Tell me: how many indoor trainers accurately simulate the wind resistance felt by a Clyde when riding at speed? My guess is: few or none.

Kurt Kinetic is probably one of the better ones. Even their own data shows that their Cyclone wind trainer requires less power to maintain a given speed than either their Kinetic fluid trainer or a real bicycle. The data and graphs on the third page of the PDF are particularly informative: if you're using their Cyclone wind trainer, it looks like you'll be riding 2mph faster indoors than you would outdoors!

What happens if you weigh more than the 165lb rider the Kurt trainers are calibrated for, though? Do the trainers generate a slower speed for a given power output, to simulate the increased air resistance that a larger rider will feel during an outside ride? Nope! If you're outputting 258w, the Kurt Kinetic is going to be spinning at 20mph. If you play with the Kreuzotter equations, you'll see that a 200lb rider should be seeing 18.7mph on the speedo and a 250lb rider should see 17.3mph.

All of this dovetails pretty nicely with my own experience: it's virtually impossible for me to maintain the speeds I see on the trainer when I'm riding my bike outside. Maybe if I ever get down to 165lbs the number will match up. Until then, I don't bother comparing the speeds from the trainer with speeds on the road...