How to hack a Bosch Performanceline CX Speed limiter (Trek EBike)

How to hack a Bosch Performanceline CX Speed limiter (Trek EBike)

This project requires a bit of soldering experience, but is possible for a moderately skilled DIYer. Feel free to create your own fork of my code if you like. If you have questions, feel free to ask. This hack will work with almost any EBike.

Code can be found here:

Arduino –
FTDI Programmer –
Prototyping board –
Header pins –

Voltage regulator –

Light cable –

390 Ohm resistor –
51K resistor –
Omron relay –

Many of these parts can be found on Ebay or Amazon for less if you are willing to look around.

Readers Comments (19)

  1. Nice one Alex. May be a second camera would help to show the detail. Yep good videos cost money to make and loads of time to edit. Looking forward to more content. Congrats. Andy

  2. The moment you said I have to build something I’m OUT

  3. I just bought a 2020 Trek powerfly 5. Will this hack still work?

  4. Will this hack work with the Gen 4 version of the Bosch Cx motor?

  5. Just tape the magnet to the sensor!!! Always do 00 mph and motor NEVER turns off!!!

  6. Will this hack also work on the Bosch active line plus drive unit?

  7. My concern with this video is over the "Bosch light cable". Maybe I missed it, but how does a "light" cable help with speed sensing… So far the other videos, about that cable, speak about powering a light, not speed sensing. Details NEEDED/REQUIRED!
    Is this simply a way to get people to purchase this cable, and then it’s too late to return after if does not live up to what it was pitched as.

  8. Looks like ibcrazy the antenna genius from VAS

  9. Is it possible to hack it so that you can use motor power without pedaling?

  10. Hi Alex 😂😂😂 from FPV to Ebike 👍🤘 greets my friend from #OliFPV 🍻

  11. Ha Ha…Alex Grieve. I came here looking how to hack my PowerFly LT7.

  12. Michael Christopher November 25, 2020 @ 8:04 pm

    Does hot glue insulate electrical components? Ive never had luck with that. Back polyurethane adhesive works good too. I should hack my powerfly!

  13. hi , big fan of your videos.
    is there away to hack the walk assist button to make the bike move fast without pedaling ?
    thanks mate 🙂

  14. Maybe it’s best to add that You are voiding your warranty on your bike.

  15. Thanks for upload. VERY FORTUNATE PROUD new owner of the 2019 TREK FS 5. Now feeling out the best hacks for my Mtn e-Biking future. It’s a great time to be alive, you know what im say’n?

  16. Wait this isn’t a video on how to build fpv antennas?

  17. Thanks for the video, very interesting and useful. And I’m glad you pointed out that this isn’t something one necessarily HAS to do.
    I just wanted to add a few things for viewers in the EU or at least here inBelgium. You will not just lose your warranty if you “upgrade” your e-bike (which, for me, makes it a valid option once the warranty runs out), less convenient is the fact you will face legal consequences if you “forget” to inform your insurance company about the classification-change (from bicycle to speedpedelec or motorcycle) and your e-bike gets speed-tested by the coppers, which they start to do more and more. You will pay handsomely for the ticket and will be forced to take insurance anyway. So it’s best to make sure you’re properly covered, especially since your legal worries are gonna be multiplied when you’re involved in an accident. My colleague was caught up in an accident on his way to work, riding on his “tuned” e-bike. His bike was pretty much destroyed by that pickup truck and the accident wasn’t really his fault. But nevertheless the police tested his e-bike, found out what he’d done and informed the insurance company of the pickup truck. They argued that the accident was not caused by the driver of the pickup but by the “unexpectedly high speed” of the bike which had led their client into an error of judgement. They didn’t wanna pay for the destroyed bike and asked the biker to pay for the scratches on the pickup.
    In the end, a judge decided that nobody was gonna pay anybody and each had to take care of his own damages.
    So, my colleague tried to get the money from the employer’s insurance which covers you on your way to/from your work, even if the accident is your fault. But they argued his bike was an illegal vehicle and he got nothing. For a 4,000€ bike in ruins !!!
    And the cherry on top was the letter he got from our employer. Since he was getting more than 200€/month (the tax-free bike-incentive that employers have to give to you if you come to work on a bicycle or an e-bike that goes 25km/h max) for his daily commute, our employer forced him to pay back the last 12 months.
    So please, be smart and do the right thing.

  18. Could you please tell me what brand of mud guards you have on that front wheel ?

  19. What a great idea. Thanks for posting. I actually built one and it worked great. The second one I built didn’t go so good. All I did was extend the wires from the wheel sensor to the arduino controller and from the arduino controller to the existing sensor input on the motor. I needed to mount in a more secure location further from the motor. I am now getting erratic results. The output pulse frequency to the motor no longer divides by 2 after 19 mph and jumps all over the place. Any ideas. Is there something going on with a time lag due to longer wires? When I shorten the wires the problem goes away.

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