Maybe your new year’s resolution is to lose a little weight. Riding can be a great way to get yourself out the door and on the way to fitness, but you actually have to get the bike down from that hook in the garage and do it. I’m assuming that for most of us reading the site on a regular basis, the threat of a puncture and the need to inflate your tires on a regular basis isn’t a deterrent to getting out for a ride. But for a large chunk of the population who ride far less often, flats and under inflated tires are a big deal. In fact, Specialized cites a study from German Sport University Cologne that claims up to 90 percent of cyclists ride with under inflated tires, and 55 percent of riders have at least one puncture per year. That may not sound that bad, but when you lack the ability or desire to fix a puncture yourself and you end up having to bring it to a shop (or having the shop come to you), all of a sudden your quick ride becomes an ordeal.

Rather than dwelling on the rider’s ability to fix a flat, with the help of Tannus, Specialized is taking a completely different approach – airless tires. This certainly isn’t the first use of airless tires in the bicycle world (technically, the very first tires were airless as solid rubber). But just like all the other components of the bicycle, the technology has drastically improved with the times. Tannus announced their newest airless tire back in 2015 with their Aither 1.1 which promised better ride characteristics while maintaining the completely flat free feature.

Now, that same technology is available on the Specialized Alibi for a truly maintenance free tire that never goes flat and never needs air…

Bottom photo c. Specialized

Emanating from South Korea, the Aither 1.1 tire is completely made of a special EVA foam they call Alpha Olefin Block Co-polymer. Similar to the EVA foam used in athletic shoes, the millions of microscopic air pockets in the foam provide the tire some ‘give’ for a ride that mimics that of a tube tire, but remains completely puncture proof. There is no rubber or coating of any sort on the tire – just foam that goes into a mold. Because of that, Specialized says you shouldn’t try any rad skids and like we’ve seen on other airless tires, grip in the wet might be compromised. Equipped as a 700 x 38c tire, Specialized claims the tire and clip system has the same weight as a Nimbus Armadillo 38mm tire and tube at 900g. It also has the added benefit of being 100% recyclable.

Manufactured with the same tread pattern you’d find on a Specialized Nimbus tire, Specialized rates the tires to 3,000 km (1,864 mi).

While the Aither 1.1 tires can be mounted to many standard 21mm internal rims, in this case Specialized chose a specific rim that is 21mm wide (internally) and a bit deeper that would provide the best handling and stability for the tires. Each tire is mounted to the rim with a number of plastic tongues that thread into the tire and then snap into the rim with a special tool in about 15-20 minutes. Once the tire is worn out, you will have to take it to your local Specialized dealer to be replaced – either with another Aither tire or a standard tubed tire. The rims fitted to the Alibi will still accept a standard tube and tube type tire, even though the valve holes have been covered over with stickers.

Elsewhere on the bike, the Alibi Sport is exactly what you would expect from a $550 fitness hybrid, and more. At this price, you’re not going to be getting super high end components, but the Shimano Altus 3×8 drivetrain includes an 11-34 cassette, a Shimano triple, and EF500 EZ Fire Plus shifters with integrated brake levers. Bonus points come from the use of a standard stem (no adjustable quills) and a funky handlebar with a cross brace and Body Geometry Ergo grips. Along with the Milano saddle and large Specialized City Platform pedals, the touch points are all extremely comfortable.

The frame also has some features typically found on higher end bikes with internal cable routing and hidden fender mounts (shown installed above). There are also plenty of braze ons for racks front and rear. Called Rainbow Tint/Black Reflective, the paint on this bike is a brownish-grey with deep metal flake that sparkles in the sun and black reflective decals – which is a nice touch.

For a large hybrid, 27.69 lbs with pedals, a bell, and a kickstand (not included) seems like a very reasonable number.

First Impressions

This isn’t exactly the kind of bike I’d normally be excited about reviewing, but in this case I was very curious about the airless tires. I couldn’t wait to get the thing out on the streets, so as soon as the box arrived I was in the shop putting it together. I have to say that as a (former) obsessive compulsive shop mechanic, the build on the Alibi Sport was impressive in terms of things being greased and properly assembled. The only real issue came from a rattling in the front wheel. After pulling off the sticker that covered the empty valve hole, I was able to shake out an aluminum disc that was left inside the rim from the valve hole being punched. These kinds of things happen all the time so it wasn’t a big deal, just something that you may want to check.

