Dear r/bikewrench,
I recently bought a new pair of wheelset. My problem is that the inner tube of my rear wheels keep getting punctured. This is the third time it happened. When I checked the rim, there was a thin protruding ridge near the midline.
Is this normal? I keep getting longitudinal punctures along the inner side of the inner tube, right where it touches the rim. I have installed rubber rim tape but I keep getting the same puncture.
What can I do?
by ReticuloHaze
16 Comments
Cover the holes with rim tape
Try cloth rim tape – Velox 22mm is what I’d try
Are you using a rim strip? If not use one around the rim to protect the tube. If you don’t have one, make one from an old tube or use a couple wraps of tubeless rim tape.
Where is your rim tape?
If you didn’t remove it to demonstrate the small burr then your wheel is missing an essential component called the “Rim Strip” or “Rim Tape” which covers the drilled spoke holes. Those holes will always cause flats if they are exposed because the tube will rub against the sharp edges during normal operation. All wheels should have a Rim Strip installed on the wheel between the tube and the inside of the rim, they can be made of Nylon, Cotton, or Rubber or flexible water tight membranes (for tubeless set ups) but they are essential.
If there was a rim strip on there and it has just been removed for demonstration purposes it may be worth buying a wider one (They come in multiple widths) or a higher quality one.
https://preview.redd.it/lzewa16osytg1.png?width=1464&format=png&auto=webp&s=3b26b1ed788f0ea18b96bbeede7153686f5b3ed0
Strapping tape works great as rim tape.
So everyone is telling you to put on rim tape but reading your post you already did this and still get tears in the tube.
Obviously keep the rim tape on as it’s neccesary to stop the tube running on the bare rim/holes. You may just need something higher quality or wider as another user suggested.
Is the tear always in the same spot on the rim or is it random? You could try putting two layers of rim tape instead of the usual single layer, might give the tube a bit more protection.
Also double check none of your spokes are loose and they all have spoke nipples, if a spoke or nipple is poking up through the rim then this can cause a tear as even with rim tape it’ll put a small pressure point on the tube which can eventually cause a failure.
Another thing would be to check the rim tape itself, is there any damage to it? That ridge in the rim could be rubbing through the rim tape which then let’s it rub the tube (it’s hard to see how pronounced the ridge is in the picture, just that there is one)
I’ve never heard of or seen rubber rim tape. Use some proper rim tape. I’m not a huge fan of cloth tape (I live in a wet country and it can rot) but I’ve never had an issue with schwalbe, bontrager, whatever. Veloplugs are good too. But don’t overthink it. Any LBS will sort you out.
Do the tire size, tube size, and rim tape all match the rim well and each other? What’s the tube width range compared to the tie width? What’s your install technique? Is there too much friction? Have you tried putting some powder in your tire? Carefully run your fingers gently along the entire edge of the rim, both sides, and use very fine sand paper if you discover anything sharp. use the valve and tire label alignment as landmarks to isolate problem areas in your rim and tire. Count spokes to zero in. check the inside of the tire carefully, as well. How fast are you inflating? What pump type are you using? do you pause at partial pressure to grab and pinch and tweak and carefully seat the tire on the rim bead? Are you running too little pressure? Too much?
[Edit: Just a few things to consider…
If it’s actually a spoke hole causing your flat, try wider rim tape.]
Slit in a tube is usually a snakebite. Means you are running low pressure and the rim and tyre pinched the tube when making contact with the ground.
Check you have sufficient tyre pressure.
Check the inside of your tyre with your fingers. You can go mad over rim tape but thats not going to help if a sliver of metal is sticking through the tyre.
That looks like a snake bite.
What you’re describing – one or two longitudinal holes on the “rim side” of the tube – is called a pinch flat or snake bite flat. Your pressure is too low and during an impact the tire with the tube gets pushed down against the rim. The metal rim then cuts the tube. So, increase your tire pressure or convert your wheels to tubeless (bike shop can help if needed).
Use gorrilla tape.
One other thing you should be aware of is installation – this tube doesn’t look like ‘inadequate rim strip’ in my humble experience, it looks like a folded/pinched tube.
It may have been pinched or wrinkled in the region between the rim and the tire bead, that’s what the dark/light streaks on the tube tell me.
Be diligent on your tube swap techniques – have a bit of air in the tube to ensure it’s round when you put it in the tire, make sure it’s the appropriate diameter for your tire (too big can result in slack/wrinkles that are hard to get out), and before you inflate make sure everything is as smooth and even as it can be. This rim doesn’t have much of a bead-lock groove, so rim tape will help to create a nice smooth landing for the tube, but make sure your install technique is spot on.
If only there was some kind of specialty tape made specifically to prevent that.. 🤔