Cycling - Way Too Many Flat Tires

[Ratsima]

This on a five-year-old Trek 4300 Mountain Bike:

Over the last six months or so the number of flat tires I've been getting has increased to the point where I no longer want to go out on the bike anymore. Many of these flats are due to leaks in the inner tube about where the valve is. Some of them are just punctures. Currently I'm getting a flat about every 10 to 15 kilometers.

I took the bike to a mountain bike repair shop here in Korat. He sold me two new tires (GEAX Mezcal) with new Schrader valve inner tubes. I had a flat (at the valve) within a week. He then suggested I switch from Schraeder valves to Presta, and sold me two new inner tubes by Hutchinson, imported from France. I had a flat within three or four days - a hole right near the valve. The repair guy has inspected the rim and says he can see no reason why I'd be getting so many flats. (I guess he could have told me I needed a new rim…)

I should note that almost all of my cycling is on paved roads, in and around Korat. I never get a flat on the front tire, only the back. I've tried many brands of inner tube and, as mentioned, both Schrader and Presta valves.

I'm at my wits end. I enjoy my daily cycling, but I can't see taking three or four spare tubes every time I got out.

Any ideas or suggestions?

(I should add that when my bike was in the shop I borrowed my wife's bike. I had a flat after one day. She's not had one in five years.)

Edited June 28, 2010 by Ratsima

[paulfr]

I have a 5 yr old Trek 4300 too.

But I have not riden it in several years.

But the tires go flat too.

That must be very frustrating for you.

So much effort and still no solution.

Maybe a Trek shop in Bangkok can fix it ?

But it is a pain taking so far I know.

Good luck

[Ratsima]

I have a 5 yr old Trek 4300 too.

But I have not riden it in several years.

But the tires go flat too.

The first three or four years I had this bike I had what I considered to be a normal number of flats. But, they were always punctures. And, I always found the culprit: a thorn, a stray piece of wire, a bent nail. The normal stuff you expect.

But now, I'm getting these blasted, unexplained flats that almost always involve the rubber right near the valve stem. I've felt the hole in the rim where the valve stem comes out and it is clean and smooth.

Sabotage?

[el jefe]

I have a 5 yr old Trek 4300 too.

But I have not riden it in several years.

But the tires go flat too.

The first three or four years I had this bike I had what I considered to be a normal number of flats. But, they were always punctures. And, I always found the culprit: a thorn, a stray piece of wire, a bent nail. The normal stuff you expect.

But now, I'm getting these blasted, unexplained flats that almost always involve the rubber right near the valve stem. I've felt the hole in the rim where the valve stem comes out and it is clean and smooth.

Sabotage?

Riding an mtb on the road, you should have almost no flats.

First, you should not use presta valves in rims designed for a schraeder valve. The valve is too small for the hole in the rim. The valve will move slightly when you ride and the friction can cause the tube to fail right at the valve. That would explain the flats with presta valves. It is also possible that you bought a bad batch of tubes with Schraeder tubes if many seem to fail at the valve.

Tires dry out over time causing a higher likelihood of a puncture and it's possible that your original tires suffered from this. But the problem should have ended when you replaced the tire. Your wife's bike may also need to have the tires replaced.

It is possible that you are riding with under-inflated tires. Hitting a bump or a rock will cause a pinch flat. These are differentiated from normal punctures in that the tube will have two small holes right next to each other where the rim compressed against the tire.

You said you checked for remaining glass, thorns, wires, etc in the tire. Are the punctures always in the smae place on the tube? If so, you only have one place to check the rim for damage. And this will allow you to check the tire more closely since you'll only have to check that one spot. Of course, this only works if you always put the tire on with the label at the valve.

HTH.

[TBWG]

I have a 5 yr old Trek 4300 too.

But I have not riden it in several years.

But the tires go flat too.

The first three or four years I had this bike I had what I considered to be a normal number of flats. But, they were always punctures. And, I always found the culprit: a thorn, a stray piece of wire, a bent nail. The normal stuff you expect.

But now, I'm getting these blasted, unexplained flats that almost always involve the rubber right near the valve stem. I've felt the hole in the rim where the valve stem comes out and it is clean and smooth.

Sabotage?

Always the rear. How much do you weigh?

TBWG

[Ratsima]

I weigh 77 kilos.

I always ride with the tires inflated hard. 50-60 psi. I have a gauge.

