How to Thorn-Proof Your Bike

A few weeks ago, I got a call from Russell, a private pilot who likes to fly his folding CHANGE mountain bike into remote places for exciting adventures in his private plane. He wanted tips on how to avoid thorn flats.

How remote? And what kind of vegetation are we talking about?

Cacti in West Texas can have some awfully long thorns…

Those are some serious spikes. And West Texas cacti aren’t the only problems. Blackberries, devil’s club, goathead thorns, ‘wait a minute’ vines…nearly all parts of the country have some species that are unfriendly to inflated tires.

Basically, if you know you’re headed into thorn country, there are five different ways to address the issue of puncture flats.

1. What you already have, just tougher.

Tires and inner tubes come in thicker, thorn-resistant versions, which are tougher for thorns or broken glass to puncture. Why don’t all bikes come like this? Because extra rubber results in extra weight. How much do you want to free yourself from flats?

Using a set of these in the 80’s, I once went over 2,000 miles between flats; when I finally got one, it was from a thumbtack inserted in the sidewall at a bike rack. Even the best intentions won’t stop everything…

The Specialized Armadillo tire series has different levels of rubber thickness, with more thickness protecting more, but also offering a bit stiffer ride. The Continental Gatorskin, on the other hand inserts a layer of Kevlar clear around the tire to protect against anything–perhaps even sidewall thumbtacks.

Kevlar: If it can stop bullets, it can stop thorns.

You can also protect against thorns at the inner tube level. But thicker tubes are becoming harder to find in recent years.

Kenda owns a large portion of the thorn-resistant tube market.

FLATBIKE ASSESSMENT: Good plan. We will be including Continental Gatorskin tires standard on our upcoming CHANGE Century folding road bike.

2. Self-healing tires that aren’t science fiction.

The idea is simple. A small amount of liquefied goo stays inside your tire. When you get a puncture and the air starts leaking out, the goo rushes to the opening and clogs it.

In practice, this often works, especially if the hole is small enough, the hole is on the bottom of the tire, and the self-sealing compound in your tire is recent enough to be still liquid.

Otherwise, you end up with this inside your tires.

If you go with this approach, you probably want a tubeless tire, because there’s simply no way to change the liquid inside an inner tube. Notable self-sealing solutions are Slime and Stan’s. The website MBAction has a great review of these and other sealant solutions, with the wonderful testing warning, ‘All tires were harmed during the testing process.’

FLATBIKE ASSESSMENT: Wait & see. Some folks swear by the tire sealant approach, and we’re interested to year from you. But a tubeless tire requires a compatible rim for it. And we wonder if the time spent fixing flats on the road is simply transferred to garage maintenance, installing and removing old filler.

3. A solid choice that sometimes rides that way?

For a while, before my thorn-resistant tires, I rode a solid rubber tire. Potholes were memorable, but traction was good and I never got a flat.

On the surface, it sounds appealing. Flat tires are the #1 maintenance issue bringing customers into many bike shops.

That said, compressed-air tires distribute a shock across the entire rim, while solid tires distribute stress only locally. And some bike shops charge a premium for replacing a solid tire. Has advanced technology made a difference?

With today’s advanced polymers, there are more options and better options than ever. One example is the Tannus Airless Tire. Made of closed-cell polymer foam, it is reportedly as light as most tire/tube combos, good for over 5,000 miles and comes in 12 stylish colors. Tannus even claims a 15% lower rolling resistance.

No more flats. Ever.

During Bike Expo NY 2018, a Tannus rep offered to put a set of Tannus airless tires on a CHANGE 702 folding commuter bike, which I then rode in the 40-mile Five Borough Tour, plus another 20 riding to and from the event.

Among the joys of that 10-mile pre-ride was a surprise section on this road. It felt just like a regular air tire!

After a 60-mile day, I must say that the difference between the solid rubber tires of the 1980’s and the carefully calibrated polymer tires today could not be more stark. Even a cobblestone road was possible at 15 mph–still not fun on narrow tires, but the choice of tire composition was never in question after the first few wheel rotations.

Nexo and Ever Tires have also launched a Kickstarter campaign around their own airless options, both for kids’ bikes and larger bikes that put up to 5,000 miles on a tire.

The Nexo campaign was started by bike mechanics!

FLATBIKE ASSESSMENT: Airless tires will remain more difficult to install/uninstall. And yet, the advantage of not just no flats, but never having to pump up your tires, is near-impossible to pass up. We are working with Tannus to offer airless tires as an option on all road-tire bikes.

