Thanks for your answers, I am sort of new and I donīt know yet the differents sets of speeds and its capabilities. I am using a trek 7.3 for communting, this bike has a 48/38/28 and cassete 11-30 , 8 speed. I use the 38 with 1 0r 2 when I go for medium speed due to busy streets, traffic lights etc. But when I get an open long avenue or similar, I use the 48 with 1 or 2. Then feel like I could get more speed and stronger pedaling and the bike does not let me. So I guess I may need a bigger crank and a different cassete, waht would be a step further of what I have now?

best regards