How do you find the Treadmill to Road Run transition? Or do you only do treadmill training in the summer due to the heat?
I have free access to a fitness center at work (free weights/weight machines, cardio equipment, etc.)...if I go to this fitness center at least 10 times per month for 10 months out of the calendar year, I pay a lower health insurance premium. This is the ONLY reason why I run on the treadmill...to get those gym visits.
Otherwise I would probably wake up early and run at home before work. I used to do all of my runs on the treadmill (the furthest distance I've run on a treadmill was a 12.5-miler last year), but once I began running outside regularly I found I couldn't stand treadmill running...I think this is pretty common. Now I don't go more than 5 miles at once on a treadmill, and the only time I prefer treadmill running is for speedwork (unless there's super extreme weather - seriously heat, blizzard, etc. - but even this past week, when I was off of work, I did all of my runs outside even with the heat advisory we had).
Right now a little over a third of my weekly mileage is on the treadmill (2 mornings on treadmill, 2 runs outside)...and I think when you asked the question you were wondering if I find it difficult to run outside after running inside?? I actually find that I am slower on the treadmill...I won't bore you with my theories as to why this is, but I am definitely faster when I run outside (not counting treadmill speedwork). In general running on a treadmill is thought to be "easier" than running outside because a treadmill is softer than concrete, it pulls you along, the conditions stay the same (no heat, no wind resistance, etc.) and unless you mess with the incline you're running on a flat surface the entire time, etc. But for me the mental challenge - i.e. BOREDOM - of running on a treadmill makes it so much harder. It's worth it to me to get up earlier to get a run in and avoid the summer heat, which is what I did last week...I woke up early, sunscreened, carried water with me, and accepted that my pace was going to be slower than normal because it was so hot out. If it weren't for wanting to accumulate those gym visits, I'd almost certainly do all my runs outside.
I hope this helps!