THE CONVENIENT CYCLIST

How to Thorn-Proof Your Bike

Bike flats are a common problem. Here, on one comprehensive page, are five ways to thorn-proof your bike, from the simple to the hilariously expensive–or, if you want a faster answer, here’s the one solution we’ve already standardized on:

Armour cross-section
Thorn protection for existing tubes & 27.5″ MTB tires: now in stock at Flatbike.

5 Ways to Thorn-Proof Your Bike

A few weeks ago, I got a call from Russell, a private pilot who likes to fly his CHANGE folding 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, easy plan. We include Continental Gatorskin flat-resistant tires standard on our Flatbike 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 (The “tire coral”, not the money).

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 hear from you. But a tubeless tire works best with a compatible rim. Useful extra aids are a bucket of soap water, a sponge, and an air compressor. And after that, we wonder if the time previously spent fixing flats on the road is simply transferred to garage maintenance, installing and removing old filler.

3. A solid choice for narrower tires?

For a while, before my thorn-resistant tires, I rode a 1980’s technology, solid rubber tire. Potholes were memorable on my spine, but traction was good and I never got a flat.

On the surface, an update to this approach 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 equivalent rolling resistance to inflated tires.

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.

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.

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

FLATBIKE ASSESSMENT: Airless tires will remain more difficult to install/uninstall than inflated tires. But not by much, with the right tool. And it’s a one-time deal.

We’re sold, for selected audiences. And we’ve already put it to use. The Tannus-enabled bike below is a prototype of the low-maintenance Flatbike Road Scholar ultimate campus bike — a 23-lb, quality 11-speed that never gets flats, never needs the rear wheel locked up, never needs front derailleur adjustment… and quickly folds in half to fit easily in any apartment.

Flatbike Road Scholar

We’re currently looking for early adopters. Are you considering it? Let me know.

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 from 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. (And “Ed” in the comments has an even cheaper solution that may be more reliable.)

But it’s still not flat-proof. And you can create your own flats, both from semi-inflated tires (pinch flats) and from having your rim liner slide to the side and rough edges puncture 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 foam 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 15 mm 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 15 mm of solid tire to ride back on, protecting your rim from rock damage.

FLATBIKE ASSESSMENT: We cannot pass this up. We are now offering Tannus Armour at Flatbike, both as an add-on and as a standard equipment on our full-size folding mountain bikes.

Tannus Armour: Now available for 26″ and 27.5″ MTB tires.

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 EnergyReturnWheel.com.

FLATBIKE ASSESSMENT: Hmmm. That’s…different. Can we still afford the rest of the bike? And do 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?

See you on the trails!

Bob Forgrave's Signature

Bob Forgrave

President, Flatbike.com

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425-985-6219

 

47 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”.

    2. yes I live in southern California do you know of any bike shops that sells tanus tires and install especially in Riverside and orange counties or even orange county sanbernadino county

      1. Jesse, we don’t know about installation elsewhere in the country, but in the Pacific NW, we are selling inserts and evaluating selling the solid tires. Most any local shop should be able to handle installation.

        In our experience, installation is roughly equivalent to changing three tires. But then you’re done with the whole problem of punctures.

    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?

      Bob

      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?

          Bob

        2. Jonathan, we’re ramping up now to have Tannus tire liners in stock by mid-November, for installation on all CHANGE 612 and CHANGE 812 folding mountain bikes. No answer yet for the rugged hybrids, but we’re working on it!

    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!

      1. That would be awesome! I’d love to avoid pinch-flats with a ride like that on a potholed, curb-filled DFW commute. Thanks for this post–it’s the clearest and most informative I’ve run across so far!

        1. Zach, this high-quality, low-maintenance, completely flat-proof bike is now a real thing. Tannus airless tires, shock seatpost, 1 x 11 Shimano gearing…the works. I’ve been riding it this Winter in Seattle, in rain and over speed bumps, and it’s done well. Here’s a write-up on it.

          We’re now looking for early adopters who might want to try a bike like this in other cities. Interested?

          1. Dan, we’re amazed at how many parts of the country have goathead thorns. For tires 2″ and over, we recommend Tannus Armour inserts. We’re restocking now on these and will soon have them for fat tire bikes with tires over 3″ wide.

            Under 2″, we’re looking at several options. Armour may work at 1.5″; we’re testing it out. And with road tires, Tannus offers airless tires in different PSI equivalents. We’re experimenting with the 28mm 110psi combination shortly. What are your needs?

    1. While it looks somewhat stylish, I would tend to say it would take time for the buyer consumer to get used to the look and appearance. With that being said, I would tend to believe it would cause wind drag while riding your bike!

      1. Change does take time…if at all. Regarding wind, maybe the reason they introduced this for MTB instead of road bikes is precisely because of the increased wind resistance!

