Get some cycle practice in before you go! Your bike/bum interface, wrists and knees are at risk when you start cycling, so put in plenty of work when the pressure isn't on. Then you won't lose days to injury while on tour.
I realise Denali et al are more serious than the Munroes, but my hike 'n' bike experience suggests that cycling strengthens the muscles used for walking uphill.
Notice that I don't know which mountain is highest in Central America.
