Slime Your Presta Valve Bicycle Tubes




Introduction: Slime Your Presta Valve Bicycle Tubes

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first ...

Puncture vine (tribulus terrestris), also known as goat head thorns (The photo is from Google Images), is a big problem for bicyclists in several parts of the United States and also in a number of other parts of the world. It is certainly a problem in southwestern Idaho where I live. Even if there are no puncture vine plants in your immediate neighborhood, the thorns tend to blow into places where they did not grow. They have a knack for finding your bicycle tires. They are 100 percent effective at causing your tires to go flat.

Step 1: Slime

I have decided a sealant additive is my best choice. I use Slime, which is a brand trademark. My bicycle tubes use Presta valves, which are thinner than the more common Shrader valves found also on all automobile tires. It is easy to remove the valve core from a Shrader valve, add Slime to the tube, and replace the valve core. Presta valves have their broadest part inside the stem so that it is impossible to remove the core from the tube. 

Another Instructable slit the tube with a knife, inserted the Slime through the slit, and added a tire patch. The problem with that approach is that the least amount of Slime on the surface of the tube makes it impossible for a tire patch to stick. This Instructable will show you how to drop the valve core inside the tube and put it back in place after adding Slime to the tube. In the interest of disclosure, this basic procedure is described on the Slime website. I have illustrated it here with some things I learned by experience.

Slime coats the inside of your tire tube as your wheels roll. When there is a leak, the air moving through the leak draws some of the Slime into the hole and tiny shreds of rubber plug the hole. A tube with Slime added can last a very long time after a leak developed and sealed, even at pressures of 100 pounds per square inch.

Step 2: Remove the Nut

Use a pair of pliers to remove the nut from the thin threaded visible portion of the valve. The threads may have been crimped a little to prevent the nut coming off accidentally. Save the nut because you will be putting it back onto this thin stud.

Step 3: Drop the Valve Core Into the Tube

It sounds like the worst thing you could do, but allow the valve core to fall into the tube. Blow on the end of the valve stem a little to inflate the tube enough that the valve core can fall into the tube. If the valve core sticks in the valve stem, push the core out of the stem with a finish nail.

Step 4: Prepare to Pump in the Slime

Be sure to buy Slime designed for bicycles. The shreds of rubber suspended in the green solution are finer than those in Slime for automobile tires or for motorcycle tires. Slime comes with a clear plastic tube for connecting the bottle to the tire valve stem. It is sized for a Shrader valve. Use a brass Shrader to Presta converter. See the yellow text boxes. 

Attach the clear plastic tube to the bottle of Slime. Screw the brass converter onto the stem of the Presta valve tire tube. Connect the clear plastic tube from the Slime bottle to the brass converter. 

Step 5: How Much to Add

My tires are 700mm x 23mm. That is almost 27 inches in diameter and just under 1 inch in width. Four ounces of Slime is about right for my tires. The Slime bottle has markings in four ounce increments. Although difficult to see in the photo, you can see a slight difference in color that indicates where the level is inside the bottle. Squeeze the bottle to pump Slime into the tube. You may need to manipulate the tube to allow the Slime to pass beyond folds and crimps in the tube. You may also need to twist the bottle cap open half of a turn and allow air back into the bottle. When finished, remove the Slime bottle, the clear plastic tube, and the brass converter. Rinse the clear plastic tube so it is free of all Slime residue.

Step 6: Find the Valve Core

The valve core is easy to locate inside the tube. It has probably settled into the lowest part of the tube. Pinch along the length of the tube until you feel the valve core. You may be able to make it fall back toward the valve stem, but then you will need to locate it again. (Second photo) You will need to move it along part of the way "inch worm"-style. (Third photo) This means you pinch the tube against the end of the valve core more distant from the stem. Then pinch and push some of the tube in front of the other end of the valve and grasp the front end of the valve. Release the pinch at the rear. Pinch where the rear of the valve is now.

Step 7: Tip and Push the Valve Into Place

It sounds terribly difficult, but is actually quite easy to tip the thin end of the valve core into the valve stem. Then push it into the stem as far as you can.

Step 8: Put the Nut Back in Place

You will probably need to tap the top of the valve stem to get the core to present its threaded end. You may need to use a knife point to pull it out of the stem. Often I can simply shake and tap on the stem until the end of the core presents itself. Pull the threaded end of the valve out as far as possible. Catch and hold it with a fingernail. Twist the nut back onto the valve core's threaded end. 

If the valve does not seal and hold air pressure, loosen the nut and push a few drops of water into the valve stem to wash away any shreds of rubber that might be blocking the valve. Give the water an assist by pushing and pulling the valve core back and forth in the valve stem. Or, press on the core so a significant amount of air escapes from the tire. That usually blows away whatever kept it from sealing. Then fill the tire with air to the desired pressure.

In my experience, the combination of Slime and a tire tube is not forever. After a couple of years the tubes often develop a slit or another leak that the Slime cannot seal. I do not try to save the Slime in the old tube, but discard both the tube and the Slime. Slime has a limited useful life, anyway.

