When not to use your angles.
Angles fix a lot of everyday problems. Here are the cases where they don't, or where the angle has to be the right one.
Bike tires over railroad tracks
Cross as close to 90° as you can. At a shallow angle the wheel can drop into the flangeway gap and stop dead, throwing you off. Designers are told not to build crossings that force riders under about 75°.
Cutting flower stems at an angle
Mostly a myth. A Wageningen University researcher says the angle makes no difference to how long cut flowers last. What helps is a clean cut with a sharp blade and fresh water.
Source: Resource (Wageningen University)
Riding mowers across a slope
Push mowers go across, but a riding mower driven across a slope can tip over. Ride up and down, and only on gentle slopes.
Source: UGA Extension