What are some effective ways to decrease recovery time? I find my recovery times are in excess of 30 minutes after hard exercise, such as sprinting (on a road bike), despite exercising fairly regularly.
I think you've conditioned your body by following the same routine for a long time '...despite exercising fairly regularly...' - as Einstein said: Insanity: doing the same thing over and over again and expecting different results.
If you want to recover faster after a 1/2 intense workout - then you need to workout longer to condition your body to that and then the shorter workout will not tax your body as much reducing the recovery period. I'm not sure if that's what your intent is - is your goal to reduce recovery so you can work out more? or is it to maintain your current level but be able to get on with the rest of your day quicker? Either way, it will require varying your routine, including more intense workouts (Tabata/HIIT), and ensuring your have proper nutrition and hydration to provide your body with the fuel to recover.
30 minutes is a long time for someone in good physical condition.
The better the pcysical condition, the lower the recovery time and the faster you will be able to work on again.
If you make a short 100 metres sprint or a max-pulse cycling uphill over a long period of time, there is quite a difference. You must take in account the oxygen dept, and if you over a long period don't give your body the oxygen it strives for, you will of course feel it for just as long afterwards.
To improve your recovery effect in your body, I will suggest running and a lot of interval training - short intervals with high intensity and almost max-pulse and many repetitions with very small pauses in between, so you never catch your breath fully and never has time to get your pulse down.
I suspect you are talking about getting your recovery time after aerobic exercises decreased, and then this would be my suggestion.