Howdy -- just got an SMC Micro u-rack. First time using a breaker bar rack for me.
I was under the impression (from reading/researching online) that when my hands came off the device, the rope would gather the bars and prevent a fall, but with the three different ropes I tried (one is a pretty stiff static 11mm, one is ~12mm dynamic, one is ~11 or so, dynamic), no such thing happens; the devices just lets rope through freely. Was I confused? I'd be using an autoblock backup anyway, but I had the impression that these racks would seize up when released. It works fine otherwise (though I am surprised at how little friction it imparts... I need to wrap an additional time around a hyper bar to get enough friction for control, even after pushing the bars up, and I only weigh 150lb / 68kg).
The micro is a 9" 4-bar rack, so maybe the auto-arrest only happens with larger 6-bar racks?
Thanks for any input!