One of many things that i hate is bad shifting gears, i hate when it cant shift in one gear, ghost shifting, slow shifting, squeaking,etc.
All of this problems are caused because of bad tuned rear derailleur.
Here, in Serbia, bike shops usualy charge you 500 rsd ( about 5,6 $ ), but problem isnt money ( well, 10 $ is average daily wage in Serbia , so you could say its overprized, but...) problem is that even you want to give them money, they arent fixing that problem for eternity, its only fixed for 1000km . ( belive me, i bought new bike 3 months ago, they did zero service , and next month ( in june) they did first service , tuning brakes, gears,..., when they finished that service i bought speedometer( measuring speed, distance, ...) and since then i rode about 700km ( maybe 900 because my dad reset it 2 times) . After only 700 km cables are again losen, and my gears not working properly....................................
so we are runing into other problem, after only one month i need to go again to bike shop and they will charge me 5 $ ( first two service (zero and first one) are free) ( 5$ for me, but in usa,uk,australia, many other states bike shops are charging 20 $ maybe less maybe more) , and they will fix it, but then after 1000 km they i will, need to go again, and then again, and again,again....
also expenses are raising with every other visit, because after 3 or 4 tune ups, they will say that you need new cable (thats also 5-20 $))
so do you know where i am going, after every bike shop visit, they will say that you need some new part (it will actualy need you) but you will know how to change it alone. ( you all know that chain shoud be changed every 3000 km, casette every 6000km??????)
so enough of this theorys.
tuning up your derailleur is realy simple and fast ( i was stuned when i finished iit in under 2 minutes)