B
Bill
Guest
Last September I posted the below in reference to a tire and rim shape
combination possibly creating an airfoil that adversely effected handling.
Note: not shimmy/wobble. Most thought that it was probably some other
explanation.
The bike has been hibernating through the bad weather until earlier this
week. Yesterday the front wheel was being pushed slowly left and then right
from about 25 mph and up. Today I finally tried the bike with a low profile
Open 4CD front wheel with the same Michelin 700x25 Pro Race tire and the
bike is back up to is old prdictable self up to the 48 mph I managed to get
it to this morning.
Bill
----------------------------------------------------------
Sept 22, 2007
Surprising experience, bike has become unstable at higher speed with wider
tires. I have a pair of Mavic Expert semi aero 30mm wheels that I have
ridden for years with 700x23 tires. They have always tracked well and
ridden very predictably. A few weeks ago I decided to add some comfort and
went to 700x25s. Same brand/model of tire, Michelin Pro Race. At higher
speeds the bike suddenly wanted to wander and veer from side to side. At
first I thought the carbon steerer might be damaged. I pulled it to
double check. Certainly looks rock solid.
Turns out the problem is repeatable at 28 + mph. I believe the very round
profile of the larger 700x25 in conjunction with the aero rim is acting as a
wing. When the airflow is slightly off center at 28 mph and up it creates
lift that pushes the wheel one direction or the other. When it is brought
back across center the lift is transferred to the other side and forces
oversteer and instability. Anyone else experienced this problem with an
aero wheel and larger OD tire?
Bill
http://groups.google.com/group/rec....aero+wheel+instability&qt_g=Search+this+group
combination possibly creating an airfoil that adversely effected handling.
Note: not shimmy/wobble. Most thought that it was probably some other
explanation.
The bike has been hibernating through the bad weather until earlier this
week. Yesterday the front wheel was being pushed slowly left and then right
from about 25 mph and up. Today I finally tried the bike with a low profile
Open 4CD front wheel with the same Michelin 700x25 Pro Race tire and the
bike is back up to is old prdictable self up to the 48 mph I managed to get
it to this morning.
Bill
----------------------------------------------------------
Sept 22, 2007
Surprising experience, bike has become unstable at higher speed with wider
tires. I have a pair of Mavic Expert semi aero 30mm wheels that I have
ridden for years with 700x23 tires. They have always tracked well and
ridden very predictably. A few weeks ago I decided to add some comfort and
went to 700x25s. Same brand/model of tire, Michelin Pro Race. At higher
speeds the bike suddenly wanted to wander and veer from side to side. At
first I thought the carbon steerer might be damaged. I pulled it to
double check. Certainly looks rock solid.
Turns out the problem is repeatable at 28 + mph. I believe the very round
profile of the larger 700x25 in conjunction with the aero rim is acting as a
wing. When the airflow is slightly off center at 28 mph and up it creates
lift that pushes the wheel one direction or the other. When it is brought
back across center the lift is transferred to the other side and forces
oversteer and instability. Anyone else experienced this problem with an
aero wheel and larger OD tire?
Bill
http://groups.google.com/group/rec....aero+wheel+instability&qt_g=Search+this+group
