Is Presta valve lock nut useful?

[ManBearPig]

Ciao.
I have always had lock nuts with Presta valve inner tubes on my Giordano road bike, but there are a few guys I know who take them off. I understand that there is a chance that you can overtighten a lock nut and therefore irritate the tube in a way.

Do you leave lock nuts on and why? Have you experienced any advantages & disadvantages of having a locking nut?

[Painkiller]

There are pros and cons to each valve system. as for the Presta the lock ring is a Pro. it keeps stem in place should the tire become to low to push the pump valve on. Great feature! Finger tight is all u need to do once tire is inflated. For this reason I prefer schreader tubes with this type of stem also

[Jesper]

(03-06-2021, 08:00 AM)ManBearPig Wrote:  Do you leave lock nuts on and why? Have you experienced any advantages & disadvantages of having a locking nut?

I agree with Painkiller.
I have always used them, and have never experienced any problems. On my regularly used bikes that get higher mileage/Kms; I use 2. I do not over tighten the one at the rim, but I tighten the 2nd one hard to the other which acts as a "jam nut" and keeps both from loosening. Never an issue with that method, nor any tube damage.
I also tend to cut a small rubber "washer" made from old tubes and place it down on the valve stem before tube installation; Presta and Schrader. It needs to fit tight around the stem; I have to stretch it a bit. I always do this when using high pressure tires (>95 psi/6.5 bar); I usually ride at >120 psi/8 bar. It prevents the tube from pushing into the rim orifice and potentially damaging the tube in that area; especially if the rim tape has shifted over time. When installing a new tube I only tighten the nut enough to keep the tube in place. Once tube and tire installation is complete, including inflation, will I tighten the nut to the rim and add my "jam nut". On most rims (vintage, anodized, painted, chromed, and/or new) I use a small nylon washer between the nut and the rim to keep from marring the rim surface, always finishing using the second "jam nut" with that type of application.
I would venture to say that a few riders may exclude using them as a another means of weight reduction; and here I am adding more!

[ManBearPig]

Thank you @Painkiller @Jesper

[ChaseCal]

(05-17-2021, 02:12 PM)ManBearPig Wrote:  Thank you @Painkiller @Jesper

along with Jesper and painkillers response, I have seen people really torque these more than they should and they start to rip the valve and then complain that their tires keep going flat, so the only disadvantage I see is that. and then there is if it gets loose. rims are drilled to let the valve through easily so there is a little play in them. if you don't have the nut tight on the rim then the valve stem will rattle around the rim and it gets kind of annoying. like Jesper said, he uses two, this will keep that rattling from ever happening and I agree with doing it.

[ardy22]

I find it to be very useful.

[Deynolds]

Lock nuts are typically used to secure Presta valve inner tubes in place on bicycle rims. They screw onto the valve stem and help to prevent the valve from being pulled into the rim when inflating the tire.
There is a small chance that over-tightening the lock nut can cause damage to the valve stem or inner tube, but if the lock nut is properly tightened to the manufacturer's recommended torque, this risk is minimal.
Some people choose to remove the lock nut for ease of use or aesthetic reasons, but this can make it more difficult to properly seat the valve stem in the rim and can increase the risk of the valve being pulled into the rim during inflation.
In general, it is recommended to keep the lock nut in place unless there is a compelling reason to remove it. If you do choose to remove it, make sure to take extra care when seating the valve stem in the rim and inflating the tire to avoid any potential issues.

[ReapThaWhirlwind]

I would imagine they are very useful, but I've gotten pinch flats despite them being there and fully secured.

[enkei]

In my experience, they're definitely useful for holding the valve in place when inflating the tube. Used properly/intelligently, I can't see any practical disadvantage to them.