Crank Brothers

Kronolog Seatpost

Choices for dropper-posts have expanded as quickly as 29er wheels have taken over cross-country trails, and the freshly designed, 125mm-travel Kronolog builds on Crank Brothers' established position in this market segment. It's the only infinitely adjustable, fully mechanical Seatpost -- i.e. no messy hydraulic fluids and blown seals -- on the market and it weighs almost 100g lighter than its stable mate, the Joplin R.
With the number of hydraulic posts on the market, it's hard to believe almost a decade ago we were limited to chunky mechanical units ... until 2004 came along, and Maverick introduced the innovative, but fussy, Speedball. It was groundbreaking for its use of hydraulics and suspension-based technology vs. the steel-spring-loaded, cable operated options available -- and it paved the way for modern, suspension-influenced designs.
In fact, Crank Brothers' own Jolpin post can trace its roots directly to those early Maverick droppers. Thankfully, it's happily received a healthy dose of respected Crank Brothers ingenuity and quality control to iron out those well-documented Speedball quirks. The Kronolog, however, is a fresh design that marks a drastic turn from hydraulic back to mechanical actuation.
The market's now populated with hydraulic posts from major suspension manufacturers, so it's interesting to see Crank Brothers pull this 180. But, the decision to do so has sound reasoning behind it. To begin, let us explore the cable-actuated clamping mechanism.
The Kronolog is the only mechanical post, and among a few hydraulic units, that's infinitely adjustable. To do this, it uses two locking plates located parallel to each other. They're situated perpendicular to the post's movement so the upper shaft can slide through the plates when they are unlocked by cable tension. Once tension is released, a spring loads the plates, effectively locking the post in place.
The simple twin-locking plate design does not require 'weighting' the saddle to prevent jamming, and it allows you to lift the bike from the saddle without affecting position or operation. Lift some hydraulic droppers by the saddle and you'll wreak havoc on the seals, air/hydraulic preload, or screw up saddle position. This might not seem like a big deal, but when you're portaging over fallen trees, loading the top of a shuttle rig, or dragging up cliff faces like Fruita's Edge Loop, you're probably not too focused on where you're lifting from.
The mechanism is located on the lower portion of the seatpost, which results in a stationary position for the cable mount. Most dropper posts suffer from a surplus of cable required to allow four to five inches of travel because they are connected to the upper, moving portion of the post. This inevitably results in  advanced/sloppy cable-tie trickery or the cable/hose will rub the frame, tires, or your legs in the lower position -- not exactly an ideal situation during aggressive riding.
The Kronolog's lowers also house an air sprung system for preload that's adjustable via a bottom mounted Schrader valve. It's obviously going to be much lighter than a coil spring, and air pressure changes also affect return/lowering speed. This simple spring makes sure it's easy to fine tune the Kronolog for rider preference, and keeps with the post's simple and light design.
The upper is oval shaped, and slides on bushings sealed from dirt inside the lower. This results in minimal saddle slop, and near zero play at the nose of the saddle. The oval shape is also essential to produce a flat surface to permit positive purchase when the locking plates are engaged.
Unlike most designs, the upper tube and saddle clamp head are forged from one piece of aluminum. This eliminates a bonded, and often creak-inducing joint between the clamp and shaft. The trend of less-is-more approach is also evident in the clamp design as well, which uses a single bolt to secure the saddle.
The post is operated remotely only (there is no post-mounted lever option), via a bar-mounted thumb lever. It can be fitted to the top, bottom, and either side of the handlebar. It uses a standard shift cable, but Crank Brothers recommends using 4mm brake housing instead of shift housing, because the wound brake housing is more flexible for cleaner routing.
The Kronolog measures 217mm from maximum insertion to the saddle clamp when at full height. While total available travel is 125mm, it can be lowered by adjusting internal spacers. It comes with all hardware and cables/housing necessary to set it up out of the box. The Crank Brothers Kronolog comes in two diameters; 30.9 and 31.6, and two colors; Red or Black.