ryan.enn

I've owned my Diamondback Trace 3 or 4 years now. Both tires have always had issues with slow leaks meaning that within a few days, my tires would be down to maybe 70% of what they were. I always attributed the slow leaks to having Presta Valves, something I was unfamiliar with until I got my diamondback. However, last week, my front tire was completely flat. I pumped it up, but today my rear tire is completely flat. My bike stays locked in my gated patio so no one is missing with my tires. These are stock tires and wheels.

Can someone help me figure out what is wrong with these tires? Are my tires defective or is deflation just supposed to be expected? I'm not a huge bike rider, I just ride my bike on the weekends and to get to work some times, but I'm going to start hauling around my daughter to day care in the mornings on the bike and I want to make sure I don't run into any issues. Any suggestions would be greatly appreciated.

10 Wheels

Buy some New tubes.

Look for leaks in the old tubes

tyrion

You need to play detective here, find the location of the leak and determine what caused it. It could be something on the rim or something on the tire or a defective tube. Once you find the leak examine the corresponding place on the tire or rim.

Before you take the tire off you might mark where your tire sits on the rim, or remember how the markings (logos) on the tire relate to the valve hole on the rim.

It's usually a tiny rough or sharp spot on the rim, a tiny wire or glass sliver or thorn in the tire. The valve itself is rarely the problem, but the valve stem sometimes is - make sure it stays more or less perpendicular to the rim.

rm -rf

"slow leaks"
You have larger tires, about 40c, 1.5 inches wide. These would be inflated to somewhere around 50 psi to maybe 70 psi. That should take weeks or months to get mostly flat. Even a road bike tire, with 100 psi or more, that needs to be topped off after a few days, will take at least a few weeks to get very soft, and more than a month to get completely flat.

I think the air pressure goes down faster at the beginning, then the rate slows down as the pressure reduces.
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completely flat overnight

Reasons:

1. playing with it. Can your daughter figure out how to unscrew the presta stopper and let the air out?! Who else can get back there?
Since the front was flat just once, and now the back is flat, a puncture seems unlikely!
Each tire has gone completely flat just once, correct? No air at all -- you can use your thumb to press the tread right down to the metal rim? And the tire is okay the next day after reinflating?
Normally, this would be reason number 3...


2. a slow leak from a pinhole. Either from a sliver of glass or a tiny wire from a truck tire belt. These can be very hard to find, buried into the tire tread. The sliver or wire may be still there, and will puncture any replacement tube eventually. I use a combination of using a cotton ball to snag it's fibers on the sharp thing, probing in small cuts, and bending the tire tread.

Pump up the bare tube to double it's width, or even almost triple width. Screw the presta stopper back down.
Most leaks I can find by the hissing sound, or by holding the inflated tube up to my cheek, and feeling the air flow.

But I've had to put an inflated tube into the bathtub, and look for small bubbles forming on the tube. I have to wipe it with my fingers to remove the stray bubbles that form when it's put under water, then see if a bubble re-forms after 5 or 10 seconds (then one more wipe off to verify it). These can be hard to find. Check the valve for bubbles, too.

You really need to locate the hole so you can look at that part of the tire for the sharp thing. So -- just take off one bead and remove the tube. It helps if you can mark the tube with a rotation direction, so when you find the hole, you can hold the tube beside the tire and go that far around from the valve hole. (Otherwise you have to look that far around in both directions.)

If the hole is on the "inside" portion of the tube, there's something on the metal rim, a sharp spot or an uncovered spoke hole.

This is why riders mount the tire with the logo at the valve hole, so when they take the tire off, they know where to line up the tube with tire to locate the section with the sharp thing.


3. a defective valve. I've never seen one. Rare. And very unlikely on both tubes.

ryan.enn

My daughter is only one so she is not the culprit. Yes, they literally went flat to the point I can press the tire to the rim with no air in between overnight. Both times I rode to a park in the morning, checked it the next morning and each one was respectively completely flat. The only odd thing is that I leave adapters on both presta valves at all times so that I can use a more common pump. However, I've had those on there for over a year and only now is the time that they are going completely flat.

So I seem to be reading that slow leaks are normal and acceptable for bikes of this type? I will probably have to take the bike to a bike shop to have them diagnose and then fix whatever is wrong with these tires causing them to go completely flat. Although I am pretty handy and was hoping I could address this myself, I do not want to be taking chances when I'm riding around with my daughter. Thanks all for the suggestions.

rm -rf

~~~~~
EDIT -- It appears the tires only go completely flat once, then are fine. Not a puncture, not a pinch flat.
~~~~~

Oh, just one year old.

Each tire was fine after it went flat and was pumped back up? No significant pressure loss over the next few days?
I don't see how a presta adapter could cause this.

