Oval Biners and Ascenders

When/why do you need to use an oval biner instead of a normal/modern D shaped biner.

First with a standard jumar type ascender. In normal jugging mode I assume it doesn't matter. What about when attached to the top hole for example when top rope soloing? Always/some of the time/doesnt matter? Why?

With a microtraxion? For hauling? For top rope solo? Why?

Sorry if these are obvious, I couldn't find good explanations on google.

Not sure why it would matter on an ascender. I like to use ovals with a microtraxion because it loads each side of the device, each "plate" evenly and does not cause any twisting. This is something I started doing with the old pro-traxion, where it really mattered, because a non-oval would torque one side and allow the haul line to come off the pulley and wedge between the side plate and the pulley. I'm not sure if it really matters with a microtraxion, but since I already have the locking ovals leftover from my protraxion, I still use them on the micro.

oval biner

Petzl diagrams specify the OK M33 (an oval biner) as the attachment for the ascender in this setup but don't elaborate on rationale. I don't have spare oval lockers at the moment so if it doesn't matter in this circumstance I'd do without.

Nathanael wrote: Petzl diagrams specify the OK M33 (an oval biner) as the attachment for the ascender in this setup but don't elaborate on rationale. I don't have spare oval lockers at the moment so if it doesn't matter in this circumstance I'd do without.

I kind of see it on the top hole, for the same reason I mentioned above. There are two parallel holes on the top, and if you use a non-oval it can kind of torque one side. To be honest, I rarely use the top holes of my ascenders and I don't use them for TR self-belay. I have two micros if I want to do this and I do have two locking ovals.

biners can jiggle all over and get caught in weird ways when TR soloing (more so than jumaring or ascending where youre always loading the ascenders)

for jumars the wider width of the top part does indeed get caught quite a bit when TR soloing ... it also gets pulled up at weird angles sometimes, putting a biner in the bottom hole and then around the rope helps

to be blunt if yr doing alot of TR solo ... a microcender works much better than a jumar .... a microtrax also works decently untill your rope gets thick and fuzzy (i dont use new ropes for TR solo)

my suggestion is to stick with ovals for that application ... for some devices something like a belay master would also work

;)

Nathanael wrote: Petzl diagrams specify the OK M33 (an oval biner) as the attachment for the ascender in this setup but don't elaborate on rationale. I don't have spare oval lockers at the moment so if it doesn't matter in this circumstance I'd do without.

That's a recommendation, not an absolute requirement. You can use a pearabiner as well (class HMS). The main issue is if you use a D carabiner on the top hole, it might not fit or the biner might be hard to thread through. Ovals should be used on pulleys that have two separate sideplates that do not meet in the middle because otherwise you will not load both sideplates evenly, which will cause the pulley to twist sideways under load.