Bicycle Mechanics - I keep on getting flats... WHY!?

Today I got another flat, the 3rd in as many weeks. Each time there is no indication of where the flat came from, it just happened. We put in air and the tube will not even hold and there is no indication of holes in the tube, no glass etc. I even bought new tires and the problem is still there. It always happens in the last 10% of the ride, but that could be because the road is quite bumpy there. The only thing that gets me thinking is that the rim tape is slightly gone around the valve stem area.

Would not having a little bit of rim tape around the stem be causing the flats? I checked for metal particles, lose spokes, etc and had multiple people look at the rims and they see nothing wrong besides the rim tape problem. I even switched to a long stem tube and the same problem...

Ideas? I am going to the LBS tomarrow for new tape but I am annoyed at the problem.

Have you put the tube under water to see where the hole is?

Pinch flats?

Sounds like you have a prime suspect already. When you check your tube for the hole, don't be afraid to stretch it out a bit. A lot of leak holes are very small and only noticeable when inflated real big and soapy water is applied. IF the holes are in the inner diameter than eureka, youve got rim tape.

Velox.......the chris king of rim tapes

Electrical tape.......the oops-I-got-home-and-forgot-to-buy-any-tape of rim tapes.

I prefer duct tape. :p

Do you have to tug your valve chuck off your valve stems when you put air in your tires or does it "pop" right off without a fight?

Too low an air pressure maybe? I always run at least 40 lbs. and usually 55-60 in front & rear tires. I RARELY have a flat, and yet ride in some unbelievable areas. Check the tube position to the rim position & see if there's a small burr that needs sanded away.

I don't use rim tape.... Oops, I forgot, my wheelset is UST.

Under inflating tire?
Spoke protruding?
Burr on rim or near valve stem hole?
Tube properly installed (not caught under bead)?
Using proper tire tools to install tire (some folks use screwdrivers!)?

Put talcum powder on tube and then install tube and put tire on without using tire tools (builds up thumb muscles!). Then inflate to about 20 lbs. Deflate tire completely then reinflate to recommended pressure listed on the tire.

If the tube doesn't hold air find out where it is leaking. That is generally pretty easy when at home. On the road (or trail) sometimes more difficult. Match that up with the rim or tire and you have found your problem. One other possibility is the rim tape is put on wrong. Some wheels have offset spokes joining the rim. If the tape is not installed properly that could cause a problem that is harder to diagnose. However your post would lead me to believe the wheel has some age on it and the rim tape may have been there a while.

Under inflating tire? --- NO 120 PSI
Spoke protruding? --- NO -- Checked
Burr on rim or near valve stem hole? --- Did not see any -- will recheck
Tube properly installed (not caught under bead)? --- NO --- installed correctly
Using proper tire tools to install tire (some folks use screwdrivers!)? --- Yes using proper tools, speed levers, tire levers, hands.



However your post would lead me to believe the wheel has some age on it and the rim tape may have been there a while.


Actually no, these are race x lite areos, less than 3 months old. Tape looks good, just missing the small section by the valve hole.

The last time I found a small hole (very small) in the tube but it was so small it did not make since that the tube would flat instantly. This time no hole but the tuber would not even inflate... i.e. no air at all would stay in tube. I do not know how long it took to go flat, I was on some rough road at high speed and I felt it go flat.

I just replaced the tires hoping a slightly tougher tire would help reduce flats.I just got to work and I could not fill the tube up to see where the "hole" is if there is one. Usually though if I can fill the tube partly then I can find the hole... no luck this time.

Most of the indicators that you mentioned would be a flat right away, not 65 miles into a ride. I am a little heavy and I wonder if that could be the problem (well 229, 6'6"). Well I am going to buy some new tape tomarrow and check the hole where the valve is to see if it has any shards. I ride fast and when I hit something the result may not be good. Funny thing I do not have this problem with my training rims...

Leaking valve? Try new rim tape also, and maybe some thorn-resistant tape for between the tyre and tube.

