I've generally seen two kinds of locks for adjustable trekking poles. Twist lock and clamp lock (Clamp lock is also called "lever lock" and "quick lock"). What are the comparative advantages and disadvantages of clamp vs. twist?
Basically twist locks (in my experience) are a pain. They suffer from a number of issues:
- They're difficult to undo
- It's impossible to grip them with gloves on, this is a problem when it's cold
- The lock without careful maintenance can lock solid (had this happen a number of times to mine). This can be very difficult to rectify (especially without the help of a pair of plyers, etc)
The only disadvantages of clamp locks that I'm aware of are:
- They're newer and tend to be more expensive because of this
- They make the pole more bulky when stowing away
- They can come undone if you catch the latch
Generally, the mechanism is simpler and just less likely to foul up. You may have guessed I prefer the clamp to the twist lock, which is odd because both my poles are twist lock ones :(
@Liam's answer above is great but I wanted to add one additional con of the clap lock system.
You need a screw driver to adjust the tightness of clap based poles so you probably can't do it in the field.
I have a pair of clam locks similar to these:
About once or twice a year, I need to tighten the screw that that controls how tightly the clap lock is. Typically, I realize that I need to tighten the screw when I am miles away from the trailhead where I don't have a screw driver.
I think this wouldn't be a problem with a twist lock pole.
Clamp locks are the safest and the best design. The clamps are designed to fit flush to poles -I have never encountered the clamps opening by catching on anything for over 10 years owning the poles and I do a lot of hiking and snowshoeing with these. I used to own the old twist poles and they are lethal. Everyone I know who have the twist locks ask me to help fix them as they cannot loosen or cannot tighten or they fail or collapse when used which is dangerous. They throw these twisties out and then use common sense and buy the clamp lock poles and are happy.
One thing to bear in mind is that the twist lock will last a lot longer than the quick lock. This is because of the way the mechanism works. Each time you lock and unlock, there's a little wear on the mechanism in the case of the quick lock. With the twist lock, the wear is so slight as to be negligible.