Tip: My tubeless sealant in tubes experiment
 

I moved to Denver 1 year ago, and have been commuting daily (99% of the time) at a distance of 36+ miles roundtrip per day. The first few months, I got quite a few punctures, more so once I discovered the many gravel trail options along the way. I didn't want to go full tubeless since I switch tires frequently depending on the situation and weather conditions (road tires, gravel tires, studded ice tires), and I don't have room to store different wheel sets with different tires in my apartment.

In October of 2018, I put tubeless sealant into my tubes in each of the different tires I'm using. The result is after 7000+ miles in all conditions, even some epic rocky single track, I've had 0 flat tires!

I'm currently in the process of experimenting with the new blue Bontrager tubeless sealant in some inexpensive road tires. My plan is to ride in the worst possible conditions (in the gutter with all the road debris, in the grass along the sides of the bike paths, and LOTS of gravel), and see how they hold up after a month or so. I made a video on the process and I'll make a follow up video with the new experiment results.

I also put sealant (homebrew) into my commuter tubes, and I guess it got rid of flats. I didn't have that many to begin with, decent suburban roads/bike lanes, wide schwalbe marathon tires with low pressures, etc.

But recently a 3-day slow leak developed into a half-day slow leak, and I needed a tire change, so I pulled everything off, and found I needed THREE patches! I guess two of the holes were sealed (well enough) by the sealant, but when I took the tubes out and inflated them without the tire to support, stuff got jostled and the holes became open?

BTW I put the sealant into tubes with 'non-removable' prestas. That locking nut doesn't want to remove, but get some pliers on it and that sumbich WILL unscrew all the way off. You have to be careful then and catch the core as it falls into the tube. Secure it in its place inside the tube with a binder clip or clothespin while you put sealant in, then push that core back up and screw the locking nut back on.

Yeah, that's what I used to do back in the day to put slime in presta tubes. Seems like most presta tubes available these days have removable valve cores, so it's a pretty simple task to put whatever in them. I do feel like tubeless sealant works better than slime though.

I used Stan's sealant in tubes for a season and was pleased, but found that Flat Attack pre-filled tubes were a better alternative. Their sealant is gauranteed for 5 years so it doesn't need to be "refreshed" from time to time to remain liquid. The sealant is also supposed to be biodegradable which makes me feel all warm and fuzzy for using it. Despite many punctures, I haven't had a flat on the road in over three years. When a puncture occurs, the tire loses a little pressure, I stop and remove anything I find on the tire, add air or CO2, give the wheel a spin and ride on.

Marc

I find I have to look fairly 'hard' (i.e. click a couple more web pages) to find tubes with removable cores, but I am cheap so I wouldn't spend, say, $8 on a tube

In my experience it's hard to know whether a tube will have a removable core. Internet sale pages often lack detail.

But aside from that, I have two questions for those who put sealant in their tubes:

1. When the sealant does its job and seals up a leak, is that flat now fixed? Or will it open up again if you run out of sealant?

2. Can you patch a tube that has sealant in it? I tried this a dozen years ago, using Slime tubes, and it didn't work. Something about the Slime sealant.

1. The flat is mitigated, really. I guess there's a little latex plug blocking the leak, but in my case pulling the tubes out and pumping without a tire opened up pinpricks I didn't know I had.

2. Yes. (although it probably depends on the size of the pinprick/cut/tear). Sealant is generally not as messy as Slime. Usually it has the consistency of cream, with some kind of added chunkulant (glitter, rubbersand, fibers) to help plug holes. If you are holding a tube with the puncture upwards to patch it, any sealant inside will tend to drain away from the hole. Wipe the surface dry if necessary, and then it is no problem to sand and vulcanized-glue patch. In my experience, even though sealant that might come through the hole to contact the glue and patch, it does not weaken the bond or work the patch off.

What about performance? Does it add much to the tire weight and rolling resistance?

Obviously it's going to add some weight. I usually go a little overkill and add a complete 4oz sized bottle to each tube, although 2-3 is sufficient. Weight wise, it's probably less than tire liners. The tires I got the 7000 miles on were lighter weight tubeless gravel tires. I went through 2 sets, and although it's probably not a good idea to reuse a tube with lots of little pinhole plugs, I did it anyway and didn't have any issues. I would say overall, a lighter gravel or touring type tire with a tube and sealant is probably lighter than something like a Schwalbe marathon tire with a tube. I used those for a couple of years with maybe 1 flat, but I don't really care for the ride quality nor the weight. They definitely felt heavier to me plus with the super thick rubber, they kind of feel like riding on garden hoses.
There's definitely pros and cons to any "flat resistant" setup, but so far, a lighter, more supple tire with a tube and sealant seems to have the least amount of compromises that I've found.

I work at a bike shop that sells Trek. All Bontrager presta tubes have a removable valve core. $7.99 +$4.99 for a bottle of sealant seems like a pretty inexpensive investment if you can get 6 months to a year without any flat tires.

