The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Category: Recumbent Bicycling

Cruisin’ the streets

Another Bike Flat: Michelin Hair

Rode around the big block on some errands, stopped at the Vassar Farm garden to haul some squash home, rode off… and the bike handled poorly. Well, with a few dozen pounds of produce in the panniers that’s not unusual, but this was worse. Yup, another flat.

This time, however, our daughter was home and could rescue me in the van. Back in the shop, I found this obvious suspect:

Embedded glass fragment

Once again, however, this wasn’t the problem, as the tire liner was barely scuffed. Those are glass fragments inside the gash, which might actually be the same one as before.

There weren’t any other pointy objects embedded in the tire, but the tube wouldn’t stay inflated long enough to find the leak. I took the tube upstairs, submerged it in a pan of water, and found a rash of holes. Not pinholes, not a failed tube, but a series of punctures.

Steel wire fragment

Examining the tire liner revealed the cause: a strand of what my buddy DBM calls Michelin Hair poking through the tire liner. It’s a fragment of the steel belt from a car or truck tire, most likely shed from a disintegrating semitrailer recapped tire.

There is absolutely no defense against these things, because they have razor-sharp points on both ends where the wire fractured. When the tire picks one up, every rotation drives it through the rubber, the Kevlar belt, the tire liner, and the tube. The usual symptom is a slow leak, eventually followed by a row of holes in the tube as it shifts position under low pressure.

In fact, the tube had a slow leak since I installed it a few weeks ago after a tube failure. I wondered if I’d inadvertently installed a fold, but now I think I ran over this wire during the first few rides and it’s been getting worse ever since.

That tube is a goner! I installed another Schwalbe tube and we’ll see what happens; one has been working fine on Mary’s bike for the last three months.

Here’s a look at the steel wire from the side:

Steel wire fragment through tire liner

It was completely through the liner, with only a stub sticking out on the tire side. There’s certainly a matching hole somewhere on the tire, but it’ll be indistinguishable from all the other nicks and gashes.

2010-10-22
Biting Through the Bite Valve

I carry a water pack behind the seat on my Tour Easy, with the hose over my left shoulder and the valve captured by a magnetic thingie pinned to my shirt. On a recent ride I hit a substantial pothole while drinking from the tube and managed to bite completely through the miracle plastic “Bite Me” valve, mostly due to clenching my teeth in concentration rather than from the impact.

Bitten bite valve

A few days later my dim consciousness finally took note that the water kept draining down into the pack between sips: every sip came with a mouthful of air.

A year or so ago, the original valve developed a nasty case of embedded gunk and I picked up a quartet of Genuine Nalgen valves (or a credible imitation thereof) from the usual eBay supplier. I wonder if the reservoir and tubing will outlast the remaining two valves?

2010-10-09
Tour Easy: Underseat Pack Repair Finished

So, after a bit more than a year, I replaced the cracked backing plate in the other ERRC underseat pack on my Tour Easy. The first plate held up much better than I expected: hasn’t cracked or poked through the pack fabric.

This repair followed the same outline, including cutting off the ripped netting on the outside of the pack and marching the pack into the clothes washer for a spin with a few shop rags. Reassembled everything, put it back on the bike, and … the new aluminum extrusion across top of the plate smacked firmly into the water bottle holder clamped to the rear of the seat frame for the amateur radio.

Underseat pack vs radio holder

The extrusion is the lump running horizontally, just under the seat cushion. The corner of the pack extended rearward (left) of the water bottle holder’s black plastic body.

The original flexy plastic pack plate simply bent out of the way, but that’s not going to work now.

So I loosened the clamp, moved it a bit more to the right, and tightened it up again. I’d originally located it at the far right end of the straight part of the seat frame, so it’s now edging into the curved part that eventually forms the right side of the frame, but it’s good enough.

My shop assistant says she wants another water bottle holder for an actual water bottle on her bike. I say she should just go to the shop and make whatever she wants, then install it. Negotiations continue…

2010-09-27
Experimental Determination of Squirrel Sprint Speed

So there we were, biking along the northern segment of the Dutchess Rail Trail, when a squirrel scampered up a fencepost a few hundred feet ahead of us and struck a classic tree-rat pose: standing up atop the post, tail arched behind, front paws together.

As we rolled closer, the squirrel noticed us and, as squirrels are wont to do, panicked.

*Must* *run* *away*

Squirrels tend to escape up the nearest tree, which works perfectly with most predators. In this case, though, the squirrel was already as high as it could get on the post and there were no trees within jumping distance.

Decision time: can’t run up, can’t escape to the side, must not run toward the threat.

*Must* *run* *away*

So the critter lit off along the top rail, hurdling over the protruding fenceposts in a dead run, as fast as its little legs could carry it.

Which, as it turned out, was just over 15 mph. We stopped pedaling and coasted, but this section is slightly down-grade and we didn’t slow very much.

The thing was running at my eye level, about five feet to my left, and kept pace with us for maybe a dozen fenceposts. Finally it decided this tactic wasn’t working and dove off the fence into the bushes beside the trail.

Squirrels must produce adrenaline like I produce saliva.

And I really, really need a helmet camera…

2010-09-23
Bicycle Computer Failure: It’s The Connector

While walking home with the bike, I noticed that the odometer wasn’t matching up with reality. This generally means the front-wheel magnet sensor got whacked out of line and, given that I’d just laid the bike down on that side, that’s what I expected to fix.

As it turned out, the failure meant it was time for the more-or-less annual contact cleaning. The three tiny contact balls on the bottom of the Cateye Astrale tend to collect enough dirt over the course of a few thousand miles to become intermittent. The balls lead to the wheel and pedal sensors, with a single common wire.

