PRO is Shimano's house brand and the Koryak Dropper has a 170mm drop, internal routing and infinite position adjustment. It's proved to be a smoothly functioning post, with a well-made lever - it’s only compromised by the unreliable single bolt clamp for the saddle.
Built out of 3D forged aluminium, the post offers a very useful 170mm of drop. That is actuated by the smooth and ergonomic lever, which can be set in multiple positions. It uses internal cable routing, with a standard Shimano cable, to trigger the drop.
The lever is a nicely made, and not as flimsy as other levers I’ve tested, it also has some clean details that really add to it. The textured thumb paddle is handy for a little more grip when using it in the wet. The barrel adjuster is a good size, with areas removed to create texture to turn it, but also remove (a tiny) amount of weight. It's an obvious bonus of having Shimano as your parent company.
The movement of the post in use is smooth, and the return back is a good pace without it being too sudden or rocket like. The 170mm of movement may mean it’ll cause issues in some frames with being able to insert the bottom half in far enough, but didn't cause any issues on my bike. The lever feel is nice and smooth, with the setting up just being the usual internal routing install - depending on your bike how simple that is.
Weighing in at 560gm, its not overly hefty, but no lightweight either. There is no adjustment to the return speed but it's a good, reliable speed with a nice ‘thunk’ at the top. It's infinitely adjustable, which I personally prefer.
Clamping the seat is a bit of a pain, the single sprung loaded bolt design is in-line, so if you need to run the saddle back much, it creates a lot of force and can lead to the saddle rotating up or down, either on some dodgy landings or hard turns. I ended up using some thread lock to get it to stay put and wasn't using running the saddle far back. Once set, it was no problem, and I swapped saddles out and found it clamped up fine.
The obvious advantage to the post is the amount you can get the saddle out of the way when you need to - 170mm is a lot of drop and allows the saddle to be really low (it’d struggle to be much lower on a regular post). The benefits are obvious, loads more room to move around the bike, and less likely to bang into the saddle on more rowdy trails.
I feel like the post, although well made, is a little bit basic but the price makes up for the lack of refinement. Its not bad or shoddy, just not quite as polished as perhaps you'd expect. The post had very little fore/aft movement in it initially, and whilst it's increased a little, it's not continued to get progressively more so.
It's been ridden in a very unseasonal prolonged dry spell, and dealt with a lot of dust, and more recently very wet rides. I’ve raced it and used it for several days at bike parks, and its been pretty faultless - I’d rate it a little higher if the saddle clamp was better, but its a functional, no-nonsense and reliable seat post.