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Air Free Tires

Update September 2015: I have not used these tires in over four years since selling the Ultimate Commuter Bike 2.0. Furthermore, for my race bikes I switched to tubeless tire with sealant, which have all the advantages of conventional tires (fast and good ride quality) and airless tires (no flats). I highly recommend tubeless tires instead of the solid Air Free Tires in this post. See my post on tubeless road tires.

A couple of weeks ago, on a beautifully sunny day in Northern Colorado, I went into garage and looked at Carrie, a.k.a. Ultimate Commuter Bike 2.0. I had a meeting to go to in town and it seemed like a perfect day to go there on a bicycle.

I rolled her out only to be slightly distressed by this: a squishy flat tire. No, make that two flat tires! Shaking my head, I leaned the bike back against the wall in disgust and jumped in the Alfa Romeo instead.

This was the second time in a month that a flat tire on the commuter bike prompted me to use an internal combustion engined vehicle instead of pedaling. Clearly, if the bike was to live up to its billing as the “ultimate” commuter, it was going to have to be a little more reliable. Something would have to change.

I decided to try a product I’ve researched ever since getting a frustrating three flats in the 2002 Knoxville Double Century: Air Free Tires. Air Free is a distributor of closed-cell polyurethane-nylon tires that don’t require air and hence cannot go flat!

Solid tires have been around for eons—they were the dominant tire type on all types of vehicles before Charles Terront won the first edition of Paris-Brest-Paris on Michelin tires, which popularized the pneumatic design. However, they fell out of favor for various reasons.

Cycling guru Sheldon Brown explains,

Airless tires have been obsolete for over a century, but crackpot “inventors” keep trying to bring them back. They are heavy, slow and give a harsh ride. They are also likely to cause wheel damage, due to their poor cushioning ability. A pneumatic tire uses all of the air in the whole tube as a shock absorber, while foam-type “airless” tires/tubes only use the air in the immediate area of impact.

Airless tire schemes have also been used by con artists to gull unsuspecting investors. My advice is to avoid this long-obsolete system.

Sheldon’s warnings were enough to dissuade me from trying airless tires for four years—until now (being fed up with dealing with flats while commuting). During that time, Air Free Tires—whose website went live in 1999—has managed to stay in business, indicating that it was more than just some “crackpot” scheme. Yet, there seemed to be few reviews and lack of consensus on these tires, mainly because few people—perhaps scared off by claims such as Sheldon’s—refused to try them.

Indeed, most online discussions about them were generally held within recumbent circles who are more apt to try something different. Yet these discussions were somewhat (unintentionally and ironically) undermined by Air Free Tires’ founder/president Hugh Waters, who expected to produce a new, resilient “Open Road” line of airless tires which would offer as low rolling resistance as top-of-the-line Michelin pneumatics. Those posts ultimately had these effects:

  1. They gave readers the impression that Air Free’s existing stock of road tires must be woefully inadequate if Hugh was saying “just wait for our Open Road tires.”
  2. They made customers like myself put off trying Air Free’s existing tires and wait for the Open Road tires (which never made it to mass production, I think).
  3. They caused other readers to discount altogether the discussions on the assumption of bias since so many threads contained page-long posts by the president of a major source of airless tires.

It’s a pity, because after trying the tires myself, I’ve concluded that not only have modern airless tires been unfairly maligned, but they are a very viable alternative to pneumatic tires. Below are my impressions from both objective and subjective tests.

The Setup

I ordered a pair of Air Free Daytona HP (HP = “high performance”) 700×20 tires for my Cannondale CAAD3 bicycle. This is a bona fide race bike that Mario Cippolini rode to many stage victories in the Tour de France in the late 90s that I am nevertheless using as a (fast) commuter bike. The frame is extremely stiff and was accused as being one of the harshest riding frames in the world. (Indeed, Cannondale introduced S-bend chainstays and designed in more resilience into subsequent model lines to address these claims). You would figure that if tires were exceedingly “harsh”, I’d feel it with this bicycle.

Before mounting the Air Free Daytonas, I had been riding the bike with a Michelin Axial Select tire in the front and a Continental Supersport Ultra in the rear. These are the benchmarks for my comparison tests.

Carrie with her new tires during a nighttime commute ride.

Ordering from Air Free

In the message boards, many people said that Hugh Waters was great to deal with (including taking the time to answer questions over the phone) and his company provided great service with fast shipping. However, there were a few dissenters who claimed his company wasn’t shipping product and was being unresponsive.

In my case, I ordered online from the airfreetires.com website. I placed my online order around noon on December 6th and received them via UPS Ground on December 13th, for a turnaround time of five business days. I was happy with that.

