I played around with my rear derailleur trying to learn. I looked at various YouTube videos, looked up Park Tool and other pages, learnt about H / L screws, the cable itself etc etc.
I tightened the cable keeping the chain on the biggest wall in the chain ring and the smallest in the rear sprocket, tightened the H screw correctly and tried shifting upwards. It shifts correctly for 2 gears, but it simply refuses to go to the top 3. (3 chain rings and 6 sprockets) .
I can see the derailleiur move a little but it is not enough to pull it upwards. However, it switches perfectly between the smaller 3 rings (Note: This happens on all 3 of the chain rings)
What am I doing wrong? (Note: I could take this to a bike shop and have it repaired, but this is a old bike and I am just trying to learn the mechanics here)
Additionally, what's a good understanding-bike-mechanics book you guys would suggest? I have seen plenty of YouTube videos and read online, and the one small "bike maintenance" class I have in my city teaches how to change tubes after a puncture and some minor lubing and stuff ..