If you are getting repeated flats, I think thaat it's important to figure out where they are coming from. You have already checked out most of the likely suspects. Try this:

Before you do anything with the rim tape, examine the rim tape all of the way around. Check every spoke hole. If you can find one where the tape exposes even the tiniest sliver of a hole in the rim, that's your culpret. Ideally rim tape should be wide enough to completely cover the rim from flange to flange, but even Velox doesn't offer enough sizes to fit every rim.

Ok here we go... I went to the LBS and talked with them after they looked at the rim...

The tape sucked... replaced. I brought in 4 flat tubes and we looked at them. 2 were caused by the little area around the stem... the major problem though is pinch flats... here is why.

I ride fast...

yes I weight 6'6" 230 and ride 25 MPH+. If I hit a pot hole at that speed and have all weight on the saddle I get a pinch flat. We traced back the 2 tubes with pinch flats and the problem stemed from my high speeds over rough roads, first one I hit a small pot hole at 28 MPH, the last one was some rough roads at 20 MPH. They recomended that I "take the lane" more often when the sides of the road are crap expecially when the road is that bad. They also recommended a much higher pressure on the tire 130 PSI. That should help the problem.

Ok here we go... I went to the LBS and talked with them after they looked at the rim...

The tape sucked... replaced. I brought in 4 flat tubes and we looked at them. 2 were caused by the little area around the stem... the major problem though is pinch flats... here is why.

I ride fast...

yes I weight 6'6" 230 and ride 25 MPH+. If I hit a pot hole at that speed and have all weight on the saddle I get a pinch flat. We traced back the 2 tubes with pinch flats and the problem stemed from my high speeds over rough roads, first one I hit a small pot hole at 28 MPH, the last one was some rough roads at 20 MPH. They recomended that I "take the lane" more often when the sides of the road are crap expecially when the road is that bad. They also recommended a much higher pressure on the tire 130 PSI. That should help the problem.

If your bike has clearance for it, why not run 25mm or 28mm tires?

Sounds like you are a pretty experienced rider... but I will suggest riding light off the saddle in the bumps and anywhere youthink you may risk a bottom-out or risk a tire trauma. I apologise if you already know this but lots of people have this same issue and noone tells them... better safe than sorry eh?

I am 300lbs and rarely have a flat (I used to as I did not realize floating in the seat was that useful).

I am trying to work on that... usually I just pedal out of the saddle over the nasty stuff, sometimes it is unavoidable... usually at high speeds in and out of pace lines.

I have thought about that, I am running 25's on my trainer. On my road rides and racing I prefer to run the 23's because they seem to handle better. If this does not improve (I am sure it will) then I may have to...

I hate being so big sometimes, the problems usually pop up when I am riding so fast that I lose attention of the ground and what is going on around me... like in a pace line or racing. I will have to pay more attention to the ground as well as around me...

The roads around me SUCK! Full of pot holes and junk... probably like everywhere else.

Another reason to "take the lane!"

I am trying to work on that... usually I just pedal out of the saddle over the nasty stuff, sometimes it is unavoidable... usually at high speeds in and out of pace lines.

I have thought about that, I am running 25's on my trainer. On my road rides and racing I prefer to run the 23's because they seem to handle better. If this does not improve (I am sure it will) then I may have to...

I hate being so big sometimes, the problems usually pop up when I am riding so fast that I lose attention of the ground and what is going on around me... like in a pace line or racing. I will have to pay more attention to the ground as well as around me...

The roads around me SUCK! Full of pot holes and junk... probably like everywhere else.

Another reason to "take the lane!"

i was 6'3'' 220 before i dropped some weight, and I experienced very few problems at high speeds in chicago, AKA pothole, roofing nail, and broken glass central, because i never let my tire pressure drop below 125.

on my old POS schwinn i got like 4 flats in a week and 3 the next. there are these damn thorns where i live but now ive only had 1 flat on my hardrock with specialized enduro tires

I had a pair of AlexRims DA28's, and the drill holes where the spokes were inserted into the rim were not ground down. The burrs cut straight thru the light rim tape that came with the wheels, but the cuts weren't easily seen. Replaced the light rim tape with cloth tape and fixed my multi-puncture problem straight away. I could also have taken to the rim with a dremmel.