Tires, Suspension Losses, Comfort, and Speed
The Terry website has posted a podcast interview with Bicycle Quarterly editor Jan Heine concerning tire performance. For years, bike geeks have believed that hard, narrow tires are significantly faster than wider tires or narrow tires used at lower air pressures. This understanding was confirmed by rolling resistance drum tests, which isolate the rolling resistance of tires on a hard, smooth surface. But rolling resistance alone doesn’t explain tire speed. Suspension losses need to be factored in when evaluating tire performance. Even on smooth roads, suspension losses are considerable, and tires (whether narrow or wide) with supple casings perform better than those with stiff casings (whether narrow are wide). Tire construction and proper inflation have much more to do with (actual, not perceived) speed rather than width, and tires that are too narrow (no matter how well constructed) are slower than the same tire in a wider size because of the excessive suspension losses of tires that are too narrow. All this and more in the podcast above, including why hard tires feel fast precisely because they’re inefficient.
Bicycle Quarterly has been experimenting and reporting on tire performance for the last couple of years. The interview will recover some of the finding for subscribers, and provides a concise summary for those who haven’t read the reports on the experiments.
On a related note, those who don’t subscribe to BQ can view Frank Berto’s tire pressure chart, republished in the magazine a couple of years ago. It’s a good resource for the home or shop.
Wow, somehow I thought Jan might have a deeper voice. ;)
At the speeds I ride…;-)
I have long subscribed to Frank Berto’s tire pressure chart. I typically end up running my rear tires at maximum pressure due to loading, but can get away with a bit lower in the front. Makes for a more comfortable ride.
Aaron