Originally Posted by HillRider

Years ago Trek made and sold a handlebar stabilizer similar in concept to the OP's photo which was sold under their "Wrench Force" name. It was two telescoping aluminum tubes, 1/2" OD outer, 3/8"OD inner, that adjusted in length from 20" to 35" and had a thumb screw to lock them at the desired length. There was an adjustable rubber strap at each end that went around the handlebar and the seat post to hold the front wheel and fork steady. I got one as part of a package deal with my "Wrench Force" repair stand (a relabeled Feedback Sports Elite) in the 1990's when Trek was discontinuing the Wrench Force product line.