Review on Transform Your Bike With KEYWELL Presta Valve Adapter - 6 Pack, Convert To Schrader With Ease And Inflate With Standard Pump Or Compressor by David Lamfers

If you’re reading this like I did trying to figure out "how” this works, it’s simple, they simply screw right onto the valve.The problem I found with this is on that the lock on the tube valve will screw down when you screw this adapter on effectively closes that valves and it won’t allow air in.To best this, push the adapter down snug and then start screwing.You also don’t need to leave these on if you don’t want, you can put them on when needed and take them off or keep a pair in your bag in case you need air at a gas station or something.