To start off with ill let you know im new to cycling, well, new to anything more advance than just simply riding, have never dne any mechanical work on one before, so I dont know the correct terms but I will try and describe it as best as I can.
Well, I let a friend use my bike a while back and got it back today, and it wont shift anymore lol. I can shift into very few gears. The bike is a GT Avalanche 3.0 21 speed, all stock, nothings been changed. The front gears will shift between the first and second smallest with no problem, but when I try to go to the largest it just makes grinding noises(chain rubbing) and then often the chain comes off. With the rear gears all it does is stay in whatever gear I can manually put it in, wont shift at all. This was the last time ill let anyone borrow it, thats for sure.
I asked around at a couple stores and they said it would be 45$-49$ to tune it up, but everythign else is fine, only problem is with the gears, I was wondering if anyone knew a website with instructions on how to adjust this without spending the 49$, and waiting another week to get my bike back. Thanks!