The first question-I am a lightweight, 120 lbs, riding a Redline flight monocog(15" frame) HT. My body gets bounced off the saddle riding roots or things like that. I know to expect this, but is there anything I can do to help with this situation like lower air pressure or something else. I run converted tubeless at 22 lbs right now. Eventually I will get a FS but not right now. I would just like a little help for when I am sitting down & pedaling. The second question-has anyone used a 38 tooth cog in back? If so, was there any issues? Thanks for any help.