Modern bikes allow novel attacks too. I wrote a blog post about how to downgrade the firmware of a Shimano Di2 groupset and doing a replay attack to shift someone elses bike.
https://grell.dev/blog/di2_downgrade https://grell.dev/blog/di2_attack
https://grell.dev/blog/di2_downgrade https://grell.dev/blog/di2_attack
> must be within a couple of meters of the bike
The range of radio transmitters/transceivers can be increased, and accidental transmissions from various things could affect it.
Choosing to allow any kind of remote control over a manned vehicle is a risk. There can be benefits, but winning a race may not be worth giving up your life.
Similarly, I don’t want IoT devices and won’t connect them when I have to buy them. I’d prefer to keep my thermostat and appliances safe, and a neighbor can turn them off if I forget.
Once I had the proper tool, I wired mine. They are all internal so I don't think I'll need to replace during the lifetime of the bike.
[1] https://bettershifting.com/installation-guide/connect-12-spe...