Archive for category Recumbent Bicycling

APRS Turn Slope Units

There’s a fundamental error in my writeup about setting the APRS Smart Beaconing parameters for the bike trackers: I blundered the units of Turn Slope.

Rich Painter recently explained how that works:

I ran across your blog on Smart Beaconing and saw something that needed correction.

You state the Turn Slope is in units Degrees / MPH

This is incorrect. Although the term Turn Slope is not a real slope (such as rise/run classically) that is what the originators used albeit incorrectly. They do however correctly attribute the units to MPH * Degrees (a product and hence not really a slope).

In their formula they calculate a turn threshold as:
turn_threshold = min_turn_angle + turn_slope / speed

Looking at the units we see:
= Degrees + (MPH * Degrees) / MPH

which yields
= Degrees + Degrees

Which makes sense. It is too bad that the originators used the wrong term of Turn Slope which confuses most people. A better term would have been Turn Product.

In looking back over that post, I have no idea where or how I got the wrong units, other than by the plain reading of the “variable name”.

As he explained in a followup note:

As for units… I was introduced to making unit balance way back in 1967-1968 science class in HS by a really fine science teacher. It has served me all my life and I’m thankful for that training.

I have ever since told that teacher so!

A while back, our Larval Engineer rammed an engineering physics class head-on and sent me a meme image, observing that I’d trained her well: if the units don’t work out, then you’re doing it wrong.

Yes, yes, I do care about the units:

Give a shit about the units

Give a shit about the units


Delicate Tire Tracks in the Snow

Seeing this early one wintry morning made me wonder if somebody had ridden away on our bikes in the dead of night:

Bike Tracks on Snowy Driveway - overview

Bike Tracks on Snowy Driveway – overview

A closer look, as seen from the garage door:

Bike Tracks on Snowy Driveway - detail

Bike Tracks on Snowy Driveway – detail

We’d gone for a ride two days earlier and, apparently, our tires deposited enough salt dust (?) on the driveway as we rolled them out of the garage to melt the light snowfall. I’m not sure I can believe that, as those same tires left no trace of our return from that same trip, when I’d expect them to carry more dust.

If it’s a thermal effect, it was produced by one brief contact with tires kept in an unheated garage and rolled over an asphalt driveway, after exposure to ambient conditions for two days.

Truly a puzzlement…


Dutchess Rail Trail: Timing Is Everything

The Thanksgiving Snowfall didn’t amount to much, but it did bring down a bunch of branches across the area. A few days later, as we rode along the DCRT on an errand, we admired the freshly sawed fallen trees and piles of brush by the side of the trail: evidently, a DC DPW crew had just cleared the trail.

Then we encountered this at Mile Marker 7.0:

DCRT - fallen tree

DCRT – fallen tree

As nearly as we can tell, that tree fell minutes before we arrived; the trunk snapped about five feet off the ground. There were bike tire tracks on the (wet!) trail directly below the trunk, but none stopped on one side and resumed on the other, so we were the first bikes on the scene.

We portaged the bikes, continued the mission, and called it in when we got to an information sign with the DPW contact number.

Timing is everything!


Sony HDR-AS30V Audio: Fake Fur FTW!

A scrap of fake fur cut to fit the outline of the Sony HDR-AS30V helmet camera and stuck in place with a square of double-stick foam centered above (or below, in the normal orientation) the lens:

Sony HDR-AS30V - fake fur installed

Sony HDR-AS30V – fake fur installed

Snippy remarks about what that looks like will not be tolerated, m’kay?

It reduces wind noise to an occasional rumble from strong gusts and even those don’t crush the AGC. My side of our radio conversations became clearly audible, as did shifters clicking and gravel crunching. There’s still plenty of noise, but now it comes from actual sound sources that don’t overwhelm the amp.

A layer of ordinary adhesive tape still covers the mic pores and the fur’s fabric backing extends over the tape, so the combination must muffle the sound at least a little bit. Given the source material and my hearing, it’s Good Enough; Golden Eared Audiophiles need not apply.

I also cannot detect any difference between the left and right audio channels, so the stereo separation at 15 mm isn’t worth much. I don’t know if the camera swaps the audio channels in video flip mode; that would be a nice touch.

The hairs extending outward beside the lens occasionally blew into view, so a haircut is in order:

mah00242-075 - Fake Fur in view

mah00242-075 – Fake Fur in view

Perhaps a clip that snaps over the skeleton frame to hold a neat patch of fur in place without adhesive on the camera body would be even better?


Shimano SPD Pedals: Cleat Oilers

Here’s the solution to creaking SPD pedals due to hardened shoe cleats gritting on hardened pedal latches:

Shimano SPD pedal - cleat oiler

Shimano SPD pedal – cleat oiler

Those are carefully shaped snippets of open-cell foam tucked around the springs under the movable latches, loaded with a few drops of penetrating oil, and ridden for several months. Nary a squeak or grinding sound has emerged: far better than the results after I added a drop of oil whenever either of us heard that sound.

