I was recently a victim of my first flat on my new bike (a thumb tac on a bike path no less).
I have found it very difficult to find a replacement tube that fits my rim.
The original tube was a CST 700 x 19/23C 60mm Presta.
I can’t find the CST tubes for sale anywhere in Australia (only USA), so I have tried two other makes: Tioga and XTECH.
The issue with these two is, when I mount the tube and tyre, and inflate the tube, the tire does not sit within the rime, but bulges outward from the rim where the base of the valve is. The valves does not poke out of the rim as far as it should either.
It appears that the material around the base of the valve is two thick, preventing the tire from fitting in the rim.
The CST tube isn’t as thick around the base of the valve. Not by much, but definitely not as thick.
Does anyone know where I can find the CST tube or another tube that may fit? Or are there any stores in Melbourne who could help me?
The photos below show the issues when inflating. The silver valved tube is the new one wich doesn’t fit, the gold one is the original CST tube.
Easily fixed: when you have pumped up the tube enough for it give just a bit of resistance (about 20 psi I reckon), push the valve up towards the tyre and seat the tyre bead properly. Then pump up the tube, giving the valve a push up towards the tyre another one or two times and making sure the bead is still seated if necessary
Don’t do up the nut before you inflate it. Fixing the base of the valve firmly while the air pressure is trying to shift and expand it inside the tube is likely to break the valve base off - as well as producing the symptom pictured above on narrow rims. Folly is right in rectifying this problem though - just push the tube up inside the tyre by pushing on the valve.