    1. That’s quite an accomplishment; goathead thorns are legendary! For now, we’re focused on a highly-rated liner (Tannus Armour), but if flats are still an issue in goathead country, we may recommend puncture sealant as well. Thanks for the feedback, Scott!

      1. Bob, you mentioned Tannus Armour will have fat tire (20″ x 4″ is my tires) options in the near future. Later this year or next year? I live in Austin, TX, and will try regular liners with sealant but will keep an eye out for your products if I still run into issues. Thanks, Chuck

        1. Hi, Chuck. I just checked, and Tannus offers Armour for 11 widths of 20″ tires, but not 4″. Currently they go up only to 2.5″, so a long way from fat bikes. In fact, they have only one size Armour for fat bikes, and that’s 26″ x 4-4.8″wheels (what we carry).

          I’m a bit concerned about the regular liner + sealant combo approach. The whole premise of sealant is that it moves freely to the hole. If you’ve got a standard liner in the way, or a liner + inner tube inside the liner both in the way, then sealant effectiveness is reduced. So I’d go with EITHER the tube + standard liner approach or the sealant–not both.

  1. I would used the Bell solid rubber inner tube but it’s size only fits 1.75 to 1.95 and I ride a motorize bike 25 to 35 MPH I like 2.25 width need all the rubber I can pay down on the road I ride rural areas that are miles from any resources and sometimes taking 200 + mile trips.
    The solid rubber tires I know are pass down from generations from Grandpa to son to Grandson to great grandson now that is a dependable tire 70+ years instead of the demonstration stick a thumb tack in one sticks several pocket knives no flat. About changing the tire at bike shop there damn stupid you don’t cut the solid inner tube you cut the warn tire down the center comes right off no problem.
    Anyone got a link to solid rubber tires with a size 26″ X 2.25″ I would be happy to have.

    1. Having personally ridden one of those old-style tires for 2000 miles, I know how rugged they can be. I also know how firm they were; I remember feeling pothole collisions in my neck!

      Modern materials have increased not only the distance possible (4,000+ miles) but also, thankfully, the ride comfort. Tannus has a variety of solid road tires, but as you note, nothing more than about 1.4″ wide. The reason is one you’re not as susceptible to on a motorized bike–weight. Even the lightest polymer weighs more than air. At some tire size, it’s too much of a difference.

      The compromise is the Tannus Armour inserts, which are in 26″ x 2-2.5″. The combine a wrap-around protective liner with an innertube that can have whatever psi in them. Some downhill MTB riders take them down to 15psi. Road riders probably more. The point is, pumping up your tubes becomes a “sometimes” thing rather than a routine thing. And if you still get a flat, you can ride it that way to safety with no harm to the rim. We’ve got stock on Tannus Armor–including this size–as of yesterday.

    1. Yes, but honestly, I don’t see it happening soon. For narrow tires, a solid tire can weigh less than tube + tire. For mid-range tires (up to 2.5″), an insert can allow you to run a thinner tire with no performance loss–same weight. But at 4″, any solid tire or insert is going to weigh more.

      It’s possible that a Tannus Armor insert for a smaller tire on a larger diameter wheel could be cut and placed inside a 20×4″ tire, but I have no idea about the effectiveness of that. Definitely off the beaten path.

  2. I made over 3K Km using a liner. NO FLAT , and often found glass shard ,cable staple and even once a metal screw . IDK about other solution but IMHO a good quality liner that is the widest you can get is worth every cent . before your buy one look the reviews about it and Ride Safe for ….. until you need to change your tires ,Cheers

  3. I have a mongoose BMAX. It has 20″x 4 1/4″ size tires on front and back. Absolutely love the bike, it’s my daily driver. But I go through inner tubes, at least one every two months. I even think I have a motocross bike inner tubes in it now. Thinking well they’ve got to be a little tougher, than a bicycle brand. And just cause I had them and they actually kinda fit. But i guess what its coming up on spring and my back tire is flat. Its hard enough just trying to find a place that either has them or that can order them. And I most always ride on the road. Maybe some grass. But bumps, pot holes, ledges, and curbs. Are the only “hazards” I really put it through. Only thing I can think of would be replacing the rim liner. Maybe and a second layer. And I like that idea of a tube liner, but I doubt I can find one for that wide of a size tire. Any thoughts or ideas?

    1. Great question, Brody. First, yes, 4+” wide tires get us into “fat tire” territory, beyond where Armour inserts apply (up to 3″). So let’s work the problem another way.

      You’re getting chronic flats on a bike that you love, and that’s hugely frustrating. Something–probably the same something–is causing all the flats. Before we get into some common causes, do one thing. Pump up one of your leaking tubes and hold it under water in a sink or bathtub, turning it until you see the stream of bubbles.

