Schrader to Presta Issues ?

[groberts]

In an attempt to improve the road performance of my Trek 830 MTB I've changed the tryres from 26 x 1.90 to 26 x 1.50 Marathons and, in addition, the innner tubes from Schrader to Presta - running at 80 to 100psi. As the Presta valve is narrower than the Presta valve it does not now completely fill the rim hole but is securely bedded down against the rim with the locknut. Can this causue any problems e.g. a point of weakness in the future? There does not appear to be any problem but it just occurred to me that it might be?

[robgul]

You can get small "doughnuts" or grommets that shut the rim hole down to the Presta size - you may find that the pressure of the Presta (without the grommet) may rub the tube around the valve and wear it away (depends on the rim tape and how tight that is to the hole ... and some rim tapes are quite hard and may also worry away at the base of the Presta valve stem.

Rob

PS - have you remembered you either need a different pump - or a Presta to Schrader adaptor!

[meic]

Yes it can cause problems like the valve getting severed from the tube.

It is best to fit special overpriced adaptors made of rubber that sleeve the hole down to size.
Failing that make a little patch out of old inner tube with a hole in and put that on the valve to protect the inner tube where it touches the rim.

There are plenty of people riding around doing just that, including me.

[DaveP]

I'm not trying to be negative here - I'm just curious.
Is it actually necessary to change valve types in order to run higher pressures?
I used to believe that this was the case but then I realised that truck tyres routinely use Schrader valves to hold in 150psi and they can go for a very long time without needing to be topped up. I suppose they could be made to a different standard than the ones you find on bike tubes.

Does anyone know how we ended up with two types of valve in use in the first place?

[Cunobelin]

Buy Schwalbe tubes as the ring has a flange that centres the valve. You can also buy a lon valve and then place the ring on inside the wheel, so that the tube is centred and the valve protected at no extra cost.

[Mick F]

Does anyone know how we ended up with two types of valve in use in the first place?

Three types:
Woods

valvewoo.gif (8.69 KiB) Viewed 2000 times

Presta

valveprc.gif (7.85 KiB) Viewed 2000 times

Schrader

valvesch.gif (7.46 KiB) Viewed 2000 times

Any road up, here's the opposite problem - Presta to Shreader:
viewtopic.php?f=5&t=34488

[Edwards]

I have a bike that is drilled for Schrader and only had a Presta inner tube in stock.
I needed to put the bike on the road so used a metal washer as a temporary solution.
This was until I could get the correct tube for the rim, I now have to change the tube (I bought spares as well).
Personally I would rather use the one designed for the rim.
Schrader will hold high pressures, the down side as told to me by a trusted LBS. Is supposed to be the loss of air when removing the pump.

[Velorum]

Ive had tubes tear at the valve seat running Presta fittings in rims designed for Schrader valves when at high pressure.

I now run Schraders at high pressure - which is not a problem. I have a good quality foot pump with accurate guage for use at home - the only downside is getting hold of a pump to carry on the bike that will reach the required pressure in the event of a puncture- this is where Presta is superior IMO.

[DaveP]

Thanks for the link Mick. CJ's contribution would seem to settle the biggest part of my curiosity!

I did think that the Woods valve was now a historical curiosity. Deservedly so!
When my parents went on cycling trips to and around the Trough of Bowland in the early fifties they used Woods valves. I could tell this from the contents of their puncture repair kits which I found recently!
I had them on my first tricycle. I was the only kid in my class to have pump up tyres and was very proud of them, but the truth was you only had to leave the room for the rubber to perish and let everything down

[Mick F]

Presta has many advantages over Shrader.
Smaller
Lighter
Neater
Easier to pump because you don't have to overcome the spring
Has a smaller hole in the rim = stronger rim
Comes in a variety of lengths for different rims
Easier to deflate for tyre changes
Clamps in the valve hole - best thing is to use a locknut on the inside as well as the outside

[Phil_Lee]

Presta has many advantages over Shrader.
Smaller
Lighter
Neater
Easier to pump because you don't have to overcome the spring
Has a smaller hole in the rim = stronger rim
Comes in a variety of lengths for different rims
Easier to deflate for tyre changes
Clamps in the valve hole - best thing is to use a locknut on the inside as well as the outside

I agree with the first 7, but the 8th is just plain wrong.
All valve types are available with threaded stems, if you really must clamp them to the rim.

The clamping is a great way of disguising tyre creep until the valve rips out of the tube. I prefer to be able to see the characteristic angled valve that shows this is happening before it becomes a problem.
If you do it tight enough to really clamp, you will need to carry an additional tool to deal with punctures.
If you screw the collar down fairly loosely on an inflated tyre it becomes almost immovably tight when the pressure drops after a puncture, but if you only do it up to be hand tight on an uninflated tyre, the collar will be several millimetres clear of the rim once the tyre is inflated.
The best use I have found for those collars is as a locknut for a valve cap, but that's only of use if you get problems with people letting tyres down when the bike (or car, motorcycle, truck, etc.) is parked.
I prefer to avoid threaded valve stems because they chew up the pump chuck, and I never clamp the valve to the rim.

[Mick F]

As much as I don't want to say you are wrong, Phil, it's not my experience.

I remember reading on here about problems of valves being ripped from their tubes, and thinking that I'd never had it. Then it happened to me!

...... So, I used a lockring on the valve before fitting the tube, then another on on the top. I can't say that it's done any of my tubes any harm - yet.

[meic]

Ive had tubes tear at the valve seat running Presta fittings in rims designed for Schrader valves when at high pressure.

I now run Schraders at high pressure - which is not a problem. I have a good quality foot pump with accurate guage for use at home - the only downside is getting hold of a pump to carry on the bike that will reach the required pressure in the event of a puncture- this is where Presta is superior IMO.

I havent had that yet but like many others I have had tubes tear at the valve seat running Presta fittings in Presta rims, there has been a thread on this becoming quite common in recent years.

Although I notice that one of my rims (a Chrina I think) has a presta size hole in the spoke side of the rim and a larger Shraeder size hole in the tube side of the rim's double box.
The worst of both worlds?

[groberts]

Thanks for everone's input - it never ceases to amaze me how such an apparently innocuous item can generate such a variety of responses. I have decided to changed to change to presta for two reasons (i) so they're the same as my other bikes and there is no pump confusion (ii) in my expreience I have found it much more difficult to achieve a good pressure using a hand pump - yes I have a track pump but that's no good once I'm on the road or away for a preriod of time.

If I can find them I'm inclined to try the grommet idea, failing that a piece of old innner tube ref Meic, possibly with an internal locknut (belt and braces style!) - Mick I presume by that you mean an additional threaded collar on the inside and outside of the rim?

Thanks again to everyone.

[Mick F]

- Mick I presume by that you mean an additional threaded collar on the inside and outside of the rim?

When you buy a new tube, it comes with one lockring on the valve.
When I chuck out an old tube, I keep the valve-cap and the lockring, consequently, I have some spare rings.

It's one of these rings I screw right down the valve before fitting the tube. When the tube and tyre are fully inflated, I screw on another ring. The use of two rings holds the valve solidly so when pumping, I'm not straining on the valve/tube interface.