"The different ways to connect with your stud"
The Bolting Bible
The Book of Anatomy
Welcome to our free course as our way of contributing to the bolting community. It's nice to understand what you are clipping and trusting with your life, even if you never plan on installing or removing bolts. We believe that if someone is going to spend their time and money to bolt something, they probably want to do it as good as possible. Hopefully, the Bolting Bible gives you the tools you need to do a great job. Get it?
This book is in a blog format. The main blog points to all 17 chapters, and at the end of each chapter, it points you to the next. A downloadable pdf is available HERE.
What's a Hanger
A hanger is how you interface with a bolt. Unless you glue a "P" into the rock, every other bolt needs a way to clip carabiners to it or have a rope connected to it. Standard hangers start as a flat oval-ish shaped metal pancake that is stamped with a big hole you clip to and a small hole for the bolt and then folded 90 degrees. Some hangers are stock rod bent and welded into a similar shape as a standard one. The idea is to have a rounder surface for your carabiners and even your ropes if you want to run them directly into the hanger.
Materials
Hangers can come in steel or aluminum, though, aluminum hangers are rare and were made for lightweight temporary uses. They are not as strong as steel, can corrode, and it mixes metals because bolts are not made from aluminum, so you can get galvanic corrosion if left permanently installed. This photo shows the aluminum corroding while the bolt is also rusting.
Fixe sells PS (plated steel) which is cheaper than stainless but then they rust and corrode if used outside, and even quicker if the bolt is stainless, don't mix metals. They are intended for indoor use such as climbing gyms. I know paying $1.83 (PS) vs $4.95 (SS) per hanger is tempting, but don't do it! You can tell the difference between the two by color, PS is more shiny and SS is is more grey, in most cases. Also PS is magnetic and SS is not.
Stainless steel hangers are the only kind of materials that should be used for hangers since we should only be using stainless steel bolts. PLX hangers are phasing out with the new EN standards of 316L. All the major brands sell 316L stainless hangers, see the buying guide below. Titanium hangers are pointless since we don’t have titanium mechanical bolts.
Shapes
FLAT STOCK
Bent flat stock is generally 3mm thick and comes in the standard diagonal most often seen. Fixe and Petzl have dimples punched into them to prevent spinning which is nice but not essential. Bonier makes unique bent hangers called the DUPLA and PINGO, which are flat stock shaped so that no sharp edges touch the carabiner or rope.
Offset or horizontal hangers have a straight bend allowing permanent rings or quick links to be offset to the rock so a rope isn't being smashed up against the rock at an anchor. Don't pull them in tension as they lever the bolt. They have their benefits but are not common and intended to be used only at anchors.
ROUND STOCK
Bent and welded round stock is generally 8mm and is formed into the same shape as a standard hanger, but the benefit is that it generally has less of an impact as they don’t shine quite the same way as flat hangers. They are also kinder to carabiners, not that it's a huge issue, and you can run a rope directly into them. Welds add a level of risk as a point of failure or increase the risk of SCC (stress crack corrosion) in certain harsh environments, though it is unlikely. If an area has that risk, you'd be using Titanium glue ins anyways.
Chains are also a form of this but are not ideal as you have to add a stack of washer under the first chain, putting extra leverage on a bolt. These are usually selected because they are "cheaper" but they aren't if you get stainless chain and stainless washers. It's common to have chain as part of an anchor but please don't directly attach them to the bolt.
What happens if you put a rope in a sharp hanger???
Standards Vs Offbrands
EN 959:2018 is a European standard for the safety requirements and test methods for climbing anchors. It says the eye shall be wide enough to accommodate two "pins", one with a diameter of 15mm for the lower part and one with a diameter of 11mm for the upper part. So at least two carabiners can always fit in a hanger. A minimum of a 10mm hole for the bolt is because bolts smaller than 10mm aren't strong enough to be used in most anchors in today's standards. It also requires stainless if outside and that it is at least 2.9mm thick metal without sharp edges (a minimum of a 0.2mm bevel).
Off-brands are fairly obvious as they have almost no markings, and though they are simple chunks of metal with no moving parts, the quality of the stainless could be unreliable. We don't find off-brands are any cheaper, and if they are significantly cheaper, then it's a red flag. Homemade hangers are typically thick flat stock with two holes punched in them and often look like they were made on a farm. Most of the time they are not stainless...shocker! Just think about Leepers that were recalled because they would break under body weight because of nerdy metallurgic reasons. If you are installing hangers that thousands of people that you don't know will be trusting with their lives, use quality please.
