UKC

For a bit of context I took a novice to shorncliff at the weekend for some easy trad mileage, I myself dont climb trad that often but enough to know how to place gear and happily climbed upto HVS. I've followed a fair few routes upto E4 there, and have held a big fall on to a microcam at wintours.

Walking along the base of the crag I was showing him how to place gear, and placed a cam in a crack haphazardly gave a sharp tug, and out it came. Tried to explain that a badly placed cam is dangerous, and moved on to another perfect parallel sided crack. Spent a bit of time placing it perfectly, all lobes equally in contact, and managed after a few hard tugs to rip this one out. Now I would have said this was a perfect placement maybe i was wrong. I also thought any time the coefficient of friction was greater than 0 it held. This freaked me out a bit, and I swapped my cams for my hexes. Ive always been a bit suspicious of cams as I can easily see a nut is bomber. The only cam i placed that day was as the first piece, to stop my wires unzipping.

I've read a few other threads warning of cams and limestone, but have also followed up a few harder routes in the wye, where majority of the protection placed was cams. Is wye valley lime particulary bad and should cams be a pretty much a last resort, as a "anythings better than nothing scenario"? Certainly I wouldnt want to be using them for a belay.

In reply to SFrancis:

Most of my climbing has been in the Wye, and I've always been dubious about cams there. It was a revelation to finally climb on grit and find that cams actually stay put!
They can be useful, just not in a parallel crack. I use them more like an expanding nut, as long as there is a constriction then they will be fine. I've fallen on them and they stayed in. They are a bit of a last resort though, almost anything else on my rack is preferable to a cam round there. Tricams, offsets, micros are all better than something that depends on friction to work.

In reply to SFrancis:

I'm generally suspicious of cams in limestone cracks anywhere, even on grit I think you need to take the time to place them carefully.

In reply to SFrancis:

Yes and no. It rather depends on the rock in the immediate vicinity of the placement. Some placements, although nominally sound, are worthless. As they say in those newspaper competitions, 'Using your skill and judgement...'. Slamming in a cam because it's easy is not a good way to proceed.

A smooth-sided crack, or one with bit of a crust, is unlikely to be a sound choice for a cam.

In reply to SFrancis:

Avon Gorge has the same issues, not that there are that many cam placements there. It's something to do with smooth quarried limestone IMO. In any case cams for me are a last resort, a nut is ALWAYS preferable.

Al

In reply to SFrancis:
I think most climbers have now realised that cams in Limestone are prone to failure due to the smooth surface of the rock. I try only to use them in irregular cracks rather than in parallel ones for this reason. Hexes and wires appear to hold much better. Cams in Grit stone horizontal breaks can be life savers. So I found out!

In reply to SFrancis:

I think it's only parallel limestone cracks you should be worried about. In reality there are plenty of small constrictions you can use which often don't fit a nut. I have used plenty of cams on belays (not as the only piece mind you) and they haven't ever fallen out - it's all down to the placement.

In reply to springfall2008:

I agree that it's parallel cracks that you need to worry about but they don't just fall out, it can require some considerable force. For example, I placed a small cam in the Avon Gorge that looked superb, I tugged it in every direction as hard as I was able to and it stuck but for some reason I was still a little doubtful so I retreated to the ground where I was able to pull with a little more vigour and out it popped.

Al

In reply to All:

It definitely didn't just fall out, and it looked fine until it finally pulled. It sounds as if I need to get a bit more canny with my cam placements on limestone and place them in constrictions. Bit of an eye opener anyway, glad it was at the bottom of the crag, and not something I learnt about the hard way. Cheers for all the replies!

In reply to springfall2008:

No, cams are terrible on limestone, especially wye valley. Go and test them with some falls. Or even just sitting on them. You'll remove them from your limestone rack swear to god.

In reply to zimpara:

There definitely seems to be a place for them, since my post here I climbed a few more routes at shorncliffe and found they were perfect for slotting in the weird pockets where a nut would be a bit marginal. Just not sure if I trust them for slippery wye valley cracks e.g. Organ Grinder.

In reply to SFrancis:


Organ Grinder swallows wired hexes

In reply to SFrancis:


Yup, try climbing African killer bees or The Split on the Fly Wall (Wintours Leap) without cams!

In reply to SFrancis:

My first ever fall onto a cam was on Organ Grinder. It held. It was in before the slippery crux sequence though.

In reply to zimpara:

Are you a bit mad? Saying cams are terrible in limestone but to be sure test them by lobbing onto them? By your logic that's a great way to have an accident.

Cams are not terrible on limestone. They are unpredictable on smooth sided low frictions cracks. But then there's nothing else available what else are you going to do? I know what I would do

In reply to springfall2008:

Did them both before I bought my first cam. Don't recall it being a problem.

In reply to SFrancis:

I challenge anyone operating around the grade to climb The Russian without cams Fact is if it's all you can put in then go for it. Everyone has stories of 'that bomber nut' falling out but some shit piece saving their life, cams are no different.

I've done a fair bit of climbing at the Wye and I don't really remember finding any slate-esque perfectly parallel smooth cracks. Most of the time there are small pod/constrictions in the crack you can seat the cam in that stop it getting pulled out.

In reply to SFrancis:

What make of cam was it, different manufacturers use different camming angles and different grades of aluminium, some go for a camming angle that gives a greater range, but the trade off is less friction, and generally the harder the aluminium used for the lobes the lower the friction for a given camming angle.

In reply to springfall2008:
i have climbed quite a lot around Avon and wye haivng lived in brizzle. If the crack is well polished even constricting cracks can be unpredictable, can't remember the climb now but it was on wintours I think and a well polished constricting quite shallow crack and every time when pulled the lobes just depressed and it dropped out the bottom. In the end went for a very average nut instead ( the crack was so polished that didn't look like it wouldn't just pop out the front of the verticle crack with any sideways pull on it.

