Specialized Alibi review£400.00

Hybrid bike with stock airless tyres

BikeRadar score3.5/5

We’ve all been there, riding with the family, towing a load of groceries or half way to work on a rainy commute and bang (well maybe not bang, probably more of a ‘sssssssss’), and you have a flat tyre.

For a lot of you reading this review, a puncture is a minor inconvenience, five minutes max and you're up and running again. But, for the majority of the population it means a trip to the bike shop, money out of your pocket and maybe a day or two without your bike.

Then there is the fact that the majority of people are riding around on under-inflated tyres. You only need to stand next to your neighbourhood bike path or a college campus to observe this, and as you probably know, under inflated tyres lead to pinch flats.

So for the latest edition of its Alibi fitness bike, Specialized has decided to solve this problem once and for all by speccing the bikes with its own Nimbus Airless tyres.

No pumping required

The Nimbus tyre, is actually a Tannus Aither 1.1 with a Nimbus tread pattern
The Nimbus tyre, is actually a Tannus Aither 1.1 with a Nimbus tread pattern

Solid airless tyres are not a new innovation and have been around in the bike industry for some time now, and when they first came out offered about as much dampening and traction as skateboard wheels.

However, as with everything else, they have improved significantly and are now a viable option for some riding applications.

While the tyres are branded as Specialized’s Nimbus, they are in fact a Tannus Aither 1.1 with the Nimbus tread pattern. Tannus is based in Korea and also makes foam rubber for running shoes and football helmets, producing its first prototype airless tyre back in 2004.

Thirteen-years on, the Aither 1.1 is the brand's latest tyre and is made from ‘Micro Closed Cell Polymer Resin’ with a structure similar to that used in lightweight running shoes. There is no rubber in this tyre, it’s just foam that goes directly in the mold to make the tread pattern. Like with athletic shoes, the tiny little air bubbles in the structure of the foam allow it to squish a little bit for more compliance.

According to Tannus, the “Aithercompound” uses a unique foaming process that offers good grip and low rolling resistance. In fact, it goes as far as saying that the Aither 1.1 "now has the rolling resistance rate that closely matches premium pneumatic city bike tires, taking this a step closer to ideal bike tire.”

The rubber, or foam rather, that comes on the Alibi is a 700x38c tyre and is mounted to the rim using little plastic beams that are snapped into the tyre bead of the rim with a special plastic tool. To do it yourself can be a fairly fiddly and labour intensive process, but luckily Specialized has taken care of the heavy lifting.

Hidden under that sticker is a valve hole, just in case you decide to swap to standard tyres
Hidden under that sticker is a valve hole, just in case you decide to swap to standard tyres

Specialized Alibi ride impression

So how do they ride? I have been riding around town on the Alibi for a few months now and the Nimbus tyres feel a bit like an extremely over-inflated tyre and are quite hard.

Slotting in under a grand, the Alibi offers decent performance and parts for the money

Big cracks, curbs and manhole covers send quite a shock through the saddle and handlebars. There is some definite give to the solid tyres, but it doesn’t quite measure up to a pneumatic version.

In the past, there has been a sizable difference in rolling resistance between a standard and airless tyre, with the latter feeling like you're riding with the brakes on. The Nimbus tyres on the other hand roll pretty well and the gap between the two different types of tyres is considerably smaller.

There is still a bit of extra rolling resistance, but let's remember this bike isn't doing turns at the front of the peloton.

Considering the speed this bike is going to be ridden, the foam tyres offer plenty of traction on dry pavement and I didn’t feel as though quick corners were going to result in a wheel breaking loose and ending in road rash. When it’s wet however, the tyres were noticeably less sure footed and the foam doesn’t provide the same grip that a rubber tyre does.

Specialized says the Nimbus tyres should last 3,000km / 1,864.11mi, but unfortunately when you do need to replace a tyre, unless you have the Tannus tool, you’ll need to go to a Specialized dealer to get it replaced, but you're not necessarily locked into another airless tyre. Should you want to swap back to a regular tyre and tube, the Alibi rims do have a valve hole, but it's hidden under a sticker. Once the airless tyre is shot, it's totally recyclable too.

