how to switch bike gear side?

You have to swap the crank arms... most BMX spindles are equal length on both sides so you shouldn't have a problem, but that isn't the end of your problems.

You'll need to have a wheel with a flip flop hub as well as a left drive cassette or freewheel. If you just flip the existing wheel you'll only be able to pedal backwards.

Ugh!!! So sorry but this is the very first time I ever heard of a bike like yours. If you do that you will have to change your rear wheel hub and sprockets, the brake system if you are using discs, and also your crank arms must be reversed but you can not do that because the threads will have to be changed into the counter clockwise position. I don't think you can do that, why not just use a conventional bike, anyway it does not care whether you are Right Footed of Left Footed.......

Every bike I have ever seen always had the gears on the right hand side, even the European ones I have seen over here so I have no idea what you are talking about.

I assume all you would need to do is reverse the chainset. You would need an appropriate tool to remove the crank arms and a Bottom Bracket removal tool. Flip over and then fix back together.

you ought to use the gears in any combination, yet you do no longer % to be on the biggest kit (which ability cog) in the front and the smallest in the lower back, and vice versa. For flat floor using, you are going to be on "2" in the front and someplace in the middle for the lower back gears. while taking place a hill, placed the front one on "3", and going up hills, the front one on "a million". regulate the lower back gears so as that possible pedal actual with out too lots or 2 little resistance.