For the last two years I've been training using my time trial bike (bmc tm02), ive been using it for both flat surfaces and lots of climbing . I live and work in Beijing and it's always a big risk taking this type of bike out due the chaotic traffic. I can not afford a carbonframe road bike or even really decent aluminum one. I ended up buying a cheap first level entry bike which I will use for long ride for endurance. A trek series one (8 speed). Obviously it feels a lot heavier, and going slower . My Theory was to train on this bike for a while , maybe three months , and perhaps Due to the weight and all other aspects it would me me a stronger rider . So next time i use the tt bike I should fly. I don't know , what do you think? I could always sell the trek bike if i have made a big mistake
I don't see any issues with that at all. I'm actually doing something similar - - after 12 years away from multisport training and racing, I decided to start racing mountain bikes last year. I do at least half of my training on my 17 year old 9 speed road bike, and most of the balance on my heavier trail bike. As I get closer to racing season, I mix in one ride every week or two on my race bike so I feel comfortable on it.
I would recommend that you do the same as you approach race season - - maybe ride your TT bike once a week on a faster ride or intervals, so the race position isn't a surprise on race day. In the meantime, get in some good miles on your training bike!