Everytime I rerolled a piece of gear, I would get run speed up like 2 times. Are there certain gear that have a higher percentage of getting certain abilities or is it just bad luck?
Each piece of gear has a different brand, which is more likely to show up on that piece of gear. Rockenberg gear, for example, is most likely to get Run Speed Up. Some brands (Cuttlegear, KOG, Fantimisu, Squid Girl) are exceptions and have no sub ability bias.
Then again, it could just be bad luck. The gear rolling system can be really annoying sometimes.