For the record, I don't much care either way. As long as a "challenge" doesn't equal time wasting micromanagement, I'm pretty forgiving on game mechanics. That said, no, I would never expect zombies to outrun or even pace someone peddling along at a good clip on a bike. Can I accept it as part of the game? Yes. Would I find it immersive? Not in the least.As an immersion warrior and as I described in the rest of my post which I hope you did read, I don't find periodic electromagnetic pulses too much of a stretch, compared to the sudden lightning, red sky and glowing zombies. The bicycle simply doesn't have to get disabled, since it should be the slowest vehicle in the first place, not allowing you to safely escape the horde.
I feel roughly the same about BM EMP pulses. Could be a fun challenge (if it affects generators as well), but is, IMO, also a highly obvious attempt to hinder the player's progress at that point to create the illusion of difficulty. For me, it wouldn't be immersive at all and wouldn't create any sense of real sense of urgency to be barred from a vehicle since I already don't use them to escape the horde. Part of that is, admittedly, personal playstyle. I fight the horde because I like it and don't care about what might be options outside of what to do if my plan A and back up plan B fail. Can I escape on my motorcycle? Yes. Does it lessen my sense of achievement or drive to make a base, weapons, etc? Not at all.
To me, it's like saying 'we're going to let you build steel walls so you get the feeling of progression and safety 6 days a week, but on the 7th we're going to make each zombie's individual block damage take out steel in one hit because you're too safe now'.