Workshop tales, trials and disasters.
Maintenance tips, techniques and myths.
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20 posts • Page 1 of 1
A query, what is the advantage of a schrader valve over a presta valve. It appears most road bike tubes use presta valves whilst most everything else is schrader
Just wondering why. It did mean I had to go and buy a new stand pump to get Cecil tyre upwards of 100 psi as hand pump for MTB did not suit (not complaining though as it is a good solid pump and at $80 it wants to be)
I've been running Schraeder on my bikes right up until two days ago (new wheels), but I've been using 22mm MTB rims for all that time. With today's good materials technology, I don't think we need to worry about rim strength on anything except the thinnest rims running the highest of pressures.
Schraeder valves let you insert sealant by removing the valve core.
There's a screw on adaptor to let you use Schraeder pumps Che.
Both my bikes run Presta for whatever reason.
...whatever the road rules, self-preservation is the absolute priority for a cyclist when mixing it with motorised traffic.
London Boy 29/12/2011
IMHO, comparing similar tubes, not much, except Presta drilled rims are incompatible with Schrader valves, won't fit the hole, but Schrader drilled rims theoretically can fit either valve, therefore are handy if you're running short on spares. Some people worry (especially at higher pressures) that using Presta in the larger Schrader holes, the gap may pinch/cut the tube, or allow tube to bulge outwards.
Other advantage of Schrader is you can pump them at any servo, or someone with a compressor, without needing a Schrader-Presta adapter, but that's not recommended anyway. Unless you're stuck without support and/or pump in a no-LBS town or something.
Again, we need to look at history to find the answer to why the Car valve/Schrader valve even exists in bicycles at all .
Not so long ago, there were only two kinds of bicycle valves in use. The Woods/Dunlop/Bicycle valve & the Presta/French valve. The Presta was used in High Pressure tyres as it had the ability to seal at high pressure & could be mechanically locked there. It was a good reliable design.
The Woods valve was used for everything else, but the simple one way valve technology that was mainly in use began to get unreliable at pressures much above the rated pressure on the sidewall of your average Roadster tyre [Inflate hard]
Even my lovely whitewall racing tyres, the Dunlop Speed in 28x1-1/4x1-3/8 [a narrow low pressure race tyre of 1-1/4" size but to fit the 28x1-3/8" rim] are pressure rated at 'Inflate Hard'
Don't laugh, Goulburn to Sydney races have been run & won on these.
Anyway, enter the lazy cyclist of the 80's bike boom who wanted to pump up his tyres at the local service station. Firstly, the car nozzle wouldn't fit the small diameter of the Woods valve & secondly, if you used a displaced Schrader tubeless valve stem as an adaptor, the high pressure of the service station air supply often blew the surgical tubing of the Woods valve apart as it was not designed for this level of pressure or volume.
Eventually some bright spark decided that the 'car valve' [often pronounced 'Shrarder' back then] could be made to fit through the same hole as the Woods valve & tubes that were Schrader equipped started to some into the market, steadily replacing the Woods, but it took some years before old stocks of the Woods valve equipped tubes were pretty much exhausted & the Schrader valve was all that was available. This wasn't until the 90's people, hardly the day before yesterday in the big picture.
So there's your answer. Presta for high pressure, & Schrader, which replaced the Woods, for low pressure. Yes, I know that Schrader can handle high pressure, but it was used initially as a 'replacement' for the low pressure Woods valve.
This picture [from another thread] illustrates the simple, low cost, environmentally friendly construction of the original Woods valve design.
If you have ever bought a puncture repair outfit that had two short lengths of surgical tubing in there, ..... well this is what it was for.
Carbine & SJH cycles, & Quicksilver BMX
Now that's AUSTRALIAN to the core.
I have Presta on one of my 26" wheelsets - the one with the skinny road slicks.
They definitely hold their pressure better at 60 to 80+ psi than the Schrader valved set I had the tyres on previously.
At the 30 to 40 psi I tend to run my 2.1" Velociraptor's at on Mr Hyde, the Schrader's seem fine.
Interestingly, I run Mr Hyde's rear shocker at 220 psi and never have to top up the pressure by more than the 10 psi I lose from filling up the shock pump hose when I connect. It has a Schrader valve. Go figure.
Last edited by Hawkeye on Tue Jan 08, 2008 10:00 pm, edited 1 time in total.
Or is it a case of the presta valve tubes you've used are better quality than the schraeder valved set
Not trying to be controversial, but there are two aspects to keeping the air in.
I use both and have developed no preferences at all as a result
I had a good bike ... so I fixed it
Only 2 aspects?
