How to bolt rock climbs, and how not to

In 2009, there was a tragic accident in the Blue Mountains in Australia where a well-loved local climber lost his life due to a bolt failing. The bolts in question were placed by non-local climbers who used small-diameter expansion bolts which are not appropriate for the rock (soft sandstone). To read more about this check out Simon Carter's blog.

This video demonstrates how bad the bolts were...

The take home message here is that certain bolts work in certain circumstances. Understand that rock is highly variable (very soft through to very hard) and the right hardware and technique is required to get an acceptable result. The recent bolt failure and its shocking consequence was the result of the route equipper choosing perhaps the worse possible bolt for the job. This bolt would have been 100% fine in hard granite, but is death in soft rock. Local knowledge is key, as is arming yourself with all that we know about bolting. Now is a good time for climbers to learn more about the bolts they often put blind faith into. Check out these resources...
  1. 2009 - Soft Rock Bolting Guide compiled by Mike Law. All the latest research (not only for soft rock). (PDF)
  2. 2010 - Anchor Testing in Soft Sandstone by Mike Law
  3. Safer Cliffs Australia - Bolt Types
  4. Jim Titt's Bolt Products website which contains heaps of good info
  5. Steve Hawkshaw's Honours Thesis: Strength and reliability of chemically bonded rock climbing anchors in sandstone (PDF)
  6. My article: "An analysis of climbing on the island of Kalymnos with respect to new routes, the safety of fixed hardware, and route maintenance now and in the future"
Steve's thesis indicates that epoxy based glues are twice as strong as polyester glues, and that deep threading on the shaft is nearly three times stronger than the next best thing: grinding and notching. Additionally, U-bolt shaft spacings should be no less than 45mm.

The good, the bad and the downright ugly
READ THIS: This is for glue-in bolts. The treatment of the shaft of the bolt is
of critical importance to the bolt's strength. If you can't get a deep thread, you
must grind and notch your glue-in bolts.
Here's a 2010 video testing U-bolt anchors in extremely soft sandstone:

Current world best-practice bolting methods (Updated Dec 2013)

Rock is a finite resource. Putting in sub-standard bolts which last for a few years before a rebolt is required (see below) is just not good enough anymore. We should all be shooting for 50 years or better lifespan.

Home-made versus certified products
For many years climbers (me included) have been bending their own U-bolts and making their own hardware for using on rockclimbs. There have been no known failures I am aware of, and typically, things are well over-engineered. The point is, using products that are certified (EN959) removes one uncertainty out of the "is this bolt safe?" equation. I believe as time goes by we will (and should) see less and less home-made hardware on cliffs.

1. Titanium -- We now have certified titanium bolts available. Titanium is the best material because it does not corrode. These are the finest bolts available right now. Cost is about twice what a regular stainless steel glue-in costs. No big deal. These should be used in any seaside application or where the rock is corrosive. Note that some cliffs are very corrosive irrespective of how close to the sea they are.
Eterna - world's first certified titanium bolt for climbing.
2. Premium Stainless Steel -- All stainless steel rusts, but different grades are more/less susceptible. The grade of stainless steel matters. Most 'regular' stainless steel is grade 304. 304 does rust, sometimes within a year of placement and I have witnessed plenty of instances of this with my own bolts. Because of this, I now suggest that all climbers place a minimum of 316 grade stainless steel hardware. A higher grade of stainless is termed '316 L' and is the low carbon version of 316, and is currently (2013) being used successfully in seaside applications such as Kalymnos, Greece.
A Raumer stainless steel lower-off in Kalymnos.
Fairly new, yet rusting is well and truly underway.
3. Zinc plated, cadmium plated, galvanised, or "other" -- Do not use. In any environment. Ever. Unfortunately, the great majority of American sport crags are littered with non-stainless hardware. It's been a long-running issue that American route developers used the cheapest expansion bolts available, and these were typically zinc plated. We are now feeling the effects of this 10 and 20 years later with huge efforts (and money) being needed to rebolt thousands of routes all over the country. So please do not contribute to this issue.
The haul from your typical American sport-route rebolt.
These were zinc plated expansion bolts.
Expansion bolts

Expansion bolts are still the most commonly placed bolts on the planet. But they are not the best. Glue-in bolts are the best. The reason these are used are because they are easy to place, and can be loaded immediately (important for equipping steep routes). The tru-bolt (or "parabolt" in Europe) is the most typical bolt used throughout Europe. However, it is not the best choice.

