Why do I get so many flat tires?

[PistolSlap]

I have a road bike, and I get flat tires on the rear wheel at least once or twice a week. Sometimes it can happen twice in one day. The problem is, I don't know what is causing it. I have had definitive puncture flats, where I am riding along and everything is fine, then seconds later I am flat, and I usually find a piece of glass or something sticking out of the tube -- but this is not like that.
What happens is I'm fine while I'm riding, but then I'll put the bike away for a few hours and when I come back to it, the tire will be flat. So I have to remove the wheel (which is a pain in the ass on the back wheel) and replace the tube or patch the tire, but before long it happens again. The holes are not ever in similar spots around the circumference of the tire, and are not in the same spot around the circumference of the actual tube (facing outwards/inwards/sidewards, etc).
I have shraeder road tires which say I should fill to 95 psi; I keep them around 90.
I thought it might be a problem with the rim tape and spokes, so I replaced the rim tape so I was certain none of the spokes were poking through, but I still have the problem.

Can anyone give insight as to why I keep getting flats?

(Would it help if I were to switch the front and back tires to see if I still experience the issue on the rear tire only, or if I then experience the issue on the front tire in that case which would suggest the issue is with the wheel itself...?)

[DaveM]

The first question is are the punctures consistently on the rim side of the tube, the tire side of the tube, sidewall, or some combination. If they're coming from the rim side, check for burrs, spokes poking through, etc. Another possibility is pinch flat - usually two small cuts right next to each other on the side of the tube. But it sounds more like you're getting punctures from the road. If so, I recommend a new tire. Old tires will sometimes become very prone to punctures. I assume it has to do with the rubber getting less elastic and easier to cut through. Tires with kevlar or other puncture resistant belts are definitely more tough. The downside is that they are typically a little slower than a high quality, non-belted tire. But I suspect any new, good quality tire will help.

It is somewhat normal for the rear to flat more than the front as it has more weight on it and you probably don't do as good a job avoiding road debris with the rear.

[nfmisso]

In addition to Dave's suggestions, in no particular order:

* tire liners - if the problem is road debris, they will help a great deal; I like Stop Flats 2 liners.
* increase the tire pressure to 95 to 100 psi.
* change to Presta valves, you will need a bushing like this: http://www.amazon.com/Panaracer-Schrader-Presta-Valve-Nut/dp/B001CJZ2M4/
and keep one of these with the bike, one with your pump, and spare:
http://www.amazon.com/Kool-Stop-Brass-Valve-Adaptor/dp/B0017RN34K/
* thorn resistant tubes.
* Kevlar belted tires - definitely. My choice are Kenda Kwest.

I average about one flat a year on my 18 mile round trip commute. Glass is never a problem; the last flat was a 2½" galvanized nail.

[PistolSlap]

Why is it important to switch to Presta valves?

[nfmisso]

Presta valves hold pressure better/longer than Schrader and loose much less pressure when you remove the pump.

[1FJEF]

(07-21-2013, 04:10 AM)PistolSlap Wrote:  The holes are not ever in similar spots around the circumference of the tire, and are not in the same spot around the circumference of the actual tube (facing outwards/inwards/sidewards, etc).

He said there's not a consistent area of puncture.
Presta valves won't fix holes which he says he finds lol.
What bike?
What size rim? Tire?
How much do you weigh? Are you getting one hole, or two when you puncture?

[Warren]

I am getting pinch flats on my rear wheel almost every second time I ride. They occur at different places on the wheel and after going over even small holes in the pavement. I have tried two different new tires and gone to bike shop where rim was examined and new lining put on. Problem continues. What can it be?

[cny-man]

(10-04-2014, 11:25 PM)Warren Wrote:  I am getting pinch flats on my rear wheel almost every second time I ride. They occur at different places on the wheel and after going over even small holes in the pavement. I have tried two different new tires and gone to bike shop where rim was examined and new lining put on. Problem continues. What can it be?

Pinch flats have only two causes:
1. Improper mounting. One would assume that's not the problem if the shop did the mounting and you still had the problem.
2. Impact. Due to riding tires that are not sufficiently inflated or are not properly matched to the rim width, your weight, or riding conditions