18 May 2018

Without Air Or Tubes, In 3D.

Three years ago, "The Retrogrouch" wrote about one of the most interesting and enigmatic companies in the cycling world.

Zeus probably came as close as any bike manufacturer to crafting all of the parts for its bicycles.  Of course, they didn't draw the frame tubes, which were usually Durifort, Vitus or Reynolds.  But they, or one of their subsidiaries did  make all of the other major parts, except for the tires.  But you could still ride Zeus tires on your Zeus bike.  How's that?, you ask.

Well, there was a company in the US called Zeus that made them. But they weren't the kind of rubber someone riding a Reynolds 531 frame with Zeus 2000 components would have wanted.  The appeal of that tire, the Zeus LCM, was found more among novice commuters and folks who didn't want to get their hands dirty or scratch their just-enameled nails. (I can understand that!)

Those tires were airless and didn't go flat because they were solid polyurethane rubber.  I tried them for a half-century and a few days of commuting. I wondered whether I had just experienced what it was like to ride a "boneshaker"!  

As so often happens when a new product comes to market, people think the idea is new when, of course, it isn't.  And when it disappears, it will probably return and have another generation of consumers believing they've just witnessed the most wondrous innovation.

Well, it turns out that the airless tire has been revived during the past few years.  Three and a half years ago, The Retrogrouch wrote about a new crop of such rim coverings. 
They were not solid, like the Zeus, but like other offerings that preceded them, they had solid inner tube-like inserts.  

Now a German startup company, ProFLEX, has created its own version.  This one does not have an insert but, unlike the Zeus, it is not solid rubber.  Instead, it is supported by a complex honeycomb-like structure inspired by a car tire Michelin introduced last year.  That network mimics alveolar structures like the air sacs of lungs:  solid on the inside and more flexible on the outside.  

(Or, since we're talking about Michelin here, we could say it's the inverse of a baguette, which is crunchy on the outside and chewy on the inside.)

The ProFLEX has one more thing in common with the Michelin tire:  It is 3D printed.

ProFLEX tire

Although I am not sure I would switch over to such tires, I would be curious to try them. I wonder whether their ride is more akin to that of pneumatic tires (most likely heavy ones) or solid tires like Zeus.

None of these airless tires, by the way, should be confused with tubeless tires, which are filled with air and can therefore be flatted.  I know:  Bill and I stopped to help a fellow who'd just been sidelined with his tu
beless tires.  


  1. Interesting Justine. It doesn't look like they'd corner well, but who knows, maybe it'll be as good as sliced bread?

    Speaking of tires, did you ever try Specialized All Condition Armadillos? It seems like you can still buy them from Specialized (but not anywhere else that I can tell) ... I've been wondering how they might compare to Continental Gatorskins, it seems some people like them, while others do not. Typical I guess.

  2. Hi Justine, I also rode to work on that froggy, froggy morning (didn't see smoke however) and later in the evening during that Stormy, stormy Daniels commute (tried to beat it but I guess I misinterpreted my Storm Radar app, or it was wrong). I saw a large fallen tree across my path in Prospect Park, so had to continue down Prospect Park Southwest.

  3. Bet they would work well on a Mars or Moon bike...

  4. I can't comment on airless tires but tubeless are wonderful. Their feel is very much like a tubular. What isn't so wonderful is keeping up with the sealant. It's a PITA. If it isn't kept fresh and topped up you're going to get a flat. I've been caught out twice this way. It's prone to dry out especially in summer heat.

    I see that Finish Line has come out with a new sealant they claim never dries out. I'm eager to try it. It could be the answer to a prayer.

  5. My cyclocross bike originally had tubeless tires. Actually, it was set up for tubless tires, but the previous owner had given up on them and put tubes inside. I think they were Stan's.

  6. Monkey--I wonder whether Stormy Daniels had anything to do with that fallen tree! ;-)

    Coline--I wonder how they would work in low-gravity environments like the moon.

    Phillip and Steve--Thank you for sharing your experiences. As I've mentioned in an earlier post, I tried the Zeus airless tires and didn't like them. (At least I didn't have to pay for them!) I suspect other solid tires, or tires with a solid insert, would have a similar feel, but I would be interested in trying the "honeycomb" tires to see whether there's a difference. As for tubeless, I haven't tried them, mainly because I have so many tires and wheels that use tubes, but I'm not averse to them. If the Finish Line sealant is as advertised, or someone else comes out with a sealant that doesn't need to be replenished, tubeless may well be the future.