4. Like solid tires, but not.

We got this tip from a reader–thanks, Donny–and it has developed into a brilliant idea that’s worth a category all its own. But first, let’s take a step back and look at what riders (road and MTB) actually do with their tires.

Road riders have a preferred pressure that must be maintained over time for maximum efficiency. They rack up many miles on pavement that may occasionally have a pothole, broken bottle, or goathead thorn. Under low pressure, ‘pinch flats’ may also occur, without any obstacle in the way.

Goathead thorns: Nasty stuff.

MTB riders vary their terrain–one day dirt trails, another day lots of bumps and big jagged rocks–so their tire pressure varies accordingly. The rockier the terrain, the more pliable you want your tire to avoid punctures. Broken glass isn’t usually an issue, but goathead thorns and cactus thorns are worse.

So while an airless tire might make sense for a road bike rider, it would take away the ability for MTB riders to adjust pressure for different terrain. Enter a new category: the tire liner.

A tire liner goes between your tire and innertube, protecting against puncture.

A tire liner is inexpensive. The one shown here form My Tuffy is just ten bucks, with a 70% satisfaction rating. Folks have ridden over 1000 miles with it, and even ‘successfully’ run over broken glass.

But it’s not flat-proof. You can still create your own flats, both from semi-inflated tires (pinch flats) and from having your rim liner off to the side and rough edges puncturing  your inner tube (anyone have a name for that?). And tire liners are no match for goathead thorns.

Now here’s where it gets really interesting. Suppose you took the inflated tire idea, and the solid tire idea, and the liner idea, and melded them together into a single product that inflated but was thick enough for goathead thorns?

Tannus Armour tire insert
The Tannus Armour: an MTB-focused liner that’s finally designed for goathead thorns.

The Tannus Armour is a liner–the red part–with 15mm of the Tannus solid-tire material under the tread of the tire, and 2mm on the sides. It’s like having most of the advantages of an airless tire, plus the ability to adjust pressure to your terrain.

Even in the worst case scenario, with a random goathead thorn doing a stealth insertion from the side that goes through tire, 2 mm liner, and inner tube, giving you a flat…you still have 15mm of solid tire to ride back on, protecting your rim form rock damage.

FLATBIKE ASSESSMENT: We cannot pass this up. We will be discussing sourcing from Tannus, so you can get it with other Flatbike components to make biking easier.

5. And now for something completely different…

What if price were no object, and you could just optimize for the ride on your own wheel? This is the idea behind the Energy Return Wheel.

According to company literature, not only does this completely flat-proof option perform as well as a standard mountain bike wheel, but it outperforms a standard wheel, particularly on uphills. Available for the low, low price of just $2,699 from

FLATBIKE ASSESSMENT: Hmmm. That’s…different. Now we have to clean the insides of the tires after a ride?

Overall, that’s five different ways to solve the flat-tire problem. Which one works best for you? And what do you think should be standard on our rugged, full-size folding bikes?

See you on the trails!

Bob Forgrave's Signature

Bob Forgrave





10 thoughts on “How to Thorn-Proof Your Bike

    1. It sure seemed like that to us! I imagine there are lots of R&D dollars to pay off, but that’s more than most folks spend on a whole bike, so what would you put it on?

      And this is a MTB wheel, so you’re going to be spending a lot of time hosing mud out of the inside crevices of your “tire”.

    1. Hi, Donny. Goat Head thorns are the worst…except maybe Devil’s Club!

      You are absolutely right about tire liners being a useful addition to this listing. We’d never heard of them until after the article; now it seems this product category is worth a blog of its own. Do you have experience with them there in Goat Head Central?


      1. I’ve run tire liners since the late ’80’s. While they’re not completely flat proof, they do reduce the number of flats significantly… and I’ve had my tires looking like a studded ice tire after running through a patch of goatheads. I’ve also had the tire liners cause a flat. Bought cheap ones years ago. After about a year in the tire, the liner cracked and gnawed a hole in the tube. They are a great option for the budget rider, and very simple to install. Definitely a must for kids bikes!

        1. This is great to know, Jonathan, and something to consider adding to our upcoming bikes. Do you have a favorite manufacturer of tire liner?


    1. Thanks, Jessica! We’ve been looking forward to this improvement for a long time. And…interesting side-note on this topic…we’re moving closer to a bike introduction this fall with Tannus airless tires standard. Just need to get some testing miles in first!

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