The sealant in the tube idea is nothing new. Specialized has been selling their AirLock tubes for years. They work very well, but proved to be redundant for my situation. Just be sure to rotate the valve stem correctly before attempting to put air in the tube to keep from getting sealant in your pump nozzle. I think the AirLocks sell for about $10 a piece if I remember correctly.


-Kedosto

Edit: $12 on their website.

I do this on several of my bikes. Worked well with the exception of when I had a dozen (no joke) goatheads once and when a large piece of glass made it through my commuter tire another time. The sealant wasn't enough to mitigate those flats when I was on the road, but they appeared to have sealed after some time when I inspected the tubes later at home. The only other thing I'll mention is that some sealants are too thick to inject into a presta tube without removable cores (ie, with only the valve pin removed).

It adds as much weight as the weight of the sealant you put in. I'm not sensitive enough to detect any difference to the ride feel, but it's sloshing-at-the-bottom weight, not rotating weight, so I don't think it would be that big a deal. I can't imagine it would make any difference to the rolling resistance, that's a function of the tire impacting the ground

I have had mixed results.
Works great on a 2" or wider tire. Almost too good (It worked so well that I didn't notice a nail was in the tire, then the nail went through the rim side of the tube and sealant did nothing for that).

Did not work at all for me on 700c tires.
- Does not seal pinch flats (or spoke caused holes) as it does not seal a leak near the rim.
- For some reason it didn't seem to want to seal any holes in the 700c tubes.

I have had several "flat attack" tubes that had a defect where they all blew a hole (about an inch from the valve) when they were aired up. That was a big turn off and quite a mess.



Centrifugal force usually spreads it out pretty evenly when riding, so in my case I have found it to be rotating weight.

weight or rolling resistance bothers anyone, tubeless will save you a couple watts and maybe some weight over using an inner tube.

Good to know. All Schwalbe tubes have removable cores. Most of the generic Taiwanese tubes I've bought don't.

I'm not going to die on either of these hills, but (a) I think since the sealant is not attached, and can be 'left behind' as the wheel spins up, its weight would have less effect than, say, heavier tubes or tires. (b) rolling resistance doesn't bother people that are not trying to go fast. Like me.

So a follow up to this post, after 2 months and almost 1200 miles, 0 flat tires.

I haven't tried the blue Bontrager tubeless sealant but on my MTB tubeless setup I use the regular Bontrager sealant. I find a huge advantage of it over Stan's is that when the Bontrager dries it doesn't ball up, instead it forms a layer inside the tire that seems to be protective even all dried out. I probably wouldn't put Stan's inside a tube because of the inability to remove a Stan's monster but this gives me inspiration to try a lighter tire while keeping tubes filled with sealant.

Specialized tubes have removable cores.

There's a GCN video that I can't find where they did this and then hammered a nail into the tire to see if the sealant worked in the tubes. It did.

Because of that video I tried it as kind of a poor man's tubeless alternative on a gravel bike for a while. I had very good luck with it, don't recall having any flats. Sealant isn't supposed to protect from pinch flats but it sure seemed like it did.

Eventually I got a tubeless wheelset, but I still have a couple non-tubeless bikes that I'll squirt Orange Seal in the tubes every once in a while for insurance.

I haven't watched your video. Did you find holes that the sealant had sealed?

For me with skinny (28mm) road tires the problem with tubeless is not punctures (sealant caught'em all!) but just keeping the tires on the rim. Putting sealant in tubes sounds great to me.

@HardyWeinberg, what do you mean keeping the tires on the rim?

Please explain...

Hardy - I’m guessing you have a bad tire rim combination. As there is no good standard, some tire-wheel combos are too tight (and won’t go on), and some tires are too loose.

Contenital (and others) have developed a new standard they plan on rolling out in 6-12 months that should address that issue. Right now, high pressure road tubeless is hit or miss, unless you match your tire to an approved-tested rim. High pressure road tubeless also requires a hooked rim. Personally I’m fine with some fast 32mm tires running hookless at >70PSI.

I hope the sealant spins with the rest of the tire. It is a vicous fluid. If it doesn't, then you have fluid resistance (like air resistance, just a whole lot more) between your stationary fluid and rotating rim/. (Reality check here - it won't take long at all for that resistance to have speed up the fluid to tire speed, so it will rotate.)

At a slow enough rotation, the sealant will continually flow to the bottom of the tire. At a fast enough rotation, centrifugal/centripetal force will create a radial pseudo-gravitational force that will distribute the liquid evenly all around, and I imagine it will remain relatively stationary (relative to the rotating frame of reference of the tire), except for bumps. In between, other stuff happens. In particular, accelerating from a stop, there will be some lag as the fluid is dragged up from its pool on the bottom and flung out to the tire. The physical force that makes that happen doesn't come from nowhere, it comes from your legs. But it is probably imperceptible.