WHEEL STAGGER, SET AND DISH

By Ced Lewis

Experience would indicate Stagger usually occurs in wheels with more than 10 spokes. The reason for this, and particularly applicable to wheels with small diameter hubs (naves), is that the spoke pockets (mortices) become close together and when, at the same line , form a ring of weakness. By staggering the spokes, this “shear ring” is eliminated thereby reducing the possibility of the hub collapsing.

The amount od stagger is usually ½” (half an nch), being a quarter of an inch on each side of the normal spoke line. This means that when spokes are positioned at the bottom of the wheel when fitted to the vehicle, they will either be in front of, or behind, the true vertical which is normally achieved by an unstaggered spokes where the Set of the axle end is such that the bottom spoke is verticle so that the optimum weigt-carrying position is obtained.

Obviously the angle of Set is equal to the angle of Dish in the wheel, although Dish is not normally talked of in degrees of angles, but rather by the amount by which the front face spoke at the tang shoulder projects forward of its entry into the hub (i.e by dropping a vertical line at 90 degrees to the hub axis , e.g 1” Dish.

Dish was introduced into wheels to give added strength to resist the continual “hammer” on the inner face of the hub, from the side to side movement of the body of the vehicle and any external forces against the outer edge of the tyre (e.g. Kerbing). Staggering the spokes increases the effect of the Dish marginally because it introduces a small amount of triangulation (as in the bicycle wheel spokes) further strengthening the wheel.

Finally, with a Warner type hub, where an iron sleeve is shrunk onto the wooden hub, it is possible for the spokes to remain in line, as the iron sleeve is spread two-thirds of the hub length providing strength and support, the spokes being morticed inton the sleeve and into the wooden core of the hub.

These are generally used on lighter vehicles, both passenger and commercial, where wheels have 14/16 spokes and small diameter hubs (6” or 7”).

As a matter of interest, in both parallel and tapered bore sleeves these have to be shrunk onto the hub and, in fact a 5’ Escape ladder built by the author in 2004 were fitted with tapered sleeves to accommodate 16 spokes.