It's a problem and a grey area. I've yet to have problems with my homebrew stuff but I've already had some conversations with LE that stopped me (fortunately not while exceeding the limit) because my bike looks more than a little weird.
And no, it's not just the components. The reason for that is that the bike motor, controller and rear wheel + sensor all have to be 'just so' for the speed limiter to work properly. There are some defeat tricks, usually stuff that fools the sensor by doing a neat little bit of Bresenham on the input signal but the smarter bike motors realize this is happening and will happily brick themselves. The latest generation Bosch is afaik not yet hacked and this is not for lack of people trying.
And no, it's not just the components. The reason for that is that the bike motor, controller and rear wheel + sensor all have to be 'just so' for the speed limiter to work properly. There are some defeat tricks, usually stuff that fools the sensor by doing a neat little bit of Bresenham on the input signal but the smarter bike motors realize this is happening and will happily brick themselves. The latest generation Bosch is afaik not yet hacked and this is not for lack of people trying.