I've also climbed a fair amount in Swanage, the more compact polished rock subluminal end cams are pretty dubious, but on the ruckle they mostly seem to bite on the rougher more textured rock there - on the whole. I think if they hold given a tug they should probably take a fall.

In reply to SFrancis:
As above - if they hold a sharp tug they should grip for a fall, in general if you are relying on any gear it's often best to back it up but cams on limestone more so imo. Especially wye Avon stuff, it's quite compact and smooth in the main.

In reply to CurlyStevo:

Yes agreed, you have to check your placements - this is nothing new for any climber right?

In reply to springfall2008:

Unpredictable. There's a clue. Doesn't matter how new a climber one might be.

In reply to SFrancis:

I once fell pretty much the full length of the ramp area at Avon. I had 2 cams rip out, the top one I was kinda expecting, but the one below I was very happy with when I placed it. Fortunately my belayer was incredible and kept me off the deck, but he didn't have to lower me far the the ground! Haven't really trusted a cam since! (Irrationally I might add).

In reply to SFrancis:

"I also thought any time the coefficient of friction was greater than 0 it held."

Cams exert an outwards force pretty much twice the pull and you have two sides to share the load. So long as the coefficient of friction is >0.25 the cam <should> hold (caveats apply). For most rock / alloy combinations the coefficient of friction for smooth surfaces is around 0.3 and a bit so cams hold. Polished limestones can have lower coefficients of friction and, without rugosities, edges, constrictions and the like, cams are known to fail.

Cam design could be altered to increase the sideways force to make the cams stick better but at the expense of lower camming ranges - AFAIK no one makes cams like this, presumably because the market and the safety margin is too small (plus when the cam range becomes too small additional caveats apply).

Before someone says, "why not make the cam stickier?", you need to consider the pressures under the cam - the contact area is tiny (compared with a foot or tyre) and the softer, stickier materials aren't up to the pressures and shear forces involved (in theory you could have lots of sticky lobes or really fat ones to spread the load but cost of extra weight (caveats apply)) .

However, if any one fancies falling onto an inflatable rubber bladder then we could get right onto designing the next generation of protection with sticky rubber ballons (errm perhaps not)...

In reply to duchessofmalfi:


That's what Totem did. Their cams are designed to increase sideways force, without reducing the camming angle. Very clever, and great bits of kit for Wye limestone.

In reply to Hooo:

No - Totems have pretty much the same camming angle, range and sideways force as the rest. You may be conflating the blurb they released about flaring cracks (which is pretty much true of all cams) with the camming angle. You can't increase the sideways force without reducing the camming angle (caveats apply).

What Totem have done is engineer the cams with separate loading attachments to each pair of lobes allowing you to load each side of the cam on its own. This allows two-lobe placements for aid (not protection) and possible makes placements more stable.

In reply to duchessofmalfi:

They also have a few extras like a softer metal, rounded edges etc, and they do stick better. Having used them aiding in Yosemite they are better than BD, Wild Country, DMM. OK so 90% of placements work with most cams, but Totems and Basic Totems (Alien based) work on the rest, for body weight + placements.

In reply to duchessofmalfi:


Not true per se - youtube.com/watch?v=qIAZ4DFyUNQ&

It demonstrates that the totem design allows full strength at the entire range of expansion - something single or double axle cams cannot claim. While the expansion ranges might be similar to conventional cams, they are not of equal quality.

In reply to philhilo:


Don't forget the extremely narrow head width. Able to place them in pockets where conventional cams get refused entry at the door.

In reply to zimpara:

What are you on about now? A clue to what?

In reply to SFrancis:

In my case a very small fall onto a seemingly securely placed #1 cam in a non-parallel-sided limestone crack led to instant failure of the placement when loaded, a 5m ground fall, a sub-talar and a class 5 calcanial fracture, a 6 hour operation, 9 pins and five plates, a serious case of compartment syndrome, 7 weeks in hospital, followed by intensive painful physio and rehab, with over 8 months spent in a wheelchair and on crutches. A notable highlight was an extremely nasty cold-turkey experience after coming off a highly-addictive 6 month long Oxycontin trip.

Recovery has literally taken 7 years and is actually still continuing , with 2 more operations in the meantime - one a sub-talar fusion and one to remove all metalwork so that I could continue climbing - and consequent long stints on crutches. I have lost 90% of my ankle flexibility, have a permanent limp and have constant low-level pain due to arthritis. Further surgery will probably be needed in future.

Cams in limestone cracks? Oh deary me, I should have known better ...

Have a care.

In reply to Dave Williams:

Cams are much trickier to 'get right' than other gear on any rock so failures like the bad one you had are more likely I guess. On the flip side, I remember my mate having a fall on a 00 Friend at the top of Darius after the dubious bolt, placed in extremis. It held OK. In fact I think he's had a few lobs on small cams in limestone

Where I really like cams is below a wire. In this case they are pretty good at protecting the wire from any outward force if the rope angles are not quite ideal.

In reply to GrahamD:

Yeah if I can I always like to place a cam as the first runner. Or anything other than a nut that cant be lifted out! Like you say good with weird rope runs too

In reply to Dave 88:


Definitely one of the scariest trad falls i've seen! Hope you're well mate

In reply to duchessofmalfi:

No - Totem cams take advantage of leverage to exert a greater outward force than a conventional cam. It's explained on this thread, after some confusion at the beginning.
http://www.ukclimbing.com/forums/t.php?t=615357

In reply to Kemics:

Alrite mate! I don't think I've climbed harder than VS since! It completely ruined me, but at least I walked away from it. You too, thanks for stopping me from dying!! Bloody limestone....