Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
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…
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.
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.
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.
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.
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.
A discussion on that post reminded me of this old project: replacing the chain pulleys in the midships chain tensioner on my Tour Easy recumbent.
The problem is that the original pulleys used steel bearings in a plastic race, for reasons that I cannot fathom. They last for a few thousand miles, then get very wobbly and noisy. The solution, as nearly as I can tell, is to replace them with pulleys using cartridge bearings.
This is what one looks like after four years slung below my bike. Surprisingly, the bearings still feel just fine, even though they’re not really sealed against the weather.
Tour Easy – Cartridge Bearing Chain Tensioner
Gotcha: the OEM pulleys are not the same OD / number of teeth as pulleys found in rear derailleurs.
Soooo, after a bit of Quality Shop Time, I had these…
Tour Easy Replacement Idler Pulley
This is where you really want an additive machining process, as I turned most of a big slab of aluminum into swarf while extracting each pulley.
The first step is to drill holes around the perimeter where the chain rollers will fit, plus drill out as much of the center bore as possible. Then mill down to the finished thickness across the roller holes and helix-mill the bore to size.
Side 1
Flip it over and mill the other side to the proper thickness.
Run it through the bandsaw to chop off all the material beyond the outer diameter.
Grab what’s left in the three-jaw chuck and mill around the perimeter to get a nice clean edge.
Side 2
And then it Just Works. I made another for Mary’s bike, but she said it was too noisy (which is why they used plastic rather than aluminum) and I swapped it for a Terracycle idler.
This is from back in the Bad Old Days before EMC2’s version of G-Code supported loops. You don’t need to see that code, trust me on this.
So the bike started making a weird whistling squeak. Noises on a bike are never a good sign, but it took me nearly two weeks to banish this one…
Differential diagnosis:
Toward the rear: not pedals, not chainring
Only while pedaling: not sprocket cluster bearings
Depends on chain speed: not sprocket
Conclusion: it’s the chain.
My shop assistant had done a massive chain-cleaning and lubricating exercise when we got back from vacation, so I guessed that a few links (of 250-ish) had escaped proper lube. I gave ’em a dose that didn’t help, so I went Old Skool on the thing.
Coiled it flat in a saucer, immersed it in denatured alcohol to displace air and water-based cleaner inside the links, then drained the alcohol. Poured a generous layer of light machine oil over the whole affair, let it sit for a day. Drained for a pair of rainy days by hanging from a floor joist in the basement. Used up a bunch of rags while wiping the thing down (I have an oily-waste can, they’re not sitting in a wastebasket).
Misrouted chain in rear derailleur
Put it back on the bike, only to discover the chain was now vibrating something awful. Checked the rear end and found that I’d managed to route the chain through the rear derailleur along almost the right path…
Fixed that and the squeak was still there. OK, it’s not the chain.
The only remaining possibility: derailleur jockey pulleys.
Took ’em off without dismounting the derailleur and, lo and behold, the steel-on-plastic bearing surfaces were bone dry and a bit dusty. They’re supposed to be self-lubricating, which is probably true for the first few thousand miles, but I cleaned ’em out and added a dab of grease.
Problem solved… for a while, at least.
The only downside is that the chain will be flinging oil for the next month, no matter how often I wipe it down. There’s a good reason I stopped using light machine oil on chains!
The Smell of Molten Projects in the Morning 