Section 7 - The Book of Glue In Bolts
"Sometimes it gets sticky when thou shoves it in, but be sure it gets hard!"
Glue in bolts are better in many ways but installation is trickier. They are stronger, last longer and more convenient to use since many don’t require hangers. However, the holes have to be really clean, the glue has to mix right AND fill up the whole hole… all without getting it everywhere. Also, the bolt isn’t adjustable later so it better be right. They can last a long long time and can be the best option, especially in soft or layered rock, so let’s go over what you need to know so you can do it like a pro.
Chapter 1 - Bolt Types
I suppose you could glue anything inside of a hole, but if you are installing glue in bolts, I assume you are thinking long term and want to do it right. It is NOT recommended to use mechanical bolts with moving parts like we described in the last section. The glue wouldn’t grab the right parts, like sitting on the sleeves and not the actual stud, and the mechanical parts get gummed up by the glue and aren’t free to do what they need to do. And any properly placed mechanical bolt is going to fit the hole so tightly, there wouldn’t be any room for the glue and therefore push it all out. There are bolts specifically designed for glue, so let’s go over our options.
U shape bolts
Also called staple bolts, these are almost never used in highlining as they require two holes and have twice the impact. And consider that the 2 legs rarely share the load so you don’t necessarily get 2x the strength. If one leg goes, so do you. AND… when holes are drilled that close together, it could weaken the rock. The benefit to these is that they do test stronger when being pulled straight out than the P shape bolts. Please don’t buy any ol’ U shape bolt from the hardware store! If you must use them, please use Titan’s because they are very corrosion resistant and rated for 15kn with an MBS rating of 30kn but commonly break above 50kn.
Single Rod glue in bolts
Climbing-specific glue-in bolts generally have an eye at the top so they don’t require a hanger. These are nice because you can thread it with a static rope eliminating the need for quicklinks. The single rod, or solid leg bolt, has grooves or notches on the shaft for the glue to have something to grab. This is critical as epoxy glue doesn’t grab stainless steel very well, but stainless is critical for longevity. The single rod options are either welded like Fixe’s or Bolt-Product's or forged like Petzl’s (10mm bolt requires a 12mm hole and a 14mm bolt requires a 16mm hole). Welds aren’t ideal, especially where SCC (stress corrosion cracking) is a concern. Either way, it is important to bury the weld under the glue, requiring a notched hole (see chapter on installation), not a pile of glue. These fixed eye bolts can only be used in 1 direction, otherwise they can be twisted, breaking the glue bond.
“P” shape or Continuous Rod glue in bolts
Another option is a continuous rod that is like a U shape bolt, except it is “P” shaped, so it shares one hole like the everlasting titanium Titan Eterna bolts, the bomber Twisted Leg Bolts, and the wave bolt. Some of these bolts both require a hammer which is unusual for a glue in. The wave bolt requires a lot of hammering as it fits tight like a compression bolt, and Titan’s Eterna and Bolt-Product’s Twisted leg bolts requires a little bit of hammering because the neck gets tight. The reason for this is so the bolts don’t fall out before the glue hardens, as they are often installed by climbers in vertical or overhanging rock. The titanium bolts will last longer than you will because it is significantly more corrosion resistant than 316SS or even the fancy Duplex Steel. We are fortunate to have them available as a glue in option, as titanium is still a bit too expensive to manufacture as a mechanical bolt. The 316SS Twisted Leg bolts are crazy strong at 79KN (or even 100kn if you get the Twisted Leg 1.4462SS). The glue holds all these bolts well from either notches in the legs or the bent/twist pattern which snuggles that bolt in the security of all that gooey glue.
This is literally a ½” threaded rod glued into a hole that is ⅝”. Just like everything, too much or too little is bad. If your hole is too big, bigger than 2mm or ⅛” bigger than the bolt, then the glue starts to get compromised. And if the hole is too small, and the rod barely fits, then there will be hardly any space for the glue… which is what holds the bolt in the hole! It is also important to use stainless steel (SS) and not cut the end that will be exposed to ensure you have really good threads for you to screw your nuts. Cutting exposed ends also risk leaving iron deposits embedded into your precious SS that can cause corrosion. Threaded rod gives the option of using hangers, removing hangers, or turning hangers so the same bolts can be used for multiple lines. The risk with these is that the threads can get damaged, especially if removing hangers is frequent and then you are left with a useless stubby sticking out of the rock. These don’t save you any money as you need to buy a SS nut, washer and hanger to match the metal you are using.
