I am not paid or sponsored by Park Tool. I am only promoting my business & service Bosque Mobile Bicycle Repair LLC. How to use a Presta Valve on a Bicycle. They are more delicate than Schrader valves, be careful. To inflate or deflate unscrew the little nut attached to the shaft. When done finger tighten gently till no air escaping. Not all have removable valve cores. ‪@parktool‬ https://www.parktool.com/en-us/product/valve-core-tool-vc-1 Bicycle repairs completed at your location, onsite. House calls, job site & in the field. Book online at www.BosqueMobileBicycleRepair.com Don't load & transport your bike to the shop. How valuable is your time? Now located in Denver Colorado USA. Follow me on YouTube, BlueSky, Instagram, Rumble, Odysee, Linked in, TikTok Snapchat, Pinterest, X, Facebook #bicycle Park Tool #mobilebicyclerepair #bicyclerepair #bicycle