 2.833 — End of the flinch:
T = 3.000 — Now I can lean and turn left:
T = 3.267 — This better be far enough left:
T = 3.333 — The door isn’t moving:
T = 3.567 — So I’ll live to ride another day:
I carry a spectacular scar from slashing my arm on a frameless car window, back in my college days: the driver flipped the door open as I passed his gas cap at a good clip. The collision wrecked the window, the door, and my bike, but didn’t break my arm, sever any nerves, or cut any arteries. I did discover human fatty tissue, neatly scooped from under my arm onto the window, is yellowish, which wasn’t something I needed to know.
Searching for Raymond Avenue will bring up other examples of bicycle-hostile features along this stretch of NYSDOT’s trendy, traffic-calmed design…
NYSDOT re-striped Rt 376 using paint with sprayed-on glass beads, rather than plastic strips, which produces lovely rainbows when the sun comes from directly behind. Alas, my helmet camera can’t resolve faint colors against the background glare and doesn’t show the circular reflection cutoff:
However, the scattered beads light up the pavement’s cracks and crevices.
Four days later, the drifts of beads have dissipated to leave bright reflections anywhere the tires don’t reach:
That’s along the big traffic circle at the Raymond / Collegeview / Forbus intersection.
Riding into the Village of Wappingers Falls, there’s a lumpy patched pothole just ahead of the fairing & front wheel:
You can watch (and I can hear) the fairing flex as the front end jounces over the patch:
The hydration pack slung behind the seat also jounces and, when the reservoir bag bottoms out, the sudden pressure increase squirts water out of the bite valve, all over my face and goggles, and way out in front of the camera:
The camera runs at 60 images/second: those 28 images span all of 450 ms.
Two seconds later, the droplet stabilized into a nice round lens:
The low humidity of a lovely day evaporated the drop after another three minutes…
Within the space of four days, we had three rear-tire flats:
- A tire liner wear-through, after which I didn’t replace the liner
- Four miles later, a blowout through a tread gash previously covered by the tire liner
- A puncture flat directly through the tread
Basically, erosion from the (last remaining, I think) liner in the rear tire of Mary’s bike caused the first flat; I patched the tube and didn’t notice the gash. After the blowout, I patched the tube again, booted the gash (with a snippet from a roll of PET bottle plastic I carry around for exactly that purpose), stuck an ordinary patch atop the boot to cover its edges, and the whole mess has held air just fine for the last week. I’m reluctant to mess with success.
Not having a tire liner caused the third flat, this time on my bike. The wound looked like a nail or glass shard punched directly through the Kevlar armor behind the tread. Fortunately, it happened (or, more exactly, I realized I had a flat) half a mile from home, so I fired a CO2 cartridge into the tube and pedaled like crazy, which got me halfway to the goal and I rolled the rest of the way on a dead-flat tire.
Ya can’t win.
So I picked up a pair of Michelin Protek Max tubes, the weirdest things I’ve ever stuffed into a bike tire:
The bumps along the tread surface are much larger and uglier than shown in that picture:
The rubber forming the protrusions has the same thickness as the rest of the tube, so you’re looking at soft, flexible shapes, rather than thick bumps.
The “liquid” inside must be a thin film over the inner surface. I’ve never been a big fan of tire sealants, mostly because they’re reputed to ooze to the bottom of the tire into off-balance puddles.
For future reference, the Official Quasi-Instruction Manual / Blurb (clicky for more dots):
We’ll see how well these work…