TIRES FOR ALL SIZES AND SURFACES
Bike tires can be confusing – especially to the young rider who is still exploring the technology. And here are some basic facts from which to start research. With the aim of answering this question: How do tires affect my ride? For a start, you can spend less time dealing with punctures if you go tubeless.
Let's commence with some basic properties of pneumatic tires: Rolling resistance, mass, resilience and grip.
Rolling resistance
Imagine a tire chosen for breaking records on a flat road time trial course without any sharp corners. It will be skinny, thin-walled and run at a high pressure, hard as stone above 100 pounds per square inch.
Where the rubber meets the road, such tires – which may be 23mm or even less in cross section, with the thinnest tread possible – leave two tiny contact patches, a little bigger than raindrops. In such a tire, speed is all. Stability, safety, control, grip and comfort have all been sacrificed for the sake of light weight and low rolling resistance.
Easy rolling is boosted by the size of the wheel. A bigger diameter means there's less effort. And this may come down to tire dimensions.
A 29-inch tire rolls better than a 28-inch – even though both tires fit the same size of rim, with a diameter of roughly 26 inches. When a tire with a 40mm cross section is fitted, the outside wheel diameter is about 28 inches. But with a 29er tire, this dimension swells to nearly 30 inches.
This size of tire demands a frame with wider clearances – which resulted in today's highly-popular 29er carbon wheels. On MTB tires, tread patterns reign supreme, and they have high rolling resistance. But that's not important in a daredevil downhill charge.
Now for the other extreme form of tire, as fitted to a fat bike from ICAN's 2021 line-up, such as the tri-spoke SN04 bike. Speed is the last thing desired. Sheer velocity is trumped by the need for strength, traction, comfort, control and stability. Extreme off-road knobbly tread patterns give traction in snow, mud or beach sand.
A fat bike tire runs at comfortable pressures as low as 8 psi, and can reach the colossal cross section of 4.8 inches – on a 26-inch diameter rim. A resilient tire like this has a big contact patch.
There is a world of tire sizes between the two extremes we have covered so far. Now let's get down to what the novice bike rider enjoys most – and the tires required for her chosen form of the sport. If you're paging through a catalogue of complete bikes, look at the wheel and tire information first. The outside tire diameter of 700 cm is found on racing road bikes.
Then come three diameters of tire, measured in inches at 26, 28 and 29. There's also a 27.5-inch which is suitable for short riders, who take a frame size that's too small to accept 29er tires.
How to choose suitable size wheels
Cross section is where the road bike rider will find a lot more choice in good tires. Road bike tires are basically intended for a paved surface, so they're narrow.
- If you race, you should be looking for a cross section of 23mm.
- If you commute on bad roads with sharp flints, potholes and cobbles – sometimes in the rain, look for a fatter tire.
- You'll be safer on tires measuring 28mm or even 32mm, with a tread designed to give good cornering grip on slippery surfaces.
Reasonable rolling resistance
Once we get out of town and into the great outdoors, a beefy tire cross section is essential for survival in the wild. A complete MTB supplied from an ICAN warehouse may have tires measuring up to 2.5 inches wide.
The fatter the tire, the greater the shock absorption on a rocky surface, and the greater the grip on the ground. Especially if the tread pattern comes well with the surface.
Trail and enduro tires are fairly fat at 2.36 inches, but feature closely-spaced knobs which give a reasonable rolling resistance.
Tires built to take extreme punishment in downhill competition are the heaviest and fattest of all, with a tread pattern of large widely-spaced knobs. Where you need to seek expert advice is with full-suspension mountain bikes. Many of these beauties run better with a rear tire which doesn't match the one fitted to the fork.
