Changing valve types on a hybrid

trad

I have a Carrera Subway II hybrid. Got my first puncture yesterday.

Can I retro fit new tubes with presta valves as opposed to shraeder valve ones?

Will I run into trouble with the different size valve rim hole? ie punctures at the valve? Tyres are 26X 1.6

manwithaplan

Is this because the prestas are easier to pump on the side of the road?

You can get rubber grommets to take up the extra space. I'm not sure they are strictly necessary - the nut on the valve will be there anyway.

HivemindXX

I've pretty much ignored the valve type when buying tubes and my MTB (26") and Hybrid (700c) have never had any problem.

I was unable to fit a schraeder tube to someone elses hybrid because the hole in the rim was too small. The reverse has never been a problem that I've been aware of.

I'm guessing that you want to use presta for higher pressure or to use a pump that doesn't work with schraeder? If there's another reason I'm interested to know since it might prompt me to go for one type over another.

trad

I had a compact pump with me and it was useless. I have a decent Zefal HP/X pump that I can fit on the bike and a track pump at home. That's what's prompting the change.

Thanks for the info,.

Keep_Her_Lit

trad wrote: »

Can I retro fit new tubes with presta valves as opposed to shraeder valve ones?

[SIZE=-1]Yes but would recommend using the [/SIZE][SIZE=-1]above mentioned[/SIZE][SIZE=-1] adapters.[/SIZE]

Will I run into trouble with the different size valve rim hole? ie punctures at the valve? Tyres are 26X 1.6

[SIZE=-1]I have suffered a couple of punctures of this type in the past, though not since fitting adapters. The punctures happened only when inflating, not while on the move. The risk is greater when inflating with a hand pump, since the valve stem tends to get yanked around more than when using a track pump. The exposed part of the tube around the base of the valve stem rubs against the edge of the larger valve hole and with enough pressure behind it can let go. Not much fun when you're on the side of the road, especially if you're not carrying a spare tube (maybe CO2 cartridges are the way to go, though I haven't used them).

Fit the adapter from the inside of the rim, since this is where the additional support is needed. [/SIZE][SIZE=-1]Since you're using 26" x 1.6" tyres, you may be less prone to this type of problem anyway (I assume you're not whacking them up to 100psi!).[/SIZE]
[SIZE=-1]

[/SIZE]

trad

Anywhere I'd get the adaptors LBS preferably?

I pumped them to 4.5bar before I left for work yesterday which probably dodn't help.

cdaly_

I would screw the valve nut down to the base of the valve before fitting it. That way it's inside the wheel and will take the pumping abuse.

blorg

cdaly_ wrote: »

I would screw the valve nut down to the base of the valve before fitting it. That way it's inside the wheel and will take the pumping abuse.

Don't do this, it causes punctures at the valve as the edge of the valve nut eats into the tube (I have personal experience of this.) Even a very small ridge of any sort on the rim inside will puncture a tube- I have had the edge of a tyre boot do it in only 1 day's cycling.

FWIW, my touring rim (Mavic A719) suits both types of valve and came with the rubber grommet fitted on the outside. I don't know how well it might work on the inside, just saying that is how it comes if you buy a wheel, maybe it is the right place for it. I could see it causing a puncture on the inside if there was a ridge left. I put a bit of electrical tape over the valve hole on the inside to cover the sharp edges. This has reduced the number of punctures I get during inflation (I used to get quite a few.)

trad

I changed both tube last night and decided to fit them normally fitting the lock ring outside the rim. Pumped them fairly hard and are still inflated. I'll take it out later and see how it goes. Thanks for all the input.

Keep_Her_Lit

blorg, I used to insert the adapters from the outside too but decided they weren’t much use there, especially when I saw them wiggling half way out. Granted, the valve stem will still be correctly centred, which is good, but no support is provided at the base of the stem, which I think is more important for puncture protection. I’ve had no problems since inserting them from the inside, since the ridge around the top of the adapter is very shallow (much shallower than a lockring).

The metallic adapter sleeves seem to be designed to be inserted from the inside:
http://www.parktool.com/blog/repair-help/tire-and-inner-tube-replacement
http://wheelsmfg.com/content/view/513/38/

cdaly_

blorg wrote: »

Don't do this, it causes punctures at the valve as the edge of the valve nut eats into the tube (I have personal experience of this.) Even a very small ridge of any sort on the rim inside will puncture a tube- I have had the edge of a tyre boot do it in only 1 day's cycling.

Ooh, interesting. Even the round edged ones?

I did get two friction/chafing punctures this week. These are down to a cut in a gatorskin where the inner edge of the cut is rubbing the tube.