5

There is a very small cut 1-2 millimeter or less long in the inner-tube, right next to where it's the bottom of the Schrader valve. The cut is only 1-2 millimeters far away from the valve's bottom.

The hole has a shape of a cut, parallel to the valve's edge, and it's very close, so it's very obvious likely that the valve was part of the reason (the other reason being the valve moved a lot probably because the inner-tube was not inflated.) Air escapes out of the hole so it needs to be repaired.

I don't know if I can put a normal patch, because if the patch's edges detach even only a millimeter from the inner-tube, the hole will no longer will be covered and air will again escape. Any idea? I give my 2 ideas:

  • Take a bike patch and cut a round hole in the middle, and then patch the inner tube with it, as if it were a ring, hugging the valve by all sides.

  • Get some super glue or cement that covers the hole somehow.

  • 2
    Not just only 1-2 millimeters but you are going to get some flex near the valve. Can try a big patch with a hole but most likely you are just going to use up a big patch. Glue alone is not going to fix it. – paparazzo Nov 17 '15 at 16:32
  • If the valves shifts due to under inflation that will happen – paparazzo Nov 17 '15 at 16:47
  • 7
    Honestly unless this question is just about the technical possibilities, just get a new one. The headache won't be worth the five-ten bucks for a new tube. – MikeTheLiar Nov 17 '15 at 22:01
  • 1
    You patch it by tying it into a knot, dropping it in the trash, and buying a new tube. (Note that this sort of damage is usually caused by careless installation of the tube and tire, though riding the tire while flat can also cause it.) – Daniel R Hicks Nov 18 '15 at 0:31
  • 1
    More likely you're going to lose money because the patch will not be applied right / take most of the time. – Batman Nov 18 '15 at 1:11
13

That's a very hard area to patch properly (if its even possible), and I'd recommend putting a new tube in instead of trying to patch it. .

I'd also check that the rim tape on the rim is intact and in good condition, cause otherwise if its busted, you're going to get another cut. Also, as pointed out by ChrisH in the comments, rough edges on the rim hole can also cause this problem (you can use a small file to smooth them out, if that is the case).

  • 2
    Two other things to check as it's so close to the valve: that there are no rough edges on the rim around the valve hole; that you're not using a Presta valve in a Schrader rim without something to protect the tube. – Chris H Nov 17 '15 at 16:34
  • I'll not accept your answer because probably someone knows a way to fix it. Then I'll accept that. – Santropedro Nov 17 '15 at 18:04
6

Get a Dremel (rotary tool) with a cone shaped sander (e.g., the 3/8 in bit shown below). The sander will need to be wider than the diameter of a bicycle Schrader valve stem. You will use this to form a hole in an appropriately sized patch (i.e., a patch larger enough to have sufficient material on all sides of the hole). The hole needs to be the perfect sized so that it just fits snug over the Schrader valve and will take force to move up and down the valve stem. This will be a hard exercise and you may wreck a patch or two. Use a slow sander speed on the Dremel and take your time!

Dremel sanding tool heads

Once you have the appropriate patch, you will need to prepare the tube all away around the Schrader valve (i.e., sand/scuff and patch cement the tube up to the base of the valve stem).

The final step is somewhat tricky as well. Slide the tight fitting patch down the Schrader valve stem until it is just above the prepared area. Make sure the patch is sitting perpendicular to the stem. Take both thumbs and quickly and evenly push the patch down on the prepared area.

Do all your other typical finalizing steps such as massaging the tube and patch to ensure a tight bond.

  • @Criggie - thanks, corrected. I blame the auto-spell check that keeps overriding what I type! No user error here... nope... – Rider_X Nov 17 '15 at 21:10
  • I was capable of understanding this. Still, I have questions, from a non-native english speaker perspective: 1)I don't know what a Dremel is, seems a tool for making holes. I searched here: en.wikipedia.org/wiki/Dremel and it says it's a brand. I don't know what tool do you mean by dremel. I think you mean a rotary tool in general, not only for holes right? Similar to this one: img.alibaba.com/photo/52128656/Hand_Drill.jpg Without the drill bit – Santropedro Nov 17 '15 at 22:31
  • My other question is about the procedure: The patch has to be over the metal base of the stem? Seems to me like no, right? I think it doesn't have to be even touching any metal of the stem, or only barely touching. – Santropedro Nov 17 '15 at 22:44
  • @Santropedro - A Dremel is a brand, it is a variable speed drill that is easy to hold for fine work. It also typically comes with an assortment of specialized tips for sanding and cutting. I added an image of special tool tips that can be used for sanding, that can be used to bore a hole in the patch. – Rider_X Nov 17 '15 at 23:03
  • 1
    @Alexander - keeping garbage out of the landfill is simply an "exercise?" I would disagree, it is the future! – Rider_X Nov 17 '15 at 23:23
5

Based on your description of the cut, it was caused by the rim and the under-inflation.

