I'm a total bike mech newb. I have a Kona hardtail mountain bike. I commute to work and back year round with annual temps between -30 and +30C (-22 and 86F). Round trip is 10km (6miles). I have done this for 23 months. The original drive train is about 2500 to 3000km old. The rear derailer is about 1500km old.
For the last 6 months, I have had to start from red lights in an easy gear otherwise my pedals rotate but I don't move forward. I showed my chain to my LBS and he nearly kicked me out of the store because his tool couldn't even measure just how far gone my chain is. I replaced the chain and rear gears this weekend. Then I take my bike in my alley (it's paved), put it in a hard gear, stand up and try to accelerate quickly, once again my pedals rotate but I don't move.
Given the age of my drivetrain and the neglect, should I just go ahead now and replace my chainrings and derailer cogs?