Similar snippets tucked under the forward latch fell out without affecting the results, from which I conclude:

  • The front latch doesn’t squeak
  • The foam on the other side is Close Enough
  • Penetrating oil oozes into a thin film over the whole pedal

The cleats don’t quite touch the ground when we walk, so we’re not leaving oily footprints.

Should I ever install new pedals, I’ll see if a larger foam block can span the gap between the front latch on the top and the movable latch on the bottom.


Sony HDR-AS30V Audio vs. Wind Noise

With the Sony HDR-AS30V in its skeleton frame atop my bike helmet, the audio track for all my rides consists entirely of horrendous wind noise. You can get an idea of the baseline quality from the sound track of a recent Walkway Over The Hudson crossing.

The camera has two mics, although I’m not sure 15 mm of separation really produces meaningful stereo sound:

Sony HDR-AS30V - front view

Sony HDR-AS30V – front view

Note that two of the five pores on each side are closed flat-bottom pits. As with earbud vents , it must be a stylin’ thing.

I added a rounded pad of the same acoustic foam that forms an effective wind noise buffer for the boom mic:

Sony HDR-AS30V - foam mic cover

Sony HDR-AS30V – foam mic cover

That reduced the overall noise load by buffering direct wind impact, but non-radio conversations remained unintelligible; there’s just too much low-frequency energy.

Surprisingly, closing the mic pores with ordinary adhesive tape didn’t impair the audio in a quiet room:

Sony HDR-AS30V - closed mic pores

Sony HDR-AS30V – closed mic pores

Out on the road that’s even better than foam over open mic pores; I think it reduces the peak volume enough that the internal compression can regain control. Sticking the foam pad over the tape slightly reduced the noise during high-speed (for me, anyhow) parts of the ride, but didn’t make much difference overall.

The wind noise remains too high for comfort, even if I can now hear cleats clicking into pedals, shifters snapping, and even the horrible background music when I’m stopped next to the Mobil gas station on the corner.

Next step: raid the cloth scrap box for a flap of faux fur to make a mic mop. This might be an opportunity to recycle some roadkill


Threading the Bicycling Needle on Raymond Avenue

The NYS DOT’s original planning documents said that roundabouts / rotaries weren’t optimal for pedestrians or bicyclists or large trucks, but, because DOT likes rotaries, that’s what they built on Raymond Avenue. However, they didn’t relocate the drainage lines under the road and left some catch boxes in awkward spots.

This Google Street View image from a few years ago shows the College Avenue intersection from northbound Raymond Avenue, with the catch box in the lane:

Google Street View - Raymond northbound at College

Google Street View – Raymond northbound at College

Raymond is basically the only bicycle route into Arlington from the south and has “shared roadway” signs, but the design flat-out doesn’t work for bikes and the implementation leaves a lot to be desired.

Here’s what it looks like from the bike:



Note the deteriorated asphalt and longitudinal cracks near the white fog line next to the curb. That forces bike traffic another few feet into the deliberately narrowed traffic lane at the entrance to the intersection.

Mary’s about as far to the right as practicable (that’s a legal term):



I’m angling over from the middle of the lane, because, unless I take the lane, motorists will attempt to pass us in the rotary entrances. The asphalt on the far side of the box has subsided several inches into a tooth-rattling drop, you can see the crevice adjacent to the right side of the box, and I know better than to cross steel grates while turning.

Notice that the Google view shows four bollards marking what DOT charmingly calls the “pedestrian refuge” in the median, but only two appear in my pictures. NYS DOT recently removed half the bollards from each refuge and relocated the remainder, apparently to reduce the number of street furniture targets. Early on, they were losing one bollard per intersection per year, but that’s slowed down now that they’ve stopped replacing smashed hardware.

It was never clear to me why putting nonreflective black bollards a foot or two from the traffic lane made any sense, but that’s how it was done. Most of the relocated bollards stand close to the center of the median, so maybe it didn’t make any sense.

Anyhow, bikes can’t stay too far to the right after the box, because the asphalt has crumbled away in furrows around Yet Another Crappy Patch:



That’s pretty much the state of the traffic engineering art around here. A while back, the NYS DOT engineer in charge of the project assured me it’s all built in compliance with the relevant standards.

It’s worth noting that Mary’s on the Dutchess County Bicycle and Pedestrian Advisory Committee, so we volunteered to count cyclists and pedestrians on Raymond a few months ago. When I say that we’re essentially the only cyclists riding Raymond Avenue, we have the numbers to back it up. Everybody else rides on the sidewalks, despite that being of questionable legality and dubious for pedestrian safety, because, well, you’d be crazy to ride in the shared roadway.


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