Tubes
Tubes are thin, for lighter weight and improved flexibility. This allows air to diffuse through the tube, just like an inflated balloon goes flat gradually. It's not really a "leak", which is a hole in the tube.

The heavier "thorn proof" tubes are much thicker, and will lose air pressure quite slowly. But the ride isn't as smooth on rough roads.

The bike shop will have difficulty finding out why your tires went flat, since it doesn't happen every day. They'll probably just check the rims and tires, and install new tubes, and see what happens.

~~~

It's a good idea to be able to change your own flats, bringing a small pump, tire levers, and a spare tube along on the ride. Practice it at home, so you know how to take the front wheel off (easy) or the back wheel (a little more complicated). Learn how to remove and replace the tire without pinching the new tube. And how to tighten the axle quick release correctly.

NormanF

If a pinch flat, replace the tube - they're cheap and install Tuffy liners while you're at it to prevent future flats.

Pompiere

Make sure your tubes are the correct size for your tires, i.e. 32mm tube with a 32mm tire. Some people get away with using a size smaller to save a bit of weight. However, it stretches the rubber thinner when you inflate it, making it more prone to flats.

bobwysiwyg

I've run into this. I now carry a pair of tweezers to pull the little burgers out.. assuming I locate them.

mulveyr 

Every tube loses air over time; they're made of rubber after all, and air molecules can penetrate them. It's not a case of "bikes of this type."

Presuming your adapters are for Shraeder valves, it would be best to get rid of them, or at least stick them in a seat bag. It's entirely possible that they're holding the valves open just enough to allow air out--and even if you've had them on for a year, things move around.

You don't need a bike shop for this. Pump up the tires, remove the adapters, make sure the valve is completely closed, and go riding.

Jean_TX

My guess is that leaving the Presta-to-Shrader adapters installed all the time is the problem ... because the Presta valve is not absolutely closed off.

Scooty Puff Jr

I think its just normal air seepage from the tube.

coominya

I have never heard, or experienced such a thing. I run 60 psi in 65 psi rated tires and only have to top them up 2 or 3 psi every 2 weeks.

ryan.enn

Thanks everyone for your responses. I ended up getting new inner tubes at Dick's sports and installed them myself. It wasn't as hard as I thought it would be. Both tires have been holding air perfectly fine since then. The rear inner tube definitely had a hole in it. I could hear it leaking when I pumped up the tire. The front one I'm still not sure what the issue was but as I said the tire has been holding air just fine since I installed the new inner tube.

Cgswss

I guess I'm old but I would just pump the tires up to max pressure and spray the tire with soapy water. Dish soap works good or I use the stuff they make for blowing bubbles (Mr bubble). Leave the cap off and spray a lot around the valve. If you get bubbles from the valve or from the rim around the valve, I would just get a new tube. I wouldn't throw the tube out, I'd just fold it up and put in my saddle bag along with my CO2 inflator. Pretty much the same thing as removing the wheels and putting in water except you don't have to remove the wheels unless you have a bad leak.

My bike has perfectly good 700c x25 and I always pump them up before I ride. I use 110 psi and find I loose about 10 psi per day if I let them set

Scooty Puff Jr

I've never heard anyone experience "only" losing 2 or 3 psi every 2 weeks, that's incredible and very rare. Are you running tubeless tires ? Heck, my car tires lose 1 or 2 psi a month.

jase33

The most common issue I see with tubeless is people are impatient and tend not set them up properly. I run tubeless and lose maybe one psi per month and that's only in one tire, mostly the rear. Of course I spent three days setting up the wheels and most people probably don't do that. Does that make me special??? Please say yes...please!!!

BiciMan

For future reference, this is always a good clue..

coominya

No, and factory tubes too. But the toughroad comes out with 700x50, whereas your DS4 runs 700x38. As you rightly noted, the bigger the tire the longer for a pressure drop. That's just based on volume. Also the lower the pressure run the lower the drop. What pressures do you run?

Oh, add some user error into my calculations too. I pump my tires up with a 12V car pump, and not an expensive one, so the gauge probably isn't all that accurate, but to within 2 or 3 psi I believe.

Scooty Puff Jr

Okay, I see that we're both running different set ups, I have to remember that my "hybrid" is really more of a road bike now. I run 100psi in my 700x28 Schwalabe Marathon Plus' and will lose 5-10 psi in a week, I'm using the stock tubes that came with the bike.

I think your 2-3 psi a week sounds about right with your set-up, but if you're only losing 2-3 a month, thats just awesome.

coominya

Yes that is a road bike, actually I classify mine as a "road" bike. After all, any bike you ride predominantly on the road is that by definition. 100psi and 28mm tires, yes you'd have to pump those up every day nearly if you wanted to maintain an accurate pressure.