I’ve been trying to get a puncture in my bicycle tires for over two years now. So far, I’ve failed miserably.
Background History
I’ve been a bicycle rider since I was a kid, but I didn’t get serious until I got a job in a midsized town at the ripe old age of 21. Work was not within walking distance. I didn’t want to buy a car to commute to work and I held off buying one until I was in my mid-twenties. That really helped my bank account, and I got lots of exercise. The local weather was generally fair and rain free, so I had many days where cycling was a joy. I mostly stayed on blacktop roads and simple daily chores like grocery shopping could be mostly managed on the bike. Even after I bought my dad’s old car, I would choose to ride my 10-speed bike over driving.
I did have trouble with a nasty invasive plant that produced steel hard seeds that had spikes worthy of a caltrop. The seeds abounded in many grassed areas. The local bike shop sold a thick flexible plastic insert for the tires that solved the problem.
Fast forward 50 odd years. I still ride when the streets are dry, and the temperature is 28°F or above. I moved to a different town and situation seeking employment and bought a house within a ridable distance to work. I had a recumbent (a bike you ride reclined) for years and then a 29er (a bicycle with 29” diameter wheels.) I had no problems with punctures causing flat tires. I only had to replace tires as they wore out.
Then, I remarried after my wife passed. My new wife and I both sold both our houses and bought a house in the woods eight miles from work. I still wanted to ride as much as possible and my solution was a fat tire e-bike. I reasoned that the fat tires would be great, as the roads were not. It didn’t hurt that the bike was stable on dirt and gravel roads. They make useful shortcuts at times. The pedal assist meant I could get to work in about 30 minutes. I have a second battery for longer distance rides.
Unfortunately, our town is growing markedly and there are a lot of building projects under construction. This creates trash that needs to be dumped. Stuff falls off the contractors’ dump trailers, lands on the roads, and generally winds up in the bike paths where I ride.
So, with wide tires on the bike and a plethora of nails, screws and steel slivers, I got punctured tires and tubes. At three to four punctures a year, and at $60 a tube repair, things added up ($180-$240.) Yes, I could have put in a new tube myself, but I didn’t mind supporting the bike shop until this went on for 5 years. It’s also a tad embarrassing (and oh, so helpful, mind you) to have a local community police officer deliver you and the bike home, or the bike shop van come to take your bike. Again. And again.
I thought there must be a solution to this irritating dilemma. The shop technician sprayed in a flat tire sealant. That failed. The shop suggested heavy-duty liners like I used on my old 10-speed bikes. They failed. They suggested an expensive tire insert that acted somewhat like a run flat tire in a car. They failed, although I did leave them in the tires.
Research
Now I have had a lot of experience using the internet as a research tool. I had a vague recollection of a solution I had come across that was sold in the UK. After trying multiple search criteria, I came up with Kevlar® bike tire liners. Bingo! They made them, but at the time, they were for smaller width bike tires.
My thought was that I could make my own.
I measured the circumference of my fat tires with a tape measure and cross-checked with a diameter times π calculation. I would need that measurement to buy material, although it’s sold by the yard. The road contact surface of the tire was 4” wide. That would determine the width of the liner strip.
Kevlar® was invented by Stephanie Kwolek in the mid 1960s while working for Dupont. She was looking for a material to replace steel belts in automobile tires (Source: Wikipedia.) Most folks know Kevlar® as the material many projectile resistant products are made from. It has many other industrial uses which I won’t go into.
I called DuPont, and they told me they didn’t make the Kevlar® cloth. They make the fiber. They gave me the names of several companies that sold the cloth. After a few misses, I contacted a company that had what I needed. I explained the problem I was having, and they were willing to sell me the cloth. (In researching this article, I contacted a different company and they, too, would sell me the cloth by the yard.) The salesperson then asked what type I wanted. It turns out you can buy what they described as either bullet proof or knife proof. The knife proof is a tighter weave, and it comes in a 58” widths. Jackpot! What is a nail but a tiny little stiletto.
There are several names for the cloth as well as technical designations. If you are going to make liners as I did, locate an online supplier and ask for the tighter weave cloth.
I ordered the knife-proof variety of Kevlar®, and a pair of Clauss® Kevlar® shears. (Sorry if the ® is getting a little ®edundant, but it’s ®equired.) The shears are serrated to cut this specific product. You can buy electric shears to make the job faster if you are contemplating making a lot of tire liners.
Testing Unfamiliar Materials
When the cloth arrived, it was a pleasant-looking soft canary yellow but was decidedly slippery stuff. I cut off two small rectangles to do a glue test. I used a contact rubber adhesive that I use in leather work to make holsters. It wouldn’t stick and just peeled off. More research was needed. I called my leather supplier, and they said there was a specific contact adhesive made by Barge for nylon called BargeSuperStik cement. I ordered a 32-oz can.
When it arrived, I took the two test pieces and smeared the glue on. It has a gelatinous, transparent consistency but there was no brush in the can. I found a disposable brush in my house painting box and brushed the glue on one side of each piece. I would recommend using disposable gloves. I did, as any liquid glue is messy. After letting it dry for a few minutes I pressed the two pieces together using a wallpaper seam roller and held them up. I tried to peel them apart and they just would not stick. I also remembered they dried quickly, well short of the 15-20 minutes I usually allow for the rubber cement I used for leather. Was that the problem?
