weird: getting pinch flats when commuting
 

Now that the weather has warmed up I'm doing my 10 mile roundtrip commute 3 to 4 days a week and loving it. I'm getting a series of flat tires (same as in the past, this happened last season too) that is getting increasingly frustrating. I'm riding an old Diamondback Apex with 26"x1.75" Conti TravelContacts. I inflate the tires to the published max of 80psi before every ride. My tubes are either Bontrager or Kenda.

Here's the kind of flat I'm getting about 2 times per week:

- always on the rear tire
- always on the rim side of the tube, not the road side or sidewall
- the hole (actually a slit) is always about 1/8" long or a little less
- the hole is always in a different location on the tube
- sometimes I will arrive at work or home OK, only to find the rear tire flat when I go back to the bike hours later

So apparently I'm getting some kind of pinch flat. I've checked the rim & found no burr or other thing that would obviously cause a hole; the rim is nice & smooth. The rim tape is rubber and seems to be in good shape.

Now I am a heavy rider. Wearing my jersey, shorts, shoes & helmet I weight about 235lbs and additionally I have another 5-8lbs of clothes & food on board. But heck, people bike around the world with 80lbs of gear on their bike and do fine. I make an effort to avoid running over anything obvious on the road, and when riding over unavoidable edges of pavement and such I take care to slow a bit & move some of my weight forward to take some load off the rear tire.

So what are my options? Is there a heavier duty rim tape or rim liner (not tire liner) on the market? How about tougher tubes? Or do I have to get my wheels rebuilt with a different rim type?

I wonder if running a bit under the max tire pressure would help at all? Say, 70 psi?

Your rim tape can't handle the high pressure. Get some quality cloth rim tape and you'll be fine.

If your having pinch flats, that means you're bottoming out the tire. The solution to that is more pressure, not less. However, if you are near or at the recommended max pressure of your tire, then maybe a new tire is in store.

That happened to me for a little while. I figured out that I was (barely) catching the tube under the tire bead as I re-set the tire on the rim. I found out that I'm less likely to do this if I give the tube a bit of shape by giving it a single pump of air before putting it in the tire.

Sounds like a rim tape failure to me. Is it just one hole or sometimes two? One hole is a pinch flat on one side OR a rim tape failure. two holes is a pinch flat.

It's possible that your air gauge is faulty and reading high. Consider checking your tire with another gauge to eliminate that possibility.

Let us know when you figure it out.

+1 Money post. High tire pressures + Non gazelle rider = nice thick cloth rim tape.

It is just 1 hole.

I emailed this post to a local guy who is a longtime bicycling coach & expert. He said:

"Rubber rim tape is not reliable! Replace it with Cloth Velox tape or plastic Ritchey tape. I can almost promise that this will stop the flats."

So I'm going to look for replacement rim tape at the LBS.

did you ride for a long time with no flats, and are now getting them one after another?

If so, also pay attention to what DallasSoxFan posted regarding pinching the tube.

When I replace a tube, before I inflate the tube I always go around the rim on each side pushing the tire wall inwards until I can see the bead all the way around for each side, making sure there's no tube showing. Because if there is any tube showing when you do that, the tube will be pinched between the tire and rim when you pump it up.

Yeah, rubber rim tape is what cheap chinese bike makers use so they can get away with 3 cent rim tapes instead of spending the whole dime. It's only really good to get you out the door on a cheap bike.

No this has been an ongoing problem with this bike.

I'm surprised that the manufacturer used the crappy rim tape. Everything else on the bike is good to go (for a 1993 bike). I'm just glad that it looks like the rim tape fix will be simple.

Dont use your tire levers to install your tires and get new cloth rim tape.

You need to think larger numbers. If a manufacturer saves $0.25 centes per bike on rim tape and they sell 100,000 bikes, they've made themselves $25k

I picked up some snap-on rim tape made by Specialized at a LBS today. Heavy rain is predicted for tomorrow so I'll ride on the new setup starting Friday and I'll update the thread after a few weeks.

Thanks to everyone for your fast & informative responses. It was very helpful.

Last night I installed the new snap-on rim tapes. The rear wheel (the problem wheel) had the skinny, soft, crappy rubber tape. But the front wheel had a Velox cloth tape on it. Weird.

Man those spoke holes in the wheel have sharp edges; no wonder I was cutting the tube every week.

Almost 3 weeks later and no flats. Woo hoo!

Velox tape is great stuff. Of course, you have to read this to appreciate it fully.

I'm going to posit another theory. You have a chunk of glass or tiny wire that embedded in the rubber, and then wormed its way past the flat protection of your tire. The kevlar and ceramic anti-flat layers of modern city and touring tires are great against sharp punctures, but rotten against abrasion. The sharp thingy didn't pierce your tire, it rubbed its way through, and is now poking into your tube. This is why it's in a different spot every time: you put on the tire at a different starting point at every time. If it was rim-tape failure, or another problem with the spoke or wheel, it would be in the same spot every time, as the tube has to go in the same spot every time due to the stem.

Take a cotton ball, and rub it lightly along the inside of your tire... when it snags, ever so gently, you've found the culprit. You may need to bend the tire a bit to simulate being under load. If it's glass, find the teeeny little hole on the outside of the tire, and work at it with tweezers or the sharp little metal awl on a Swiss Army knife, and be surprised as a big ol' piece of glass pops out. If it's metal, work at it from the inside: you won't be able to find where it went into the rubber, as it's probably a piece of one of those sharp little wires from a car tire carcass, and the hole will be too hard to see.

Hard to see how that is the problem when the slit punctures are on the rim side of the tube along the spoke hole line, not the tire side of the tube.

Still no flats. Good to go!