I have one bianchi strada lx. I have put crank 53/39 and cassete 9 speeds 12-25. On my mountain bike trek 830 antelope i put 52/40 crank and has 7 speeds cassete now 13-30 but is too wide. What sizes crank you think is good for road bike and mountain bike. To go fast in flats and have low gears for hills but to keep good cadence too