Strengths
Many hangers are rated for 22kn to 25kn just like the carabiners generally attach to them. However, some hangers have broken past 50KN as seen in our BoltBuster tests in the BOOK OF NUMBERS. The hanger strengths vary on normal size hangers around 25kn but Fixe's stainless ½” and 12mm hangers are 30kn certified with a 44kn ultimate breaking strength and we have occasionally achieved up to 60kn! CMI’s ⅝ hanger is rated as one of the strongest hangers at a whopping 44kn but broke in our BoltBuster tests as low as 33kn in shear, because it puts too much stress on one side of the hanger. In tension, with a large enough shackle, it is full strength. It isn’t made for climbing so don’t buy them. Every hanger made today is as strong or stronger than the aluminum carabiners we will be clipping to them… as long as they don’t corrode.
Chains are super strong enough at 30kn to 60kn. Basic new steel chains used on ⅝” bolts that we tested in sandstone broke in the 60kn range when they broke. The bolt broke more often. Just because they are strong doesn't mean they should be used. If they aren't stainless they will rust and even if that doesn't reduce the strength, it leeches the zinc coating all over the rock leaving stains. It's also not just the strength of the chain, but the 2nd chain doesn't sit flush with the rock, so a stack of washers goes under the first chain pulling higher up on the bolt and creating a lever that can bend the bolt. Basically, you end up getting less strength out of your bolt.
These chain link bolts should only be used to pull shear (sideways) and should not be used to pull a bolt in tension (straight out) because it deforms the chains significantly even though it is at forces you wouldn’t get in a normal use. We do not know the strength of zinc plated chains after corrosion has begun.
Not every hanger you'll find in the wild is new or up to today's standards, we tested a bunch of old hangers in this EPISODE. Some were old, rusty, recalled, burnt, or speciality aid hangers and all broke between 17kn and 36kn.
Temporary vs Permanent
In theory, you can remove a hanger held on by a nut but there are specific temporary hangers for permanent bolts without hangers. These bolts could be compression bolts like button heads or carrots, wedge bolts with or without nuts on them, or sleeve bolts (usually small and rusty) but they all have a little space between the head and the rock for you to fit a temporary hanger. This is more common in a bolt ladder while aid climbing than a sport climbing anchor, or if you are way in the back country and the bolt is rarely used.
Rivet hangers can look like offset hangers and they just slip on but don't slip off as long as a carabiner is inside of them. There are also rivet hangers which is a loop of steel cable. These are all available on Skots Wall Gear. We tested Skot's rivets in this EPISODE. The loops were almost twice as strong as the butterfly rivets!
Buying Guide
DON’T BE A CHEAP ASS AND BUY PLATED STEEL HANGERS. THOSE ARE FOR INDOOR GYMS.
All prices below are as of April 2023.
FLAT STOCK
Fixe Hardware's 316L SS for $4.89. It has an MBS of 25kn and broke at 30kn or higher in Bolt Busters.
Raumer's 316L SS is $3.99
Petzl's 316L SS ranges from $2.17 each to $8.76 each.
Austria Alpine's 316L SS $3.90 at Team Tough (US based)
ROUND STOCK
Vertical Evolution has a 316L SS hybrid ring anchor welded to flat stock for €5.99 at Canyon Zone.
Bolt-Products makes one from a 8mm 316SS (A4) welded rod for a 12mm bolt at a price of €5.20. Bolt Product's are rated for 45kn and we could NOT break them in tension at 42kn and in shear at 52kn as the bolt heads would snapped off first so they are bomber.
Bonier makes unique bent hangers called the DUPLA and PINGO, where it is bent up on both sides and shaped so that no sharp edges touch the rope. They only come in 304SS which is super good enough for most situations. We did break tests on them in this EPISODE and like them very much, however they are difficult to find/buy as the company is in Brazil. jgarr_18@yahoo.com is a US source to buy them from. Please contact me if he says he doesn't sell them anymore so I can remove this from here.
More is NOT Better?
Holy moly! Why is this so big??? There is always a reason that something is the way it is. In this case, too many climbers in a popular area were using the tree and damaging it, and as obtrusive as this is, it does scream "hey, use this instead". Yes it's strong enough, no we don't have to test it to know that. But holistically, it makes clipping a carabiner to this obnoxious at the very least to weakening the full potential of the carabiner at the worse, because it's pulling too much on the gate side. Maybe a nice wood sign nailed to the tree might have been a better solution?
CMI has an oversized hanger that is intended for aborists work like rope course but it's not stronger because it's bigger. If you pull in shear, it puts all the force on one side of the hanger making it break around 31kN (still super strong enough). Only when you pull in tension with a large connector does it even achieve it's MBS of 44.4kN. NOTE: We've had some standard hangers break at 60kN. Their oversized hanger is good if a tree is growing around it but not for the visual impact of our climbing areas.
What's Next?
You can always go back to the main part of the BOLTING BIBLE HERE
Feedback, typos or more information is always appreciated. HMU at ryan@slackline.com
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