The punctures are almost always in the same place on the tube: right near where the valve connects to the tube. Sometimes I find a tiny pinhole in that vicinity and sometimes it's a tear. Last night I removed the tire and tube from the rim and checked with a magnifying glass the area of the rim around the hole and the hole itself. There is just nothing there that would cause the punctures. It's smooth. The rim tape is in tact. There are no burrs or anything else that would cause a puncture.

The most recent failure was with a Camel tube that has a threaded valve stem and a nut which secures the valve stem in place. I tried this because I thought the failure might be because of the valve stem moving or being bumped causing stress and a puncture or tear.

[OriginalPoster]

You say that your shop inspected your rims, but did they try changing the rim tape (which is on the inside of the rim and will come into contact with your inner tube when the tire is inflated). You may have a spoke poking though the tape. Just a hunch.

[Ratsima]

The shop did not change the rim tape. I carefully inspected it last night and it is as smooth as a baby's behind. No sign of anything poking through.

[el jefe]

The shop did not change the rim tape. I carefully inspected it last night and it is as smooth as a baby's behind. No sign of anything poking through.

If all of your flats are at the valve hole and you are using a plastic rim strip, replace it with a cloth rim strip. Your plastic strip is vibrating or moving and that slight motion is causing the hole. That's the only possibility left.

[TBWG]

The shop did not change the rim tape. I carefully inspected it last night and it is as smooth as a baby's behind. No sign of anything poking through.

If all of your flats are at the valve hole and you are using a plastic rim strip, replace it with a cloth rim strip. Your plastic strip is vibrating or moving and that slight motion is causing the hole. That's the only possibility left.

I think a new wheel is called for, plus some carbon fibre protecting liners.

TBWG

[el jefe]

One more thing to try:

Take one of the flatted tubes. Cut a piece from it, about 1 inch square. Cut a small hole in the center. Put this piece over the valve of your new tube then install as usual. the extra piece of tube will protect the new tube from any small rough edges on the rim's valve hole.

Please let us know if you ever figure out the problem or what you ended up doing as a solution.

[Ratsima]

Frankly, I've been avoiding riding. Since there's no readily apparent cause, I figure it's a run of bad luck. Sort of like the fact that I've had six nearly new hard drives fail in the last 18 months or so. No explanation, just bad luck.

El Jefe, I like your idea. Next repair will get an extra layer of rubber in the valve area.

[gareth1978]

The flats you're getting aren't just 'bad luck'. I'm a road cyclist (the tires I use puncture easier than MTB tires) and if I get a puncture more than once every 500kms I feel hard done by (I actually get them much less than this). Of course there are times you get 3 in 500kms, but once every 10-15kms is ridiculous. Everything other than the rim tape and rim/wheel itself has been isolated... so it's time to isolate the last two possibilities - start with the rim tape since it's cheap and if worse comes to worst, buy a new wheel. The fact that all your punctures are in the same spot tells us it's not just chance...

Your hard drives dying aren't bad luck, either.

[T_Dog]

I weigh 77 kilos.

I always ride with the tires inflated hard. 50-60 psi. I have a gauge.

The punctures are almost always in the same place on the tube: right near where the valve connects to the tube. Sometimes I find a tiny pinhole in that vicinity and sometimes it's a tear. Last night I removed the tire and tube from the rim and checked with a magnifying glass the area of the rim around the hole and the hole itself. There is just nothing there that would cause the punctures. It's smooth. The rim tape is in tact. There are no burrs or anything else that would cause a puncture.

The most recent failure was with a Camel tube that has a threaded valve stem and a nut which secures the valve stem in place. I tried this because I thought the failure might be because of the valve stem moving or being bumped causing stress and a puncture or tear.

Ratisma, Trying lowering your pressure to about 25-40 PSI if you are using tires in the 195 width area. I've never run pressures as high as yours, but when I was having my failures, it was ALWAYS on a day where I pumped a little extra for a long road ride. Mountain bike tires and tubes need to be run at lower pressures than road tires. I think you might just be exceeding the strength of the tube.

You can run very low pressures on mountain bike tires. When you get too low, you will get a "snake-bite" flat from a root or rock that causes two slits on both sides of the tube from the sudden friction of the tire forcing the tube to rub suddenly. That is a sign you are too low.

[Ratsima]

I'll try lowering the tire pressure.

My wife managed to retrieve the inner tubes for the most recent three failures:

1 - Has a tiny pinhole about 1.5 cm from where the valve meets the rubber. I can find nothing on the rim that would have caused this pinhole. I judged it too close to the valve to attempt a patch. A manufacturing defect?

