New Crank Brothers Kronolog Adjustable Seatpost – Tech, Interviews & Specs!
We jumped the gun a bit on our original post about Crank Brothers’ new Kronolog adjustable height seat post. Since then, we’ve spoken with CB’s product development manager, Chad Peterson, to get the details.
Even they’ll admit the Joplin was an underperformer, which begged the question: What did they learn from it?
“We learned a lot!” Peterson says. “Actually, it’s a completely different body, damper… everything’s different except that it raises and lowers. The Joplin was actually something we licensed from Maverick. There were a few things we didn’t like about the design. It was good at the time, but there’s always room for improvement. When you pulled up on the saddle, it would raise up and everything would emulsify inside. We also wanted fewer moving parts, which means if there is a problem, it’s easier to identify. But it’s also less likely to have anything go wrong in the first place.”
Falling into their Iodine collection, the Kronolog features an entirely new design with some unique touches. First, the basics: It’s a mechanically controlled, air actuated infinitely adjustable post. What that means in lay terms is that it uses a cable to release the post rather than hydraulics, air pressure inside the tube moves it back up and there are no preset positions between full up or down.
Now for the details…
The Kronolog has a new, proprietary locking mechanism that locks the post into place for both upward and downward movement. Push down or pull up on your saddle and it shouldn’t move unless you’re also depressing the thumb lever.
On the non-telescoping section of post, a standard shifter cable enters the bottom of the control section, leaves the housing in a lower Jam Plate and is fixed into the upper Jam Plate. When the release lever is pushed, the cable pulls both plates toward each other so they become parallel and release the inner post, as shown in this photo held “open” with a zip tie. In this position, the post is free to slide up or down. The jam plates encircle the post and clamp in the front and rear, one angle up, the other angled down. Since the arms are juxtaposed, each one works to prevent either upward or downward movement. Peterson says the design is patent pending.
One of the other unique features is their two-stage hydraulic air damping. To control the rate of drop and return, you simply adjust the air pressure via a Schrader valve (hello, shock pump!). To keep it from smacking you where the sun don’t shine, Crank Brothers gave it a central chamber that slows things down a bit before it tops out. During the last inch of upward travel, air pressure builds under the primary plunger and is forced through the small bypass opening, which damps the movement (aka “slows it down”).
“The Kronolog is unique in that it’s a combination mechanical/hydraulic post. Most mechanical posts aren’t infinitely adjustable, they have fixed stopping points. And, other mechanical posts don’t have any damping, so you can’t adjust the speed and force with which it aims upward at parts of your body you don’t want struck with speed and force.”
Eagle eyes will notice this design places the cable mech on the stationary lower part of the post, reducing the total cable length and keeping it reined in. Even better, you can position the cable entry point at the front or rear of the post for installation versatility. To attach the cable, a small cover slides down to access the fixing bolt.
The plunger itself is a single piston air spring, much like a bike pump, moving on Norglide bushings. The internal diagrams we’ve seen indicate a fair amount of overlap between the two tubes, which contributes to the robust strength claims. CB says it’s twice as strong as other dropper posts.
The post has a “unique keying system” between the quill and shaft that give it “substantially improved rotational stability.” It’s a head smackingly simple how-has-no one-thought-of-this-before design:
“We didn’t do a traditional key way like you see on other posts, including the old Joplin,” said Peterson. “We shaped the the sides of the telescoping post flat for a significant amount, more than 10mm on each side, and the front and back are rounded. It’s one of those ideas that’s very gratifying.”
Unlike small keyed sections, the broad flat surfaces are less likely to wear down and lead to play…rotation stability really is built into the larger design.
It gets better. The thumb lever is easily swapped from left to right by simply removing the T-25 Torx bolt, flipping it over and threading the barrel adjuster into the other side. Brilliant. This also means you could easily mount it on the underside of your handlebar, helping you keep a good grip on the bar when the trail gets sketchy.
The new Kronolog has a few more tricks up its sleeve. For one, it’s about 50g lighter than its predecessor, coming in at a claimed 465g for the 30.9 post and 477g for the 31.6. The remote weight is 28g, putting the whole package right around 500g-ish, maybe a bit more with cable and housing.
Post length is 405mm and it has a 125mm (5″) travel adjustment range. Looking for shorter travel? No problem, you can add spacers in 20mm increments to shorten its range.
“Another unique thing about our post is the inner tube is 3D forged. Most posts have a bonded seat clamp fixed to the top of the telescoping section. We use (the forging) process on our Cobalt stem, as do a lot of other brands, because it’s much stronger, and it makes this post super strong. It passes EN standards at 2.7x the required fatigue testing, meaning our post can get OEM spec on bikes sold in Europe. The saddle clamping mechanism is identical to the one on our Cobalt Post.”
It’ll retail for $300 / €300 and come in Black/Red shown or Black/Black. Aftermarket color kits will be available in April for $45 to replace the anodized bits with either gold, blue or orange to match the rest of your Crank Brothers parts. Warranty is two years with proper maintenance, by which they mean wiping it down every few rides and applying a couple of drops of oil under the dust seal. They also recommend replacing the O-rings every 75-100 hours and an annual inspection of the seals, Jam Plates and bushings.
“It’s very simple, there’s not much to go wrong,” Peterson said. “Another benefit to this design is that we can adapt it to a 27.2 seat post, something no one else is doing in dropper posts. We’ve got that coming soon, but no ETA yet. It’s still in development.”