It should be noted, however, that the Daytonas were not shipped directly from Air Free, which is based in Florida. Instead, they were shipped (and, I believe, manufactured) by Nu-Teck, which is based in Englewood, Colorado—about 70 miles from where I live in Fort Collins. In fact, the invoice I received says the tires I ordered were “sold to Air Free Tires,” but shipped to me. Therefore—at least in the case of the Daytonas—Air Free is simply being a distributor for Nu-Teck.

Air Free (as I write this on December 18, 2006) is selling the Daytonas for less than what Nu-Teck is charging for them (if you were to buy from Nu-Teck directly).

(Update October 2007: I have been getting several reports from people, including my good friend Adam, about long processing or shipment times by Air Free Tires. See the comments left by readers at the bottom of this page. The impression I am getting is that Hugh Waters means well, but he and his company are very disorganized. They appear to have been that way for years. Buyers beware—one may be better off dealing with Nu-Teck directly for the Daytonas.)

(Update September 2008: I am getting complaints about Air Free Tires and their unresponsiveness weekly. I’d recommend not doing business with them and ordering directly from Nu-Teck instead.)

(Update February 2010: The Better Business Bureau has registered at least 66 complaints against Air Free Tires Inc. and has given it an ‘F’ grade. Absolutely do not try to purchase anything from this company.)

Cost

Air Free right now has a special deal going on where you can buy two Daytona HPs for $50 total (plus $10.20 for shipping and handling via UPS Ground). I think that is a pretty darn good deal. By comparison, normal clincher tires retail for around $20-50 each if you avoid the lowest-end stuff.

Individually, an Air Free Daytona HP is going for $39.63. Nu-Teck is selling the same tire for $39.95. Nu-Teck’s shipping and handling charges are also higher ($13.95), making it cost effective to order from Air Free.

Weight

The weight of the Air Free Daytona HPs surprised me, especially since Air Free Tires advertise them as being 450 grams.

In fact, when I received them and put them on my digital scale, one weighed 340 grams, and the other, 355 grams!

In contrast, here are the weights of my previous pneumatic tire setups (all weights are measured weights, not published ones):

Michelin Axial Select 700x23c: 255g
Regular butyl tube: 95g
Velox cloth rim strips: 15g
TOTAL: 365 grams

Continental Supersport Ultra 700x23c (wire bead version): 290g
Regular butyl tube: 95g
Velox cloth rim strips: 15g
TOTAL: 400 grams

Note that when using an airless tire, you do not need a tube or rim strip. So, in fact, the 700x20c airless tire setup is actually lighter than the 700x23c pneumatic ones (in these cases, 10-45 grams less rotational weight). Granted, 700x20c pneumatic tires are generally about 20g lighter than their 700x23c brethren. Therefore, if we were to strictly compare 700x20c airless vs. pneumatic tires, they should weigh about the same and there is no weight penalty.

Additional weight is saved by not having to carry spare tubes, a pump or CO2 cartridges. I.e., one can will save about 0.5-1 pound of non-rotational weight by not having to carry these items on a ride. (Less things to be stolen off of a commuter bike, too.)

Mounting

According to Air Free’s website, any 700c wheels with a bead width of 14-17mm and depth of 6mm would accommodate a Daytona HP. My rear rim (on a Performance-brand wheel) measured just over 14mm so I did not expect to have a problem. My front rim—a Mavic Open 4CD—measured 13.4mm for its bead width, but since the Air Free website specifically said “such as the Mavic Open Pro” rim, I ordered a pair of Daytona HPs anyway.

I am happy to report I had no problems installing the tires on either rim. Mounting the airless tires was actually surprisingly easy (contrary to others’ claims). When I received the tires, no instructions were given. I had first envisioned installing them with tire irons, but this did not work. I then busted out a lead knockoff hammer and pounded the tire on. That worked.

My technique of using a lead knock-off hammer seemed very effective in mounting the tire!

Not only did using the knockoff hammer install the tire easily, it also convinced me that the tire was capable of absorbing ample amounts of shock to prevent wheel damage. No damage was done to the rim with this method, as the tire effectively damped each of my blows.

A rubber mallet probably would have worked as well. Don’t ask me about a sledgehammer.

I have yet to try to remove the tires. (I understand one uses tire irons to do this. A thinner flat-bladed screwdriver would probably be better.) However, considering how snugly they fit on the rim, I am absolutely convinced the tires will not peel off on their own under any circumstances while riding.

