I forgot to tighten the handlebar clamp bolt all the way on my Basso.
So I go out for a ride and all is well, until I'm going down the block and see the the traffic light is green for me, but I will have to sprint to make it. So I stand up on the pedals, lean forward and put a lot of down pressure on the hoods. Well, the bars roll down under the weight and I immediately fall forward with my chest laying on the bars with my head way out over the bars and I have no control and can't get to the brakes.
Luckily, thankfully, I rolled into the curb and rolled off the bike onto a patch of grass on the sidewalk, a rare find in NYC! Could have been ugly had the bike rolled into traffic or I miss that beautiful lonely patch of grass!