I second everyone who said it is so much better to ride indoors with friends/family. Longest trainer ride for me was 3hr 45min, on a computrainer at the LBS. I get in a 3+ hr ride once per week all winter. No way I could do that at home alone. 4days per week total on the trainer for a combination of intervals and endurance rides. Great gains can be made, so it is totally worth it come spring.