Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Here’s the status of the AA NiMH packs I’ve been using with the radios on our bikes, plus three packs I made up last year and have been keeping on the desk to measure their long-term storage characteristics. Click for more detail.
Bike Radio Pack Status – 2010-03
The “Tenergy 09 x” packs are new & unused with, frankly, disappointing capacity of about half their 2.6 Ah rating. That’s not much better than the used Tenergy packs (T9x and RTU x), which is either a Good Thing (they have good long-term stability) or a Bad Thing (they’re grossly over-rated to begin with).
The two Duracell packs are far better than any of the Tenergy packs.
The three 6-cell packs along the bottom are fading fast.
The previous test runs are there, albeit with a 1 A discharge.
This season I’ll use some Li-Ion packs that weigh twice as much with three times the capacity… plus a built-in charge gauge, pessimistic though it may be.
Mary & I did the weekly grocery run today, with a few add-on errands.
I’m (finally) shipping the Totally Featureless Clock to my friend and hauling a bag of shredded leaves (the first of a dozen) with which Mary mulches the plants in her remote garden plot. We dropped off the leaves and some garden gate fencing (from her bike), then continued on for groceries.
Trailer with Package and Shredded Leaves
Mary returned to the garden to spend the afternoon coaxing the plants to grow nicely, while I hauled the TFC (and the groceries) to the UPS inlet.
Trailer with Groceries and Package
And then I hauled the groceries home. Most of the four bags of chow fit in the trailer, with squishable fruit & veggies in the bike panniers. A whopping 13 miles, all told, but a good time was had by all.
The trouble with bicycles is that they have approximately the cargo capacity of your car’s glove box. Panniers help, but for bulk capacity you need a trailer. Think of it this way: these days, a good trailer costs maybe three or four tanks of gasoline.
If you keep coming up with reasons why you can’t get your butt on your bike and “I can’t haul X!” is one reason, a trailer might be the answer for reasonable values of X. It’s no good for plywood sheets and water heaters, but I’ve hauled plenty of other X that would ordinarily call for a car trip.
It’s an old B.O.B Yak. Works fine, tracks well, doesn’t wobble, carries more than you think possible.. Just do it!
We each put about 2000 miles a year on our bikes, most of it on errands just like this. That’s not many miles by bicycle fanatic standards, but we do lots of other stuff in addition to biking…
Search the blog for “trailer” and you’ll find a few other hints & tips.
Finally got around to hacking PowerPoles into the coily cable from those Li-Ion packs, suitable for powering the amateur radio HT on my Tour Easy. The cable has surprisingly fat conductors, on the order of 22 AWG, that (when doubled over) half-filled the 30 A PowerPole terminals. I remembered to use the blue-and-black color code for 9 volt power on the second and third cables…
The right-angle connector activates a switch that turns on the pack’s voltage regulator, which means that leaving the cable plugged in slowly discharges the battery. They self-discharge by about half in two weeks, which means that it’s not absolutely urgent to unplug the battery at every stop, but … I’d rather have an actual power switch.
I also want to bypass that regulator, so as to get more voltage out of the pack. That may not be feasible, as I suspect they’re using the pass transistor as part of the over-current shutdown circuit, but it’ll be interesting to find out. So this is in the nature of a test to find out how well the lashup works before cracking the case.
This view of the installed pack is looking down on the butt end of the bike, which is leaning against the Shelf O’ Crap in the garage.
Battery on Tour Easy Rack
A four-inch length of adhesive-backed Genuine Velcro mates the battery to the rack, although I stuck both Velcro strips to some carpet tape in the hopes that’ll stick better than the OEM goo. Hooks on the bike and loops on the battery, which means the battery won’t affix itself to everything else in the universe while off the bike.
Went to roll the bike out of the garage and the rear tire was dead flat. You don’t even need to look at the tire, you just instantly know something’s wrong: the bike feels funny with a flat tire.
The picture shows the problem: a pinhole in the tube. Nothing penetrated the tire, nothing went wrong with the tire liner (you can see this was a few mm from the edge, so it’s not an abrasion flat), there are no problems anywhere. Just a tiny hole in the tube.
As nearly as I can tell, the tube simply failed at that point, without any external aggravation.
Popped in another tube and it’s all good, but … I guess it’s time to buy some new tubes: the new one came from a box dated May 90.
Finding a flat in the garage is much much better than finding a flat on the road.
After replacing the seat strut screws, I found a Round Tuit lying there on the workbench, right next to the rear reflectors I’ve been meaning to install for a truly embarrassing period.
Recumbents don’t have the usual assortment of standard-sized tubing in the usual road-bike places, making common items like reflectors difficult to attach. The ideal spot on our bikes is at the base of the VHF/UHF antennas, right next to the white blinky LEDs, but, alas, that’s 20 mm in diameter and the reflector clamp barely shrinks down to a bit under 28.
Turns out that a chunk of 1.5 inch PVC pipe has a 4 mm wall thickness, so wrapping a layer of that around the antenna base will do the trick. I whacked off a length of pipe, faced off both ends in the lathe, and put a shallow recess around the middle of the ring to capture the reflector clamp.