It’s more than just about the tyres you know

The cables are internally routed
The cables are internally routed

Slotting in under a grand, the Alibi offers decent performance and parts for the money. The alloy frame is high quality with smooth welds, and has rack and fender mounts galore. I just wish it wasn’t Marine Blue.

For me at least, if I’m running errands and leaving my bike locked up somewhere I want it to be the most drab boring looking thing so that when a thief is choosing their next victim it's somebody else's bright blue paint job that catches their eye. That said, in the US and Australia it comes in black too.

The use of a standard stem and bar is also a welcome addition as it will stand up to more abuse, be easier to maintain and is lighter too.

Using a tried and true fitness geometry, the Alibi puts you in a comfortable upright riding position that also allows you to maintain good steering control. This in combination with the Body Geometry Ergo Grips and Milano saddle, complete with scuff guards, means you can cruise along taking in the sights rather than being distracted by how uncomfortable your derrière and hands are.

The Alibi also comes with Specialized’s City Platform pedals, which measure 100x100mm and are textured for surefooted pedaling.

The City Platfom pedals offer tons of surface area for a good connection with your foot
The City Platfom pedals offer tons of surface area for a good connection with your foot

It seems Specialized designed the Alibi around simplicity, and while the more expensive models come with a triple chainset, my test sample only had one gear at the front.

This does limit the gear range available, but in combination with the Shimano Altus/Tourney mix 7-speed drivetrain, complete with a 34t MegaRange cog, it should be more than enough if you live somewhere relatively flat. Plus, with no front shifting and a solid chainring guard you won’t have to deal with a dropped chain either or greasy chainring marks on your calf.

Speaking of the chain, Specialized has equipped the Alibi with a KMC rustproof chain. Given that I have seen a Shimano Dura-Ace chain develop rust when left unattended for 15min after it's gone through a chain cleaner — and the inside of my aluminium (you know the metal that’s not supposed to rust) BBQ is rusting  because of salt spray off the ocean — I’m in the perfect position to test this claim.

Throughout the test period I stored the Alibi in the full bore of the ocean spray and so far the chain is completely rust free. There was a touch of surface rust on the cassette, but some WD-40 an old pair of undies and some good old fashion elbow grease cleared that right up.

While not as capable as discs, the standard V-brakes are much less temperamental and offer plenty of clearance. Oh, and they work pretty well too with little to no maintenance or adjustment.

Fuss free

Specialized's Alibi is a fuss-free fitness or commuter bike
Specialized's Alibi is a fuss-free fitness or commuter bike

Specialized's Alibi is about simplicity and reliability. With no tubes, and air in the tyres, you don’t have to pump them up or worry about flats.

There are some great urban tyres out there that nearly allow you to ride over a bed of nails, but you still need to remember to put air in them. It doesn’t matter how much puncture protection a tyre has, if it’s under-inflated it will eventually pinch flat.

Tubes fail too, especially if a bike sits in a garage for months at a time between uses it's not uncommon for tubes and tyres for that matter to literally rot away.

Yes you could argue for ultimate reliability you need a belt driven internally geared hub, but that would drive the cost up, and priced at £400 / $490 / AU$625 it's pretty thrifty — and the Shimano drivetrain, especially with only one chainring, at the front is simple and extremely reliable.

For someone who just wants get out and ride to maybe lose some weight, get the kids outside or for a quick trip to work, and doesn’t have a big budget, the Alibi is worth a look.

Colin Levitch

Staff Writer, Australia
Originally from Denver, Colorado, Colin now resides in Sydney, Australia. Holding a media degree, Colin is focused on the adventure sport media world. Coming from a ski background, his former European pro father convinced him to try collegiate crit racing. Although his bright socks say full roadie, he enjoys the occasional mountain bike ride, too.
  • Age: 25
  • Height: 175cm / 5'9"
  • Weight: 70kg / 155lb
  • Waist: 81.3cm/32in
  • Chest: 90cm/35.4in
  • Discipline: Road, mountain
  • Preferred Terrain: Tarmac mountain climbs into snow-covered hills
  • Current Bikes: BMC TeamMachine SLR01, Trek Top Fuel 9
  • Dream Bike: Mosaic Cycles RT-1
  • Beer of Choice: New Belgium La Folie
  • Location: Sydney, Australia

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