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Bacchetta G20 with Grin All Axle hub motor, Phaserunner controller, CycleAnalyst v3, and BionX 13S/48V battery. Summer tire configuration, Schwalbe Marathon Plus on 26" back wheel, and Snafu BMX 2.10 on 20" (406) front wheel. eg20_with_bionx-battery_in_mendota_photo

Photo of eG20 at Mojo Coffee ("Pandemic Mojo"), 22 Mar 2020. Running with 14S/52V Hailong S39-03 "Shark" battery. Still have Schwalbe studded winter tires on.


Sample Trip Stats []

Minimum amps, expressed as a negative value, represents the peak current resulting from regenerative braking. This is limited to approximately 15 amps to protect whichever battery is being used from being overcharged. I usually program the CA to limit forward current to 30 amps to avoid over-stressing the battery as well, since this gives me all the power I typically need. The motor and controller will go to 90 amps of input current without problems. The maxium speed of 35MPH is only if using the 14S (52V) battery. The transition of pedaling to a higher speed after reaching WOT is very smooth.

Temp C
WattHrs Used
WattHrs In
Charge/Effic %
Notes &
9.8 0:51 35.1/11.5 -14/29 6.7 38/24 137.9/13.2 150/92 14S 23 Feb 2020, high 40's; First ride on eG20.
11.9 1:02 23.5/11.4 -9.8/29.4 4.3 6/3 102.9/8.2 120/86 14S First Saturday OUST ride, 14 Mar 2020; 22 degree temps, CHILLY!
22.3 1:46 36.8/12.5 -10.6/29.4 7.3 22/16 230.2/9.6 270/85 14S 22 Mar 2010; 25/G35 MPH winds; 32-44 F temps; 21.5 mi. per GPS;
35 2:42 35/12.9 -15.5/29.5 4.6 30/25 317.5/8.6 350/91 14S 30 Mar 2020; avg 19MPH first 4 miles to rendezvous, 17 wHrs/mi, almost all throttle;
18 1:31 35.6/11.7 -15.4/28.7 16.4 24.7/22 148.7/7.1 150/99 14S 31 Mar 2020; "hilly" trip (953' elev gain); going UP High Bridge in 3:45/10.3 mi/h
38 2:56 31.8/12.9 na/21 na na 331.6/8.7 390/85 14S 5 Apr 2020; trip on DAS upright with MAC 3* motor; 1,233' elev gain to Shoreview; HWhrs:223 AvgHW:123 Avg RPM:44; battery icon = 1/3 left
19 1:41 26.8/10.2 -13.2/28 17.2 24/21 127.7/6.4 180/71 13S 18 Apr 2020; first ride after cable repair; Speed (white) wire no longer sending data, probably due to a broken/shorted Hall signal wire; hilly ride, seeing a max regen of 19.2% after descent of the High Bridge; no longer a smooth start when motor is heavily loaded and at dead stop; recharged battery with solar only.
19.3 1:40 29.3/11.5 -11.2/28.8 22.2 28.2/26.8 102.35/5.3 ~110/93 13S 25 Apr 2020: great test of motor torque - went through 70' of deep soft sand (road construction on Summit/Ayd Mill bridge); WOT kept bike moving, drawing ~ 1,400 watts (29 amps at 48 volts) from BionX 13S battery; used 5.3 wattHours/mi but still felt like I got more than enough assistance; battery icon appeared still 3/4 full at end of ride.
19.89 1:36 31.4/12.2 -15.7/28.32 11.9 35.3/28.6 150.5/7.6 13S 30 Apr 2020; test max regen while slowing steep downhill to Lilydale Marina -- nearly -16 amps into BionX 13S battery;
21.9 1:17 32/17.1 -15.4/29 10.1 42/30 312.3/14.26 324.5/96.24 13S Emphasis on speed, especially during first half of ride; LOTS of throttle use resulting in 14+ watt-hours/mile, but a 17MPH average. BionX battery was down to 46.7 volts; gauge showing 5 pixels remaining.
5.8 0:19:55 28.77/17.42 -15.4/28.3 7.5 46.6/35.7 123.85/21.35 13S Short trip; haul 80 pound load in trailer up Randolph hill over 35E; avg speed 17.42MPH for whole trip! No shortage of torque or braking, steering is fine.


First test ride results, 23 Feb 2020, Sunday; UNUSUALLY high temps in the upper 40's, very sunny. This trip consisted of going up Highland Pkwy to Snelling -- one mile uphill, mostly on throttle. Return from Snelling is almost all downhill, did mostly pedaling with purposeful regen on steeper inclines. Next was going up and down Finn once or twice, again mostly on throttle. Then to Fort Snelling overlook and back (approx 6 miles of the 9.8 mile trip) - this was also mostly on throttle. Max speed was reached using WOT going downhill on Ford Pkwy to the bridge, using a nearly constant 800+ watts. I crashed the bike on a 'trail curb derail' maneuver to test the battery rail -- it passed with flying (literally) colors -- my left knee didn't like it very much. I finished the ride home with 100% throttle. It was easy to spin the front wheel (studded tire) in snow/ice or on sandy pavement if opening the throttle quickly (don't do that so much). Leaning forward helps a lot if you need to accelerate quickly. I didn't do the full torque test going up/down the North entrance of Hidden Falls Park this time.

