New Sealant for Rene Herse Tires

Tubeless tires have changed what we can do on a bike. When the terrain is really rough, not having to worry about pinch flats allows us to run lower tire pressure for more comfort, more traction and more speed. (The speed comes from the lower pressure on rough surfaces, not from the tubeless setup itself.)

Setting up tires tubeless can be a hassle – and high-performance tires require more diligence yet. Everything that makes supple tires so fast and comfortable also makes them harder to set up tubeless: The ultra-thin sidewalls aren’t air-tight, and the tires are so floppy that the bead can be hard to seal against the rim. Supple tires need sealant to close those microscopic pores in the casing and to constantly seal the tire against the rim.

There are many tricks to setting up tires tubeless, and the right choice of sealant is one of them. Many sealants are intended for mountain bike tires with stiff casings that are covered with a thick layer of rubber, making them airtight on their own. The sealant is only intended to close small punctures, not to make the tire itself airtight and seal it against the rim. Those sealants can work OK with supple high-performance tires, but we wanted a better solution.

Over the last two years, we’ve worked with Panaracer in Japan to develop a sealant that is specifically formulated for the supple sidewalls of Rene Herse tires. (The sealant works equally well with Panaracer tires and other brands.)

The Seal Smart sealant uses natural latex and walnut shells to make the tire airtight and seal it against the rim. Thanks to these ingredients, it’s non-toxic and low in allergens. Clean-up is easy, too.

Most of all, it works really well. With every tire we’ve set up so far, the tire sealed almost instantly and held its air for weeks without re-inflating. We’ve tried it on tires that were returned under warranty because the sidewall didn’t seal. (This happens very rarely when the rubber coating is a bit too thin.) Bubbles appeared on the casing, and the tires continued to lose air. With the new Seal Smart, two tiny bubbles appeared at first, but the tires sealed fine. We wiped off the bubbles, and they didn’t reappear – the tires were ready to ride.

Of course, every installation is different, and we cannot guarantee a successful tubeless installation. Especially with supple tires, it pays to be extra-diligent when distributing the sealant inside the tire to make sure it goes into every crack. And make sure to shake the sealant vigorously for a minute or more to distribute the solids really well: If you’re just injecting white water into the tire, it won’t seal…

The new Panaracer Seal Smart comes in 500 ml (17 oz) bottles – enough to set up 4-6 tires and replenish your sealant frequently. It is in stock now.

Further information:

About Jan Heine

Spirited rides that zig-zag across mountain ranges. Bicycle Quarterly magazine and its sister company, Rene Herse Cycles, that turns our research into the high-performance components we need for our adventures.
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26 Responses to New Sealant for Rene Herse Tires

  1. Damian says:

    Thanks Jan. The cost of delivery to Europe ($37.25) means this is uneconomic. Are there European distributors?
    Damian

    • Jan Heine says:

      Sealant is mostly water, so it’s heavy, and the 1 liter bottle will do a dozen tires or more, depending on your tire size.

      Our European distributors will have the sealant in stock soon. Check 2-11 Cycles in France, Dailybread in Germany, Sven Cycles in the UK, TacTac in Switzerland or Just Pedal in the Benelux.

  2. Eric says:

    Very cool! I use sealant in my ultra-supple tubular cross tires after the first puncture, and it has kept me running for hundreds of miles afterward. I wonder if this would be a better sealant for that purpose. 99.9% of the time, it’s just a teeny glass sliver…

  3. Rick Thompson says:

    Orange Seal has been working very well in my Snoqualmie Pass EL tires. There is some sidewall leakage but it does not seem to be a problem. Protection against goatheads has been 100% effective for over a year, no on-road flats. My main issue is that it dries up in 2-3 months and has to be checked and replenished. Would this new sealant last longer? If it seals the sidewalls that might be where most of the evaporation is happening.

    • Jan Heine says:

      We’ve used Orange Seal in the past, and it works fine. The new sealant works even better, and also doesn’t seem to dry up quite as quickly.