Cateye Astrale contacts

You can see that they’re not shiny little factory-fresh bumps. Here’s a detail of the upper-right one on the base to the right. Even through the horrors of a tight crop from a hand-held shot, you can see the problem.

Cateye Astrale – contact detail

No big deal, just wipe ’em off and apply a bit of DeoxIT to make ’em happy again for another year.

2010-09-18
Bicycle Tube: Complete Failure
Glass shard in tire

On my way back from a ride around the block the back tire went pfft thump thump thump. I’m 1.5 miles from home: fix or walk?

The first step: always examine the tire to find the puncture, before you move too far. Finding something sticking out of the tire means you’re well on your way to fixing the flat. Lose the entry point and you’re left to blow up the tire and listen for escaping wind. So I picked up the butt end of the bike, spun the wheel, and this little gem heaved into view…

That area of the road has seen several collisions in recent months that left the shoulder littered with broken automotive glass. The shard in my tire glistened like a diamond, because one side was flat and mirrored; perhaps it’s from a headlamp reflector or side mirror. The pointy end went into the tire, of course…

Glass fragment and puncture

Well, a single-point failure like that is easy to fix, so:
- remember that the hole is a few inches spinward of the label
- shift to small chainring / small sprocket
- get the tool bag out
- lay the bike down (it’s a recumbent, this is no big deal)
- release the rear brake
- release the skewer and whack the hub out of the dropouts
- apply tire irons to get the tire off
- pop the tube out and examine the innards
No pix of any of that, but suffice it to say I was astonished to discover that the glass penetrated the Marathon tire’s Kevlar belt just barely far enough to poke the Slime tire liner, but not enough to leave more than a hint of a mark on the tube. Definitely not a puncture and certainly nothing that would account for a sudden flat.

That glass shard is not why the tire went flat! Tire liners FTW!

Examining the rest of the tube revealed this situation a few inches anti-spinward of the glass fragment.

Failed tube rubber

There’s a row of holes across the tube, with no corresponding tire or liner damage at all. As nearly as I can tell, the tube rubber simply pulled apart across that line, all at once, and the air went pfft just like you’d expect.

That’s not survivable, but I don’t carry a spare tube (well, two spare tubes: 700x35C rear and 20×1.25 front) on rides around the block. Long bike tours? Yup, spare tires & tubes because I’m that type of guy.

Anyway, I’ve got the tube in hand, so what’s to lose? Scuff it up with the sandpaper and yipes…

Tube after scuffing

What’s not obvious in the picture is that all those little spots around the big holes are pinholes. The whole area of the tube must have gotten just barely enough rubber to cover the mold.

I know as well as you do this isn’t going to have a happy outcome, but I slobber on the cement, let it dry, squash on a big patch, install the tube & tire, fire a 16-gram CO₂ cartridge into it, and … it doesn’t seal.

The tube is several-many years old, probably from whoever was supplying Nashbar at the time, and it served well, so it gets a pass. I’d rather tubes fail in the garage than on the road and sometimes they do, but that’s not the usual outcome.

My ladies were out gardening at the time and a long wheelbase ‘bent isn’t the sort of thing you can stuff into a friend’s car. Not to mention that my ladies had the magic phone.

So I walked home.

Sometimes a man’s gotta do what a man’s gotta do.

Memo to Self: Schwalbe tube at 8910. Reversed(*) the Marathon’s direction.

(*)They’re directional, but when they get about halfway worn I don’t see that it makes much difference. The rear tire on my bikes wears asymmetrically: probably too many tools in the left underseat bag.
2010-09-15
Third Eye Hardshell Mirror Repair

Alas, the mirror I installed this spring didn’t survive our bicycling vacation; it succumbed to the second of three stuff-all-the-bikes-in-a-truck schleps arranged by the tour organizers. Being that sort of bear, I had a spare mirror, duct-taped it in place, lashed it down with some cable ties, and we completed the mission.

So.

Back to the Basement Laboratory Plastic Repair Wing.

The strut broke just behind the ball at the mirror, which implies the mirror plate got stuffed against something, rather bending the strut. The ball joint still worked, so I maneuvered the stub perpendicular to the mirror.

Drilling the strut

Normally I’d try to re-glue the joint as-is to get the best fit, but past experience shows that if it breaks once, it’ll break there again. I wanted to put some reinforcement into the strut, not just depend on a solvent glue joint. Some rummaging in the brass tubing stock produced a 1/16-inch diameter aluminum (!) tube about 18 mm long: just what’s needed.

So I filed the deformed plastic flat & perpendicular to the stubs, mounted the strut in the 3-jaw chuck on the Sherline’s table, lined the spindle up with the axis, and poked a 1/16-inch hole into the strut. The alignment looks decidedly off in the picture, but it’s actually spot on: what you’re seeing is some swarf clinging to the far edge. Honest!

Then I grabbed the mirror plate in the 3-jaw, lined up on the stub, and drilled maybe 4 mm down, which was roughly to the middle of the ball. The tubing was a firm push-fit in the hole and I hope it won’t over-stress the plastic into cracking.

Gluing the mirror strut

Run the spindle up, remove the drill, grab the strut in the chuck (actually, I had to swap in the larger chuck first), dab some Plastruct solvent glue on both ends, align the strut with the stub (they’re actually square in that section), run the spindle down to ram the tubing into the strut, then a bit more to apply pressure to the joint. I made the total hole depth about 2 mm longer than the tubing, so as to avoid the embarrassment of having the ends not quite meet in the middle.

No CNC; pure manual Joggy Thing action.

Let it cure overnight.

It’s now back on Mary’s helmet, with a pair of black cable ties ensuring that it won’t pop off, and seems to be working fine. I’m sure the ball joint will fail later this year, although that won’t be due to this repair.

Mirror on helmet again

2010-09-04