Pedals won’t complete a rotation When I get on my bike and pedal when the right hits the top I can’t pedal and it stays and it keeps happening when the right goes to the top it stops and I can’t keep pedaling how to fix and any thoughts
If the cranks are prevented from moving at the same place in their rotation, they are most likely catching something on the frame, rather than the problem being with the gears or chain. 

Some basic troubleshooting you can do:


Hold the bike of the ground, slowly turn the cranks forward and backwards by hand, look to see what they might be catching on. Sometimes the front derailleur gets rotated around the seat tube and sticks out into the path of the right crank arm.
Spin the rear wheel forward to make sure there is no problem with it.
Pedal backwards slowly and examine the chain, make sure no links have come apart. The side plates can stick out and catch in the derailleurs.