Originally Posted by
ofajen
Lifting the bars would require a net torque rotating you and the front of the bike around the rear wheel contact point: “a wheelie”. This becomes a problem on very steep inclines.
You don't have to be pulling up (lifting) on the bars to do a "wheelie" on a steep climb. Simply pedaling can do the trick.
My front wheel starts lifting on each downwards pedal stroke around 13%. I can keep the front wheel down for a while by lowering my chest to the bars, but that's good only up to about 15%. At no time am I lifting the bars, but I do pull back on them to keep me from sliding off the back of the saddle. Above 15%, I'm standing any way. Then the problem becomes rear wheel traction.