This is Part 1. Part 2 focuses on tools to carry. This post was updated on 27 Dec to report the results of the tubeless installation with FlatOut sealant.
So… I try to ride to work every day. My office is 4.4 miles from my residence, but since I am trying to get as much exercise as I can, I may take up to 15.5 miles to get there. Thats all on city streets, which translates to potholes, nails, staples, steel shards, rabid rats and whatever else the mean streets throw at me.
With one break of about 15 years, ending about 5 years ago, I’ve been doing this since the mid-1970’s, and that includes shopping and errands as much as possible. I do actually own a couple of cars, but I’m trying to completely replace them.
As such, I have spent more than enough time on the side of the road, dealing with punctured, flat and damaged tires.
What Not To Do
Be a weight weenie. If you want the most responsive ride, and are willing to work thru flat tires to get it, fine keep your wheels light weight, your tubes ultralight and your tire casings thin. Thats not me and we’ll be doing the polar opposite of this philosophy: going almost literally for Bulletproof.
What TO Do
Everything described here is about flat prevention. I have tried just about every anti-flat tech there is. I won’t be describing all of it and just focus on where I have evolved to today – probably after trying a lot of other things that you are thinking about trying yourself. I am this kind of guy: I use the best. Not because I can afford to throw money at the problem but … because I need to keep rolling; not walking. Nothing sucks worse than flatting on a cold winter night after work (well, maybe getting hit by a car but you know what I mean). What you see here is what I’d call state of the art to keep me on the road and not on the side of it.
If you have a bike where such tires can fit, these are the Holy Grail. I have found, for instance, the Continental Contact Plus City tire is to all intents and purposes invulnerable. I found it also wears like iron, so you will get lots of miles out of a set. It is E50 rated so its got a seriously sturdy casing.
It is less expensive than the Schwalbe Marathon Plus (which garners all the mindshare for this class of tire) but essentially the same performance: Flatproof. The Contis are cheaper because in part Continental is fighting to take market share from Schwalbe, and partly because they sell into ebike rental fleets where cost is a big factor.
If you can get this tire on your wheels, consider it seriously. Be aware however that it rides hard. In other words it sort of feels like you are rolling on a smooth rock (full suspension would be a big plus). Thats the price you pay for modern, genuinely flatproof tires so either live with it or look to a different solution.
If you have a fat bike, don’t worry about what flatproof tires would do to your ride comfort because you can’t get them for fat bikes. They would weigh a ton.
Thorn Resistant / tough / Smart Inner Tubes
I’ll make this simple: If using tubes, use thornproofs wherever possible. Always. Here again, if you own a fat bike you don’t have to worry about it because they don’t make them for fat sizes. Again because of the colossal weight.
For fat bike riders, scan the marketplace (it changes by the month) and look for the thickest tubes you can get: 1.2mm is the most I have been able to find, and only sporadically. The thicker the better.
What do I mean by “smart inner tubes”? Well, the tubes aren’t smart but you need to be when choosing the size. This is a little counter-intuitive, but you want to always try and oversize your tubes. If you have a 26×2.8″ tire, a 26×4.0″ tube is perfect for it. Why? Because the tube doesn’t blow up like a balloon inside of the tire. In fact it may not be distended in the slightest.
Try blowing a balloon up full and then barely touch it with a pin. BOOM. Now take another balloon and just put a puff or two of air into it, so its barely stretched out. Tap it here and there with that pin. Different result entirely. That same idea holds for tubes. The trick is if you are doing this, you are going to need to work more carefully to get that tube in under that tire safely without it getting pinched under the bead (top tip: Barely inflate it so it is not sufficient to hold shape… that will happen when you are stuffing the tire onto the bead). Once the tube is safely in and the tire is mounted, you are golden.
Oh and, like I said you need to be smart. So when using oversized tubes don’t overinflate the tire past its rated max. You will find that using a bigger tube means it is capable of tearing your tire apart from the inside. I’ve never seen anyone actually do this. Just Sayin’… don’t be That Guy.
DIY Belts Under Tires
There are many such products, with Mr. Tuffy being the oldest of the bunch and arguably the most effective. I started using Tuffy ages ago when it first came out, on road bike tires. That polyurethane formula was damn near impregnable. You did have to fiddle with it a little to get it centered on the tread, but the result was well worth the effort. Sadly I have found that the new-generation Mr. Tuffy that is made for Plus sized and fat tires (XL thru 4XL sizes) never met a nail it didn’t like. My Tuffy 4XL had a zero percent (0%) effectiveness rating at turning nails. I gave it plenty of chances to redeem itself. Its hard to hate the Tuffy people too much for this as a properly thick belt would (drumroll) weigh a ton. Sound familiar?
