There are a few ways to determine the size of a spindle. Remember when measuring that tapered spindles use two different size bearings. The first way is by using a digital caliper. Place the caliper on the bearing locations on the spindle. The number is the diameter of the spindle therefore the inner diameter (ID) of the bearings used on the hub. The following decimal diameters are the bearing/hub size converted:

 

0.75	¾”
1	1”
1.0625	1 1/16”
1.25	1 ¼”
1.375	1 ⅜”
1.75	1 ¾”

 

The second method is by using a flexible tape measure. Wrap the tape around the spindle at the bearing locations. The number is the circumference of the spindle. Use the table below to determine the bearings required for your spindle.

 

Fractional Circumference Measurement	Decimal Circumference Measurement	Fractional Bearing/Hub Size
2 ⅜”	2.355	¾”
3 ⅛”	3.14	1
3 5/16”	3.33625	1 1/16”
3 15/16”	3.925	1 ¼”
4 5/16”	4.3175	1 ⅜”
5 ½”	5.495	1 ¾”

 

The third method is to remove the bearings from your old hub. A part number should be visible on the bearing. The part number can identify what size spindle you have. Use the table below to reference the standard industry part numbers for bearings and their respective size.

 

Bearing/Hub Sizes (inches)	Industry Part Number
¾”	LM11949
1”	L44643
1 1/16”	L44649
1 ¼”	LM67048 or 15123
1 ⅜”	L68149
1 ¾”	25580