UKH

So I'm thinking about single axle cams and their advantages and disadvantages. I know what I think they are but I'd be interested to know from the average Joe what they think the disadvantages are and whether the ones I know of actually affect people under real world conditions.

Please note, I am 100% NOT interested by range arguments, as I have that covered, what I am particularly interested in is how often they are overcammed and how often the cam lobes reverse whilst extracting them making it awkward to get them out. Personally in 25 years of climbing I've rarely had a cam lobe invert, and lost one cam due to over camming, although I've seen many more. And if you can think of any other disadvantages, let me know...

Tricky one. Trying to isolate the number of axles from the other designs is really rather hard, if not impossible...

The only cam that I've actually managed to irretrievably damage recently was a small blue BD C4. In hindsight it must have been over-cammed as my partner couldn't remove it and by the time I finally got it out with some considerable effort on abseil the axles were just bent enough that it's no longer serviceable. 

I think double axles can definitely get at least as badly jammed as single axle ones, so I don't think there is much in it either way as regards that as an issue.

More generally, climbing at Gogarth, Rhoscolyn etc.. , I absolutely love cams with extendable slings. The rest of the time I rather dislike them. Other than that, provided the cams are a coherent set racked on quality colour-coded wiregates, I genuinely don't have a massively strong preference between any particular models (single axle, double axle or totems) sold over the last decade.

I'll be replacing my second set of original Dragons at some point with some Dragon 2s but that's due to cost rather than any massively strong attachment to the design. 

With single axle cams , the load on the axle from the lobe is always 90 deg minus the camming angle in a parallel crack even if one side of lobes is more rotated .

Thus may not be the case with twin axle design  if the two axles are not at 90 deg to the main load on the sling.

Best do some triangle of forces calculations to see if this is an issue with contorted placements.

I suppose as far as overcamming goes, I know when I got into climbing the general opinion was that double axle cams were less prone to getting overcammed, and although I remember seeing a double axle cam stuck deep in a crack, it's something I've seen maybe once? Whereas I have seen dozens of single axle cams stuck, usually because the tip of the cam rotates so far that it becomes jammed against the opposite wall of the crack meaning that no matter how hard you pull on the trigger, you can't retract the lobe any further because it's mechanically impossible. Notionally I think the reason double axle cams get stuck less is because the double axle design prevents the lobe from rotating into contact with the rock wall. 

What about lobe design? Are you at all bothered by whether a lobe has been forged, or cnc machined? Or would you not even know the difference? 

At the expense of some range , why not have lobe stops that prevent inverting? Or stop overcamming.

What would be a design USP is a better trigger wire system , more durable , more lobe rotation /pulling range, and somehow geared to enable far stronger lobe  springs.

Definitely concerned about saving weight if it doesn't compromise something else.

Whether that weight saving is achieved through forging or machining (or both) I'm not too bothered, although I could no doubt work it out. 

I'm certainly very tempted by the latest lighter weight BD C4s with their new lobe design which is very obvious in the larger sizes, but I haven't paid any attention to the manufacturing method.

It's quite interesting, just for lockdown giggles last night I totted up the weights of a set from grey to grey BD and WC and they came out exactly the same... DMM was just over 100g more - not a massive amount I suppose... 

Double axle cams usually have a passive strength. I don't think single axle cams tend to have camstops. 

I've not experienced it myself, but I've seen worrying reports & pictures of how the necessary slots in the cam lobes to accommodate  the second axle leaves a very thin potential weak spot in the lobes of small twin axle cams.

Depends on the cam - larger ones like DMM 4CU's, Wild Country Tech/Helium Friends, HB Quadcams all had camstops. Maybe lower quality kit doesn't... but also microcams like Aliens don't have them.

I think that the popularity of dual axle cams has little to do with how much more effective they are in use and more to do with other factors. I had various of Dad’s friends (mostly rigid) when I began climbing and thought little of it. I went to the states in about 94 and bought a set of camalots (single stem).  At the time, they were much better in use than rigid friends. I still have those cams which have been reslung a couple of times. Along with more modern iterations, they still get used when more of the same size is required and still feel reassuring. Quad cams were a pain and tech friends with the weird plastic thing just seemed a bit shit. The larger wild country friends had an uncomfortable trigger which was hard to use.  In terms of losing cams, I have recovered other people’s of both kinds and have never unintentionally abandoned one. They are normally overcammed and then moved into a worse place before abandonment. I am not sure if I have supplied any useful info. 
 

james

The main disadvantage is they don't last as long.

On single axle cams, the lobes get bent around on routes and in transit, and then the trigger wires bend, fray and eventually break.

This results in rewiring them, or more likely they go in the bin.

Double axle systems remove this movement and prevent the problem.

Regards them getting stuck; I have had to work hard to get double axle cams out a few times, but single axles seem to stick much more for the reasons you described above.

Cheers Dan. Would you say this happens to microcams as much? I’m assuming you probably have some aliens or similar in your arsenal? 

Probably not so much - I've still got a 1.5 flexible friend from our Bath days.

Small cams benefit far more from the double axle increase in range. My small blue c4 was ace. 

But below that it's all single axle - my c3s don't bend out of shape. My friends aliens seem to wear out quickly, despite their holding power.

I've not tried the new generation enough to have an opinion. 

Yeah, something about the old friend trigger wires made them last better... and as you say bd did too - those i’m pretty sure its the way the ferrule is crimped as the ferrule is crimped in the middle but not the end, which puts the flex point away from the stress raiser caused by the crimp...

OK, another question to you all. How important to you is it to have lobes which can be independently manipulated? I can’t say I use this feature but others might? I reckon most people just pull the trigger? 

One thing I like about the double-axle cams that I have versus the single axle cams is just that they feel more solid. My 0.5 C4 just feels so much more bomber in the hand than my no.1 Helium friend.

The trigger action on my double-axle cams seems smooth and the cam lobes tend to stay in the correct orientation. I don't like how, with some of the (DMM 4cu, WC Helium and WC zero) single-axle cams I have that have suffered a bit of minor abuse, the cam lobes never sit correctly, but are slightly disagreggated. I've had lobes on single axle cams that have become completely disaligned from each other. Moreover, it seems a little unnerving when you can slide the cam lobes back and forth along the axle a bit too easily.

Another note: when I look at the New Friends next to the Helium Friends, the narrow and rounded lobes of the Helium friends make me feel as though they're more likely to skid, whereas the fat lobes of the New Friends seem like they'd give greater surface area for gripping.

Finally, I've also had cam lobes get snagged on the trigger wires. This has only really happened with a large 4cu - but after it happened a couple of times under duress, I got rid of it. I also managed to overcam this cam once - placing it whilst stressed. I managed to drag it out sideways, though I had to ab for it.

I'm not saying any of these things really affect performance - even the trigger wire/lobe snagging could probably have been solved. But, subjectively these things make me prefer the Dragons, C4s and New Friends.

Independently manipulated, or lobes which have independent holding power like Totems? I don't think I've ever needed to manipulate lobes separately but having a cam which holds better in offset placements is great. 

That's one of the reasons why I love totems. The lobes look rougher and flatter, therefore giving more confidence. I don't know if they actually 'bite' better and give more confidence but they appear to, and that'll do me. 🙂

OK - interesting. I've not had single axle cams other than microcams for a while so my memories a bit faded on some of this stuff. I mean Helium cams, yeah there are some people who love them, but not very many... there's a reason that they came and went pretty quickly...

I meant independently operated by the trigger rather than independently loaded like Totem...