Fat Tubes - 35+mm width with smooth presta valve stems?

[Look585]

Anyone have a source for smooth (unthreaded) valve wide tubes? I am using Michelin A2 25-32mm in 38mm tires and would like something a bit wider. I hate threaded valve stems!

[mktng]

im sure someone will ask.

but .

why ?

[Look585]

Why wider tubes? or Why unthreaded stems?

Threaded valve stems serve no purpose (for me) and are harder on the pump head I prefer (Hirame).

Wider tubes simply because the 25-32mm Michelin's I use for road width tires (28-32mm) need to stretch an awful lot inside the tire when inflated. A better fit would seem an improvement.

[mktng]

fair enough.

i use these.

good option for what youre looking for.

https://www.competitivecyclist.com/challenge-latex-tube

[dddd]

Presta pump heads that are still in good condition are supposed to grip the smaller-diameter threaded area only.
Many pump heads that are either worn out or have been forced onto the major threaded diameter will no longer seal reliably on the smaller threaded tip area that the cap screws onto.

The reason why gripping the smaller diameter is better has to do with the ratio of grip area to pressure area. The smaller tip has a reduced grip area, but the pressure area (the cross section of the gripped area) is doubly reduced due to this area being proportional to the square of the diameter.

So the bottom line reason why gripping the smaller diameter portion of the valve stem is better is that it requires less contact force to prevent the pump head from blowing off, and less contact force prevents the sort of wear/distortion of the rubber over time that further compromises the integrity of the attachment.
The smaller diameter area and reduced contact force will also require much less force to pull the pump head chuck off after inflating, which reduces the stress on the attachment of the stem to the tube itself, which is often a point of failure.

If there are tubes with valve stems that are unthreaded out to the smaller-diameter tip of the stem, then those might be the best for those of us who don't use caps on our road bike stems. Not so common though since the only stems I've seen that appear completely unthreaded are stem extenders that unscrew from the tube's stem and are not actually part of the tube.

I would bet that a great majority of Presta valve users are unaware that their new pump is designed to seal onto the smaller cap-thread diameter of the stem. It's why I don't loan out my pumps, because they seem never to seal properly after being forced and clamped onto the major diameter of the stem.

Even on a tube with wrench flats on the smaller threaded tip of a removeable valve core, almost all still-good pumps will seal perfectly on the smaller diameter core threads, the only exception perhaps being some ultralight pocket pumps like my SKS sub-40, which cannot inflate a tube with wrench flats.