Once assembled, it was straight out for a test ride where the tires felt… mostly normal. Honestly, on smooth pavement, most consumers would probably not even realize they were on different tires. There is a bit of compliance to the Aither tires that makes them comfortable to ride, though they do ride like a 38mm tire inflated to 55-65 psi. The only time you may notice that something is different is on big impacts – riding over sewer grates, curbs, etc. In these instances, the tires do have a noticeable thud that is a bit more aggressive than a tube type tire, but you have to consider that big impacts on a tube tire could result in pinch flats rather than just discomfort. I have yet to ride the bike in the rain, but traction on dry and damp pavement was certainly adequate.

Ironically, after riding around town and down to one of my favorite photo spots in an alley behind buildings which is notorious for flats, I got back to my shop and found a small piece of metal sticking out of the tire. Surely, this would have caused a flat on a normal tire, which is one of the strangest parts of this bike – I’m so pre-programmed to carry a tube and a flat kit, that I feel almost naked taking it out for a spin. Never again do you have to worry if your tires are inflated to start the ride, or worry that you’re going to get far from home and get a flat (or multiples) and run out of tubes/patches/boots/etc. You may not even think about it, but the ability to leave the pump and flat kit behind provides a sense of freedom that many casual cyclists will love.

Now, is this going to replace my bikes with tubes/tubeless/tubulars? Of course not. While the Aither tires seem to offer plenty of performance for those interested in a bike like the Alibi Sport, there are still performance advantages to be gained from more traditional tires. That isn’t to discount the Nimbus Airless tires and the Alibi Sport however. I liked the bike so much that I bought it and gave it to my dad for Christmas. Realistically, he’s the perfect use case for the Aither tires. Riding mostly in good weather with my mom on camping trips or occasional jaunts around the neighborhood, in his case the peace of mind provided by never having to use a pump again seems to outweigh the performance benefits of a standard tire. Or at least, that’s my theory anyways. In reality, this will be a great opportunity to see what he thinks of the tires after a season of use and how they’re holding up.

Specialized Nimbus Airless tires are available on the Alibi, Alibi Sport, and Alibi Sport EQ in both standard and step-through frames from $490-$600.




  1. Champs on

    Urban tires are already quite good at preventing flats. Airless tires just skip the part where you have to pump them up.

    Think about that first balmy day of the year, when countless casual riders are deterred by some minor issue then take their bikes to the shop just so they can complain about the repair backlog. With a belt drive and airless tires, your bike is basically ready for any impromptu ride. I don’t know if that makes it worse for the LBS or people looking for excuses not to ride.

  2. TomM on

    I love this. If flat tires are truly a major deterrent to more newbies riding and getting fit, this seems like such a great idea. Glad it seems to ride well too. And I like Champs’ idea of adding belt drives (and reliable internal geared hubs).

  3. pmurf on

    I think Champs hits a really important point about the warm-weather casual rider. As a former mechanic, it sucked to see people come in with their bikes in april/may because of a flat tire…they just wanna ride the greenway with their kids. An hour later you’re telling them that dry rot tires, 2 bad tubes, and labor is $60-75 to fix. Can’t really blame them for saying “nah” and taking their kids to Dave & Busters instead.

  4. Langstergangster on

    Such a garbage bike. It rides like hospital wheelchair and the component choice is absolutely crap. Sans the continuous tire failure that many have tried for hundreds of years the bike could be decent with am internally driven hub w/ belt drive, if you are looking for something for people who want a low maintenance bike. The people who would buy a bike like that have no need for a front derailleur and lubing a chain. Plus the low end derailleurs tend to need more work and more time in the shop.

    Specialized makes some decent bikes and has enough money to make an affordable low maintenance belt driven bike that is not based around a failed idea from over a hundred years ago.

    • Casey F. Ryback on

      That really ISN’T a garbage bike – it is mostly all name brand componentry in the drivetrain, and barring any damage from collisions or rust, it will work just fine for a long time. Just because you run high end components on your bike doesn’t mean that your average first-time-rider will spend that kind of money. Shimano Altus works surprisingly well.

      Plenty of companies offer off-the-shelf belt-drive internal hubs, but I’ve never seen them cheaper than the $700 or $800. Unless it’s a 3 speed Nexus, which has a very impractical range for the new cyclist, it isn’t gonna happen.

    • Runwhatubrung on

      Our shop has sold several of these bikes since getting them in September and all of the riders have loved them. The base model Alibi actually comes without a front derailleur and sells for under $500. I’m not sure what kind of components you are expecting on a bike for less than $600, but the parts are actually very comparable to what a bike of that type and price typically comes with.