I called Barge’s technical support. They told me what happened was normal. To stick the pieces, I had to use a heat source on the dried glue for about 30 seconds, and then you press the glued sides together. A paint stripper or a hairdryer were suggested. You can even glue the project on one day and heat activate the glue on the next day. I opted for a hairdryer as I have a scar on my wrist from an oops with my heat gun. Warning: heat guns are dangerous, and my scar never tans. It worked and it stuck together rock solid.
With the experimentation done, I moved to prototyping.
Disclosure: Being more Efficient
I should have opted for a longer piece of Kevlar® that would completely go around the circumference of my tires. It would have made construction of the liners easier. I bought a piece that was shorter than the circumference of the tire figuring I would save a few bucks by attaching two pieces together to make a longer piece for the outer layer of the liner. I cut the strips needed and had the two pieces sewn together to make the 98” strips to fully line the tire and overlap itself a bit to get maximum coverage/protection.
The instructions below are for a nine-foot-long piece of Kevlar® cloth, 58” wide. My current contact for the cloth explained they also sell strips in narrow widths. Since you can only buy it by the yard, I would need a piece of the cloth three yards long to replicate my prototype efficiently.
Assembly Instructions
I pulled out two card tables, setting them up in the garage, so I could lay out the cloth to mark up and then cut it. A long picnic table would work well.
I would cut 6” wide strips to go across the width of the tire where it contacted the road as well as protecting part of the sidewalls. I would also cut 5” wide strips to laminate to the wider strip. The reason I glued the 6” and the 5” pieces together was I predicted that having another layer the width of the tire where it contacted the road was worth the added expense for the added protection.
Using a mechanical pencil, I marked off two 6” wide strips 98” long, and two strips 5” wide that were the same length. Using a large drywall square, I drew the lines that separated the strips.
On the 6” strips, I marked a border ½” wide on each long side. Again, the T-square was used to rule the border lines.
I cut out all the strips. Covering the two card tables with a clean painter’s canvas drop cloth, I began the gluing process. I used disposable brushes from a hardware store to apply the glue. The great thing with the glue was it dries quickly, is still visible and you can assemble it the next day. On the 6” strips I did not coat the border, only the 5” section between the lines. Since I was using a contact adhesive, you only coat one side of the 6” strip and one side of the 5” strip.
I had put a long piece of plywood on the card tables to give me a hard surface to press the seam roller against when the two glued pieces came together. For the heat bonding process, I took a 5” and a 6” strip, glued side up. I used the hairdryer to heat a 12” long section on one end of both the 6” and the 5” pieces. You need to heat the glue for 30 seconds, so I laid both next to each other to start with, heated a foot long section and then carefully aligned and pressed the 5” strip onto the 6” strip. I quickly and forcefully ran the wooden seam sealer roller over the previously heated section on the unglued side. It bonds almost instantly, so alignment is critical after heating.
I continued the process, a 12” section at a time. After the first 12” is bonded, you can lay the 6” strip on the table, glue side up, and have the 5” piece flipped back over the bonded section. The allows you to heat the next section on both sides efficiently. Heat, align, press, roll, and repeat. It went smoothly. I then repeated the steps until I had made two liners.
Installation
I had already explained what I was doing to the bike shop folks, and they were willing to do the install. Now I had to test the Kevlar® liners.
Testing
I rode a lot over the next couple of years including all of the roads that had given me punctures.
Nothing happened. No punctures.
Based on experience, I should have had at least two punctures a year, but alas, nothing happened.
The building boom hasn’t slowed, and I still bike the road to the dump regularly as well as having contractors’ trucks going past me on other roads with their dump trailers in tow. I chalk up 14-18 miles on the bike most days in summer.
Conclusion
At this point, the liners appear to be a success. I had enough material to do two bikes with a bit left over.
Caveats and Ponderings
The liners are knife resistant, but I can’t guarantee they will prevent every flat if you hit a nail or screw. There are always golden spikes lying in wait.
It will take a full day to make two liners.
The cold hard truth is the cost. The Kevlar® is $17.57 per foot (52” wide cloth priced out in mid 2025) but it is sold by the yard. The cost would be $158.13 for a nine-foot (three yards long) piece of cloth.
BargeSuperStik cement is $34.25 for a 32-oz can. This should do two bikes like mine (four individual liners.)
Disposable glue brushes were less than $10.
A pair of Kevlar shears run about $30-to-$50.
Not including shipping, liner installation, shears, wallpaper roller, glue brushes and with making two sets of liners, the cost per bicycle would be $96.19. If you had 5 bikes to work with, that cost would drop as there is enough left over to on the 9-foot section to make one complete liner for a tire. 18 feet would allow you to make 5 sets of liners for a bike my size.
I did consider making them as a craft item and selling them, but I would have to charge for the time to build the liners. I chose not to do that, but I could make them as gifta. However, it might make a good side business for a willing craftsman.
Using templates for the strips and an electric cutter would speed up the production process.
Gluing takes the most time. You just have to stick to it.
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