What Type of Tyre for What Type of Race?
Monday, September 19, 2016
There are 5 tyre diameters for modern standard adult bicycles.
- 26-inches - modern mountain bikes and many hybrid bikes
- 27-inches - an older size that was used for road bikes, but you can still get it
- 29-inches - actually the same rim diameter as 700C, but most 29" tyres won't fit 700C road rims because they're too wide
- 650C - smaller road bikes and triathlon bikes
- 700C - for modern road bikes
The tyre width you can use is fixed by the rim width and frame clearance. The most common tyre width for road riding is 23mm. This gives a good balance of aerodynamics, weight, rolling resistance and comfort.
A narrower tyre has lower aerodynamic drag and is lighter. At the same air pressure, a wider tyre has lower rolling resistance, deforms less and loses less energy on most road surfaces. This is because most of the rolling resistance comes from the heat loss of tyre deformation.
A bike frame for 23mm tyres probably won't have enough clearance between the tyre and the frame to support a 42mm tyre. Most road bike frames can take a tyre as wide as 28mm. Cyclo-Cross and Touring bikes are usually designed to take wider tyres.
The 25mm width is good and comfortable for long distance rides. Narrower widths are better for racers looking for every advantage.
The purpose of tread patterns on bike tyres is to give better grip on loose surfaces like gravel, dirt and sand. For road tyres, a grooved tread forces some of the water to the sides and reduces the amount of water sprayed up behind the wheel.
For dry weather road riding, tread pattern is not important and high performance road tyres have pretty smooth treads. But for wet weather road riding, I prefer a slightly wider tyre with some grooving in the tread, like the Continental Grand Prix 4 Season.
For racing in wet conditions, the tread pattern isn't as important as the rubber compound is for good grip and the lightest weight for performance, so something like the Michelin Grip or the Tufo C Giro Twix is your best bet.
For downhill riding/racing, the most important thing is air volume to absorb the hard impact and if you need good bite when cornering choose a pretty aggressive tread pattern.