63T-11P centertrack beltwheel

Beltwheel for Gates GT2 centertrack belt, 11 mm pitch.  63 teeth.

Mounts on 5-bolt, 130 mm BCD crank spider.  The "belt line" (center of belt, measured laterally from the center of the bike) is 1.7 mm outboard of the outer surface of the crank spider mounting "flanges."  The beltwheel slides/rotates on the the crank spider mounting flanges, which for this beltwheel must have a thickness of 2.5 mm, an outer diameter of 144 mm (2 mm outside each 10 mm bolt hole), and a circumferential width of 16 mm (3 mm on each side of the bolt hole).

One side of the bolt mounting hole has a "recess" -- the bolt head is "sunk" into the beltwheel, so that the bolt doesn't have to be longer than the 12 mm belt width plus the 2.5 mm crank spider thickness.  Chainring mounting bolts this long appear to be readily available.

Note that the bolt holes are printed slightly undersized -- 9 mm diameter.  I'm not 100% confident of the dimensional accuracy of the printing, so the position of the holes could be corrected slightly (by using the crank spider holes as a template to guide a drill).  My experience so far, however, has been that the hole positions have been spot on.