  4. Zach says:

    How does this sealant compare to Orange Seal Endurance or Stans? Is it mostly that the particles are finer?

  5. Eric Hancock says:

    Interesting. The walnuts are an unexpected twist.

    Can you share some details about how this differs from something like Stan’s regular or OrangeSeal? What is the expected replacement interval, and is it injectable via the valve?

    • Jan Heine says:

      Replacement interval depends. The more you ride, the longer it lasts. You can inject it through the valve after removing the valve core.

  6. Andrew Howe says:

    How much weight does sealant add to the tire, esp extra lights? And at what point is so thin pointless if they just have to absorb tons of latex in order to seal?
    I had some of those that were returned due to never sealing (tons of Orange seal over 6 weeks with wheels inflated, rotated, left on their sides, etc).

    • Jan Heine says:

      The sealant that the casing absorbs weighs very little, since the water evaporates. What is heavy is the sealant that is sloshing around in your tire…

      We’ve had very few tires that didn’t seal with Orange Seal. I think it may have been your tires which we used for the testing.

  7. Drew says:

    Will it work to seal punctures in butyl tubes?

    • Jan Heine says:

      Yes, you can use it in tubes, too. Make sure you are using new tires – if there are holes from old punctures, the air can escape there, and the space between tire and tube fills with sealant, creating a mess without sealing the puncture.

  8. Nestor Czernysz says:

    Why not a powdered version….just add water?:)

  9. SteveP says:

    A few extra questions, if I may. Does it play (mix) well with other sealants? Is there a recommended replacement interval? What is the low temperature limit (for use and for storage as well – some of us have unheated bike storage in the Lands of Snow) 🙂 Thanks

    • Jan Heine says:

      I’ve mixed it with Stan’s and Orange Seal, without problems. The low temperature limit is an issue with all latex-based sealants. Once it gets close to freezing, they don’t seal any longer. (Just like latex house paint doesn’t cure when it’s too cold.) We’re researching cold-weather sealants…

  10. Bern says:

    I’ve been deliberately avoiding this stuff for decades…you’re starting to break down my resistance.

    • Jan Heine says:

      Tubes are still a great option. They roll faster and are hassle-free. Unless you ride in terrain that is so rough that you risk pinch-flats all the time, I’d stick with tubes.

      • Stuart Fogg says:

        Have you tried the Tubolito plastic tubes? I haven’t used them long enough to comment on durability but they’re pretty light. I’m getting used to the orange stems.

      • Jan Heine says:

        Hahn had them during our first Japan trip. I don’t remember why he decided to switch back to butyl tubes.

      • Oscar Méndez says:

        Well, that´s honest. Nowadays everyone is “or tubeless , or go home”, so thanks Jan for pointing that out!

  11. James says:

    Love this product and the more natural approach to creating a sealant but unfortunately I can’t use it because of the walnut shells. My partner has a severe nut allergy and can’t risk sealant flying around the apartment. Interested to see what else y’all come out with in the future!

  12. SteveP says:

    I looked at the Tubolito tubes at a bike show – more for a roadie friend than myself. They would seem to appeal to true weight weenies (no offense) but limited in the size range (and what range of tire sizes each will fit) and at a high cost.

  13. John Duval says:

    Many sealants, especially natural latex, seem to spoil in the container long before it all gets used. 1 liter sounds like it would be wasteful.

    • Jan Heine says:

      The bottles have a stopper under the lid. As long as you put that back when you store the bottle, the sealant will last indefinitely. (This replaces the ‘factory seal’ which, once broken, exposes the contents to constant air exchange.)

      And there was a mistake in the original posting – the bottles contain 500 ml, not 1 liter. That will only do about 4-6 tires, plus you need more sealant to top them up. We don’t sell the small bottles, since you need three bottles for a set of tires. Then the temptation is not to use enough sealant, and that is when the problems start…

      • Kurt says:

        Your sealant will last longer if you push the air out of the bottle. Squeeze the air out and close the lid. It looks ghetto but it works.

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