What’s the deal with plus-sized mountain bike tires? Does size really matter?

Fatbike Ride Revolution Cycle Edmonton

There used to be a time when mountain bike tires came in one size and width but those days are long gone.  Now-a-days tires come in all sizes, from 26 inches with a width of 1.8 to 2.4 inches, to fatbikes which are 26 inches with a 4 inch width, and up to a 29 inch tire with a 3 inch width. What’s the deal with all the different sizes?

Tread pattern and composition of tire have been the factors that have been most modified in tire technology and then the focus turned to the frame: suspension, composition, cranks, chains, you name it, it’s been modified. All of a sudden eyes, and money, began to turn back towards the tires but on their diameter and width. The increased dimensions lead to larger rims, wider and taller forks, and a greater concern about tire pressures. Plus sized bikes have been trending in the bike community for the past year when the bigger brand like Trek and Specialized started to jump on it; they are bikes with larger than 2.3 inch width tires and any increased diameter of tire. The larger tires, whether talking about width or diameter, are meant to improve traction. Tire pressures can be lowered to less than 15 psi to increase contact with surfaces; this becomes important in conditions like snow and sand. Fatbikes were one of the first of the plus-sized bikes to come to market; these have similar diameter rims (26 inches) but wider than the usual tire (4 inches). Fatbikes have become the trend for winter riding, more-especially in Edmonton, and if you look into any bike shop you’ll find an endless supply. I tired fatbiking for a previous column on CBC Radio, and noted both the positive and negative aspects of this style of bike. My biggest concern was it’s utility in all seasons: yes winter does last upwards of 6-8 months, but the conditions on our roads and trails are not powdered wonderlands of snow all the time. I’m not a bike-o-phile so it seems a bit unreasonable to purchase multiple bikes for each season… which would also break my bank account! The trade-off of traction to road-worthy performance was the biggest concern – we have a lot of single track trails in Edmonton, but we can only get to them using roads and paved trails.

27 inch plus sized bike Edmonton Specialized

Along came my friends from Revolution Cycle who offered to kit me up with a plus-sized bike that had a 27.5 inch diameter, 3 inch wide tire for a test ride. At first glance the Specialized Fuse Pro looked almost like a regular mountain bike but slightly off because of the height difference in the tire. The big difference was felt when I started riding with it during the Revolution Cycle Fatbike Ride day; I felt like I could absolutely fly on this bike while on concrete, trails, and hard packed snow. On more traveled surfaces the bike was faster, more aggressive, and generally a more fun ride for me in comparison to the Blizzard Fatbike that I rode less than a month ago. Riding the Fuse felt more like riding a regular mountain bike with no suspension on the rear. Even on some of the technical trails I was able to gather enough momentum to tackle similar obstacles as the fatbike. I’m not a proficient mountain biker by any means so it’s difficult to really see the difference in performance in the more difficult terrain; I had to walk both bikes up the exact same locations. I did however feel more safe on a fatbike while tackling the trails. The tires on the Blizzard were at a lower pressure which provided more traction but also sacrificed a bit of the speed; so I felt a bit more stable. The Fuse feels fast even with the tires deflated to handle the terrain; the bike feels similar to a standard mountain bike. The speed may also be due to the hardtail – there’s no suspension in the back of the bike – in comparison to a full suspension bike so they are definitely not direct comparisons.

Ultimately if a person is going to purchase a plus-sized bike they need to consider a few things:

  • Majority of the conditions you want to ride in:
    • if it is winter or sandy technical trails? I’d look at a fatbike
    • if it is a day to day commuter with some weekend trail rides? I’d look at a 27.5 or a 29
    • if you are looking for a year round ride? I’d look at a 27.5 or a 29
  • How much do you want to spend on consumables:
    • Since fatbikes are the rage right now, the prices for spare tires and rims are a little less
    • the 27.5 and 29 diameter tires are more rare so generally the cost of the spare tires and rims will be a bit more.
  • How trend savvy are you?
    • I’d say that many of these bikes are leaning towards bike tech heads: people that love talking about gear, tire pressure, etc… If you’re one of them, plus-sized bikes are your jam.
    • If you’re a day to day winter bike commuter, you can also look at other things to increase traction like riding on slightly lower tire pressures, or purchasing studded tires. Much like running, my main sport, you can go wild on purchasing winter tech gear but some of the classic tricks like drilling bolts into the shoes work as effectively.

The industry has not agreed on one standard diameter and width for these plus-sized tire bikes and ultimately this is why there is a such a diversity products available. The biggest thing manufacturers know is that anything larger than the 29 inch diameter negatively affects the bikes performance in all conditions. It’s interesting to track the evolution of products in this category and certainly trying things out before purchasing them is important. You can rent fatbikes and plus sized bikes at two main stores in Edmonton:

I would definitely recommend checking these places out and trying out the bikes under as many conditions as possible before purchasing. Ultimately any piece of equipment is about enhancing your personal experience so get out there and have fun!


About Chris Tse

I’m a scientist turned owner of Blitz Conditioning, a Fitness Columnist at CBC Radio on Thursdays at 8:20 am, and owner of Tse Social Strategy. Follow me on Twitter or Read my full bio.

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