Crank Brothers Kronolog Dropper Post

When it comes to product design, Crank Brothers has built their name on doing things a little different. The first product they released was a unique telescopic tyre lever that pivoted around the wheel axle; called the Speedlever it was a bit of a hit back in 1997. Their real claim to fame came in 2001 with the launch of their distinctive Egg Beater pedal—a super-light and simplistic design that remains popular to this day.After buying the rights to the Joplin dropper seatpost a few years back (it came from a small US company called Maverick), Crank Brothers has been working on their own unique design. The goal was to minimise complexity and solve all of the reliability issues that have plagued dropper posts—the $390 Kronolog is the result.

To simplify things, they’ve skipped hydraulics altogether and employed a mechanical locking mechanism. The inner part of the post (called the ‘quill’) slides through a pair of spring-loaded steel plates. In the fixed position, the spring forces the plates to sit on an angle and this locks the quill in place. Pulling the release mechanism holds the plates together; this opens up their grip on the quill and allows the quill to slide. It works just like a woodworking ‘quick clamp’, allowing the quill to slide and lock at any point within its travel. Simplicity is a good thing, as in theory it means there is less to go wrong.

Aside from simplifying the mechanicals, the most obvious benefit of the design is that it allows the remote cable to enter at the base of the post. Currently, most dropper designs have the release cable mounted up on the moving head of the post, and with the saddle dropped you wind up with a big loop of excess cable. In addition to looking pretty untidy, the cable can sometimes interfere with the rear tyre and suspension when the going gets rough. With the Kronolog, the cable remains in the same spot regardless of your saddle height—a real bonus.

The pitfall here is that the cable mounting port takes up 65mm of the seatpost length, so you’ll need a decent amount of post exposed to utilise the full height adjustment range. To run the maximum 125mm of drop, you’ll need to have at least 220mm measured from the centre of the seat rails to the top of the frame. Crank Brothers supplies the post with a limiting spacer that takes the travel back to 100mm for those with bigger frames or shorter legs—with this in place you need 195mm or more between the rails and the top of your seatpost collar. While the post comes with the cable mounted at the front, it can be swapped to attach at the rear. The swap requires a bit of disassembly but the package comes with step-by-step instructions to guide you through.

With an air spring to push the post back to full height and a simple locking mechanism, the Kronolog is pretty light. Our sample was 480g plus 28g for the remote, toss in a length of cable and the whole package came to 558g—it’s around 15g more than claimed but still at the lighter end of the dropper post market.

Just Read the Instructions!

Whilst simplicity and dependability was a prime design objective, it only takes a brief internet search to find plenty of Kronolog users claiming to have encountered problems. Some say they have have only ridden twice on a brand new post before having it slip and fail. It’s safe to say that much of this comes back to incorrect installation, as there are a few specific rules that you need to follow when setting up the Kronolog. First up, there needs to be sufficient slack, or free-play in the inner cable, or the locking mechanism can partially release when you turn the handlebars. Partial release is bad, as the locking jaws will score the quill as it slides through.

You also need enough slack in the outer housing to allow a few millimetres of movement where cable enters the seatpost. Whilst its position is fixed, it does need to move up and down a little when you push the release lever. Incorrect setup in this area can cause the cable to bind, and a jammed cable can also lead to partial release of the mechanism and scoring of the quill. The final important point relates to the seat clamp; you need to ensure that the nylon ‘bridge’ is centred between the jaws of the one-bolt clamping mechanism—mess this up and the plastic bit will break.

These specifics are all set out in the instruction manual (plus a bunch of good online videos), but we all know that most people don’t read them until later—they’re generally too keen to get their bling new bit fitted and hit the trails! In this case we ensured that our post was fitted properly, as we wanted to see how the Kronolog fared after many months of riding. Over time Crank Brothers has made a number of design tweaks, all aimed at eliminating the setup issues. Our post was the most recent version available at the time, so it included a stronger spring behind the release cable as well as a small indicator window on the lever that makes it pretty difficult to stuff things up.

