than those on a bicycle. They are never "interlaced" in the manner described above, nor are "radial" builds recommended (only wheels without brakes). Motorcycle rims are dimpled toward the hub at each spoke location, and the holes for the spokes are drilled into the dimples at an angle. This angle is a function of the cross-pattern used to lace the wheel, the diameter of the hub flanges, and the width of the hub at the flanges. Conical-hub wheels have a different angle drilled into one side of the rim when compared with the other side. Adequate spoke tension is very important with motorcycle wheels, because of the greater torque applied to the wheel by an engine or disc brake. Loose spokes on a wheel fatigue rapidly and break, usually at the bend where they attach to the hub. When this happens, the wheel must be rebuilt using all new spokes, because even unbroken spokes in such a wheel are fatigued, and will usually break when tightened during the truing operation. Spoke length The correct length of spokes required can be calculated using rim diameter, hub flange diameter, hub width, lacing pattern, and number of spokes. See and. These calculations can be done either by hand (the old-fashioned way - with a pen, paper and calculator) or by using a computer. There are many programs available and they range in complexity from simple Excel spreadsheets to stand alone desktop applications and web based calculators. An alternative method is to refer to a table which has the spoke lengths for a number of common hub and rim combinations. Other conventions A good wheelbuilder will ensure that the valve hole lies between two nearly parallel spokes to ease attachment of a pump head. This does not affect the structural integrity of the wheel, and this rule is usually observed. If the hub has a maker's label on its barrel, it is convention for the label to face (and be readable through) the valve hole. The rim labels should be readable from the right-hand side (drive side) of the bicycle. The hub labels should face in the same direction front and rear (generally so they are readable from the seat), this means that even an undished, symmetrical front wheel has to be laced to the rim the "proper" way round, if perfection is the aim. See also Bicycle mechanic Bicycle wheel Blacksmith Spoke wrench