Check the valve hole in the inside of the rim with your finger. It should be smooth with no sharp edge, and no burl or daggs on the corner. If there are. file or sand or trim them off with whatever tool you have available.

It could be the rim tape was missing or not covering the hole - you may consider replacing that if it doesn't look right.


Now the tube is probably rubbish. However a patch costs a lot less than a new tube so its worth trying to patch.

  • Buff the area on the tube, which means all around the valve stem plus the area of the cut.
  • Use sufficient vulcanising fluid on the tube, and leave it for 5-10 minutes till its cured.
  • I'd suggest you use a paper hole punch to put a round hole through your patch before unpeeling it from the backing paper/foil
  • EDIT Could also use a hot soldering iron to melt/burn a suitable-sized hole in the patch, but this could weaken the patch, ignite the glue or rubber or plastic/paper backings. Could also leave a crispy ring around the hole best to use the hole punch above.
  • It would be handy to have a helper slightly stretch the patch so you enlarge the hole as it goes over the valve.
  • The blunt end of a pencil or a small flathead screwdriver will help as a poking tool to encourage patch into place.
  • Then press and roll the patch on like normal, paying attention to all the edges.

Do not add extra glue to the patch once its in place.

Otherwise its time for a new tube, they're not expensive.

  • Notes: 1)My bike doesn't have rim tape 2) Buffing the area on the inner-tube means cleaning and preparing for the glue, right? Also buffing implies sanding a little bit? (I'm very newbie repairing flat tires) 3) You are saying a mehod similar to my idea "item 1" on the post right? A ring patch? If it's that I understood. – Santropedro Nov 17 '15 at 20:28
  • @Santropedro 1) buy and fit some rim tape. 2) yes, buffing means to lightly abrade the outside of the rubber tube, around the puncture hole. This exposes fresh rubber to the vulcanising fluid, otherwise it doesn't bond properly. 3) Yes a ring patch. Use a hole punch to make a nice clean round hole, don't bother using a drill or scissors or a knife. The worst possible outcome is you've wasted a patch and your time and still have to buy a new tube. – Criggie Nov 17 '15 at 20:42
  • Good answer but this is a lot of work. Realistically what chance do you give the patch? – paparazzo Nov 17 '15 at 21:17
  • @Frisbee I'd give it 1/3 to 1/2 chance of success. But if it works, then the patch should be fine for years. Once a patch takes it tends to be stronger than the rest of the tube. – Criggie Nov 17 '15 at 21:46
  • 1
    And I give 2-3 patches and at best 1/4. At $1 a patch and $8 for a tube the economics are just not there even if you working for free. Still I admire you answer. +1 – paparazzo Nov 17 '15 at 23:38
2

Here's what I would do:

  1. Find a patch that will be large enough to cover the hole
  2. Draw a dot on the patch where the valve stem will be
  3. Tape the patch to a piece of wood
  4. Find a drill bit that is the size of the valve stem
  5. Drill a hole in the patch at the place you marked in step 2
  6. Remove the tape from the patch
  7. Patch the hole as you normally would using rubber cement

This will work as long as there is enough space between the valve stem and the hole for the patch to seal the hole.
If the hole is right at the valve stem then you can try cutting the valve stem off of a similar tube (a used tube that you can't use anymore) and cutting the rubber off of the base of about 1/4th of the valve stem. Create a patch from that with as much rubber as you need to cover the hole and part of the valve stem on your flat inner tube. Applying heat (using a heat gun or some other method) and pressure to patch when it's setting also helps the patch seal so the tube will be good as new.

If the drill is spinning fast enough it will make a hole in the rubber no problem. You could use a soldering iron to make a hole also if you don't mind the smell of burning rubber.

  • 1
    A drill will not work, it will shred the butyl rubber and not make a clean hole. Another option to make a smooth round hole could be a well-applied hot soldering iron, but I'd go with the paper hole punch first. – Criggie Nov 17 '15 at 21:45
  • 1) I don't understand what is taping the patch to a piece of wood. It's only to get fixed to drill the hole, right? 2) The explanation following: "If the hole is right at the valve stem then" I don't understand at all. You need to use another tube, to waste it? Please explain it better. Cutting the valve stem off? I don't get it. – Santropedro Nov 17 '15 at 22:50
  • (@Criggle) Another way of making the hole might be one of those hole punches for making holes in belts. – PJTraill Sep 20 '17 at 17:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.