Disadvantages of the 'Tru-bolt' style of expansion bolt
  1. Cannot be extracted from the hole to allow for clean replacement. Must be cut off using a cordless grinder and then beaten back into hole and the hole patched with epoxy and camouflaged. Not great!
  2. Because the thread sits exposed from the nut, it can foul the carabiner leading to dangerous orientation of the carabiner. There are cases where this has led to a carabiner snapping.
  3. Sideways forces on the hanger cause the nut to loosen. If the nut loosens completely, the hanger falls off and the climber has no protection. This happened to me recently during a fall. I was very lucky to escape injury. Many routes are missing hangers due to this issue. 
Tru-bolts can foul the carabiner. This can be the result.
Typical Europe bolt. Cadmium plated hanger and
non-stainless Tru-bolt. Dissimilar metals corrosion.
This one is from Gorges du Tarn.
A better choice IF expansion bolts must be used - the Flush-head dynabolt

Flush-heads offer all the advantages of the trubolt, and eliminate many of the disadvantages. They have a low profile and do not snag carabiners as readily, and they do not loosen as easily as tru-bolts. I had listed "easily replaceable" in the advantages, but now having tried to carefully replace 50+ of these, they are in fact not easy to replace, and tend to spin in the hole which makes extraction difficult. Regardless, they remain a very good protection option and are produced by many fastener companies (e.g. Powers, Ramset, Macsim) and are available worldwide.
12mm x 75mm Flush-head dynabolt - a better choice than trubolts.
Rebolting strategy

We should be improving the route with each rebolt. So if a route has expansion bolts and is rebolted, this is the time to upgrade to glue-in bolts. The expansion bolts can then be removed (or cut off with a grinder) and patched. If glue-in bolts are being removed, heat the bolt with a blowtorch to melt the glue, and then extract [although the times I've seen this done it has been a shitfight, so if anyone has any tips, please post a comment]. Re-drill and re-clean the hole and re-use.  

Glue-in bolts

There are many types/configurations of glue-in bolts (ringbolts, U-bolts etc.). As discussed above, it is important if something is being glued into the rock that is 316 stainless steel or better.

A well-placed, well-recessed French glue-in ringbolt at Vernasque.
I don't know the material composition of these but I have
yet to find corroded one.
To recess or not to recess?

Recessing a ringbolt means to drill a small channel at time of installation to ensure that the ring is countersunk deeper in the rock and cannot be subjected to sideways forces which could spin the ring and potentially break the glue bond.

316 stainless glue-in ringbolt (shaft ground and notched), correctly recessed.
The fact is, with quality epoxy glue, no fall or other force possible by climbers in normal use could break the glue bond. HOWEVER! It is still best practice to recess all ringbolts as it makes the entire unit stiffer and less likely to transmit flex into the glue and surrounding rock.

Horrible non-recessed ringbolt.

Hammering in - careful!

If your glue-in bolts require you to tap them in with a hammer, use a small wooden block to protect the bolt. Hitting your stainless bolt with a regular hammer will embed iron in the bolt and hasten the corrosion process.


For starters, only ever use two-part injection-gun glue (also called cartridge glues). Never use capsules! Never use a one-part glue dispensed with a caulking gun you might find at a hardware store.

You will need a special gun (somewhat expensive and usually specific to the glue/brand), and a special helical mixing nozzle to mix the two parts dispensed from the tube. There are many types of injection glues. Just because it comes in a tube/cartridge, doesn't mean they all have the same composition. Glues generally fall into two categories: epoxy-based glues and polyester-based glues. Epoxy based glues are twice as strong as polyester glues and are definitely the ones to use.

Results from testing in soft sandstone. Source: S Hawkshaw thesis.
Glue strength - compiled by Source: here.
The strength of the glue is not even the main reason for using epoxy-based glues. The main reason is working lifespan. Polyester glues are porous and start to degrade and break down in as little as a few years. In the "real world" at Diamond Falls in the Blue Mountains, bolts glued in with polyester glues have been found to last 8 years of "moderate use". This is not good enough.