Riding Impressions

After I mounted the tires, it was time to try them out. I ended up doing errands around town, riding the bike 15 miles.

When I first got on the bike and started moving, they seemed to roll just fine, like a normal tire. The tires did not seem to decelerate any quicker (or slower) than my former pneumatic tires when coasting, suggesting that there is not a huge difference in rolling resistance.

Indeed, when I rode over to the library 5.8 miles away (being sure to ride at a normal, comfortable effort, which included a lot of coasting especially around Old Town), my average speed of 14.6 mph was not significantly different than normal. Compare this to my other commuting rides.

One thing I did notice that when I was coasting, the bike felt a little more squirrelly, like a very subtle weaving. I attribute that to a ridge along the center of the tire that is a remnance of the moulding (manufacturing) process:

Top profile of the tire after it was mounted onto the rim.

I only felt this while coasting, and it was not very disconcerting. Also, it looks like I could easily shave off this ridge with a razor blade or Dremel (rotary) tool, but have not done so yet. In any case, I expect this ridge to naturally wear off with riding.

Other than that, I thought the tires rode marginally harsher than pneumatic tires, but not vastly so. They may have also felt harsher because I expected them too (the power of suggestion). When I rode home in darkness—which I believe accentuates one’s sense of feel—I would not have qualified the tires as “overly harsh”.

Air Free rates the Daytona HP as being “equivalent” to a 90-psi pneumatic tire, but maybe Air Free meant that they have the equivalent rolling resistance of 90-psi pneumatic tires. In my experience, 90 psi for a pneumatic 700x20c tire is a little soft, and the Daytona HP rides harder than that.

One thing I loved about these airless tires was their feel when I would rise out of the saddle. With pneumatic tires, rising out of the saddle usually is accompanied by a mushy “squirm” (either in feel or sound) of the front tire. There is less “squirm” felt with these tires. You would think “well, of course they must ride much harsher too then,” but the polyurethane/nylon material seems to absorb shock well.

In fact, when riding home, I purposely jumped curbs, rode over branches, potholes, and a hard-packed dirt road to further test the shock absorption abilities. I never felt unduly beat up and I would have sworn that the tires rode no harsher than the last time I rode over the dirt road with pneumatic tires. The beauty of the airfree tires is that you can ride through all of these things without fear of getting a flat tire! I felt the shock absorption was good enough that no rim damage would occur, either.

Cornering Impressions

I have yet to really lean the bike at an aggressive angle while rounding a sharp corner at race speeds, so I can’t comment too much here. But going around corners at normal speed, so far they have inspired as much confidence as normal tires.

Wet-Weather Riding

It hardly rains in Northern Colorado (especially in the winter), so I have yet to try them on wet roads. I have read one report that Air Free tires don’t grip as well in the wet, but cannot comment on that other than I suspect the report was exaggerated.

Assuming they do ride well in wet-weather conditions, their “flat-free” advantages are potentially even more significant, considering that pneumatic tires are more prone to flatting (since debris sticks to tires and then get rolled over… see my 2005 “Butterflood” Double Century report).

I will report back later when I’ve had a chance to ride in adverse conditions.

[Amendment 12/24/06: As tested a few days later, the tires did well on wet roads, okay through very shallow snow and slushy ice, and was terrifying on hard ice—just like regular tires. I thought there was no perceptible difference in performance at all between airless and pneumatic tires in these conditions.]

Durability

Since I have only started using these tires I can’t report on how long they last. If anything, I expect them to last much longer than regular tires. I usually have to replace regular tires after 1500-3000 miles as they noticeably start getting more flat tires. With airless tires, even if much of the material is worn down, “getting more flat tires” is a non-issue.

Conclusion

I am impressed by these tires. They have convinced me that all generic claims made about modern airless tires—heavy, poor rolling resistance, hard to mount, crackpot money-making schemes, etc.—are bunk.

That they ride harsher than pneumatic tires may be true, but only marginally so. I personally don’t think they ride all that uncomfortably (and note that when I did my commuting rides, I was wearing jeans instead of padded cycling shorts!), and I especially like how I no longer have to worry about flat tires, carrying tire changing tools, or pumping up the tires before going into town.

They are perfect for the Ultimate Commuter Bike, and I believe they may even viable for training rides for competitive cyclists who don’t want to deal with flats. The main people they would not be suitable for are racers and people who are really picky about ride quality (most of these people ride sew-ups anyhow ).

If you try them out, please let me know what you think.

Here's a profile of some solid polyurethaneylon from airfreetires.com.
Another view.  The tire is very flexible.
It was quite easy to "stretch" the tire over and onto the rim.