Chapter 2 - Bolt Buying Guide
Fixe SS Glue In - Not recommended - Not fond of welds and for same price you can get something much better from bolt products, see below
304 Stainless Steel 12mm x 8cm long is $9.00
Hole required 14mm or ⅝” x 95mm long
304 Stainless Steel 10mm x 8cm long is $6.75
Hole required 12mm or ½” x 95mm long
304 Stainless Steel ⅜” x 6.5” long is $7.50
Extra long bolt for soft rock
Hole required 12mm or ½”
316 Stainless Steel 10mm x 8cm long is $16.00
For corrosive environments
Hole required 12mm or ½” x 95mm long
Commonly used, but there are no ratings available, and the welded eye is not ideal, and their 304SS version should stay far far away from the ocean, Thailand or anywhere really.
Bolt Products - If you want super strength and great prices then these are your bolts. I highly recommend.
Website to purchase listed bolts below is a one page wonder, scroll to find
Solid Leg series
10mm comes in 304SS and 316SS and breaks at 40kn
Lengths available are 80mm, 100mm, 120mm and 140mm
These require an 11mm hole or larger
Prices range from €4,95 to €5,75
Team Tough is a US based company and sells the 10mm x 100mm version but claims it only needs a 9mm hole and that it is rated for 35kn. A bit confusing but if in North America it is an option though I highly recommend the 12mm below.
12mm (Crux Monster) comes in 304SS and 316SS and breaks at 60kn
Lengths available are 100mm, 120mm and 150mm
These require a 12mm hole
These have the thickest rod for the best bend radius to thread rope into
Prices range from €7,50 to €8,40
Twisted Leg series
6mm rod fits in a 12mm hole but the rod is a bit too narrow to thread our static ropes directly into. Also the next size up is double the strength.
8mm Rod Twisted Leg comes in 304SS and 316SS and break at 79kn!
8mm SEAWATER Twisted Leg series is the fancy 1.4462 Stainless and breaks at 100kn!!!
Lengths available are 80mm, 100mm, 150mm
These have a larger eye opening as extra purchase option to which can make rigging a bit nicer
Prices range from €9,00 to €11,60
Petzl - Too small and too big for my taste and the prices are ridiculous, plus there are no clear ratings… not recommended
Wave Bolt - These win popular award but I’m not that fond of them. They require a special tool to hammer in and spin as you hammer them so you have to hit them sideways after they are in the hole nice and tight. Drill your hole bigger than they recommend and they might be a good option. They also have not been properly tested, they are strong, but not have been tested repeatedly until the bolt breaks.
316 Stainless, ½” x 4”
Requires a ½” x 4 ¼” hole
9,100lbf shear it did not break and the rock they tested it in broke during the tension test at 8000lbf
316SS, ½” rod for 5/8” hole and cut to 5” - Costs $8.10 for 10” which you can cut in half and the SS nut and washer are $1 each on the same site. So $6 plus a $6 hanger from Fixe because SS needs to be compatible.
***Don’t buy home depot unrated rods. Buy rated threaded rods that are the correct length, or double length and no longer, so you can keep the factory finished end exposed and put the cut end in the hole with the glue. The cutting wheel will embed particles into the metal that can form rust otherwise.
Threaded rods end up costing what a titanium bolt does, petzl’s bolts are too small or too big (16mm holes are hard) and too expensive, Fixe has a weld so there not ideal, the wave bolts are ok but install can be a bitch, Bolt-Products has the muscle and are awesome (solid leg series has welds but they are twice as strong as Fixe’s) and the Titan Climbing sells titanium bolts which will last a very long time. If removing hangers or turning them is critical, then you will need threaded rod. Keep in mind that titanium isn’t necessarily stronger than steel, though it often is. Its strength to weight is what makes it shine, and we recommend these because they are significantly more resistant to corrosion than even 316SS or Duplex stainless.