Which are better: road tires, off-road, or fat tires?
June 4th 2018
This question is a bit like asking which is a better vehicle–a car or a truck? They have different functions, and function drives form.
First, let’s start with some definitions. The rough dividing line between road and off-road tires is about an inch in thickness; Above that, tires are generally measured in inches, and below that, tires are generally measured in millimeters.
- Tires measuring anywhere from 23mm to 32mm, are traditional road-bike tires, AKA skinny tires, with maximum air pressure anywhere from 100 to 120 psi.
- Tires measuring anywhere from 1 inch to 3 inches are off-road tires, AKA mountain bike or balloon tires, running at 25-50 psi.
- Fat tires 4-5 inches wide are usually for snow, running at no more than 10 psi.
From the start, you can see that fat tires are their own beast. Anyone trying to to ride those on a road will be pumping them up beyond spec, dealing with phenomenal friction anyway, and often combining them with an e-bike to handle all the extra work.
Road tires are optimized for pavement and packed gravel.
A couple of years ago, I did the Seattle Century bike ride on the 1.5-inch, all-terrain tires of a CHANGE 611. After riding to the event, of course. And with minimal training. Even without the tire selection, those are ideal conditions for coming away sore.
But when matching speed and cadence against other riders of similar ability, I had the distinction impression that I was working harder against friction. And I was. The combination of more surface area (from wider tires, plus lower psi) and extra weight (from more tire rubber and more wheel) means that I was expending more watts to achieve the same result. Above 80 miles, the energy usage really started to add up.
The opposite experience, on the same bike, came this past weekend, when my wife and I enjoyed 12 miles of paved trail. We passed folks on 2.5-inch tires with MTB tread, clearly working hard to push those knobbies up hills with any speed.
At that riding distance, I didn’t notice difference vs. my riding partner’s narrower 25 mm tires (on the 702 commuter bike), but when I rode a bike like that in NYC’s 5 Boro Tour last month, it seemed downright sporty, even after 70 miles and lots of post-ride exploring.
If you ride mostly on roads/trails and are willing to keep your tires pumped to the necessary level for a road tire (or ride a Tannus airless tire, as I did in the 5 Boro Tour), then a road tire of 28mm or less may be best for you.
Off-road tires are optimized for soft surfaces.
Now and then, I take my 1.5-inch tires off the beaten path. Maybe it’s a grassy or sandy area. Definitely not snow; that’s another use. And surprisingly, not mud either, as the smooth tires that deliver somewhat low friction on roads end up delivering very low friction on wet mud. Mountain bike tires were designed for gripping in mud.
MTB tires are ideal for rocks, loose dirt, mud–anything you may encounter on an unfinished trail. Their lower PSI, combined with knobby tires, offer increased traction in critical situations where road tires would simply spin or slide.
WARNING: Off-road doesn’t mean worry-free everywhere. Two road conditions are surprisingly treacherous for mountain bike tires, as that heavy traction may suddenly disappear:
- Large gravel on pavement. Wider tires offer more opportunity to catch gravel pieces between tires and pavement, where it acts like ball bearings to remove all friction. Or, a single piece of gravel can lodge between tire knobs, providing another way to lose traction.
- Wet train or streetcar tracks. MTB tires are better than road bike tires for dealing with tracks in the road. But if the tracks are wet, you may have sliding knobs on metal.
These cases don’t require an abundance of caution, just an awareness that you’re situationally not invincible. If you come across either problem, just ride slower and avoid sudden turns until you’re past the danger.
Hybrid tires are mostly road tires, for places that are mostly roads.
So where does that leave the relatively smooth 1.5-inch tires like on the CHANGE 611 rugged hybrid and CHANGE 609 mountain bike?
Hybrid tires are great for places like this photo above–usually road, but not always. Heck, even the shocks on the CHANGE 609 might be a plus.
But if your concern is less than that, such as omnipresent road debris that might give you a flat, a hybrid or MTB with hybrid tries is still an option, you have other choices as well…
Flat-resistant tire technology for road bikes.
Advanced tires are now so much more than a strip of molded rubber that covers an inner tube. Today’s Continental Gatorskinflat-resistant tires consist of three layers of penetration protection, including Duraskin® and PolyX Breaker fibers with Kevlar–the stuff that stops bullets in combat.
Fancy. But what’s the real-life impact? Consider this review from roadbikereview.com:
‘Bought my first set in July 2013 and just replaced in April 2016. I got nearly 6,000 miles of wear over this period. I am a big rider at 235 and inflate to approximately 105 lbs. I do not believe I got a single flat during this period. Am a recreational triathlete and ride about 2800 mile/ yr. the comfort on long rides and confidence of remote likelihood of a flat are what drives me to buy these. The really long life is an added bonus.’
OK…we’re sold. This is going on every CHANGE Century folding road bike we build. What about other bikes? Is a CHANGE 702 commuter bike in your future?
Bob Forgrave is president of Flatbike, an
ecommerce company offering full-size folding bikes
and kits to make any bike take up half the space.
2 responses to “Which are better: road tires, off-road, or fat tires?”
Can MTB tires survive goathead thorns from puncturing your tubes?
Those thorns are extra nasty when riding on the street. I tend to ride on old dirt roads and deer trails or across open meadows and down to creeks.
While MTB tires look gnarly and rugged, they are surprisingly not. They are simply optimized for friction with lots of dirt-grabbing knobs. In fact, some manufacturers, attempting to counter the weight of all those solid-rubber knobs, may make the rest of the tire thinner to compensate, resulting in a less-rugged tire. And of course, more surface area + more remote usage = more potential for goathead flats.
What to do? You’ll see some tire manufacturers referring to Kevlar, but read carefully… they are talking about the sidewall bead, not a layer of protection in the tire. A common answer is to ride tubeless, with “slime” that fills in holes, as long as you do the maintenance to remove, clean out your tire, and replace the slime every year. At least it’s happening in the garage, not on the trail.
Another option is a Tannus Armour insert. It’s a molded later of special foam that is so rugged, you can ride at pressures down to zero PSI. Goathead thorns go in, but can’t come out, protecting your tube.