Hi i ride outside and in have even fallen on knee not to be recomended but lucky okay.Only trouble i have is tkr leg is longer with it now being straight so riding style slightly different from before,this is only problem i have had and tried everything shorter crank arm, blocks on pedal, seat raised,but now after first 500 yds i am okay. Just be aware take it easy at first i did not and had a lot of trouble with swelling but now bike and swim indoor trainer was great to get me going again.Good luck to you hope you are having better biking weather than i am in uk.