Cadence sensor/no-pedal mod ?

[xtian]

Just got my XP2.0, tweaked menus for best top speed and power, and rode around. With strictly throttle, speed tops out at 22mph, and if I pedal (at all), top speed is 26. That's fine, I'm happy with the top speed. However, at 26mph, I cannot pedal fast enough to engage the gears--this is a common complaint, and I don't want to replace the gear ratio...that's not the solution I'm after. I discovered I just have to pedal very slowly (maybe one revolution every second or so) to tickle the cadence sensor, and I can maintain top speed. And if I stop pedaling but hold the throttle open, speed drops back to 22. The ONLY way to achieve top speed on this eBike is to pedal a little bit. I want to cruise for miles at top speed WITHOUT pedaling. It's uncomfortable to pedal with no "load" against your feet, and dangerous anyway--you need to keep your feet firmly planted!

There must be a way to trick the controller into thinking you're pedaling. I tried to trigger the sensor, which is mounted at the base of the left crank, but it will not respond to a small neodymium magnet. Any ideas?

I see that the sensor has three wires, which means it's probably a simple hall sensor, with wires for +5v, ground, and signal out. I have ordered a 555 timer which will allow me to output a square wave pulse, and I'll see if I can use that to simulate pedaling.

 

[Johny Rocket]

FYI but doubtful you'll get caught, you are converting the bike to a moped under legal definition. Cop sees you're going over 20mph without peddling, busted lol. Some States treat mopeds without any regulations anyway so no worries if you live in one of those.

 

[xtian]

I guess I should have said, "Legal issues aside..."

 

[Johny Rocket]

The most common cadence sensor

 

[Johny Rocket]

While you're at it dual batteries might be helpful. I have this that allowed me to mount a huge 20ah second battery to the rear rack while still keeping the OEM battery. https://area13ebikes.com/collections/batteries/products/dual-battery-parallel-connector
Good source for other cool ebike stuff too

 

[harryS]

The signal from the cadence sensor is an symmetrical square wave. It's different when pedalling backwards vs forward. So you will have to analyze it, and set your electronics to simulate a forward signal. Should be easy enough for you young techies.. It would take me too long to relearn that stuff.

It's interesting that you go faster on ghost pedal assist than with pure throttle. While your brake levers will shut the controller down while squeezed on, you might want to rig your brake levers to also toggle your timer so it has to be restarted for safety.

 

[Dorkyman]

Wait a sec, why not just drop in a different freewheel? One of the first things we did to our XP2.0st bikes was to install an 11-34 freewheel. Changes the personality of the bike completely, and you're not pedaling like a zombie at higher speeds. Cheap fix.

 

[xtian]

Wait a sec, why not just drop in a different freewheel? One of the first things we did to our XP2.0st bikes was to install an 11-34 freewheel. Changes the personality of the bike completely, and you're not pedaling like a zombie at higher speeds. Cheap fix.

Thanks, but no. I don't want to pedal, period. (At least for the sake of this mod).

Now I have proof that my idea will work. See my test:

My square-wave signal generator module will arrive from Amazon this week, so I'll keep y'all updated.

 

[xtian]

I found the simplest possible solution. Simply short the two pins shown below using a momentary switch and a 1K resistor. The 1K resistor prevents the short from drawing too much current (4.5v drop across 1K = 5mA). You just need to tap the button a couple of times each second (say, 120bpm, for the musicians out there). I went for a test drive, and it works perfectly! Now I just need to mount the button where my thumb goes, just under the throttle. (You need 60" of hookup wire to reach from the PAS connector to the throttle controller on the handlebars.)

I don't plan to plug in the crank sensor again. Effectively, PAS is moved from my feet to my thumb, making my ride more of a motorcycle than an eBike, which is exactly what I want.

 

[xtian]

Now that I received a 3-pin cable and the 555timer module, I made some progress. The waveform photo shows the output from the cadence sensor--roughly 7Hz, 25% duty cycle, 4.7v peak. I hooked the 555 module to the eBike's 5v supply and adjusted its output until it looked similar--but this did not trigger the motor, because the output voltage of the 555 was only ~3.6v. I used a 9v battery instead to power the 555 module, and the output square wave rose to ~6v, and that worked perfectly to trigger the motor. So, I've ordered a small DC-DC boost converter, and will continue this project when it arrives.