Training on aluminum bike 8 speed

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