E. Buygum
Registered user
If the bike is simply slowing in a straight line it's negative acceleration in the same plane.
Quite.
Normally the acceleration/ deceleration forces act through the tyre contact patch. The bike pivots around the centre of mass, tipping the bike's nose upwards under an accelerating force and downwards under braking. Just pivot a match box between two fingers and push at a bottom edge, the front will, of course, tip upwards when the box is pushed from behind and vice versa. The bike's suspension will compress at whichever wheel is under more than the usual weight distribution. I haven't tested it but presumably a braking force applied above the centre of mass (high branch, tightly strung piano wire...that sort of thing) would cause the rear suspension to compress, rather than the front.

that was the first time with the brakes full on