After decades of swearing by Tuffy, on fat tires I was forced to abandon it for what I consider to be its natural enemy…
Tube Sealant (Slime!)
With Mr. Tuffy failing to deliver in fat city riding (maybe it still works on goatheads), I turned to the most widely available and well known alternative: Slime tire sealant.
Remember… I am riding with tubes and not going tubeless. You CAN use tubeless sealant in inner tubes. I suggest you don’t. I have used both Stan’s Tire Sealant and Orange Seal Endurance Formula in tubes. Both did a great job of sealing the tire once the sealant leaked out of the holes in the tube… but the air kept coming out of the tube and leaked thru the spoke holes (that means a LOT of sealant gooshed out along with the air… that is a mess you need a toothbrush and an hour per wheel to clean up).
To be fair, I did have instances where both sealants worked to seal goathead thorn holes on a tubed tire. But after the above catastrophic failure (lots of goatheads… like 50 per tire) I abandoned tubeless sealants in tubes. They just do not have enough fibers to seal more-stretchy tubes with the same level of reliability as tube sealant.
Where was I? Oh right… Slime. Tubes. Slime worked very well for me, I found if I could hear the hiss-whack-hiss-whack-hiss quickly enough, I could jump off the bike (stopping first) pull the nail, jump back on and get rolling with enough air still in the tire the sealant could plug the hole. If I wasn’t so fast I might need some co2 to give a fast rush of air so I could get that roll on. And if I did have a leak that didn’t seal up completely, many times it slowed the leak enough I could turn and haul ass straight home so I could do my repairs sitting in my garage, with a soda and a sandwich, rather than sitting on a rock, or on the curb in the sun.
Slime was of course, a mess. A huge mess in some instances. But it worked. However it is only rated to work on holes up to 1/4″ in size. Over that and you could be walking. I’ve had that happen more than a few times (we’ll get to tools and roadside repair in the follow-on post to this one).
Slime is rated to last about two years before it dries out. I’ve had it dry sooner (about a year). Once its dry its worthless. You really should just replace the tube at that point as its really heavy and won’t do you any good any more. With respect to dosage: Rule of thumb from user groups (my experience is the same) is to double the recommended dose. A fat tire bike can and should use a full 8 oz bottle of the stuff. Work down in dosage as your tire size decreases.
While Slime has been knocked off of its pedestal by the following product, it is still in wide use across the bike world. Thats why I am leaving a full discussion of Slime here rather than ignoring it as old news…
Tube Sealant (FlatOut)
So… Slime dries out and it is only good for holes up to roughly 1/4″ in your tube. Is there something better? There is and its called FlatOut. You want to use the Sportsman Formula for a bike.
Unlike Slime and most sealants out there, FlatOut is advertised to last for “10+ years” which translates to “forever”. It doesn’t dry out.
It also advertises itself as working on holes up to 1/2″ wide. Double the size of Slime and other sealants. I’ve only been using it for several months and about a thousand miles, but it has already sealed a few holes for me… one of which was a piece of jagged metal so large I doubt Slime could have handled it at all.
It was enough to make me start believing the 1/2″ hole claim. Between that and what you will see I say about using FlatOut in a tubeless setup below, I’m fully satisfied its a better product.
The label on FlatOut indicates nowhere that it can be used on bicycles of any type. Hearing that others had been using this but nobody could say for sure if it was fit for purpose, I called FlatOut and asked. I got hold of their product manager responsible for bikes. It turns out the Sportsman formula was tested extensively by a manufacturer who made hunting ebikes: for hunters heading out to game stands and blinds in the boondocks. The recommended dose for a 26″x4.0+ tire is a half bottle (16 oz). The recommended dose for a Plus sized tire is about 12 oz. For smaller tires… figure something out or call them and ask for guidance.
So the dosage for FlatOut is quite a bit more than the amount that you would put in for Slime. On the plus side, its a one-time application that should last the entire life of the tire: Set it and forget it.
This one is kind of a new category unto itself. By and large it has one credible product in the category: Tannus Armour. Basically its just what it sounds like. A barrier that completely surrounds and protects the tire. Flexible enough not to ruin your ride and tough enough to stop stuff from coming thru.
There are a number of sizes. I can say the difficulty of installation can vary widely. My 29er has two slightly different tire sizes, one of which required a trim to fit. Difficulty of installation ranged from difficult to almost impossible. But I got it in. For those two installations I used thornproof tubes underneath and that probably kept me from damaging the tubes during the installation battle. Centering the armour under the tread was also difficult.
For the two fat bikes I have it installed in, both went in much more easily. One bike with 100mm rims and 26×4.8 Vee Snowshoe XL tires went smooth and easy. If anything the Tannus protected the tube completely as I levered the tire bead back onto the rim.
