I use the voluntary closing (VC) Grip 5 Evolution Prehensor by TRS on my body powered prosthetic arm - the terminal device that Bob Radocy used when winning both heat and final of the Cybathlon prosthetic arm race - for a first bike ride. No modifications of bicycle, handlebar or prosthetic arm necessary whatsoever.
I wear it to ride my Gerber race bike, the first animated image also shows the fluency of the handle bar grab with the socket mounted camera:
It stands out against the bike handlebar specific adapters Freelock and Mert hand:
- it closes very comfortably but also extremely firmly (with up to 25 kg closing force easily)
- it closes as long as I make my back round, lean back or extend the elbow, or all / any of these
- but it lets go as soon as I change position so it seems to be far safer than any of these bike specific adapters
- it remains as useful off the bike - so to go eating out, going for a drink, or using a tool, drinking bottle or whatnot while on the way, is easy (not like with the specific bike adapters)
Have not tried it for longer distances or difficult rides yet.
Are you using the Grip 5 for daily activities not over the Becker hand?
As of now, I use the (old) TRS Prehensor that I have for most really heavy and often dirty or contaminated work over Hosmer hooks. I wear a Hosmer 5 hook for office work because it gives by far the best posture and center of gravity performance for typing. I keep the Grip 5 as a "trophy" prehensor and use it mostly for bike riding, shopping or so. But for all house work, deployed on location "work" work, I refer to a TRS prehensor that I tweaked with rubber layers and glove fingers to enhance grip. I change these rubber / finger sleeve covers every few weeks because they wear down fairly quickly, but they are cheap. Rubber gloves fit over them if necessary. The Becker hand is great if it ever has to look like a hand.