Gear down a lot. Since you already have 15 tooth cog glued to your bike you cant change that. But I would go all the way down to a 46 tooth ring. Skidding will be easier, you will accelerate faster, you will be able to stop better, your will gain more stamina, and more usefull leg muscles. Everything about your riding will be better if you gear way down.

Also dont inuslt people that are trying to help you. My posts may seem annoying, but its the only way to acuratly give you advice. Any one that sees a gear ratio on a screen and tells you to change it will not be giving you the full advice you need.