      Now one of these below will apply:
      1) Leaking from the inside of the tube. Spoke heads or a sharp tube liner. This is when you create your own flats from something sharp on your rim. Tube liners are super-cheap and worth replacing. If you can’t find one your size, wrap electrical tape around the rim enough times to cover all the spoke heads with double thickness.
      2) Leaking from the outside of the tube. A persistent object. With tire off, put your thumbs together inside your tire and run them all the way around the inside until you come to the thorn/tack/glass that keeps giving you flats. Remove it.
      3) Leaking from the side of the tube. A pinch flat, between underinflated tube and rim. Keep your tires pumped.
      4) Leaking from the valve. Loose valve stem. Tighten it.
      5) Leaking everywhere. Old tube that no longer holds air. Replace it.

      That’s all I’ve got. Let us know what works, OK?
      Bob

      1. I ride with 700×23 cheap tires with the wire bead cut off inside of my 700×25 tires on my road bike. Very few flats, slightly harder to change but worth the extra time between flats. Not concerned about extra weight on leisure century rides.

        1. Brilliant, Ed. It’s hard to imagine a tire liner that’s tougher than a 3-ply tire itself. And old 23mm tires are easy to get for free. Thanks for sharing here!

          Bob

          1. Your local bike shop may be tossing out completely worn tires for cutting up & inserting. Not exactly a high-tech, high-speed solution, but it’s at least free…

  4. So here in Southern California the homeless who live at a river full of goatheads do this: take a treadbare worn down tire, use a knife to remove any remaining side tread ( rendering the tire essentially smooth) and cut away the metal bead on both sides, then use the old tire as a tire liner…you can purposely smash beer bottles on asphalt and the tubes are unbothered….side note, if you wear spandex to minimize drag from wind… But say you ride for exercise…you probably just like wearing spandex…if you want exercise wear jeans and a heavy backpack on gravel riding an $80 Walmart bike….for years.

    1. Brilliant re-use of a spent tire. This is definitely the ultimate low-cost solution! As for performance at speed–not a homeless concern–I’m tempted to try this sometime to test the effect of tire deflection.

      The old tire and new tire likely have the same circumference, yet one is going inside the other. For an example of what happens when two adjoining surfaces have a size mismatch, consider your fingers after a long time in the water. The skin’s outer layer expands, yet is fixed in place, so it buckles into a prune shape. Here, the inner layer is too big for its location, so it buckles into the inner tube. Maybe not an issue, maybe it is. But I’m interested to see if anyone doing this experiences an uneven tire with a shimmy at speed.

      Where this solution is GREAT is on a long, slow bikepacking trip where you’re unprepared for the local thorns. Stop in at any bike ship, ask for used throwaway tires in your size (when you buy a new set of tubes), install them this way, and you’re back to traveling with far fewer cares.

  5. Now down to the low low price of $1749 for the energy return wheel! (just the current price shown on the site 6/12/20).

    Found this site googling “solid bike tire”. (Have yet another flat on my cheap bike I’m riding during the pandemic since I can’t go to the fitness center.)

    1. Oooh! Now this wheel is down to the cost of one of our folding mountain bikes. Now if it would just fall another grand…

      Thanks for your interest in solid bike tires. We’ve been selling Armour inserts, but are about to investigate solid tires too. Rolling resistance is easy to measure—distance rolled vs. pneumatic tire down the same hill—but we haven’t yet figured out how to quantify vibration and ride comfort in an equally low-tech way. We’re open to ideas!

  6. I love that you wrote this article about bicycles and how to get the best accessories and needed things to avoid a flat tire. My husband has a bike which wheel is broken and he has to fix it so we want to look for an expert. I will start looking for a bicycle repair to make sure it’s taken care of, and we’ll make sure we follow your advice in the future.

  7. Great article, thanks!

    I wonder if we could slit the inside center of a flat tube and sheath it over a new one as a inexpensive tire liner, and also ward , off shifting rim strip causing flats, that we could dub inbread or inside job flats!

    1. Good thinking, Andrew. But even then, you’d have a thickness of just two tubes, easily overcome by goathead thorns. Some folks have had success with the similar method of inserting an entire tire this way, after trimming off the wire beads. The ultimate cheap solution for casual, thorn-proof, low-speed riding…

    1. Based on the “novice” concern, I’m assuming this question is actually about tire width, not tire thickness. A common width for all-terrain bikes (good for roads and trails) is 40mm, or 1.5 inches. It’s the width we have on our full-size folding rugged hybrid, which is popular among folks returning to cycling after years away.

      A wider tire won’t be any less susceptible to thorns and glass flats, but it’s more forgiving of non-regular tire pumping. If it’s low, it’s just a little slower, usually not at risk of a pinch flat.

  8. Terry again, I would like to know of a thicker tire to stop thorns from penetrating the tire and entering the tube. Thanks

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