Have a subcategory to add: how fast have you ridden on the flats, not pedaling?
Yesterday a monster storm passed through northern California and an afternoon break in the rain got me out of the house to check out the river. When I got on the levee path the wind was directly at my back and I found myself flying along on the mountain bike, coasting. Glanced at the computer to see 22 mph.
Don't think that's happened before.
Rest of the ride was harrowing in parts, especially when unexpected side winds knocked me around like a paper cup. And so very many downed trees. Peak gusts in the storm hit 60 mph.