Presta valve adapter pains.

August 3, 2009 8:06 PM

Is it a bad idea to ride my bicycle with my presta valves unscrewed and having a presta -> schrader valve adapter covering them?

For me, it's a major inconvenience to unscrew the adapter, unscrew the presta valve (the little lock-nut thing), screw back on the adapter, inflate tires, unscrew adapter, tighten presta valve, then - finally - screw back on the adapter. Would it be safe to leave the lock-nut on the valve unscrewed with the adapter protecting the "pin"? (Yes, I could just leave the adapter in a pocket or something, but I'd be more likely to lose it that way.)

Thanks!

posted by 47triple2 to sports, hobbies, & recreation (13 answers total)

The only danger would be accidental deflation, and with the adapter in place, there should be little to no danger of that. But you will be much better off just getting a presta compatible pump.
posted by idiopath at 8:14 PM on August 3, 2009

I have really hard time taking this AskMe seriously.

Like, really? It's that much of a hassle to unscrew your adapter that you're will to risk a flat or clogging your valve with dust and dirt, thus making it unusable?

Why chance it? If you're being consistent about tire pressure, you're pumping your tires up just once a week. A few minutes of hassle, once a week, versus hours of worry when your ridding? It seem really stupid to me.

Why do you even have an adapter? Buy a proper bicycle pump with a presta end. Carry a spare tube and a mini-pump if you're worried about flats on the road.
posted by wfrgms at 8:16 PM on August 3, 2009 [2 favorites]

besides, if you're using a gas station pump, you risk blowing the entire works to smithereens.
posted by klanawa at 8:17 PM on August 3, 2009

Following up on what klanawa said, if you're not using the gas station pumps--and it's true, I've lost inner tubes (and almost soiled myself) that way--then you should have your own pump with you. (You could also go with a CO2 inflation system that uses compressed-gas cartridges to inflate the tires, although you have to buy and carry a cartridge for each inflation.) It's one of those things that you might pooh-pooh as unnecessary until/unless you need it. (Ditto for a simple repair kit--tire levers, patch kit, simple multitool like the Topeak Alien for minor repairs/adjustments, spare tube, maybe even a spare spoke--and a simple first aid kit: a few bandaids, alcohol wipes, maybe some Neosporin for road rashes.)

Plus, of course, if you're in an urban enough area that there are plenty of gas stations around, there's also the possibility of thieves that will pick your bike over for stuff they can remove if they can't lift the bike itself; there go your adapters.
posted by Halloween Jack at 9:17 PM on August 3, 2009

Just screw down the presta valve and keep the adapter there as a highly functional valve cap.
posted by Cold Lurkey at 9:28 PM on August 3, 2009 [1 favorite]

I toured on a bike 1000 miles with a scrader adapter over a presta valve relatively problem free. So, nah, I wouldn't worry about it. You will lose air slowly, over time.

I would check them periodically though, clean them out, and screw them back on tightly (about as often as I would check the tire pressure, anyway).

I had one adapter (on the front tire) and considering all the other repetitious rituals of cycling, ask yourself why this "unscrewing adapter-opening valve-rescrewing adapter-airing up-unscrewing adapter-closing valve-rescrewing adapter" is such a nuisance.

I would definitely carry a spare tube or two though and a pump because when you do get a flat, who knows where you will be? Patching a tire, I've found in my experience, is worthless.

If it really is a problem beyond this, then just get new wheels made for schrader valves.

Or, if it really is a problem beyond this, just take a drill to the rims you already have and bore them fuckers out until a schrader tube will fit.
(Be sure to remove all the burrs and metal filings from the inside of the rim when you're done).
posted by at the crossroads at 9:29 PM on August 3, 2009

I have ridden my bike like this for years and filled my tires from the gas station with no trouble. Just don't overinflate them with an air compressor and you will do OK.
posted by psycho-alchemy at 10:52 PM on August 3, 2009

I finally changed out the Presta valves on my wife's bike. It was too much of a hassle, and, at least for our level of riding, the Schraders are fine. Didn't need to do anything to the rims, to make this work.
posted by Danf at 6:21 AM on August 4, 2009

Buy a proper bike pump. It's worth it.
posted by luckypozzo at 6:27 AM on August 4, 2009

Or, if it really is a problem beyond this, just take a drill to the rims you already have and bore them fuckers out until a schrader tube will fit.

This works, but:

You need to drill cleanly and deburr the hole. You don't want to leave a stress raiser there. Also, a burr could cut the side of a Schrader valve (most presta valves, at this point, are harder metal than the rim.) So, deburring is important. The hole size you need is 21/64". Centering is important, increasing in importance as the rim narrows.

If the rim is less than 1" wide, I would not risk drilling it out. You can find slightly narrower rims with Schrader valve holes, but they were made that way, and may have reinforcements to handle the load around the hole.

Despite the area being under lower stress, the weakest part of a bike rim is the valve hole, and drilling it out makes it weaker. This is fine if done correctly, and if there's enough reserve strength.

Why you wouldn't want to do this:

If you need more than about 60 PSI in the tire, getting them to that with a Schrader valve and a hand pump is hard. Not only are Presta valves smaller, but they take much less force to open, so you're not fighting 100 PSI of back pressure just to open the valve and get air into it. Personally, I find Presta valves much easier to inflate with a hand pump at the side of the road.

If you're running big tires at 30psi, this advantage disappears. As mentioned, be careful of gas station pumps. They're made to infate much larger tires, so they put out a much higher volume of air than a bike pump will. It's easy to quickly run the pressure in the tube high enough to cause failure, this often results in tire failure as well, which means, if you're lucky, you need to boot the tire and replace the tube to get home. Often, it means you walk and buy a new tire and tube.

As to riding with the adapter on. There's probably no problem. The wheel will be a little more unbalanced, but there's enough randomness in bike tires that it won't matter at your speeds. You might leak a little air, but if so, just top up with your frame pump before a ride. The question then becomes which is taking more time?
posted by eriko at 7:10 AM on August 4, 2009 [1 favorite]

hmm, yeah, i do this. seems okay to me, although what wfrgms said about it getting clogged with dirt makes sense.
posted by penchant at 8:01 AM on August 4, 2009

You should use a Schrader valve cover (the little black plastic thing that screws on to the valve) and then you won't have to worry about dirt.
posted by ssg at 9:49 AM on August 4, 2009

Considering a good-quality floor pump with a Presta valve is like $20, why not just get one? If you are riding a road bike with skinny tires, it's probably what you need to ensure that you can easily get to your desired pressure. There is no way I could get my tires to the desired pressure with a frame pump or gas station pump. The frame pump is too hard to get to high pressures (I use CO2 for flats on the road), and the gas station pump injects too much air. Small tires + large volume = blow out.

If you are riding a bike with fat tires, then you have more options. You will still do better with a nice floor pump, though. You'll get the tires to the pressure you desire quickly, accurately, and effortlessly. For $20... it's a cycling essential. (And you won't need adaptors!)
posted by jrockway at 10:55 AM on August 4, 2009