How bike computer wheel circumference change affects speed I have a cateye stealth evo+ bike computer and have been using the standard 700/25 wheel circumference that is listed in the instruction manual "2096". The value has been changed to 2143 using the rotating wheel method(stem to stem) while on the bicycle. The  wheelset and tires are the same. Will this increase or decrease my actual and average speed.
Your actual speed will remain the same. The speed displayed by the computer will be higher by 2%, as Will Vousden says. Please note that this higher reported speed will probably be more accurate (closer to your actual speed) because you measured the true circumference of your wheel (which is what I assume you mean by the "rotating wheel method").