Tennis balls serve as decent bicycle tires that don’t easily puncture | Hacker News Reader

Tennis balls serve as decent bicycle tires that don’t easily puncture

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94 pointsrolph58 comments

Everyone who plays tennis knows that tennis balls don't retain their pressure for very long once outside their pressurized cannister, though. I can't tell if this article is just ignoring that fact or if they are actually running on "flat" balls. (Balls that are too flat to play with still have some pressure and might work fine, I guess, though it seems like riding on them would just flatten them more.)

Maybe that only matters for playing tennis. These look almost like the design of any other airless tire, only instead of a rubber tire with holes in it they are holding together the tennis balls to form this sort of shape. I think it only matters that they are able to hold their shape up, not that they remain springy or anything.

Maybe they are using practice balls, which don't go flat

I'm thinking that you want them to go flat. When they're fresh off the factory floor we can think of them as perfect spheres. So while riding one ball touches the ground at its maximum radius, then it falls off a bit, then rises to the maximum radius of the next ball etc, so the rider keeps going up and down a bit.

Once they become a bit flat the 4 sides will squash down into a cube type shape, also equalizing with its neighbors so that the overall shape becomes flat and the ride becomes a lot smoother.

Oh, I had no idea! How long does a tennis ball live, typically?

Not that long. A day, maybe, before they start to feel pretty dead for regular recreational play. As the level of play goes up the tolerance for old balls goes down. In top-level pro matches they get out fresh balls several times in a match.

You can buy storage canisters with pumps or other pressurizing devices that will keep the balls fresh longer. (And may even repressurize dead balls. I've never tried that but it seems possible.) Still even at my very low level of amateur play, in my ladder league it was expected that each player would bring a fresh, unopened can of balls.

> I can't tell if this article is just ignoring that fact or if they are actually running on "flat" balls

You mean flat ball, right? They have 30 balls in a tire. If one goes flat, then they are running on 29/30 balls.

he is saying they all systematically go 'flat' (easily squishable, not firm) after they are out of their pressurized canister for a while. he isn't saying that one will randomly go flat.

This hack has been known to the dirt bike community for a while now. https://www.google.com/search?q=dirt+bike+tennis+balls&tbm=i...

Also, there's no need to make this so complicated, you can just shove the tennis balls into a normal tire.

For normal world applications, a tubeless[1] setup will perform infinitely better. Though less eye-catchy.

[1] https://www.bikeradar.com/advice/buyers-guides/tubeless/

I have two bikes - one tubleess, one tubed.

On my tubed bike, other than 1 or 2 flats in the last 5 years, these tires have required 0 maintenance. Even after dusting the bike off from the winter, they pump right up and are ready to go.

My tubeless tires are a constant source of headache. They are constantly going flat, sometimes weekly, requiring more sealant, stuck valve cores, etc.

Overall, I'd say my tubeless tires require monthly maintenance, while my tubed tires have basically never required any thought at all. What am I missing here?

I have a similar experience with tubeless, maybe half the time I setup a tubeless tire it works for weeks without refills, the other half i have to reinflate one a week. However it’s worth it because the reason I go tubeless is to have very low PSI for comfort, like around 30 PSI, can’t get that with tubes.

I would suggest looking at different tyre brands or models. I have been running tubeless (on road) for about the past 3 years...varying between 30mm and 42mm (gravel bike, but running basically slick tyres).

Different tyres have different wall constructions, and so some can leak a lot of air. I find that after I put on a new tyre, they leak air for the first couple days, but it's greatly benefited by going for a few rides (the extra pressure gets the sealant into all the nooks and crannies of the tyre casing, filling the gaps), and then maybe lose a PSI or two per week (when I run at 50psi).

I change sealant about every 6 months, just because it dries up. Not particularly due to fluid leakage.

For sure part of it has to do with my fancy ultralight Rene Herse tires.

That’s interesting. On my mountain bike that (used to) get a lot of constant use, tubeless was much better than my old MTV with tubes. When the tubes get a flat it is a whole process to get it patched, but tubeless both seem to get less flats and seal better with whatever I put in them.

That being said, tubeless tires do require being used fairly regularly, which includes pumping them up (just topping them off) almost every time you go out. Right now I haven’t gone mountain biking in quite a while so I guarantee that my tires are flat

idk there's some finesse I had to learn when switching to tubeless. They do need a little maintenance and it took a while to get a feel for it and not cause more problems.

