Fade length is a personal preference and you’ll get several ideas from the bowyers here. There are, however, some physical considerations that will make a difference:
1. The width of the limbs near the handle. As a minimum, I like to keep my fade length the same as the width of the limbs. This will lower the stress at the sharp transition angles from the fades to limbs. Lately, I’ve been making the fades longer because they’re more graceful looking (to me).
2. The type of wood you’re using and the bow design will sometimes require all the limb material you can get to ensure a durable bow with adequate poundage. In this case keep the dips and the fades short, and hold the limb width parallel past the mid point.
3. If you’re using a narrow sapling with a high crown, there will be a natural width limit on the fades and, their length will usually be whatever is pleasing to the bowyer’s eyes.
There is lots of room for variations and experimenting with the fade lengths. Some of the older bowyers, back in the 40’s, used fades that were about 1/3 the length of the limbs – they worked and they look pretty good too…
H