By another rare coincidence, 1.5 inch PVC pipe has an ID of exactly 40 mm… so cutting the ring exactly along a diameter produces the right length. The catch is that the pipe isn’t flexible at all, but brandishing a heat gun in a threatening manner solves that problem.
Reshaped bushing on mandrel
A random hunk of 3/4-inch aluminum rod is about 19 mm in diameter, so I chucked that in the lathe and shaped the saggy strip around it… wearing thick leather gloves.
It springs out to 20 mm with no problem, slides right on, and grips reasonably well. I may add a strip of tapeless sticky (think double-sided tape without the tape: just the adhesive!) under the bushing if it wants to walk away.
I made two of ’em, of course, and put a reflector on Mary’s bike while I was at it. Our young lady’s bike already has a reflector, although I should upgrade that bushing as well… it’s a layer of self-vulcanizing rubber tape that works perfectly, so this may take a while.
I suppose I should buy a length of gray or black PVC pipe, but that’s in the nature of fine tuning.
Straight up: this is about a stainless steel socket head cap screw I installed eight years ago, not the original Easy Racers screw, so this is not their problem.
I rode out for milk-and-eggs at the corner store, a flat one-mile ride, and stopped at the traffic signal. Light goes green, line of cars accelerates, so do I… and there’s a snap and the left side of the seat sags backwards. I am not a powerhouse rider and it’s March, so I’m not doing leg presses while getting up to cruising speed.
I continued the mission by sitting slightly to the right on the seat and pedaling gingerly, then diagnosed the problem in the corner store’s parking lot. If I’d been further away, I’d have done the repair right there, but I figured it’d hold together until I got home. It did.
The problem turned out to be a broken screw holding the left-side seat strut to the threaded eyelet on the rear dropout. The top picture shows the way I have it set up: seat strut clamp outboard, rack strut inboard, with a socket head cap screw extending all the way through, and secured with a pair of stainless nuts that went missing along with the broken screw end.
Screw fracture closeup
Here’s the fracture across the end of the screw, which shows no evidence of foul play. As nearly as I can tell, the whole thing snapped off in one event, with none of the crud that would indicate a progressive crack. Compared with that wheel stud, this is in pristine condition.
So it’s time to replace the right-side screw, as well, which means a trip to the Bike Repair Wing of the Basement Laboratory. While I had the bike up in the repair stand, I decided to reshape the head on the right-side screw for better chain clearance.
As nearly as I can tell, the usual practice puts both the seat strut and the rack strut outboard of the threaded eyelet on the dropout, but that seems wrong to me. The seat strut puts a tremendous amount of stress on the screw, so you really want that lever arm as short as possible: put the clamp against the eyelet. While the rack isn’t as heavily loaded, cantilevering it outboard of the clamp just doesn’t look right.
But putting the rack strut inboard of the eyelet means the screw head sticks out rather more than I’d like. Very rarely, the chain will snick against the head and even more rarely it jams between the head and the freewheel. Nothing much happens (it’s a freewheel, after all), but I think reducing the head thickness ought to help.
Reshaped socket head cap screw
So I chucked the screw in the lathe, shortened the socket by about half, and put a taper on the head. If I had a stock of round-head cap screws, one of those would be even better.
The shortened socket makes it a bit tricky to get enough bite with the hex key, but this isn’t something that requires much attention after it’s installed… and I get to do all that in the shop.
Dabs of Loctite in the eyelet and nuts, for sure!
By a truly rare coincidence, a standard 1-1/2 inch cap screw is exactly the right length.
Right-side mount
Here’s a view of the installed right-side screw, looking rearward along the upper rear triangle tube. Seat strut to the outside, rack strut to the inside, and reshaped head above the cluster.
Took the bike out for a 16 mile spin today and it’s all good.
A note for the weight weenies in the crowd: a rack on the back of the seat adds a redundant support structure. Without that, a failed seat strut can be a real showstopper. Even if you don’t use your bike as a pack mule, maybe you should add a rack.
After putting Mary’s newly covered seat on her Tour Easy, I replaced the tire liner in the front wheel; the previous tube had gone flat, as mentioned there, due to erosion from the end of the liner.
Here’s what the taped liner looked like: smashed as flat as you’d expect from 100 psi applied evenly over the surface. The tube had a rectangular imprint on it, with what looked like minute abrasions, around the outline of the tape. Nothing major, but it shouldn’t ought to look that way.
Taped tire liner
I rolled that liner up, popped it in the Bike Tire Stuff drawer and replaced it with a Slime liner. This picture shows the ends of the two liners: the brown one (bottom) is about 90 mils thick in the center, the Slime liner (top, fluorescent green) is 60-ish.
Tire liner comparison
As nearly as I can tell, I’ve never had an abrasion flat with a Slime liner, while various other brands have caused troubles.
I broke the edges of the Slime liner with a bit of sandpaper, just to see what that’ll do. Most likely, bad things, seeing as how I’ve never done that before…
The Smell of Molten Projects in the Morning 