Cricket Bat MOI

Cricket Bat MOI

Cricket Bat Moment of Inertia

This website provides the means for you to generate a moment of inertia (MOI) measure for your cricket bat.

What is Moment of Inertia and Why is it important?

The quality and performance of the bat materials aside, a functional bat is one that the player can manoeuvre at a range of speeds to make controlled strikes in defence or in attack for run scoring. MOI is the quantified value of the phenomena that cricketers refer to subjectively as ‘swingweight’ or ‘pick up’. If you want to have a bat that is optimised to your physical abilities and skill level then buying on MOI is an important step towards that. The units for MOI are Kg.m2.

Currently no-one sells bats with MOI provided.

In future all cricket bats could be sold with this value provided, and move away from static bat weight.

The method behind the MOI calculation has been validated in a peer-reviewed journal article. The aim was to find a simple way for bat makers and players to obtain this important parameter. This blog post provides some more detail, and includes a link to the journal article for those interested in the mechanics.

Instructions

Instructions on how to generate the Inputs to calculate your bat’s Moment of Inertia

To make the measurements you will need:
A digital kitchen scale (that can measure up to 2 kg)
A 12in/30cm ruler, or tape measure.

  1. Measure the handle length. With a ruler place it so the edge runs through the shoulders of the top of the blade (see Figure). Mark a feint pencil line through the splice. With the ruler measure the distance from this line to the top of the handle. cricket bat handle showing measurement lines You should be able to measure to the nearest 1mm. Record this in metres. For example, if you measure the length as 301 mm, this is 0.301 m.
  2. Measure the blade length Now measure the distance from the shoulder line to the bottom of the blade. Record this in metres. Total bat length is simply the sum of the handle and blade length.
  3. Measuring Bat Mass & Balance Point Place the scales on a hard flat surface long enough to take the whole bat. Turn on the scales, and ensure they are reading zero. Place the toe end of the bat on the centre of the scales and rest the handle end on the flat surface. Read and note the value shown (call this w1).
    bat resting on book and scales Remove the bat from the scales. Ensure the reading is zero. Now place the middle of the bat on the scales. Read and note the value shown (this is the total bat mass). Record the measurements in Kg. For example, if your scales read 1215 grammes, this is 1.215 Kg. Use all the numbers provided by your scale reading.

    bat on sales showing reading Balance point is calculated as the total bat length multiplied by w1, which is then divided by total batmass.
    Balance point = (total bat length x w1) / total bat mass (length measurements need to be in units of metres, and mass in units of Kg)
    4. Expected MOI will be in the range of 0.30 – 0.39 Kg-m2, covering bat masses 2lb5oz – 2lb14oz. But can be outside of this range if lighter or heavier bats are measured.

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About

The website content and methods in this website have been developed by David Curtis, principal research fellow in the Sports Engineering research group at Sheffield Hallam University, England. Read more...