Bike novice here looking for some advice. Been riding a 50/34 compact with 12-23 and been really struggling on long hilly rides. Want to change the 12-23 to something that gives me more gears to play with on hills. Used to have a triple and spent nearly whole rides in middle ring so want something that gives me similar range. Any suggestions? Also is there anything to consider in terms of compatibility when buying new cassette or simply case of taking old one off and new one on? Ones ive been looking at are shimano 105 which is what i have now. Planned on taking to LBS to have this done. Thanks!