Powers 5-piece 3/8 inch vs 1/2 inch

If I place a bomber nut, bottlenecked and fairly deep in good rock, I don't worry about it. I'd whip off it all day and I'd have no qualms about lowering off of it if I needed to.

This nut, in the absolutely best scenario is 12kn.

So all this hand wringing about the relative difference of waay stronger than you need vs waaaaay stronger than you need is useless.

It's been stated, 1/2 sets better in soft rock. It's also more likely to tighten up well even if the hole doesn't get cleaned as well. Larger diameter seems to weather better owing to the larger amount of metal too. 17.5kn, 25kn, 50kn, or 200kn, ultimate strength is not a reason to choose one over the other.

For being out in the boonies, 5/16 is acceptable if you get the right bolt. 

1/2” 5 piece or a glue in. Considering that the newest glue ins break at around 40-50kn+ ... Goes towards the light! Not away. You and every other climber climbing those routes will thank you in the next 20 years.

Just back up a moment. For @40-50 years, when someone got to a bolt and breathed that "sigh of relief" of being clipped to something "safe", it was a 1/4" diameter bolt. Often no deeper than 1", ONE inch, although 1-1/4 and 1-1/2" long were also there, you had no idea how deep the 1/4" version which you clipped was. AND THEY WERE SECURE. Look at your chart, compare the 1/4" strength with the 3/8" ones. Now tell me what you think. I'm not advocating going to 1/4", and I'd advocate that bigger is always better (stainless only). Certainly cordless power drills mean you can pretty much put in whatever you want. Thus, rock quality comes into play. I was doing mostly 1/2" x 7" stainless wedge anchors in one area because of rock characteristics (conglomerate -hard rocks welded into soft matrix, routes were free). Later, another formation, we put in some stubby 3/8 x 1-1/2" stainless wedge anchors into bullet hard andesite (aid climbing route). I guarantee you that they won't be failing.

A lot of it is situational. If you have to jug 800 feet to a high point and the rock is bullet hard, the bolts are smaller. If you are hand drilling, the bolts will be smaller. If it overhangs and is sure to see falls, that's one part of an equation, if it's easy or low angle that would be another. If the rock is soft, bolts will be larger and longer. See Bruce's comment upthread about using 3/8" for hand drilling at Pinnacles, there are restrictions. Aid climbing? Free climbing? etc etc.   There was a bolt ladder of 1/4" Star dryvins (so the nail was less than 3-16") up the West Face of Monkey face when it was an aid route that held up for well over 30 years as the soft Smith Rock gradually got loose around them. We'd push the nails that were working loose with our fingers. Eventually someone either didn't push it back in or it simply was time and someone ripped out 8 of them (I heard) in a row. Safe clean fall into air.

If possible, touching base with folks putting in bolts at the area you are looking at is a good idea. If it's a new area, it's your judgement and your call. If you go massively too big, it won't matter. If you go massively too small and have even a single failure, that would be unacceptable. That's my thoughts.  Good luck:-)

nbrown wrote:

Not sure if this answers Adam's hypothetical question upthread; that's all I was trying to do. 

Also, are you sure the relationship between "expansion distance" and "holding power" (I guess you mean tension?) is a linear one? May be, I just don't know.

I called it holding power to differentiate from tensile strength, which would refer to failure of the bolt itself.  Not sure if expansion distance is linear to holding power, but my intuition is telling me it is at least a 1:1 relationship. Would need empirical data to say for sure.