2 - Has a 5 mm tear at the base of the valve, right where it meets the tube. Maybe something struck the valve causing the tear?

3 - The rubber flange at the base of the tube assembly (which is glued to the tube) has become de-laminated. Another manufacturing defect?

I remain unconvinced that these were caused by something in the rim tape or the rim itself. There's just nothing there…

[mr_hippo]

I've just seen this thread, my thoughts on your problem:-

Could be a manufacturing problem. I had a run with bad tubes - always by the valve.

Old stock or badly stored stock - could be just passed the 'sell by date' and starting to perish.

If you are using knobbly tyres, change to smooth 'city' type. I see that you are using Geax Mezcal which are sold as 'semi-slick' but they are not.

Next time that you change your tyres get 26 x 1.5 as you say most of your riding is on paved roads.

Look at the sidewall and inflate to manufacturers max pressure. Do not lower your pressure as a previous poster suggested for two reasons.

1) Increased likelihood of getting a puncture. Look at it this way - when you have an injection, you are told to relax so that the muscle is not tense and the needle will go in easier. The same thing happens with softer tyres. Also there is more chance of damaging the rims.

2) You will get a smoother ride and use about 30% less energy.

Compared to me, you at 77kgs are just a lightweight. I run my road bike (700 x 23 tyres) at 120 lubs per squinch and my hybrid (700 x 28) at 100 lubs per squinch.

[Ratsima]

Could be a manufacturing problem. I had a run with bad tubes - always by the valve.

Old stock or badly stored stock - could be just passed the 'sell by date' and starting to perish.

I'm glad I'm not alone.

Thanks for your other advice.

[Ratsima]

Another flat today. This on a brand new tube on which I've ridden only about 20K. Looks like yet-another manufacturing defect. The valve became delaminated from the tube.

Here are photos of the last four flats; all of which have happened in the last few weeks:

Delamination

Delamination

Split or tear

Pinhole (on the rim side where the rim tape is in tact and smooth as a baby's bottom). It looks like the pinhole occurred at the tire's seam. Another manufacturing defect? (This was a brand new tube. It's dirty because it sat in the garden a while….)

We've got three different brands of tires here. Two from Thailand, Camel (the delaminations) and Vee Rubber (the pinhole), one from France, Veox (the split). (There was also an imported tube with a Presta valve that failed in the same was as the Veox. I can't find it to photograph.)

I don't really believe in "luck" or anything supernatural, but I'm finding it hard to believe that one person could receive so many defective inner tubes from a variety of manufacturers all in the space of a couple of months.

Please convince me I'm not going nuts.

[Ratsima]

Please? Somebody?

[mr_hippo]

Sorry that I have not replied before now but I have had a friend staying with me at the start of his 6 month South East Asia cycle tour.

Now to get back to your on-going problem. Part of your problem may be technique. How are you replacing your tubes?

Your top three photos look like 'valve creep' where the tube has moved inside the tyre and pulled the valve.

Apologies if you already do this.

Slightly inflate the tube and insert starting at the valve.

Put the free side of the tyre back on the rim and press the tyre on with both hands.

Inflate to about half users pressure and then press firmly on the tyre above the valve to make sure that the valve is properly seated. Do not pull down on the valve. If you are using Prestas with the lock ring, attach it now.

Inflate the tyre to normal pressure and screw up the lock ring.

[Ratsima]

I'm doing what you describe. You have to remember that two of the flats displayed were on tubes installed by a mountain bike repair shop here in Korat.

I don't think it's installation, I think it's manufacturing defect.

I just have hit an unlucky run from four different manufacturers.

[SomchaiCNX]

Mr Hippo 45 psi should be fine for a MTB. (nothing to do with a road bike)

Use a Kenda not Kenda light as they have similar problems.

Many years ago Vittorio inner tubes had the best reputation, however, looks like they took them of the local market for some reasons. (they are made in Thailand)

Same with Continental (made in Thailand) good stuff but difficult to find.

4300 should be double walled bontrager stuff. (with blue/white stickers on it?) Had problems with these rims myself.

Change the rim (Alex double walled) for around 500 baht and use the same spokes to rebuild the wheel, should be around 750 baht in total.

750 :150 = 5 innertubes.

[Ratsima]

Thanks.

[mr_hippo]

Mr Hippo 45 psi should be fine for a MTB. (nothing to do with a road bike)

Change the rim (Alex double walled) for around 500 baht and use the same spokes to rebuild the wheel, should be around 750 baht in total.

