3 cam units vs 4,

Original Post
Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 45

Hey everyone,

So I'm curious about people's opinions on this subject. When I first built up my rack, I went straight for 4 cam units (BD X4s, Totem Basics) because I heard that 4 cam units are inherently more stable and less prone to walking. However, some people have made the claim that 3-cam units (TCUs, C3s) actually have several advantages, especially in the smallest sizes, and I was hoping to expand upon this. The obvious advantage is profile; TCUs will fit in some funky pod/pocket placements that their 4-lobed cousins will not. Black Diamond also claims that C3s have a "constant camming angle" due to the triangle shape that makes them more stable and less likely to pull when a cam moves due to rope movement. I don't have too much experience with TCU/C3s...what do you guys think of them compared to 4-lobed cams?

Bill Lawry · · New Mexico · Joined Apr 2006 · Points: 1,402

"First lead of the week" I last did at Tuolumne, I wished I'd had a 3-lobe cam at the crux. Instead, I had to make due with 2 out of 4 lobes protecting me.

Gunks Jesse · · Shawangunk Township, NY · Joined May 2014 · Points: 63

I'll risk a first response based on my experience. I prefer the three cam units in the smaller sizes because they are narrower. In the Gunks I've found that thinner cracks can also be narrower so the narrower head makes them more usable in more placements than a similarly sized X4 or alien. I also think the wider center lobe of the C3 gives it good stability on otherwise wonky placements. But other people can argue the wider center lobe does the opposite and they have a valid point as well. It's all experiential.

Rick Blair · · Denver · Joined Oct 2007 · Points: 163

I have Metolius TCUs and Mastercams. The Mastercams are generally more useful but for the cost and weight savings the TCUs are pretty nice. For shaving weight, potential bail, horizontal cracks or weird pods/pin scars the TCU can be better.

eli poss · · Durango, Co · Joined May 2014 · Points: 136

There are a whole lot of factors to consider and a lot of it will depend on the type of rock you climb and the features it forms. In areas with shallow cracks and/or pin scars, TCUs are gonna fit better than 4CUs, although they may be less stable and will exert force on a smaller area of rock (which is bad for soft rock or choss). Alien style cams and Totems provide a middle ground with 4 lobes yet a small head width. Consider looking at Totem cams.

Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 45

Already own a set. :)

Harry Netzer · · Unknown Hometown · Joined Dec 2011 · Points: 125

Tcus don't always have a smaller contact patch, look at this picture cdn.outdoorgearlab.com/phot...

My theory is that tcus walk more, but a vertical placement will rotate in the direction of fall force. A flexible 4cu is the opposite, placing one straight out in a vertical crack and falling on it torques the lobes and stem.

Jon Rhoderick · · Unknown Hometown · Joined Jul 2009 · Points: 590

To be honest I think the nature of the placement and rope management has a lot more to do with the cams walking than any how many lobes. 3 cam units are often lighter and cheaper, important considerations when carrying more than a double rack.

Firestone · · California · Joined Nov 2015 · Points: 449

Ive heard 4 cam units walk in but 3 cam units walk OUT!

Locker · · Yucca Valley, CA · Joined Oct 2002 · Points: 1,640

The most important things to consider are Fall Factors and Micro Fractures.

Just check for those two things and you'll be fine.

Matt Himmelstein · · Orange, California · Joined Jun 2014 · Points: 95

I have only 4 lobe cams, and had never really placed any TCUs. On my last climb, we were using my friend's rack and I ended up using his TCUs very often in thin pocketed cracks. Could I have slotted in a quad? Probably, but the TCUs went in faster and were plenty secure.

That said, if the crack were longer, I probably would have placed a quad or an offset quad and been just fine with it. It comes down to where you are climbing and what is best for you and your area. I will probably end up getting some smaller TCUs based on this last experience, but I am not going to rush out and buy a full set.

Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 45
Locker wrote:The most important things to consider are Fall Factors and Micro Fractures. Just check for those two things and you'll be fine.
Quiet, you! ;)

Weight is a good point, although I feel like Totems are ridiculously light. Still, it definitely adds up. I've had similar experiences Matt...yeah, you might be able to get a 4 lobed unit into that placement, but it's not going to be nearly as solid and some of the lobes might be tipped out.
JK- · · SLC · Joined Nov 2012 · Points: 13

I place my 4 cam units significantly more often... But I'm sure glad I have a 3 cam unit (C3s in my case... VERY narrow heads) when I do use it.

When I carry doubles in the smallest sizes the second is a C3. In the .3-.4 (camalot) I don't usually carry a 3 cam until I'm carrying triples.

I had a full set of Metolious TCUs for a long time... And almost never used them. Revolutionary in their day, but in this day and age you can get the same head width in a 4 cam and much much narrower in a 3 cam.

Locker · · Yucca Valley, CA · Joined Oct 2002 · Points: 1,640
"Quiet, you! ;)"


Glad someone caught it.
Guideline #1: Don't be a jerk.

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