As long as you are aware of the key setup points and take a little care when fitting the post, it isn’t hard to mount the Kronolog. The lever can be fitted on either the left or right hand side, and it can even go under the handlebars if you’ve got sufficient space. It mightn’t have the lightest action but it’s still compact and easy enough to use. The post itself can lock in any position and there’s absolutely no rotational play at the saddle. Most dropper posts have some slop, even when brand new, so this quite an achievement for Crank Brothers. Because this is a mechanical post with no oil damping, the recoil speed is very fast. It does slow in the final 25mm of its travel but it’s still not as smooth and consistent as a good hydraulic post. It also lacks an audible ‘thunk’ that most dropper posts have when they return to full height, so this can take a little getting used to.

The one-bolt seat clamp requires a lot of torque (12Nm) via a comparatively small torx bolt. While it did hold the rails securely during the review, it also locked so tightly in place that fine-tuning the saddle tilt was difficult (I feel that a good twin-bolt adjustment system is superior).

Maintenance-wise, I aimed to do everything ‘by the book’ with this post and I looked after it in accordance with the manual. It states that you need to wipe it down after every ride and after 50-75 hours, the post should be cleaned, “as outlined in the cleaning and maintenance section of the online manual”. Strangely, this part of the online manual didn’t exist when I was reviewing the Kronolog! In any case, the main foldout leaflet that comes with the post shows you how to remove the quill and air spring, and this level of disassembly is sufficient to give the internals a good clean.

Some who are familiar with the function of the Kronolog suggest that you should unweight the saddle before the remote lever is depressed. While this isn’t mentioned anywhere within the Crank Brothers literature, it makes sense as it lessens the chance of the quill being forced through the locking jaws when they are not entirely open. To lower the saddle you first stand, then fully depress the remote, then sit to drop the post and fully release the lever whilst holding the saddle height still. It sounds convoluted but it isn’t that hard to do.

With the Kronolog correctly installed, I had no issues with slipping and it always returned to full height when required. To start with, the only hiccup lay with the clip-on cover that shields the locking jaws; it is easily dislodged and I nearly lost it a few times when lifting the bike over gates.

Going the Distance

All was well for the next month or so but, despite my best efforts to use the post with some ‘finesse’, the alloy quill still showed some marks from the steel clamping jaws. Disassembly and servicing revealed some fine slivers of alloy inside that had clearly come from the quill. It still functioned properly at this point, so the internals were cleaned and the review continued.

When the post returns to full-height, it is normal for it to ‘settle’ by 1-2mm when you first sit down. However, this movement increased to 3-4mm after four months of use. It also changed from an undetectable settling to a noticeable ‘clunk’ when you initially sat down. At the next service the wear marks on the quill were more distinct and the upper seal was worn out. While best practice dictates that the post should be stationary when you release the clamping jaws, it isn’t always going to happen that way—especially when you encounter a last second panic-drop situation on the trail. Besides, the air spring is continuously pushing up on the post, and no matter how fast you depress the lever, there will always be a split-second where the locking jaws drag on the quill as it goes up.

Although the mechanism never let us down throughout our five-month-long review, the Kronolog was clearly showing signs of wear. In addition to slipping at full height, it also developed some rotational play (although at its worst, this play was comparable to other posts when they are brand new). Everything from the quill to the bushings and locking jaws can be replaced, but it’ll mean sending your Kronolog back to the local Crank Brothers service centre get it fixed up. At least it’s backed up with a two-year warranty (assuming it is fitted and maintained correctly).

In recent years I’ve become a bit of a dropper post junkie. I’m a big fan of their ease of use and how well you can corner once the saddle is out of the way—they aren’t just for the steep stuff and on some trails I seem to adjust my seat height more than I change gears! Combine this with three to four off-road rides per week and it’s fair to say that I’m a heavy user. If you adjust your saddle height once or twice per ride, a correctly installed and maintained Kronolog may well last for years before any wear related issues arise. As simple and elegant as the Crank Brothers system is, I feel that a more wear resistant quill material is needed before this post will go the distance under a true dropper-post junkie.

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