Betteridge's law.
There have been suspicions about this for about 15 years. Yet, in that entire time, not a single road cyclist in a UCI competition has ever been found to be doing this.
Even just from a practical POV, it makes little sense. Stock road frames do not have room to even mount such a motor. You would also need a sufficiently large battery somewhere on the bike that can deliver enough power to make an impact. Examples that people have built are usually replacing one of the bottles on the frame with a battery, but that would obviously be noticed immediately upon closer inspection of the bike. Even if you can remove the battery bottle, there would still need to be some kind of cable to connect it that you cannot remove on the fly without anyone noticing while in a highly public space.
They have also been scanning bikes for years for potential signs of motors. Nothing has ever been found. So, if it does exist, someone has found a way to build incredibly tiny motors and batteries that don't show up during checks, but are still powerful enough to make a difference for a cyclist who is already pushing 400-500w or more.
The much simpler explanation is that it's a complete myth that some people keep pushing for whatever reason.
> it's a complete myth that some people keep pushing for whatever reason.
I think it's simply because the top cyclists are now blowing the performance of doped cyclists of decades past out of the water and people get suspicious. I personally think huge advances in nutrition + altitude training are making the difference, but I understand people being suspicious especially in this sport.
I agree with you, btw- I've yet to see anything proving conclusively that this form of doping even exists.
Not saying anyone does this, but my bottle holder has two screws that could easily act as contacts - no wires needed.
there is room, bear in mind such a device need only provide minute advantage for it to be significant.