hardtdavid
Member
Do you find that, even after months and hundreds of miles on your Cruzbike, you do not feel secure and completely “at one” with it’s road feel and handling?
If you haven’t done so already, try this: find your optimal---probably lower---tire pressure.
According to Frank Berto’s research, reported in Bicycle Quarterly and other places (search, or see link below), each tire on the bike has an optimized pressure, related to the tire’s width and the total load on it, bike and rider included. Below this pressure, rolling resistance suffers, of course, and you ride a bit slower. But above this pressure, comfort and handling suffer, and you don't roll any faster.
-------
Here’s the longer story, if you’re interested. I bought a used Sofrider V1, and fitted it with 100psi Kwest’s, thinking "speed," like all male lizard brains do. However, even after several hundred miles on the bike, I still felt uneasy, especially at higher speed, on descents, and on less-than-smooth roads---as if the bike weren’t firmly attached to road and could slide sideways at a any moment. Illusion, I’m sure, but unnerving just the same.
I recently bought another used V1 for my wife, but noticed that hers felt so much more solid than mine, as if, with a few more days of using it, I could be riding no hands.
What could be the difference? After much tinkering with the suspension and seat angle, I stumbled upon Berto’s research, and the real difference. My wife’s bike still has the 65psi Kwests. Meanwhile, I was running at or near 100psi.
According to Berto’s charts, being of slight build, I ought to be running the 559-40 Kwests at 50psi front, and 40psi rear. With a 100psi rating on the sidewall, I didn’t trust I could run mine that low, so I set each to 65psi.
The difference was dramatic. The bike felt solidly attached to the road. On the rougher roads, all the high-frequency chatter was gone, and I could tell where the bike was at all times. The handling on higher speed descents was grippy and sure. Even with the full suspension, the bike was now even more comfortable.
The kicker: I am no slower at this lower pressure; in fact I surely ride faster because I have the confidence in the bike to push or pull it knowing it will behave as I expect it to.
I experienced this improvement in handling and road feel a second time, days ago, when I upgraded the tires to Schwalbe Marathon Supremes. They come in only two 559 sizes, 559-42 and 559-50. I got them right before a 30-mile group ride in misty weather, and in haste pumped both to 55psi. The ride was good, but not as “supreme” as I was expecting.
With the opportunity to check Berto’s chart, the rear tire was really asking for 30-40psi, and the front for 50. I rode yesterday at these pressures.
Again, the difference was palpable, with sure-footed feel at all times. Also, on a section of rippled pavement on a curve in the middle of a long descent, where I usually ride a cautious and nervous 20mph or so, instead I rode over them at 26mph+ as if the ripples didn’t matter!! Complete confidence.
Here’s one link to the Berto’s chart:
http://www.vintagebicyclepress.com/images/TireDrop.pdf
NOTE: the individual wheel loads are important, and though the article describes how to measure them precisely, I just used a distribution estimate of 55% front, and 45% rear. It seems to work just fine for the Sofrider V1. Also, the line graph looks all precise, but using a pressure to the nearest 5 pounds above or below makes little difference. You can rider slightly lower pressure for rougher routes, and slightly higher pressure if all your roads are smooth.
And, ladies and gentlemen, may all your roads be smooth.
If you haven’t done so already, try this: find your optimal---probably lower---tire pressure.
According to Frank Berto’s research, reported in Bicycle Quarterly and other places (search, or see link below), each tire on the bike has an optimized pressure, related to the tire’s width and the total load on it, bike and rider included. Below this pressure, rolling resistance suffers, of course, and you ride a bit slower. But above this pressure, comfort and handling suffer, and you don't roll any faster.
-------
Here’s the longer story, if you’re interested. I bought a used Sofrider V1, and fitted it with 100psi Kwest’s, thinking "speed," like all male lizard brains do. However, even after several hundred miles on the bike, I still felt uneasy, especially at higher speed, on descents, and on less-than-smooth roads---as if the bike weren’t firmly attached to road and could slide sideways at a any moment. Illusion, I’m sure, but unnerving just the same.
I recently bought another used V1 for my wife, but noticed that hers felt so much more solid than mine, as if, with a few more days of using it, I could be riding no hands.
What could be the difference? After much tinkering with the suspension and seat angle, I stumbled upon Berto’s research, and the real difference. My wife’s bike still has the 65psi Kwests. Meanwhile, I was running at or near 100psi.
According to Berto’s charts, being of slight build, I ought to be running the 559-40 Kwests at 50psi front, and 40psi rear. With a 100psi rating on the sidewall, I didn’t trust I could run mine that low, so I set each to 65psi.
The difference was dramatic. The bike felt solidly attached to the road. On the rougher roads, all the high-frequency chatter was gone, and I could tell where the bike was at all times. The handling on higher speed descents was grippy and sure. Even with the full suspension, the bike was now even more comfortable.
The kicker: I am no slower at this lower pressure; in fact I surely ride faster because I have the confidence in the bike to push or pull it knowing it will behave as I expect it to.
I experienced this improvement in handling and road feel a second time, days ago, when I upgraded the tires to Schwalbe Marathon Supremes. They come in only two 559 sizes, 559-42 and 559-50. I got them right before a 30-mile group ride in misty weather, and in haste pumped both to 55psi. The ride was good, but not as “supreme” as I was expecting.
With the opportunity to check Berto’s chart, the rear tire was really asking for 30-40psi, and the front for 50. I rode yesterday at these pressures.
Again, the difference was palpable, with sure-footed feel at all times. Also, on a section of rippled pavement on a curve in the middle of a long descent, where I usually ride a cautious and nervous 20mph or so, instead I rode over them at 26mph+ as if the ripples didn’t matter!! Complete confidence.
Here’s one link to the Berto’s chart:
http://www.vintagebicyclepress.com/images/TireDrop.pdf
NOTE: the individual wheel loads are important, and though the article describes how to measure them precisely, I just used a distribution estimate of 55% front, and 45% rear. It seems to work just fine for the Sofrider V1. Also, the line graph looks all precise, but using a pressure to the nearest 5 pounds above or below makes little difference. You can rider slightly lower pressure for rougher routes, and slightly higher pressure if all your roads are smooth.
And, ladies and gentlemen, may all your roads be smooth.
