We’re riding southbound on the recently opened section of the Empire State Trail, just south of Hopewell Junction, and are approaching a dog walker totally face-sucked by her phone in the middle of the path:
Mary has been dinging her bike bell for the last few seconds and finally manages to break through:
The dog walker leans against the fence while pulling on the leash as hard as she can, as if she knows the dog poses a threat:
Which it does:
The leash is too long for close-quarters work:
Nice teeth, doggie:
Surely, the dog just wants to lick me to death:
Tell me again how well-trained this dog is:
Seven seconds after the first picture:
The dog also lunged at the pair of bicyclists following us, so perhaps this is how she makes sure it get its exercise during the walk.
As mentioned earlier, the Bafang brake sensors on Mary’s Tour Easy require a magnet on the brake levers to activate the switches. They arrived with disk magnets that did not suit the levers, so I used neodymium “bar magnets”:
That worked for a few rides, but the alignment turned out to be entirely too critical, because the magnetization is through the bar’s thin dimension, rather than along its length, making the field weakest in the direction of the switch.
That’s a slightly shorter magnet from a different toothbrush head, cemented edgewise into a holder conjured from the vasty digital deep:
The field is much more uniform on the flat side of the bar:
Some double-sided foam tape snuggles the sensor and the magnet together on the brake lever:
I coated the magnet with JB Plastic Bonder urethane adhesive in the hope of filling any gaps in its nickel coating caused while extricating it from the toothbrush head.
The rusty screw head in the upper right positions the lever at the proper distance from the grip to suit Mary’s hand. An earlier version of the holder shows the alignment:
The switch trips (opens) with the lever roughly parallel to the grip, again with the earlier holder:
A detailed view of the gap with the lever at the tripped position:
The levers have enough travel to prevent accidental trips due to light finger pressure, which turned out to be a problem with the original end-on alignment.
The brake pads don’t quite touch the rim when the switch trips, so the motor has plenty of time to shut off before the brakes take effect. It also stops when the pedals stop turning, so we should not see any disagreement between motor and brakes as to the bike’s momentum.
The wider base on the new mounts makes them much more stable on the levers, although I don’t like having them stick up so far. Mounting everything underneath the levers would look better, but any problems will be more obvious with everything in plain sight.
I may affix the magnets directly to the levers with Plastic Bonder if the foam tape doesn’t live up to its reputation. Removing them would be more challenging; a shot with a small chisel should suffice.
The front fender on Mary’s bike suffers a bit more stress than you might expect, as she must wheel it through high grass to her Vassar Farms garden plot and the low-hanging spray flap can snag on the taller greenery.
Re-slicing the original model, printing the result, and installing it took about an hour:
Affixing the strut with duct tape and a cable tie looks déclassé, but continues to work better than anything else I’ve tried: simple, flexible, easily readjusted, totally nonfussy.
At least I now use black outdoor-rated double-stick foam tape, so life is increasingly good …
For unknown reasons, the Bafang BBS02 motor puts the left pedal 15.5 mm closer to the frame than the right pedal:
The diagram presents the motor assembly as seen from the bottom, lying on the ground looking upward with your feet forward around the front wheel.
That much offset may be acceptable for some (upright?) bikes and some riders, but this seemed better for Mary:
Lekkie Buzz Bars have a matching 15.5 mm offset in the left crank to center both pedals on the frame. She’s been pushing 165 mm cranks for long enough to know standard 170 mm cranks require too much leg travel, so that’s a 160 mm Lekkie crank.
With cranks installed in the BBS02, measured from the frame tube to the inside of the crank at the pedal axis:
Bafang 170 mm: L 42, R 62
Shimano 105 triple 170 mm: L 46, R 67
Lekkie 160 mm: both sides 60
For comparison, the Shimano 105 cranks on my Tour Easy measure 35 mm on both sides with an ordinary Shimano UM-BB72 bottom bracket cartridge, so the BBS02 + Lekkie cranks put each pedal 25-ish mm farther out. However,my pedals screw into 20 mm Kneesavers, putting them pretty close to the Lekkie spacing.
We hope the additional space won’t make much difference to Mary; it’s certainly better than sitting offset to the right to match the pedals, as she’s found herself doing with both the Bafang and Shimano cranks on the BBS02. Her right shoe just barely tapped the crank, so we moved the cleat a few millimeters inboard and it’s all good again.
The Cateye cadence sensor now has a rakish tilt to match the crank offset and looks scarily exposed. More riding is in order.
The Lekkie cranks have a hollow cross-section that’s concave on the frame side, so the magnet sits on a simple riser to get it out where the sensor can experience it:
It’s held in place with good foam tape; the cable tie makes me feel better.
The OpenSCAD code for the riser fits into the GitHub Gist:
In point of fact, that array pretty much fills the M2’s platform and would require over 11 hours of print time, which is just crazy talk. Have the slicer break it into separate parts, delete whatever you don’t want at the moment, print what’s left, and iterate until you have everything you need to finish the job.
For inscrutable reasons, the Bafang 500C display includes all stopped time in its average trip speed. While that is, in fact, the average speed over the entire trip, the Cateye cyclocomputers we’ve been using forever stop averaging after a few seconds at 0 mph.
Bonus: Although the Bafang BBS02 motor knows the pedal cadence, it’s not part of the display.
The Bafang BBS02 bottom bracket shaft put its pedal cranks much farther from the Tour Easy’s frame than the Shimano cranks, to the extent that the existing Cateye cadence sensor position just wasn’t going to work, so I printed a simple clip to fit over the motor’s “fixing plate”:
It turns out putting a magnetic sensor immediately next to the winding end of a high-current three-phase motor isn’t the brightest idea I’ve ever had. The Cateye cadence display spent most of its time maxed out at 199 rpm, far faster than Mary can spin for, well, a single revolution.
A somewhat more complex mount put the sensor roughly where it used to be:
It looks precarious, but it spent nigh onto two decades there without incident, so we have precedent.
Those are the original 165 mm Shimano cranks, because the 170 mm Bafung cranks threatened to lock out her knees. More on this in a while, as it’s a more complex issue than it may appear.
Installing the Bafang BBS02 motor on Mary’s Tour Easy replaced the triple chainring, so I removed the front derailleur and SRAM grip shifter. This produced enough room for the thumb throttle and a full-length handgrip on the left side:
The right handlebar still has the rear shifter, so it requires a shorter grip:
Although it may be possible to buy such a grip and, thereby, get a backup pair of mismatched grips, it seemed easier straightforward to just shorten the grip to the correct length and be done with it.
Saw off a convenient length of aluminum rod:
Although I actually used a steady rest to produce this, it happened during a remote Squidwrench meeting and I have no proof:
The 22.2 mm = 7/8 inch end matches the more-or-less standard handlebar diameter, so the grip clamp can get a good hold:
A live center supports the right end of the grip.
The red coating seems to be gooey silicone rubber molded atop a PVC tube. Rather than (try to) use a lathe bit to cut through the silicone, I cut two slits with a utility knife and the spindle turning slowly in reverse, then peeled off the rubber between the slits.
With the silicone out of the way, an ordinary cutoff tool made short work of the PVC:
That was a cleanup pass with the utility knife, as the cutoff tool left a slight flange around part of the circumference. If I had the courage of my convictions, I could probably have cut the PVC with the knife.
Chamfer the end of the cut, slide it on the handlebar, tighten the clamp, and it’s all good.
The alert reader will note the clamp should go on first, but that would produce an inconvenient lump against the right shifter. Sliding them on backwards puts the clamp at the end of the handlebar and works out better in this admittedly unusual situation.