Well, this is a mystery to me. How does it determine speed if the data from speed sensor is indicating a slow speed (vs real speed.) It does not have (?) its own GPS. May be comparing pedal power vs reported speed ?
The only place ì imagine you could even hope to get answers to those questions are the people who write the code for speedbox.
This is an easy one, note I'm retired embedded software engineer. The CX engine electronics has access to the output from the speedbox, but it also has access to pedal movement (cadence). The relationship between these is also reliant on choice of gear, however gears don't have unlimited range and have particular ratios, unlike a CVT. Also it needs to be noted that it's possible to move the pedals at a cadence that doesn't actually provide any effective torque, in fact you may hold pedals still at times and bike may still accelerate, if going down hill, with strong wind etc. All that said, there is obviously scope for the logic with the CX motor to determine whether there are strong indicators that a tuning device is being used. The evidence for this could become stronger as your speed gets higher and how long you maintain high speeds gets longer. While the amount of assistance to maintain 24.9KPH for 1KM may be fairly high if going up a very long uphill, if assistance is demanded continuously over say 5KM at supposedly just 24.9KM, it obviously is a good indicator that a tuning device may be in use. Just the fact that bike NEVER goes over 24.9KPH (but it used to) is yet another indicator. Personally, I don't have slush funds to test this out for myself, and can't wait until sane laws that allow reasonable speeds (32KPH to 40KPH range) come into Australia and hopefully other countries. My old ebike wasn't limited, was only 200 watts and was far less frustrating that this new one in some ways. I averaged 25KPH to 30KPH on old.
I think you are on the right track to solve this mystery to me. As a side note this 25km limit in Europe is absolutely bonkers ! You can exceed this in just a couple of pedal strokes in a flat. The other frustrating part of this jockeying between riders and Bosch, why does Bosch do everything they can to prevent us riding like we want. They follow the law and they should just shut up and let others break it on their own terms. Why torture us with all these error codes and limp modes !
Well I certainly agree with you about the silly cap on speed limits on our emtb's. I don't ride on pavement and city streets. And in the off road environment, the 15 or so mph limit is absolutely ridiculous. Even at my age I can often exceed that on my pedal only bike in many places on a trail. The local trails in my area don't prohibit emtb's, and I ride a lot of places where we can also ride dirt motorcycles. I'm not talking about hooligan behavior. I'm talking about slightly upping the speed limit in reasonable conditions.
