LED Bike light - blowing at high speeds?
Most dynamos produce a dirty 6v AC, depending on how fast you are going. I don't know how they've done it, but the engineers responsible for your bike lights probably included some rectification to convert the AC to DC and maybe even integrated some circuitry to limit the voltage/current going to the leds.

TLDR; No, you'll be fine.

So, if you wanted to make your own bike lights:


assume your dynamo outputs 6ish volt AC or more or less
convert this AC to DC with a bridge rectifier
add a big capacitor to smooth out this really sketchy power source
hook up your LEDs and resistor(s) in a way that they will survive the most extreme scenario
OR
come up with some voltage/current limiting magic