    • Michael on

      When I first read your response I was annoyed because I just bought the Alibi Sport. But you are 200 percent correct!!! I rode it today for the first time after picking it up and I absolutely hate it!!!!! The bike looks good and I got the pretty red. Otherwise it sucks!!! The tires are a complete joke and the ride was miserably brutal. It handled horribly. Uncomfortable riding position. The rolling resistance was a humongous issue. Yep I hate this bike!!! It was so bad I only could ride 3 miles before turning around for home. I usually do 10-25 miles easy no problem. On the way back I got off and pushed it home probably 2 miles because of just how bad it was!!! I’m not even kidding. The gears didn’t feel right and peddling was very labor intensive. A most horrible experience. If anyone is considering this bike they should really spend some time before buying. I wanted to throw it in the woods and finish walking home. Bikes are should be fun, but not this hot mess!!

  5. CW on

    I’m not remotely impressed with these tires. They ride really hard, like hurt your wrists riding over cracks in the pavement hard, and the grip is comical. If it’s even a little wet, or under 50 degrees, they are like riding on skateboard wheels. You can loose traction with the slightest change in tire angle. It’s a good concept, but the people that this bike is marketed may not have the experience to correct a slide or put their foot out to keep their front wheel from washing out, things Ive had to do on different occasions of riding these bikes.

    • Michael on

      I was fooled into thinking today’s technology the ride will be ok….. ha!!!! Just riding in the store’s parking a few minutes is not enough to get the true feeling of these tires. But as soon as I rode away from home and noticed on the way to my 31 miles of nicely paved bike trails there was serious issues. I bought the Alibi also because it was lighter than my nice Cadillac peddling hybrid comfort bike. I wanted to travel further and faster. I could get that heavy comfort bike over 20mph and Averaged 12mph with a nice cadence. This bike no way!!! I might have got it topped out 12-14 and not long. Now my dilemma what do I with a $550 bike I hate???? Not sure if the dealer has returns on special orders as this was. Tomorrow I take it back to see if they can make it work for me!!! This should not happen with a $550 bike!! My $200 comfort hybrid was heaven and this $550 Alibi is hell!!!

  6. Rey Bingham on

    “Emanating from South Korea, the Aither 1.1 tire is completely made of a special EVA foam. . .” I’m imagining thousands of these tyres floating across the Pacific like a stale fart. . .

  7. Mike in C.C. on

    ” Once the tire is worn out, you will have to take it to your local Specialized dealer to be replaced”. Yea, no thanks. These will be expensive and wear quickly. This is a solution in search of a problem, IMO.

  8. OldFartCyclist on

    Seems like the point is being missed here. This is intended for the rider that will not be out when it is wet and is not going to ride fast enough to feel the difference in ride. If my wife had these on her and didn’t have me to take care of her flats and mechanicals, she would still be entusiatic about riding. Me? I will stick to my 300 – 325 gram combos of Conti 4000 and tubes. I have few flats since changing to these on my bikes. They are the best tires I’ve found for my area, leaving the Michelin Pro 4 far behing in terms of durability. Tires make a difference, changing depending on circumstances.

  9. Kimball Kaleach on

    I absolutely love this bike! I live in an area where flat tires are very common because of the thorns. And don’t tell me about so-called thorn-proof tires. I have been through it all: thorn-proof tires, gallons of slime, goop lined innertubes – nothing comes close to these tires. Now, I never worry about flats and it is a pure joy. This bike rides no harder than freshly pumped air tires. Super quality, very quiet, tight frame, low maintenance, beautiful handling, precise quiet shifting, and best of all, I get to ride it without ever pumping up those tires! (deleted)
    I have purchased 3 new bicycles in my life, and a myriad of used ones. This one by far is the finest ride I have ever had.

  10. AdizzleSells on

    I did a test ride on this bike and loved the minimalist feel to it and comfort. Yes- I did wonder if over time I would want a suspension system and I wish there was an ad on option for disc brakes. For $550 it’s a great bike-How many people get a flat-then the bike sits in the garage until it’s so dusty it gets sold or donated. This is a game changer-esp for those of us who hate to change tires, but want to ride 15-30 miles.

  11. Jerry Taylor on

    I had a Specialized Globe for yeas and thought the Alibi would be about the same. The airless tires feel like putty to me. They absorb a lot of the energy of pedaling making it feel like riding uphill. I’m going to put the pneumatic tires on to see if it is easier to pedal.

  12. Michael L Sherrard on

    We have had two Alibis in HI for a couple of years. Bought them used from Napa Bike Rental in California and shipped them over! My wife lover hers. She never has to call me when she gets a flat. I love mine. Sure, they are heavy and a stiff ride, but the tires never go flat. I put panniers on mine and a suspension seat post that helps the ride. I may go slower but I get the same workout in an our, and I take it places I cannot go on a MB or RB. I am thinking of putting front suspension on it. It goes over rocks, it goes over sand, it goes over expansion cracks, it goes over thorns. It even goes through lava! I call it my Lavabike and I love it.


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