GymCastic episode 23 included a discussion on backward handspring technique.
They recommended longer back handspring for power.
I advocate beginners do backward handsprings as long as possible. Straight arms. Correct hand position. Accelerating.
Manjak, famously, requires 10 sets of 5 backward handsprings a day on Tumbl Trak or Rod Floor.
But you’ll see technique change as gymnasts improve.
Longer is not necessarily stronger.
For example, here are two 2004 Olympic Floor finalists. Both superb tumblers.

Kate Richardson – distance hands-to-feet on backward handspring

Kyle Shewfelt – distance hands-to-feet on backward handspring
It was Iarov who pointed out the obvious to us at one clinic.
Kate used a classic LONG backward handspring. Kyle’s is about as short as they get. Yet both work.
Iarov prefered the short back spring for a number of reasons: less risk of Achilles injury, less risk of out of bounds, greater chance of connecting acrobatic elements. And Kyle can leave the floor more vertically. Less rotation needed to complete the skill.
To have a backspring that short, however, you need be incredibly fast and fast twitch. It’s not for everyone.
Biomechanically, I like long first half of backward handspring, short second half.
Those principles you could call simpletonisms. For triple twist you’ll use a longer second half backward handspring than for double layout.
… If you want to discuss this issue in detail, talk to a Power Tumbling coach. You’ll need a lot of time (and beer money) to talk all the nuances of backward handspring distance.
It’s complicated.