We have a serious problem in Australia now because the vast majority of route developers, particularly around the Blue Mountains have used polyester glue (e.g. early Hilti C-50, Ramset 101 or Powers KF2). The main reason for using this glue is because it is cheap, readily available from all Australian hardware stores, and can be loaded within an hour or so; allowing routes to be climbed the same day they are bolted. That convenience is great, but several years later we have bolts which are moving in their holes and in some cases can be extracted by hand.

This was polyester glue. It has now started to degrade and this bolt now
moves around in the hole alarmingly. Don't use polyester glues!
Which glue to use?

The absolute #1 best glue you can get is Hilti 'RE-500'. It is rather expensive, so you need to be rich, or have someone in industry who can source it for you.

Martin Roberts from Titan Climbing has sourced and tested a cheaper alternative, which could be good if you are from the UK or Europe. It is called 'Epo Plus' and is produced by G&B. Find out more here.

If I cannot get my hands on Hilti RE-500, I would use a two-part structural epoxy from Powers called 'Pure 150 PRO' (was previously called Power-Fast®PRO). I believe Powers is an Australian company so might not be gettable elsewhere. (Small side note - I have noticed problems with this particular glue in hyper-corrosive environments (Mt Coolum) and do not recommenced it in this case.)

If you cannot source any of the above, that is okay. You will need to do your own research to find a two-part pure epoxy glue. Ask the seller if this is the best and strongest glue available. Read the technical data sheets. Compare it with the Hilti product above.
  • Powers Pure 150 PRO. A pure epoxy.
Anchors - The quest for the ideal sport route lower-off!

Looking for the ideal sport route lower-off configuration is like a quest for the holy grail. There are so many different setups and configurations, and generally, they all generally have some advantages and disadvantages.

Let's look at a few different configurations for pro's and con's.
A custom chain setup.
Visual impact: Bad. This is a pretty visually obtrusive anchor.
Expense: Bad. High cost due to number of components.  
Rope-twist factor: Good. Low.  
Lifespan: Good. Where the rope touches are rings which spin, spreading the wear.  
Replace-ability: Good. Mallions attach the chains.  
Convenience: Bad (no clip and lower).  
Single clip safety: Bad. Ideally you want to clip to the anchor and be immediately attached to two bolts.

Horizontal Fixe rings - quite common setup.
Visual impact: Good. No chain involved, so pretty low impact.  
Expense: Not bad.  
Rope-twist factor: Not great. Even if this was threaded correctly (not like the photo) this configuration does twist the rope.  
Lifespan: Good. Where the rope touches are rings which spin, spreading the wear.  
Replace-ability: Good. Tru-bolts have been used (the only time I recommend their use!) to enable the anchors to be removed and replaced.  
Convenience: Bad (no clip and lower).  
Single clip safety: Bad. Ideally you want to clip to the anchor and be immediately attached to two bolts.

Commercial unit from 'Raumer'
Visual impact: Not great. It's a pretty big beast. The double-chain version of this is even more obtrusive.  
Expense: Reasonably expensive as this is a commercial product.  
Rope-twist factor: Good. Lowering off a single point minimises rope twist.
Lifespan: Bad. In high-traffic areas, this thick stainless carabiner will be worn through in a year or two (see right).  
Replace-ability: Bad. When the carabiner is worn out, it's quite a job to chop it off with a grinder. This leaves a spinning ring which you can lower off, or put another captive steel carabiner with a mallion. The other option is to replace the entire unit with an identical unit.
Convenience: Good. Clip and lower, baby!
Single clip safety: Good. You can clip anything and you're attached to two bolts.

Two naked glue-in rings.
Wear on ugly U-bolt. Bad!
Visual impact: Good. About as low-impact as you can get.
Expense: Good. Pretty cheap.
Rope-twist factor: Not great. This configuration does twist the rope.
Lifespan: Bad. Rope-wear will wear these bolts out (see right). This anchor can be good for very low traffic routes, but as soon as wear is noticed, install some mallions and chain.
Replace-ability: Bad. Once these wear out you have to heat them with a blowtorch to melt the glue and then extract. It's pretty full-on! Lazy people would chop them but this is messy at best.
Convenience: Bad (no clip and lower).
Single clip safety: Bad. Ideally you want to clip to the anchor and be immediately attached to two bolts.