If you're only getting 2 flats in five years though yeah stick with tubes. I get 3-4 a year and they're much less of an event with tubeless, so the extra routine work pays off.

Sometime I would go a year without flats and sometimes I would get like (this was worst ever) 5 in a month.

A lesson I've learned over years of cycling and maintaining other kinds of machines, is that all fluids require maintenance. Of course the air in the tires is also a fluid. But introducing yet another fluid to overcome a maintenance issue, is virtually guaranteed to introduce yet another maintenance issue. Ultimately it comes down to a matter of tradeoffs.

Well said. Tubeless is fora shaving off a few grams from the wheels, which translates to a very low (but measurable) energy saving on acceleration.

"Sealant, poured into the tyre or injected through the valve, helps plug any tiny leaks. This sealant stays liquid inside the tyre and will heal small punctures suffered while riding."

Isn't that basically the same as Slime, which is (from what I understand) widely reviled in the biking community?

No. I've been riding a road tubeless setup in Seattle and surrounding countryside for half a decade now and the feel has nothing to do with Slime. 55mm x ISO 559 lightweight road tires with Orange Seal. (In the NW we like wide road tires : )

Something like 10k miles later I've had zero incidents where I had to fix something on the road. You do have to more maintenance (e.g. make sure you have adequate sealant in the tires periodically) but for regular year round use especially, it is a worthwhile trade.

Not sure about road biking, but at least in the mountain and gravel communities it's almost universal. There are 3 popular sealant brands that I'm aware of: Stans, Orange Seal, and Slime.

I have been riding and racing bikes since 1990, and I think tubeless is one of the best real innovations. Fixing flats sucks.

There are (small) differences in wheel and tire design to support the sealant based system, and that makes all the difference I guess. Slime tubes are pretty reviled, tubeless is the hot thing. Besides being more reliable it also allows for lower pressures, which is probably the main reason it has become popular. There is very little downside for riders (tubeless is just a bit slower than high end tubes that very few riders use), but for the home mechanic they’re a bit of a pain to work on.

People do get annoyed with tubeless to be honest. Its a mixed bag of people who like it because the rolling resistance is 1 watt lower, and people who hate it because its a lot more maintenance keeping up with sealant and hard to patch sometimes compared to just throwing in a new tube (which a lot of tubeless users end up doing when they get a puncture flat anyhow).

Not sure if they still make them, but some many years ago I tried out some Slime tubes that had the stuff built into the tube somehow. Not only did it not work to seal punctures, it was impossible to patch.

I like the slime inner tubes. They've saved me a few times. Only on lowish pressure tyres though, I can't imagine they work well on a road bike.

On a vacation, got thorns in tires a couple of years back, my wife and I grounded until the local bike shop could get around to it.

So these tennis tires, vs what's on that bike now, perform

- worse now when good

- worse than now four weeks out (noted elsewhere, tennis balls decay fast, but

- better than now with punctures today.

Now, this is a 'clever' way to solve that. The long term solution might be 'thorn-resistant tires' (wish we'd known up front -- but they say 'resistant' not 'proof' for a reason), but if you can live with the performance hit in favour of the failure tolerance ('oops, gotta replace six balls today, not like two yesterday), I can see use cases where that's a go.

Yup, should have had a full set of spare tubes. Know that, got spares, but I don't expect three of four tires to go flat on the same day.

I guess the takeaway is, tire innovation still has some fruit to pick.

On the build versus buy axis, Solid bicycle tires are an ordinary product.

https://www.google.com/search?q=solid+bicycle+tires&ie=UTF-8...

They predate pneumatic bicycle tires.

In my country, children use tennis balls (they are cheap) to play some version of football in halls or some enclosed space. The tennis ball is shaved because it will get dirty and wet. It results in an extremely slippery and bouncy ball.

It is interest that from a functional perspective these are just traditional tires with thicker walls to prevent punctures and internally compartmentalized to reduce the impact of a puncture.

Its the same design as any other airless tire, whether it be on an electric scooter or a skid steer

it reminds me of the Titanic - because one of your compartments can get a puncture but it definitely totally won't affect any of the other ones at all.

How’s the braking performance? Wouldn’t the tennis balls function as a kind of high-friction ball bearing, and allow the outer tire to slip when stopping?

