In which we repair a bicycle tube. 2013-10-03

Hello Everyone,

Tonight, we're going to be repairing bicycle tubes.  Tubes are "fairly" cheap.  But patch kits are a whole lot cheaper.  And it's a great thing to do while watching your favorite youtube videos at night. 

What you'll need is:

1. A bicycle tube with a puncture in it.  (Tears are not something I'd try to fix.)
2. A bike pump, with a head that matches your tube.  (Schrader, presta, etc..)
3. Tube repair kit.  (Not those nasty no glue scabs.. we want this to last.)
4. Something hard and round to burnish (rub) the patch with.  (The back of a caribener, a keyring, the handle of a wrench..)
5. Something flat and heavy.  (A dictionary, your laptop, something like that.)

 So lets dig in! 

Here's my popped tube and patch kit.

To find the hole, I filled the tire, and listened.  If you overfill the tire a little the hole gets bigger, and will show itself.  It's very rare you can straight away find the hole in a deflated tube. 

I'm holding the tube on either side of the puncture.  The contents of the patch kit seem to have exploded on the table.  This is as good of a time as any, allow me to introduce you to the contents of a patch kit. 

Inside the patch kit, you'll find some patches, a tube of glue, and a patch of sandpaper.  Oh, and a set of instructions.  Since you're reading this, you can probably throw out those instructions.  Go ahead, throw them out.  I'll wait. 

Tubes are quite textured on the outside.  There's mold lines everywhere.  Those mold lines are what make patching a tube a "task." That's also why the sandpaper is in the kit.  You use the sandpaper to sand off the ridges and mold marks on the tube.   You need to sand flat the entire area the patch will cover.

Since rubber is stretchy, and wants to get away from you, it can be a bit difficult to sand.  I wrap a little bit of the flat tube around my finger.  I use very light pressure and only sand the "middle" of the area wrapped around my finger.  You'll need to do this a few times, as the size of the patch is a lot larger than your finger. 

There we go, sanded nice and flat.

Now you get to prep the surface.  Prepping the surface is another phrase for "cover it in glue."  So put a small dab of glue down, and spread it around. 

Like that.  The glue needs to be bigger than the size of the patch.  Give it some time to dry. 

While you're waiting for it to dry, get your patch ready.  In this case, I just needed a little dot of a patch. 

Patches are packaged sandwiched between a foil layer, and a celophane layer.  This is to keep them fresh.  Go ahead and peel off the foil layer.

That brown/orange stuff is the stuff that bonds to the rubber cement you used earlier.  It's soft, and pastey.  And quite sticky.  Do not touch it, or let it touch anything but the tube. 

I re-inflated the tube, to verify where the hole in the tube was.  And you'll notice the tube is shiny again, I put a little bit of glue on there again to refresh it.  Now we're ready to apply the patch. 

Make sure it's centered, and put that patch on.  Now we burnish. 

I'm using a plastic caribener to rub the patch against the tube.  This squeezes out air bubbles, and ensures a good bond between the patch and the glue beneath it. 

And that's what a properly done patch looks like.  I leave the cellophane on the patch.  Tubes are happier if they can slide and move, and when you put a patch on a tube, it gets a little stiffer, so I figure the cellophane helps.

Now, here's the bit that I learned from doing motorcycle tube repairs.  Clamping a patch, and leaving it for a few hours (ideally days..) does improve the quality of the patch.  I fold up the tire around the patch a few times, then I stick it under something heavy. 

Oh look, something heavy.  In this case, a UPS battery.

And forget about your tube for a while. 

After a few hours, you can come back and inflate the tube, to check the job you did.  This patch is doing it's job nicely.  I can now stuff this tube back into my seat bag and trust I'll have a good replacement in case I have a flat again.

Thanks for visiting.  And thanks to NegativeK for taking all the pictures.