i made a custom brake lever for ours that sits much closer to the bars. That helped him a lot and gave good confidence to get that thing stopped. I still remember the day I sat him on it with the throttle limiter turned too far out and he headed for the fence full blast. Haven’t sprinted that fast in a long time and threw my hand on the brake lever a foot before impact, while ripping him off the bike... I then went on practicing falling and crashing, to take that fear away
Two of the lessons I gave my daughter first time on the Stacyc was to keep her wrist below the throttle and to turn it so slowly, she can barely tell it's moving. But of course she's still working on balance without a motor propelling (scaring) her. She just recently got interested in trying to ride a bike without training wheels (after MA Pitt Race) so I figured strike while the iron's hot.