Center tube clamp of only 7/8" is BMX standard ..(some MTB bars Of Titanium also used 7/8" tubing, since thats what the control levers Fit

But shim sleeve halves can bring that out to 1" (1/16" thick (r), X2 =1/8" as you should Know)

the next big stem bump went to 1.25" thats the new Oversize handlebar.. ( though the bars are bulged out to the center for stiffness )