Cruising down the road on my 1990 electra glide and my speedo drops to zero. Never worked again after that. Wtf?

 

There are three components of your speedo. Start by checking that the prong of the speedo drive at the axle is still seated in the notch in the rotor. If that is ok remove the speedo cable and check for a broken cable. reinstall the cable and disconnect the cable from the speedo head. Spin the front wheel and see if the cable rotates. If it does it is the speedo head. Replace it, it happens.

 

I've been though this. Sounds like the cable to me. FYI, if it turns out to be the speedo, you can get a used instrument panel off eBay for $100 or so, and you get a bunch of extra parts out of it too. I got one off an '89 police bike, works great!

 

Cable or sender are my guesses. I've been through enough of both. If the little angle broke off the end of the sender, the part Beemervet mentions that fits in the notch in the wheel, you can (sometimes) take a punch and bend what is left into the notch and get a few more thousand miles out of it.

I've had best luck with genuine HD cables and senders. This is really the only recurring issue I've ever had with the bike, so I can't bitch too much.

 

This also made my mileage counter stop working. And if I wasn't the good person that I am, I should totally leave it broken for the next 50,000 miles and fix it right before I sell it so it still reads the same miles. Which is 51,000

 

....... and Karma would make sure that you got plenty of speeding tickets resulting in the loss of your dl.