My second installation with 80mm rims and Vee Mission Command 26×4.7 tires was more difficult, but still ok. Part of the reason was the fact the claimed 4.7″ tire size is baloney and the Vee Mission Command is really a 4.3″ wide tire.
I did try a third fat installation that was a complete failure. Using 80mm Surly My Other Brother Darryl rims and 26″ x 4.00″ Arisun Big Smoothies. Even after trimming, I (and my Local Bike Shop who gave it a try themselves) failed.
I have heard complaints about the ride with Tannus underneath the tires. I can say I have felt a difference – best description I have heard is the tires feel ‘dead’ in terms of responsiveness – but on an ebike meant for city travel its not something I give a darn about. I’ll take the flatproofing over a loss of responsiveness. Also there is an obvious unsprung weight increase. Again… I’ll take that over a flat any day.
In the spirit of overkill, I also used FlatOut in the tubes under the Tannus Armour. So far so good no flats. But if you ride long enough you know you can go months with no problems… then your luck changes and you get three flats in a week.
And speaking of overkill, on my Bullitt I am using belted tires, Tannus Armour, thornproof tubes AND FlatOut… Rolling > Walking.
I have also seen photos of Tannus Armour that has, over time and miles, compressed to being paper-thin. I’ll have to see whether that renders its protection less effective. Since as I mentioned above, I like to oversize tubes and the tubes I used under all of my Tannus installations were a bit over. In particular I used Vee 26″ x 3.5-5.0″ tubes which are small enough to work but also capable of fully expanding. So maybe that was a good choice given this potential scenario.
So only time will tell. Still, I have high hopes of at least some efficacy.
Running tubeless is a whole different world. Here again, the right choices are simple and for simple reasons. You just have to hear what they are and the benefits should be obvious.
Tubeless Valve Choice
Any valve with a metal lip on the bottom. There aren’t too many of these on the market. The ones I use are from MBP and the Orange Seal Versavalve. The MBP valves are a bit less expensive but still totally solid on quality. The Versavalves give you more stuff along with the valve. Particularly a valve core remover that screws onto the valve and stays with the wheel permanently, staying right where you could need it as opposed to being *somewhere* but you are not sure what pouch you put it in when you need it.
Why does that bottom lip matter? Because it provides a solid backstop for the gasket that sits on top of it. When you screw down the valve the gasket is smooshed into the rim hole; sealing it to the rim whether it wants to or not. For a different kind of valve with just a rubber gasket glued to the bottom, well if you have to screw it down tight, you could end up pulling the valve clean thru the rim. Also the valve is not held in a vise like it is with a metal lower lip.
Like everyone else on the planet I first tried Stan’s Notubes valves and sealant. I found these valves worked perfectly on the first seal, but over time – especially when adding air down the road – they leaked no matter what I tried (including the standard pliers-on-the-valve-nut bit). Replacing them with MBP or Versavalves solved the problem instantly. Stan’s valves do not have a metal lip on the bottom.
In the long history of Serious Tubeless Sealant, there are only a couple of mass market players.
Stan’s Notubes Sealant
Ask any internet gathering what sealant to use and you will hear a chorus of “Stans“. And to be fair, the stuff works, and it has been on the market for years reliably keeping people rolling rather than walking. I am one of them. But being the first to market, and not really having noticeably changed over the years, I don’t think its the market leader anymore in terms of performance. You can depend on it, but it has some limitations. For starters, it dries out fairly quickly. The mfr says it will last from two to seven months. Thats not a lot but back in the day it was still a miracle just to have the stuff in the tire with no tubes, and for it to work. In my experience Stan’s lifespan is a lot closer to seven months than it is to two. This may be because I use it in thick-casing mtb tires.
Next, its formula has ammonia in it… and that can be corrosive to your rims. Yes really. Google it for details if you like. Suffice it to say this is not a good thing.
Lastly… remember I mentioned that Stans dries out fairly quickly? Well how it dries is a bit of a subject all to itself. Google “Stan’s boogers” and click on the image results to see what it becomes. This translates to your not only needing to add more sealant, but to also clean out the boogers on occasion.
Orange Seal Endurance
The Other Leading Brand (which seems to be slowly replacing Stans as the de-facto recommendation) is Orange Seal. By all accounts, it works a little better than Stan’s to initially seal up stubborn wheels. Depending on who you ask, it either lasts longer. Or not as long. Yay internet! The Endurance formula is advertised to have a lifespan of six months. I have found this 6-month span to be about right. And when it does dry out… no boogers! It dries into a thin, spread-out, easily removable coating on the inside of your tire. Not enough to throw it out of balance. So every few months you add more and you can ignore cleaning it out.
Orange Seal and Stan’s both seem to last longer than advertised. But both have a finite lifespan.
So which is better?
