Does anyone find a big discrepency with their indoor vs outdoor ftp? I did a 40km ITT a few weeks ago and held an average of 290 Watts for 1:03hrs. Theoretically this gives me an FTP of 290W (maximum sustainable power for 1 hour). However, when training indoors I find it difficult to hold 240W for a 10 min interval (I did the ramp test today and scored 238W). Both indoor and outdoor were measured on the same powermeter (Powertap P1 pedals), and both were done holding the TT position for their entirety. The only thing I can think of is heat exertion (I have 2 fans going indoors but still sweat quite a bit).