Introduction: Making Your Own Self-sealing Presta Valve Bicycle Tube
Out here, in the desert town of Kalgoorlie, Western Australia, my bicycles and I have one mortal enemy. It is Zygophyllaceae, Caltrop Family - known as puncture vine, goats heads, double gees and sometimes bindi-bindi. There's a photo of these horrible plants here. They are a noxious weed out here, and this year we had more rain than usual so there are lots of them around.
I have two bikes - one is a mountain bike running Sun Rhynolite rims, with presta valves (26" wheels), the other is a flat bar roadie running 28mm 700c tyres. I have had 10 punctures across both the bikes in the 3 months I have been living in town, despite running 'Mr Tuffy's' tyre liners and heavy duty tubes.
I am told that there are only two effective ways to save my sanity by reducing the number of punctures I get - one involves spending $120 on a set of tyres, the other is putting slime in the tubes. Problem with slime is that you can't push it in through a presta valve and tubes with presta valves with removable cores are rare in 28mm or 26" x 2.125 versions.
So I decided to go old school. In this instructable I will show you how to make your current presta valve tubes into self sealing slime tubes with a little bit of surgery.
PS - slime in your tyres will add a noticable amount to the rolling weight of your bike, so it takes some getting used to, but it's worth it in order to prevent those annoying punctures.
Step 1: Find Something to 'push' the Slime Through
As we can't push the slime through the valve of a Presta tube, we need to make a hole in the tube in order to inject the slime. Obviously we want to make this puncture hole as small as possible so that it is easy to patch later.
I used the tip of this pen in order to push slime through the small hole we are about to make in the tube.... you can use anything though, just remember that the slime clots if the hole is too small (it guarantees to self-seal any hole 3mm or smaller in the tube), making it impossible to push any more through, so you need a balance between the ease of patching the hole and having it big enough to actually get the slime in there.
Step 2: Put Your 'funnel' on to the End of the Provided Slime Tube
My pen tip was slightly too wide for the provided slime tube, so I cut the tube a little, and then forced it in.
I used standard sticky tape (cellotape) which was lying around the house to provide a better seal.
Step 3: Puncture the Tube!
This is hard to bring yourself to do, but get a sharp knife and use it to make a hole in the tube just big enough to slip your slime injector nozzle in to.
Step 4: Squirt in the Slime
Carefully insert your slime-nozzle through the hole. Squeeze the bottle gently, and go slowly. Wriggle the nozzle around to ensure that some air gets back into the bottle, allowing you to squeeze in more slime. The slime manufacturers recommend 1/4 of this bottle per tyre (8 oz) but I put a little less in and it's still effective.
Step 5: Clean and Dry the Tube
Wipe the tube with a bit of toilet paper to get rid of any excess or overflowing slime. This is very important because the vulcanising glue does not work so well when there's still slime on the surface.
Step 6: Prepare for Patching
Rough up the surface of the tube with one of those metal things that look like cheese graters - you should be able to find one in any bicycle patch kit.
Then apply the vulcanising glue over an area which is approximately the same size & shape as the patch you are going to use.
Let the glue dry (i.e doesn't feel 'tacky' to the touch)
Step 7: Apply the Patch
Peel the patch from it's foil backing, place it on the patch of glue, and then using a mug or tin or rolling pin, roll back and forth over it very vigourously until the plastic on the surface of the patch gets wrinkly and splits.
Peel off the plastic, and there you have a patched self healing tyre. Make sure that when you are peeling the plastic off the patch that you peel it from the middle of the patch to the edge of the patch - otherwise the edges could stretch up off the tube and affect the quality of the seal.
Now put the tube back in the tyre, the tyre back on the wheel, and make sure that you rotate the wheel straight after inflating it to distribute the slime evenly - it will also seal any small holes that may have triggered this slime-ing tyre surgery in the first place ;)