This is we explain to you all about measuring bolts. This information can come in handy when you are trying to order a certain size bolt. Giving us the correct size ensures that we send you the right size.




First measure the flange bolt's "length" ( l ) measure from the Bottom of the head to the End of the bolt. This length measurement does not include the head and for metric bolts is in mm.

To measure a bolt's diameter ( d ) measure across the thread of the bolt. This measurement is also in mm.




The next next measurement is generally not required with us because in most cases the majority of the motorcycles and ATVs all use a standard pitch. Common metric thread pitch for motorcycle and ATV uses are M4-.7, M5-.8, M6-1.0, M8-1.25, M10-1.5, M12-1.75, M14-2.0 and M16-2.0. Where the first number indicates the bolt diameter in mm, the second number indicates the thread pitch in mm.

For example M10-1.50 indicates a 10mm thread diameter with the spacing between the adjacent "peaks" of the threads = 1.50 mm.

Typically a metric bolt's size is stated like this....

M(d/diameter)-pitch x(l/length)

For example if a bolt's diameter is 8mm with a pitch of 1.25 and a length of 25mm.

The bolt size is a M8-1.25x25




Specbolt uses 8.8 and 10.9 grade which will meets and even exceeds motorcycle and ATV manufacturer's specs.

If we want to approximately compare metric grades to U.S. grades, a metric 8.8 is roughly equivalent to a Grade 5. Grade 10.9 is roughly equal to a Grade 8; and 12.9 is roughly equal to a Grade 9. Metric nuts are marked with a single or double numerical symbol (8, 10 or 12). Always match bolts and nuts of comparable grades (use a Grade 8 nut with a Grade 8 bolt; use a metric grade 10 nut with a 10.9 grade bolt, etc.). When dealing with metric fasteners, the 8.8 bolts are similar to a Grade 5. Where you need higher tensile strength in metric, stick to 10.9. We do this for you in all of our kits

The higher the first number, the stronger the bolt in terms of tensile strength. The higher the second number, the longer it will take to enter the yield point.