So I started to train in gym,because i feel weak.I want to do higher bunny hops upcoming summer.Yes,I also need to practice more,but surely gym will help in some way.I do whole body workout,but what muscles help to do bigger bunnys :p I ride street and freeride. THANKS
I would say the muscles you woould work the most would be biceps back and shoulders and legs. Just keep doing full body workouts and you'll probably find it easier. Core and abs also.
You need to build explosive hip power. Here is a video I did on how to use a kettle bell swing to build the hip movement and power you need to bunny hop higher.
Do Core workouts (Abs, obliques, back muscles etc). This will help getting a more explosive follow through, which will help the end result. A bunny Hop takes little, or no, leg work, so try to focus more on your torso.