DnvrFox

I Finally Figured it Out!

That intermittent leak in my rear tire was driving me nuts!

Sometimes it would stay full for days, this morning after topping it off it was down in 2 miles.

In the process of trying to discover the cause, I have:

1. Removed the tube and turned the tire inside out, checking for anythning, feeling inside, using a kleenex, etc.

2. Placed the tube, as full as I could get it, in water - no leak.

3. Placed the pressurized tire on the wheel in a water trough, and turning it slowly, including the valve covered by water - no leak.

I figured it might be an intermittent high pressure leak in the Goop-filled tube, sealing, leaking and resealing. If so, I didn't want to put another tube in without knowing the cause of the leak in the tire.

Ah ha!

This morning, after going out 2 miles and then returning with a very low tire, I messed around a bit with the presta valve. I finally discovered that it was intermittently not seating properly, and I had not been rigorous about really tightening the valve stem screw.

So, I pumped her up one more time, really tightened down the presta valve, and, lo and behold, it held just fine.

As this is a pretty expensive tube, and I think I know the cause, I will not replace the tube at this time. If it continues to lose air, even after tightening the valve, I will.

At least it is not some devious thorn in the tire!

Anyone else have strange, unexplainable flats?

BSLeVan

It's the little victories that can really brighten up a day sometimes. I had a similar experience last summer. Same thing, valve not closing all the way. It drove me nuts for two weeks. I felt like I was being defeated by a stupid bit of rubber, and was not about to let that happen. The glorious feeling of triumph upon finding the cause was quite nice.

Hermes

No...but suggest replacing the tube. Flats and blowouts are always safety issues. The leak is slow...so far.

Jet Travis

+1

Artkansas 

I did several years ago, and it turned out to be the same thing, only in a Schrader valve. The valve was loose.

maddmaxx 

I have had exactly this same problem. It would seem to be more common than assumed. I know that a presta valve that is not screwed in will vibrate and leak air in small bursts.

Jet Travis

My head isn't screwed on straight, and the same thing happens to me all the time.

bkaapcke

This is why I only go with schrader valves. When I bought new wheels, I drilled them out as soon as they arrived. Prestas are just landfill in disguise. bk

Bud Bent

I have a tube on one of my bike's that doing the same thing right now. It's made me more conscious of making sure to tighten the valve well on all my presta tubes.

Digital Gee

We all knew that, but no one wanted to say it out loud.

webist

Good reminder. Thanks.

MarkAJ

Do any of you use Presta value caps? I always have and never have experienced this problem. I am thinking I have to tighten the value down to get the cap on and maybe this is why I don’t see this problem.

tlc20010

Do you actually believe that or is just another curmudgeonly remark? While it is possible to find schrader tubes for road bikes, they are very few and very far between. I think Forte makes a 700x23-28 or some such thing.

Jet Travis

pfft.

Terrierman

Good reminder. Thanks.

lhbernhardt

I've always thought Schraeder valves were for beginners who didn't want to buy the floor pump and only went for rides on weekends and aired their tires at the gas station. When I first started riding back in the 70's, serious riders used presta valves. They are just so much easier to pressurize with a frame pump.

You can make Schraeder tubes easier to pump, but you have to take the valve apart, cut the spring in half, and reassemble it.

At the bike room at work where I keep my bike during the day, I brought in an old Silca floor pump with a presta chuck for use in case I puncture on the way to work, so I can leave work with the tire fully aired. I'm sure I've pissed lots of riders off because most of the bikes in the room have Schraeder valves, and I know guys have tried to pump up these tubes with my floor pump! Har, har...

- L.

zonatandem

We always put the little caps on our closed presta valve. That's what they're for.

mandovoodoo

I would think the caps would be a good thing for protection. I used to leave them off when I rode tubulars. If the tire rolls, the cap keeps it from rolling completely. That's bad - locks up right away instead of allowing the rim to roll a bit so control can be had. Never happened to me, but that's the story anyway!

Mojo Slim

Those little caps add alotta weight, don't they?

SSP

You ride in the Rockies and use heavy Goop-filled tubes???

Having completed 5 week-long tours in Colorado, crossed the Continental Divide 10 times, and ridden to the top of Mt. Evans...I can't imagine dragging all that excess rolling weight up and down those mountains.

FWIW, it's possible the Goop itself caused your problems, by getting into the valve mechanism and preventing it from closing completely.

DnvrFox

I ride where there are oodles and oodles of goatheads (puncture vine). They blow onto the trails and streets. I have had up to 7 at one blow. I do very little "Riding in the Rockies" at this time, mostly I ride on the areas around my home.

I am aware of what the Goop causes and does not cause. I will take my chances with the Goop for less flat tires.

And I am very impressed by your accomplishments!

SSP

Hmmmm...maybe the puncture vine is only in the lowlands. I don't recall having problems with it on my tours (though I do try and lift the bike when walking across unpaved areas).

I really like the riding I've done in Colorado, and I'm even considering moving there someday. I'd like to move to Broomfield, or maybe Colorado Springs (though it may have too many whacky fundamentalists to be a viable place to live).

DnvrFox

Yes, it is a "lowlands" (we are at 6,000 ft) phenomenon. It is very prevalent ON cement trails. You would have to carry your bike continuously.