- Tube thickness when inflated
- Tube porosity when inflated
- CO2 or air used to pump tyre up
- quality of valve construction
- volume of gas contained in inflated tyre
- pressure of gas in inflated tyre
Oh, sure, that's entirely possible. The Shrader inner tubes were Innova ones I got in a 10-pack from T7, and the Presta ones I now use are Ritchey.
I do find it interesting though that high-pressure road tyres (ie, 19-23mm slicks that you would run at 110-130 psi) all seem to have Presta valves. I'm sure they probably exist somewhere, but I've never seen quality roadie rim or tubes with Schrader valves. But, that said, my shocker on the Jekyll runs at a much higher pessure than any road tyre and it has a Schrader valve as noted.
My suspicion is that air shockers and forks use Schrader valves because they're internal to the valve tube and without any parts exposed to little accidents that would result in bits being broken off. Damage to a shock like that would be a lot more expensive to fix than the loss of throwing away a damaged Presta tube.
Perhaps there are Schrader valves and Schrader valves.
The thing I always hated about the Schrader valve was getting the modern pumps on 1 when flat as the valve just got pushed into the rim. Yes, I know just push the other side from the outside of the tyre but we are trying to keep our hands clean here aren't we. I think I might put a couple of those citrus wipes in my saddle bag... I love the valve lock nut on most presta tubes, makes things easier.
On the subject of keeping clean and tubes;
Bontrager 700C x 18/25 spare tubes come in shrink wrapped plastic, much nicer for when I wear my white jersey , easier to put in a saddle bag too
The older I get, the better I was...
I loved the idea the first time I heard it, so I started shrink-wrapping my tubes myself (I own a shrink wrap machine ....)
I have used both and each have their place.
For road bikes, where you need higher pressures (for less rolling resistance = greater speeds), I find that the presta valves keep the tyres inflated at high pressures for longer. I've tried it with schraders and they tend to go flat after a day or two.
Schraders are more readily available (k-mart, big W etc) and is a more convenient and reletively cheaper alternative. I use them on my MTB especially when I go off roading and there are greater chances of getting flats. You don't need to pump them up too high either which easier on the arms when you only have a hand pump with you.
With reference to pumping the tyres up at the servos, I've found that they can only go up to 65psi (especially the newer digital ones).
It's the Vibe, It's the Constitution, It's Mabo...it's all that...
There must be different grades of valves out there. Throughout most of last year, I used slicks on my MTB wheels (either on the 'bent or the MTB) for commuting. The pressure I kept in those tyres was 100 psi. I would check them each week (sometimes forgetting for up to three weeks) and rarely were the pressures less than 90 psi. In my experience, the shrader valves maintained their pressure very well, but I don't know whether the (minimal) loss of air was due to valve leakage or simple porosity of the tubes.
However, the air shocks on my forks never varied from 105 psi, and they use a shrader valve in a much smaller chamber ..... Mr888, are you sure the valves caused the loss of air and not the quality of the rubber in the tubes holding those valves?)
Last edited by Kalgrm on Fri Jan 11, 2008 10:58 pm, edited 1 time in total.
worth pointing out that the 'digital' ones are hard coded to only allow certain pressures - i regularly pumped my MTB tyres up to 50-60psi with them, but they'd not go over 60, on that model.
If the digital ones allowed the pressure to be raised more, the only limitation would be on the air compressor driving the system - what you see is just a oversized pressure gauge that has been bolted to the ground
It could be either but my statement was based on what I've experienced. ie. 100% of the time that I rode a bike that had a schrader valved tyre and pumped to high pressures, it went flat after a day or two. On a road bike, 80-90psi in my opinion is getting flat. You can see the tyre squish down as soon as you sit on the bike. In essense the ordinary schrader type tube weren't designed to be used in high pressure situations IMO.
Having said that, there are now a range of high pressure schrader valved tubes (available from T7). It looks like I'm not the only one that faced this problem as there was an obvious need for such a product.
I suspect that the tubes I've used in the past (and speculate that the mojority has also) were of poor quality. It seems that you've been buying better quality tube Graeme. I also suspect that your shock was designed to withstand high pressure so the valve quality would be a better (is it welded onto the shock or glued on a piece of flimsy rubber like the tubes?).
It's the Vibe, It's the Constitution, It's Mabo...it's all that...
I meant to mention in my post about the shock on my Jekyll that the pressure there is 220psi. Like Kalgrm's forks, it too never varies, and sometimes it is several weeks between rides. This with a Schrader valve.
I'm impressed, not just with the valve but with the sealing of the shock air chamber over the shock shaft as it absorbs the beating I sometimes give it. No mean feat.
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