Fixe ring and chain combo.
Visual impact: Moderate. Chain always stands out, but at least this is only one length.  
Expense: Moderate. There are a few components here. Cheaper than most commercial setups though.
Rope-twist factor: Good. Placed in this configuration, the thread point acts as one. Minimal twist.
Lifespan: Good. The ring will spin. The chain is easily replaced.
Replace-ability: Good. All wearable components are easily replaced.  
Convenience: Not great (no clip and lower) but at least you have plenty of clip points.
Single clip safety: Bad. Ideally you want to clip to the anchor and be immediately attached to two bolts.

Glue-in rings with twist-shackles for "replace-ability"
For a while, climbers started to use twist shackles because they would not twist the rope and you could replace the components that wear. Seems like an ideal solution, right?  
Why this is not good: The shackles can flip around so the rope is running over the pin of the shackle. This can undo the shackle (!!). People have tried to overcome this by "mousing" the shackles in position using wire or cable ties, but ultimately, this turns into a mess. Avoid twist shackles.

"Mussy hook" lower-off. Gaining popularity in America.
This setup ticks a lot of boxes.
Visual impact: Moderate. They're very beefy, no doubt.  
Expense: Good. These mussy hooks are supposed to be quite inexpensive (available in large hardware stores like Home Depot). Beware however cast versions of these - probably from China, and strength unknown.
Rope-twist factor: Could be a big problem unless they can sit off the rock. Mike Law says "I lowered off a lot of Muzzy hooks in Owens River Gorge and they destroyed ropes by twisting, I think the fat ones have a thick spine and sit so far off the wall that rope tension pulls them over at about 45 degrees, towards each other."
Lifespan: Good. The mussy hooks have a huge rope-bearing surface and are very thick so they'll take a long time to wear to about halfway where they can be replaced.  
Replace-ability: Good. The hooks are easily replaceable via the mallions.
Convenience: Great! Clip and lower!  
Single clip safety: Bad. Ideally you want to clip to the anchor and be immediately attached to two bolts.

As you can see there is no "right answer" when it comes to bolting and anchors, but there are materials and techniques that are nearly always more appropriate than others.

Do you have information which you believe contradicts the recommendations above? Please let me know and I will update the above. I intend to keep this post updated periodically as new information comes to hand.

If you've got any questions, also post them up here.


Hawkman said...

Nice one Lee. I just wrote almost exactly the same thing on my site then saw yours.

Lee Cujes said...

Yeah thanks mate, saw yours today. I actually edited my post earlier today (after seeing yours) to include the link to your thesis and some of the conclusions from it.

Unknown said...

Great work! Been talking about this a lot lately. Some great info said...

I miss what in my oppinnion is the best solution (bolted or glued):

Moderate visual impact, no rope twist, lifespan good (ring spin), single clip safety.

bolted one can be replaced, but both can last for very long time

Lee Cujes said...

Thanks. I use that Fixe setup a lot too, and have added it in to my article on lower-off's:

Buachaille said...

The French ring bolts mentioned in the text are manufactured specifically for FFME and distributed to their equippers.
I purchased some in Paris 20 years ago and placed them back home in Scotland. They are still in great condition. They are hot dipped galvanised steel surprisingly, not stainless.

Buachaille said...

The French ring bolts mentioned in the text are manufactured specifically for FFME and distributed to their equippers.
I purchased some in Paris 20 years ago and placed them back home in Scotland. They are still in great condition. They are hot dipped galvanised steel surprisingly, not stainless.

Lee Cujes said...

Thanks Buachaille. I've been wondering about those bolts for years. They do seem to last amazingly well for galvanized, but perhaps we've just been lucky to always encounter them in low corrosive environments?

Unknown said...

Hi...what would you recommend for the best epoxy glue from Ramset?

Lee Cujes said...

Hi Ringgo. Ramset's best epoxy is 801. It will certainly do the job, and I have bolted entire sectors with this glue. It is however very sticky and has the consistency of honey, so you need lots of rags. Hilti RE-500 is better and easier to work with.