Both work fine but I give the nod to Orange Seal for convenience and no corrosion issues. One thing is for sure: Both of these sealants are more suited to small pinholes (think goatheads) than they are large tears…. jagged metal and your garden variety construction site drive-by pickups. They just aren’t made for that kind of puncture. Even Slime is better at that sort of thing thanks to its thick gooey fibrous nature versus tubeless sealant’s watery liquid latex composition.
There are some new kids on the block, however, that seem to eat the big stuff up.
Black Ox Sealant
This stuff is amazing. Just watch the videos on how it seals tires up. Whats not to love about it? Its brand new on the market and relatively unknown at present. I contacted the mfr and asked them about the product’s longevity. They responded that they are still determining that (like I said… new on the market). For that reason, I’ll keep an eye on it… and wait and see.
UPDATE, Aug 29 2021: I just checked the Black Ox website and see the product has matured a bit. They now advertise the max size of the holes their sealants can seal, and longevity. Further they have developed a second formula: Ox2. The first has been renamed to Ox1. It doesn’t look like good news as Ox1 is rated for holes up to 3/8″… and its longevity is only 2-6 months. Ox2 is rated for 1/4″ holes and lasts up to 8 months. This puts both sealants head-and-shoulders up and over Stans and Orange Seal, but well behind the next entry in this list:
Yup… FlatOut Sportsman Formula. Same stuff as was described in the Tubes section above. On the Amazon product page linked here there are videos of ridiculously large holes being nearly instantly sealed by this stuff. When I discussed the product with them, they noted they have versions for military use that seal holes up to 1.5″ wide (not highway safe but they don’t need to be). I can personally confirm FlatOut sealed a hole on one of my bikes, from a large jagged piece of metal, that I doubt Slime could have handled… Never mind Stans or Orange Seal.
Since this article was originally written I had this experience, which is the worst nail puncture I have ever experienced. On any tire with a tube or without. FlatOut solved the problem.
With a rating of 1/2″ for max hole size, its the clear leader of the pack in terms of how big of a hole it can seal. I can now say I have personal experience that backs up their claim. They say out loud it lasts the life of the tire. So put it in and forget about flats forever? So far thats been the case for me, even with multiple nails in a row that nearly destroyed the tire. FlatOut is also a lubricant so I can see using a bit of it on the lip of the rim helping to mount a tire (instead of the dish soap I use now).
In my discussion with FlatOut I asked about using it as a tubeless sealant… something they had not tried or tested. I had a game plan as a result of that conversation where they suggested to ensure an initial seal at bead seating, paint the bead with FlatOut to ensure that initial pop and seal, then load the tire up thru the valve core as usual.
Did it work? Well, I put it into play the same day this post went live, and here’s the update: Yes. Perfectly in fact. The bead-painting trick was not necessary. the bead was seated as usual with a blast of compressed air, and the sealant added after this just like any other tubeless installation. In the first few days I was losing about a pound of air per day and expecting to need to refill each tire roughly once per week. Since then the air loss has slowed and I have only needed to refill air once in about a month, after the first week. Tires are still holding without any apparent loss. When I set the tubeless wheels aside for a different set for the entire summer of 2021, when the wheels went back on in late August, they were still perfectly ride-able.
I’m running 90mm Nextie carbon deep dish rims, 1″ gorilla tape over the center depression (a unique issue with my rims) covered over by 85mm Whisky tape. 26″x4.7″ Vee Snowshoe XL tires on top.
From the looks of it, FlatOut has proven to be a sealant that never dries out and is capable of handling some of the worst things that can happen to a bike tire.
6 thoughts on “(e?)Bike Flat Prevention”
Great article. Will look to use flatout in the future. I painted the bead with stand sealant, when I went to change the tire a year later it was very difficult to remove. Made me rethink tubeless.
On Friday after work, I took the Surly, which is fat tired and tubeless, the long way home thru some trails and picked up a ton of thorns. Once home I went over the tires and just plucked them out. Numerous little fountains as expected. A few days later the tire remains as full as it started out. FlatOut before this, for me, has been big drama with big nails. This was the first time it behaved just like a Stans or an Orange Seal and just sealed up the little stuff like it was nothing.
Just curious, would you run your Bullitt with all that if it wasn’t an ebike? If not, what would you choose? It seems like Flat Out is a given, but what else?
Absolutely I would. Back in the 1980’s I rode a 19 lb, 59cm road bike that for its time was unbelievably light weight. It ran on 700x25C tires. 700x20C actually, until the Avocet K20 came out. Kevlar belted. For a small 700C race tire that was unheard of. Then, Mr. Tuffy under that. I didn’t use Slime as Tuffy and kevlar made the tires pretty much invulnerable. My point is, being flat free on a bike you depend on (it was my commuter) is worth every price you have to pay. Weight considerations are for recreational cyclists.