[kjflyfish]

I just saw this and have a reccomendation for those wanting to make their own circular bands. There is a simple formula to get the right length:

1. Measure the band stretch, multiply this by two.

2. Subtract the length of the wishbone.

3. Divide by the amount of band stretch you want, 3.5 is optimal. This gives you a 3.5:1 stretch ratio, which equates to the band lengthening by 2.5 times it's original size. This gives a good balance of power and band life.