Go gentle with the presta valve nuts. I used to have a delightful Chinese bike mechanic who called them "the work of the devil". If you take a corner too hard, the tire will deform and the tube won't be able to conform with the tire. When that happens it'll tear the tube at the base of the valve stem. Personally, I throw those little valve stem nuts away. I don't want any workings of the devil on my bike.