Calculated shear stress, now what?

I'm designing a sprocket/motor hub and I've calculated the shear on the shaft from the hub to the sprocket. But, just to be sure, you could check the math.
Torque = 63.3 Nm
Shaft O.D. = 19 mm
Shaft I.D. = 13 mm
Polar Moment of Area (J) = 9.99x10^9 m^4
Radius = 9.5mm
Material = Mild Steel (I know this is important but for now lets keep it super simple)

Shear = (T * r) / J
Shear = (63.3 * .0095) / 9.99x10^9
Shear = 60 MPa

Now what? Is 60 MPa a lot? I forget what I'm supposed to do with the that number.

[QUOTE=aakrusen;4416]forget what I'm supposed to do with the that number.[/QUOTE]

Compare to the material strength properties... Tensile, yield strength.

...and do some research on [I]von Mises[/I] for the relationship between shear and tensile yields.