750 :150 = 5 innertubes.

My only mention of tyre pressures on a road bikw was when I said to the OP that I am a lot heavier than him and ride thinner tyres at higher pressures.

It is false economy to use the same spokes in a wheel rebuild. I have built as number of wheels in my time and the chap who taught me said hat the spokes are under constant tension and to completely release them and re-tighten them puts undue strain on them and weakens them.

[el jefe]

Another flat today. This on a brand new tube on which I've ridden only about 20K. Looks like yet-another manufacturing defect. The valve became delaminated from the tube.

Here are photos of the last four flats; all of which have happened in the last few weeks:

Delamination

Delamination

Split or tear

Pinhole (on the rim side where the rim tape is in tact and smooth as a baby's bottom). It looks like the pinhole occurred at the tire's seam. Another manufacturing defect? (This was a brand new tube. It's dirty because it sat in the garden a while….)

We've got three different brands of tires here. Two from Thailand, Camel (the delaminations) and Vee Rubber (the pinhole), one from France, Veox (the split). (There was also an imported tube with a Presta valve that failed in the same was as the Veox. I can't find it to photograph.)

I don't really believe in "luck" or anything supernatural, but I'm finding it hard to believe that one person could receive so many defective inner tubes from a variety of manufacturers all in the space of a couple of months.

Please convince me I'm not going nuts.

The 3rd photo looks like it could be a defect. The others, probably not. I still say the problem is the rim or the rim strip. I only use cloth rim tape. Never have a problem with flats from the inside. Other than that, I have no other suggestions.

[T_Dog]

Ratisma, Could you take a photo of the rim where the valve goes through from the inside? Maybe some of us could see something there. From your photos, it sure does look like something is causing stress there. Sometimes narrow rims do not allow the valve stem to seat completely putting a lot of stress in that area.

[473geo]

Do you frequently brake hard on the rear wheel? This could also be causing the tyre and tube to slip on the rim.

I use an 'Armadillo' crossroads tyre in the UK - FYI the tyre pressure is a minimum 75 psi - max 100 psi, the milage I cover means the tyre walls weaken badly if the pressure is not right up there.

I had the same problem as you and came up with one of the suggestions above using a chunk of old tube around the valve hole. Unfortunately for you the 'spare' wheel I put on (which I expected to last a couple of weeks before the bearings and housing disintegrated) has lasted a couple of moths, so I cannot update on the repair job!!! rest assured I will be back to this thread one way or the other when I do fit the 'rogue' wheel!!

I have also, as suggested a while ago on another thread, started lining the tyre with an old tube,(and you now have a few of them!!!) I think this may assist the 'grip' of the inflated tube by applying more pressure to the walls and also help prevent punctures.

[Ratsima]

It's been a few days with no flats now. When I do get another, I'll take some closeups of the inside of the rim. As I've noted, it feels very smooth.

If the tube were slipping on the rim, wouldn't I notice the valve been displaced one way or another. I've always observed that the valves remain perpendicular to tangent of the rim. (There must be a word for that….)

On photos one and two, posted above, it's beyond me how stress could cause the valve assembly to delaminate from the tube; especially since these tubes have threaded valves which hold tube tight agains the rim. What could move?

In any event, thanks for all the suggestions.

Maybe it's just time for a new bike!

[473geo]

If the valve is tight to the rim so cannot move, and the tyre and tube slip, there is stress at the base of the valve where your tube is getting the tear, perhaps aided by a weak join.

If the rest of the bike is ok why not try a new wheel........you can always get a spare wheel carrier attached, never had one myself but have seen them in action.

[el jefe]

It's been a few days with no flats now. When I do get another, I'll take some closeups of the inside of the rim. As I've noted, it feels very smooth.

If the tube were slipping on the rim, wouldn't I notice the valve been displaced one way or another. I've always observed that the valves remain perpendicular to tangent of the rim. (There must be a word for that….)

On photos one and two, posted above, it's beyond me how stress could cause the valve assembly to delaminate from the tube; especially since these tubes have threaded valves which hold tube tight agains the rim. What could move?

In any event, thanks for all the suggestions.

Maybe it's just time for a new bike!

It's always time for a new bike!

If the valve remains perpendicular and you're inflating to a proper pressure, then slippage or improper installation is not the issue. It's also unlikely that you have defective tubes from more than one manufacturer. I still say the only answer is the rim strip or the inside of the rim. Or ghosts.