The balls are inserted into PVC rings, which are screwed to the hub, so they can't move. (In my mind this also means that the tire is made of PVC rings and that the balls serve more as decoration, but hey)

Exactly! Surprised I had to read this far down for anyone to realize that little detail. To be fair, the balls kind of spread the covering tire out beyond the rings...

I'm concerned about the tire slipping off on a corner, too.

Yep, that was my thought has well, certainly the in video they didn't show any type of turning with any amount of lean into it where this would have been an issue.

Seems like a gimmick to me.

I've been commuting with reinforced tyres (puncture protection) for 10 years now, and the only punctures I got was when I changed bike and did not upgrade to reinforced tyres straight away. I've not had a single puncture with reinforced tyres (though I get the most reinforced you can get). It's anecdota of course, but I'd love to know if people actually get punctures with that sort of tyres.

And this is not by virtue of having clean roads. There are potholes and there is a lot of glass on the cycle lane. Nowadays I don't even bother trying to avoid glass shard and just go straight in. One time I came home with a 0.5cm glass shard stuck in my tyre. It had not punctured the tube.

I don't have experience with tubeless designs or solid tyres, but they solve the issue as well.

Doesn't the metal ring used to bind the tennis ball lose all the springiness?

Looks like it's plastic. PVC I guess.

Okay, dumb question from someone who rides a bike but is not a "cyclist."

Road bikes have a pretty high tire pressure, to the point that the tire itself basically offers no cushion at all, on it's own. Why are these tires pneumatic at all? Why not wrap a rubber donut around the rim and call it a day? I'm sure part of the answer is weight, but surely this can be reduced either by making the rubber relatively thin, or using some sort of hard closed-cell foam underneath the rubber layer?

They exist and are called "airless tires". Tannus is one of the most popular brands:

https://tannusamerica.com/pages/tannus-airless-tires

They're solid foam and can't go flat. They're not very popular because they don't perform nearly as well as tires with tubes. They have a higher rolling resistance (ie, you have to pedal harder to go the same speed) and have a rougher ride.

Good quality tires don't puncture that often and, for most riders, are worth the trade off.

Even at 100psi, there is significant cushioning behavior from a pneumatic tire for contact patches the size that road tires do.

Solid tires crawl around the rim as you ride them. Okay for very low speeds; not okay for cycling speeds.

Bingo! That's the main reason why. Compressibility of the tire turns rolling friction into a translational force. Pneumatic tires also experience a translational force that tries to push the tire back and off the rim as it interacts with the ground.

In case you don't know, you probably don't need to pump your tire up to the stated pressure on the side of it.

Check out these guides for more specific numbers, but generally if you're ~160lbs, you can get away with 80psi or lower when running tires wider than 25mm.

https://silca.cc/pages/sppc-form

https://axs.sram.com/guides/tire/pressure

extra weight not ok

Looks a bit like tire inserts - basically foam rings you put inside the tire, common on mountain bikes. I just installed that on my bike, which not only protects my rims but also lets me ride home from the trail with a flat tire. https://www.bikeradar.com/advice/buyers-guides/best-tubeless...

During WW1 several types of military bicycle used springs in a similar manner:

https://m.facebook.com/UlsterTransportMuseum/photos/a.461285...

Inshallah someone will commercialize this and make it with actual tennis balls. I must do this.

Not using tennis balls, but this has been a real product for atv tires for a while: https://www.powersportsid.com/tireballs/

this caught my eye as similar to a concept from long past readings its not a new concept,

e.g https://www.evolutionwheel.com/blog/advantages-of-segmented-...

this was proposed for consumer automotive, as a tire with a number of wedges/segments with a sealed pneumatic core. you would buy an allotment of these tire segments and replace individual ones in moments as need be. maybe i read about it from a mid-80s issue of Omni.

i thought the bicycle would be a good start vs cars n trucks

I think Continental had something similar near production already but cannot find a link.

edit: looks like every tyre manufacturer has an "airless" product:

https://www.bridgestone.com/technology_innovation/air_free_c...

https://corporate.goodyear.com/us/en/responsibility/blog/adv...

https://www.michelin.com/en/innovation/vision-concept/airles...

The Michelin tire was on HN in 2019, with 131 comments:

https://news.ycombinator.com/item?id=20113174

This is innovation. Do stupid shit and see if it works.

stop describing my scientific method

This is wicked cool and I want it on my fatbike asap! Might need to attempt and DIY this.

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