It’s all about the edge
Judging a bat by its….. edge.
Big edges, everybody’s talking about them, on the forum, in the shops, in the dressing room. I like to go undercover into cricket shops and listen to people when they are choosing a bat, I often hear ”look at the size of this edge, its bigger than that one“ and on the forum, the first thing people comment on is ”my edge is 50mm” obviously people are prone to exaggerate. So having a big edge on a bat is no doubt a selling tool……..
But do bigger edge bats play better, I hear you ask?
Well the first place to start is with bat weight, why I hear you ask?? Well hopefully that will become clear. I think the first thing to point out is that bat weight is related to 2 things and 2 things only (not taking into consideration stickers, grips, anti scuff, toetek etc);
1. Density (of willow & handle)
2. Bat volume
Assuming that all willow has the same density (which we know it does n’t) but for this purpose we can assume it does, the main thing driving bat weight is volume. That said for every bat volume you will have a natural variation curve (a curve that is bell shaped) of bat weights (see my next blog). So, to get a consistently low bat weight with a big edge, you have to reduce the amount of willow in other areas (reducing the volume), this is predominantly done by reducing the swell height. The next time you look at a big edged bat have a look at how big the swell is, and 9 times out of 10 the swell will be reduced, and significantly smaller than a “normal” edged bat.
So to get a big edged bat you have to sacrifice height at the swell – what effect does that have on performance I hear you ask?
Well, the jury’s still debating on that one (see below) but I think common sense tells me that the more volume (mass) you have behind the impact point the better the ball will rebound (or Coefficient of Restitution CoR to all you engineers out there) . So if you middle balls on a regular basis (which is what everyone is trying to do) having a big edge / smaller swell, will actually lower the performance of your bat. However, if your most prolific scoring shot is a thick edge for 4 down third man, you might want to consider moving all the mass to the outside edge.
Without sounding like an old shampoo advert , now for the science bit (this bit is quite geeky, so you might have to get yourself a coffee to stop yourself from falling asleep!!)
First of all the perception of having thick edges will ‘widen’ the sweet spot –is not technically correct as the Sweet spot, by definition is a point (and not an area) at which there is no vibration transmitted through the blade- and therefore more energy transferred back to the ball increasing the CoR. But increasing the edge size will increase the performance for off centre impacts, so I can see why big edges are perceived to widen the sweet spot.
Everyone still awake??
Their are two scientific thoughts on bat design Vs performance and it’s my view that both are related and effect performance, which one has more effect over the other, were not 100% sure but thats a question for another day;
1. Cross sectional Stiffness
Thicker edges will increase performance* of ball impacts towards edge of bat, but as this type of bat has had its swell reduced to accommodate the increase in edge size – the performance* from the middle will be sacrificed, however any off centre hits will be better – this is where the ‘widening the sweet spot’ came from.
2. Effective Mass
This is related to the distance between the ball impact point and the bats centre of mass, the closer these two points are, the more influence bat mass has upon performance. Therefore if the cross sectional area has not changed through “reallocation” of wood from swell to edge, and the bat mass distribution has n’t changed, the performance* will not be effected – (exactly the same as perimeter weighting in golf)
As to which one is the dominant factor it has yet to be proven but I make the below assumptions;
1. Big edges reduce performance of the middle – probably
2. Big edges improve the performance at the edge of the bat, producing a bat with a “wider” less powerful middle – probably
My opinion is that this big edge phenomenon is a phase like the big bow of a couple of years back, and there is a trade off in performance to having a big edged bat.
The final decision to how big your edge is, has to be yours.
Next blogs – “matching the profile to your play” & “Bat weights – the influencing factors”
Dont forget to follow me on twitter Dr_DBacon
*performance refers to Coefficient of Restitution (CoR) or basically how far the ball rebounds of the bat…