Trip Miles: 9.768 [BC5.12 indicates 10.39 mi; WS= 1600+mm?] [GPS indicated 9.42, "First eCherry G20 Ride"; although GPS reading seemed low after Snelling and back portion, which is a measured 2 miles via map geography] CA with wheelsize ("WS") setting of 1,565 mm says 9.8, GPS says 9.4. With the Schwalbe Winter 20", the WS should be closer to 1,545 mm.
Max Temp: 38; Avg Tmp: 24;
Max Sp: 35.1MPH; Avg Sp: 11.5 MPH;
Trip Time: 50 mins 54 secs;
AMin: -14.2 (via ebrake);
AMax: 28.96; VMin: 49.9; (approx 5V sag at max load for this trip)
%Regen: 6.7%; Regen Ah: 0.1605;
Watt-hrs: 137.94; Wh/mi: 13.2;
Indicated battery voltage at end of trip: 54.9;
Amp hours (Ah) used: 2.38;
Watt-hrs put back into battery pack per watt-meter: 150 (138 out, 150 in; == 92% efficiency)

First Saturday OUST ride, 14 Mar 2020; 22 degree temps CHILLY. Down river, Shepherd, Otto, uphill to Snelling. Pulled a short but steep hill at nearly 1,400 watts, on dry pavement; no evidence of slippage, even with leaning fully back and having studded tires. Turns out the right handlebar was seriously bent inward due to the previous crash. Forgot to log trip with GPS (Strava).

Photo of eg20_ca_13-2whrs-mile






Distance Measurement

Photo of the eG20 20" front wheel, fitted with a Schwalbe Winter Marathon tire. It has 4 rows of carbide studs for winter use here in Minnesota. The "true" 20 inch (DIN 406) wheels can have tire circumferences anywhere from 1500 to 1600 or more millimeters, depending on the tire's profile. The default circumference for 20"/406mm tires is typically 1500mm.

20" Tire models            Circumference (mm)
Schwalbe Marathon Winter   1545   studded 20" tires, with RhinoDillo inserts
Snafu 2.10" BMX @ 60lbs    1559   @1560:19.29vs19.26GPS;99.8% acc. [1559:19.91vs19.89GPS:99.899%; 1558:17.18vs17.16GPS:99.88%]
Schwalbe Marathon Racer    1563   on G20 front wheel
Schwalbe Big Apple Plus    1658   via tape measure, on eRowBike
Odysee Aitkin 2.35" BMX    1658   too wide for G20 front fork!

Note that the Snafu 2.10" is the absolute max width tire for G20 (and probably G26) front fork! A nominal 2.00" would be a more practical limit.

Photo of the CA screen with the circumference of 1,565mm set for the 20" winter front wheel. See the Speed - Distance - RPM section of this site for more information about how this works with a Grin CA computer.






Regen Braking

Photo of the eG20's ebrake in the OFF position, which prevents the ebrake signal line from being shorted to ground.

Below is a photo of the eG20's ebrake in the ON position, which shorts the ebrake signal line to ground. Notice how little lever movement is required. At this point, the mechanical disc brake calipers haven't even begun to move yet.






Battery Mounts

Photo of eg20_motor_and_battery_rail

Photo of Bacchetta G2* (not mine) with "minimal" custom BionX battery mount

Photo of eg20_diy_battery_rail_and_frame_clamps.
The frame clamps were made from 5/8" polyethelyne scraps (thanks Axeman!) left over from another project using JPods Handibot CNC machine. The proprietary oval tube shape was copied from a genuine TerraTrike Bacchetta frame clamp machined out of aluminum by them (see photo below this one). A bitmap of a pencil tracing was imported into VCarve and then converted into vectors, followed by a a bit of node editing. I modified the clamps a bit so that both sides would be a bit beefier, owing to the use of plastic vs aluminum. The "rail" is a piece of 22mm OD beefy aluminum tube ("handlebar stock") left over from a rowbike project. The M22 rail clamps are made from some dumpster dive (thanks "The Finn") aluminum straps. All nuts and bolts are stainless steel.

Photo of various parts used to make the DIY rail clamps. The straps are initially bent on the hydraulic press and then finished forming using a vise and a cutoff from a scrapped shock absorber strut from a Lexus SC300. It just happens to be the perfect diameter for finishing the shape of the clamp so it slides on the tube until the bolt is tightened.






Curse of the Axle Spinouts!

Photo of eg20_front_wheel_left_disc_brake_and_wire_exit

Below are the photos of the L10 wire bundle sheared against the front fork when the torque arm retaining/locking bolt got bumped out and the motor "spun out" near end of 31 Mar 2020 ride.

The three big phase wires (blue, yellow, green) are clearly visible. Seven additional conductors carry the Hall signals (five wires), temperature/thermistor sensor (1 wire/grey), and speed (1 wire/white). The three Hall sensor data lines (blue, yellow, green) are bundled inside a foil sheath to reduce EMI. The red and black 5V supply lines are part of the main bundle of wires.

For repairing the above damage to the motor's input wiring, see this youtube video by GRIN Tech. After carefully separating all of the individual wires, I tested the phase and Hall sensor wires using the ebike tester and discovered that all of the PHASE wires were still intact -- conductively speaking. The big phase wires were bruised, but most of the damage was limited to the insulation, and very few strands were actually severed. The Hall tests were another story, whereby there appeared to be conductivity on all three Halls, but the pattern on one of the Halls didn't look quite right. Since this motor/controller *can* run in sensorless mode, I thought I'd keep my fingers crossed and go for it. I cleaned the bundle with alcohol and a toothbrush and then applied the first coat of the liquid electrical tape. I also tested the motor with a Grinfineon controller on the BogieDyno, and it ran well, although I did NOT run it loaded, nor from a stalled dead stop condition. The Grinfineon controller also supports sensorless operation, so the jury is still out on the Hall sensors. I'll add a second/third coat of liquid tape and finish up with marine-grade heat shrink tubing, and see how this works in real life.











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