All Presta valves are not created equal

Pale Rider

Legendary Member
A puncture came close to ending the ride for one of my Sunday morning group yesterday.

She had a spare tube, but the presta valve would not go all the way through the hole in the rim.

Pushing hard, we could get less than a cm showing.

There was insufficient valve sticking through for her clip-on pump to grip.

My pump - which has a threaded hose connector - just managed to do the job.

Both tubes had threaded metal valves, but the valve on the spare tube must have been slightly bigger.

The bike, for what it's worth, is a Cannondale Quick with a paired spoke pattern - she is very light.

Simple enough job to ream the rim hole a little, but as you may imagine, none of us were carrying a suitable tool.

Anyone come across this problem before?
 

ANT 666

Trying to re member
Location
N.Wales
How deep are your rims? standerd valves are 38mm long I think, if you rims are deepish the valve stems are not long enough to poke through. longer valve stem tubes are no more expensive lots of places you can get 3 for a tenner, I now always get long ones now as they will fit all my wheels just stick out a bit more on narrow rims.
 
U

User6179

Guest
Never had that but the tubes in my Cannondale were absolutely crap , they were Kenda and the valves detached from the tube , just fell out in the sink while I was looking for a puncture, never seen anything like it before.
 
OP
Pale Rider

Pale Rider

Legendary Member
How deep are your rims? standerd valves are 38mm long I think, if you rims are deepish the valve stems are not long enough to poke through. longer valve stem tubes are no more expensive lots of places you can get 3 for a tenner, I now always get long ones now as they will fit all my wheels just stick out a bit more on narrow rims.
As per my OP, it's not my bike, but the valve on the replacement looked plenty long enough, it was just too wide to push all the way through the hole.

Having said that, I didn't get the chance to compare the lengths of the old and new valves, so the new one may have been a bit shorter.
 
OP
Pale Rider

Pale Rider

Legendary Member
Never had that but the tubes in my Cannondale were absolutely crap , they were Kenda and the valves detached from the tube , just fell out in the sink while I was looking for a puncture, never seen anything like it before.
She's a keen cyclist - Lejog and the like - so I doubt the tube was original.

I don't know the makes of the tubes we were dealing with.
 
U

User6179

Guest
As per my OP, it's not my bike, but the valve on the replacement looked plenty long enough, it was just too wide to push all the way through the hole.

Having said that, I didn't get the chance to compare the lengths of the old and new valves, so the new one may have been a bit shorter.
I wouldn't have thought the cannondale quick would have a deep rim so standard tube should fit .
 
OP
Pale Rider

Pale Rider

Legendary Member
I wouldn't have thought the cannondale quick would have a deep rim so standard tube should fit .
I agree - the spoke pattern is a bit unusual, but the rim looked to be a standard depth.

I've not got all the bits in front of me to check, but I'm fairly certain the problem was the girth of the valve on the new tube.
 
Location
Loch side.
Presta valves are nominally 6mm thick. Valve holes in rims are about 6.3mm.
The clearance is too little for some valves and there is no harm in enlarging the holes in the rim. Go to 6.5mm for the hole in the spoke bed and 7mm for the hole in the tyre bed. Ideally you want the valve collar to lie flat enough in the tyre bed so that it doesn't disturb the tyre's position on the bead.
 

midlife

Guru
sometimes the rubber creeps up the threads and that can stop it seating :sad:

Shaun
 
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