There are a few different ways to do it but adjustable height seat posts all have the same purpose: to let you have your seat at the ideal height for whatever terrain you may be riding. Crank Brother's Joplin may look familiar to some of you as the original design was done under the Maverick name. Now licensed by Crank Brothers, there have been some small changes but the basic idea has remained the same.
The Joplin is offered in two versions, a slightly lighter non-remote version that uses a under seat lever, and the Joplin R (for remote) tested here. Both post's have 3" of hydraulically controlled drop and depend on an air spring to extend them when the time comes. The Joplin is only offered in two sizes, 30.8 and 31.6 mm. Thankfully my current test bike, a very capable Rocky Mountain SXC 90, takes the larger of the two sizes. While riding the daylights out the the Slayer I managed to put a godly amount of time on the Joplin R also.
What's going on in there?
Although it could have been easier to build the Joplin with a spring and pin system, it was decided to use a lighter and more adjustable air and oil combination. Functionally it is very similar to an air sprung and oil damped fork. It depends on air pressure within the inner tube to extend the post and a small oil port to keep it lowered to the chosen height.
Atop the post's head (and under the seat) sits a small actuation arm with a cable anchor bolt at one end. When the arm is activated it compresses a release button which opens an oil port deep within the Joplin's inner tube. Once that port is open the inner tube is free to travel through it's three inches of range and can be stopped at any point within that range. Remember that oil can not be compressed, that is key to the Joplin's design. Activate the lever and the oil port is opened, your body weight lowers the seat and you release the lever to close the port, thereby locking the post in place.
When the time comes to return it to a more pedal friendly height all you need to do is unweight the seat and give the lever a push. Once the lever is activated (which opens that oil port again) the post will extend due to the air pressure within it.
The Joplin uses two bushings and a single "guide block" to keep it sliding smooth. The lower bushing sits within a groove in the inner tube while the larger upper bushing is captured between the inner and outer tubes and can be easily cleaned and greased by removing the orange threaded collar. Because the Joplin's tubes are round there needs to be something to keep it from spinning in circles under you. That is the guide block's job. The guide block is actually just a simple rectangular piece that is held in place at the bottom of the inner tube with a single torx screw. It fits like a puzzle piece in a single groove or track on the inside of the Joplin's black outer tube.
The Joplin's remote lever is quite a piece of work. Instead of incorporating a simple push/pull lever, the Crank Brother's post uses a joystick of sorts to activate it's travel. The lever does not hinge at a single point but can toggle in any direction because it's not actually attached to it's perch. It fits into the perch like a socket and depends on the cable's tension to hold it in place. The big advantage is being able to push the lever in any direction you'd like. The perch is super minimal and takes up next to no room on the bars and is split to facilitate easy installation and removal. The barrel adjuster also lets you take up any slack in the cable as well as fine tune the lever throw a bit. A standard shift cable is run down through the center and held in place with a set screw. Very well thought out!
The Joplin's head is a single bolt affair that depends on two wedges to hold the angle adjustments in place.
How did it work?
I wasn't too sure what to expect at first with the Joplin aboard my Slayer test bike. I was a skeptic for many reasons: I spend too much money trying to lighten my bike to add nearly half a pound, having another damn cable zip-tied to my bike, and one more thing cluttering up my bars. There were all sorts of reasons for me not to like using the Joplin post, which is why I'm so surprised that it is most likely my pick for the one item you should
have on your pedal bike.
The Joplin was nearly faultless in use. Although the remote lever does have a lot of throw it does not take much to active the post. Give the lever a nudge and the Joplin will compress under your body weight. You can lower it the full 3" or stop it at any point before. While only dropping the post 1" may not sound like much, it was a big plus on level but fast trails where you really benefit from a lower center of gravity.
The large majority of our riding consists of a constant long climb followed by a ripping descent. Because of this I was not expecting to reap the Joplin's benefits, but I surprised myself with how often I ended up using it. The old program was to stop at the top and mumble some excuses about lowering my seat and having something in my eye. The new program is to hit the remote and drop in with no hesitations. On the trail is obviously where the Joplin really shines though. On loops that I am familiar with I can choose to lower the saddle when needed or return it to a more pedal friendly height in the blink of an eye. Trails that I didn't quite get along with before are now full of flow and momentum instead of me slogging up and over those speed sapping climbs. I've been out exploring my local mountain quite a bit lately, following moto trails off into the bush in search of that
trail. I couldn't imagine doing this without the Joplin. When you're not sure what is going to be around the next corner is where an adjustable height post really shines.
Don't want anything else on your bars? Check out the Lever version
The Joplin's single bolt seat rail clamp also impressed me. The amount of angle adjustment available is almost limitless and you can choose any position you'd like as it's not indexed like some other heads. There has not been a single creak yet and despite some hard landings it hasn't budged one bit.
Is 3" of drop enough? I run a fairly high seat, even on my DH bike, while descending. The Joplin's 3" of drop made a massive difference in my speed and confidence over a fully extended post, but 4" would have been perfect
Don't over tighten your bikes seat binder bolt or quick release as it will keep the Joplin from doing it's thing. On a long ride I discovered that my post was slipping down more and more as I pedaled along. In frustration (ok, I may have bonked 20 mins earlier!) I accidentally over tightened the quick release lever, thereby keeping the seat from returning to full height. Once I figured it out everything returned to normal.
Out of the box my Joplin seemed to have a bit more slop than I expected. I spent a couple minutes pulling it apart (it's very easy) and discovered that the small torx screw holding the glide block on was a few turns loose. It was an easy fix but I can see some riders being hesitant to disassemble the post. I haven't heard of any other Joplin's having this issue so maybe it's a moot point!
I only have one real issue with the Joplin. If you pull up on the seat while in it's lowered position it sucks air into the post and it will begin to creep back up. It turned out to be pretty annoying, I discovered that I pick my bike up by it's seat a lot! The fix is simple: unscrew the threaded collar and manually raise and lower it a few times. Problem solved....Until I do it again!
A bit more info...
The Joplin comes in only two sizes: 30.8 mm and 31.6 mm, there are plans afoot to introduce a 27.2 mm version though.
There are two versions of the Joplin, the remote lever model that you're reading about and an under-seat lever actuated version.
The Remote model weighs 534 grams, the lever version comes in at 461 grams.
Total post length is 382 mm (extended) and you can lop off a bit of extra post at the bottom if that's a bit long for your bike.
The housing stop on the underside of the Joplin's head only accepts 4 mm housing. Not a big deal as it comes with a cable and all the housing you'd ever need.
The Joplin comes with a 2 year warranty.
Retail is $340 CDN for the Joplin and $390 CDN w/ remote for the Joplin R.
The idea of adjustable height posts, and the Joplin in particular, has really opened my eyes to how much fun one can have out there in the bushes. The original concerns about the slight weight gain and extra clutter were far out weighed by the extra speed and confidence that I get while using the Joplin. Adjustable height post's are not going to be for every rider but I'm sure that the majority of us will really benefit from using one. With the Joplin you are actually buying more fun, speed, and confidence . How many products can you say that about?
Check out Crank Brothers
for more info.
In Canada the Joplin is distributed by Norco Products