One morning I was seven miles from home on my 14 mile bicycle route. Some puncture vines had blown their way into the middle of my lane. Normally, I would simply have ridden around them, but there was an oncoming automobile and I went right through the puncture vine. I stopped and picked numerous goat head thorns out of my two tires. My tires looked like a teenager with acne. There were green dots of Slime coming up out of my tires everywhere. But, my tires sealed and I rode home with no flat tires and plenty of tire pressure. I continued to ride on those tubes for quite a long, long time.  



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    72 Discussions

    You have managed to inspire and helped me get some great ideas whenever my tires go flat and I wanna thank you for that. So grateful for sharing these brilliant ideas. Keep sharing!

    1 reply

    Actually, I found this idea in some litersture from Slime.


    8 months ago

    Thanks for the post, it looks like a great idea, I use to ride mainly on the road, so I do not get puncture flats often. Would Slime help me with impact flats? I get plenty because of potholes. Also, how long does Slime lasts before getting dry inside the tube?

    1 reply

    Thank you for looking and for commenting. I have never had an impact flat like you describe. Slime is effective with pinhole leaks. Do potholes cause the tube to tear? Slime would not be effective on a tear. Once I knew how long Slime is supposed to hold up. I am guessing it would still work until one year. I usually had a failure of some kind that required replacing the tube within a year or two, anyway.

    It would probably be a good idea at the beginning on this instructable to point out that a lot of presta valves have a removable inner core which can just be screwed out...

    1 reply

    I did not mention that because I have never seen them, but, I also have not bought any Presta tubes since about 2010.

    There is a much simpler way of doing this.

    Wait until you have your first puncture on that tube.

    Or Create a hole in the tube opposite the valve if you don't want to wait for a puncture.

    Find the puncture hole

    Enlarge the hole to about 3 to 5 mm in diameter using a very sharp knife or scissors.

    Insert the slime into the tube through the enlarged puncture hole in the tube.

    Repair the hole with a patch.

    Pump up tire.

    Ride into the sunset.

    1 reply

    I believe I mentioned I was forced to ride through quite a few goats heads and I had green spots all over my tires where Slime oozed out. If that had been my first punctures, I could never have latched them all and would have had a 7 mile walk back home. But, my tires sealed and I rode home with no inconvenience. Also, in my experience Slime always gets onto the outside of the tire so that a patch will not stick. If it works for you, that is great. It has never worked for me.

    Wow, that thorn looks evil! We have nasty things up here like devils club and the like, but that is more or less stationary. nasty

    4 replies

    I have not lived in Idaho all of my life. When we moved here, flat tires on bicycles were suddenly a problem until we got educated. If you do not have them in your part of Canada, be very happy. And, they are called goat head thorns or goat's head thorns because they do look like a goat's head when viewed at just the right angle.

    The thorn in the picture we would call a "sand burr" in New Mexico. I have pulled a ton of them out of the dogs fur and my shoe laces.

    Puncture vine is known locally as "Goat head" and the dry burrs bust into chunks with two spines each that really do look like a goat's head or a bull's head, which is what we called it in Colorado. The geometry of these is such that one of the two thorns always points straight up when they lay on the pavement.

    Slime and Presta valves: It is worth using on 28mm or larger tires. I find that the slime won't seal the higher pressure needed for narrower tires. It will seal for 50mm or so, then break loose and spray for another 10meters, wash, rinse, repeat. Finally when my glasses have enough slime spots on them I will stop and patch it. I have had good luck with it in 28mm tires run at 80psi, so it might eventually keep the air in a narrow tire after enough air leaks out.

    The slime does make the holes easy to find! Yes, you need to get it all off or the patch won't stick. I carry alcohol wipes in my tool kit for this purpose, and they are also good for cleaning grit out of road rash, and slime and gnat spots off my glasses.

    Awesome - thanks so much! I found that you don't need a presta-schrader valve adapter when doing this. Just skip the connector tube and stick the nozzle of the slime bottle right on the presta valve. It fits perfectly - just just have to tip the connection off occaisionaly as you fill to let some air back into the bottle. If you aren't running tubeless and you live somewhere with goatheads, slime is key. They don't make tubes big enough for my current tire size, so sliming my tubes myself was needed.

    1 reply

    Excellent tip, thank you. I found the first tube a bit "fiddly", but after that, plain sailing.

    This is a really cool idea, thanks. I always heard of removable presta cores, but didn't now they could be pushed "inside". Have you tried this with a lighter sealant such as Stan's? Also, do you feel any difference riding with a much heavier tube (now that it has 4 oz of slime inside?)

    1 reply

    I have not tried it with a lighter sealant. I did not notice any difference in ride quality. I always felt I needed to take extra weight off of myself before I worried about extra weight on the bike.

    I wish it were original with me. The idea actually comes from Slime. I simply thought I would demonstrate it for the benefit of those who had not seen it, and include a couple of perspectives from my own experience.