COMMAND POST BLACKLITE GALLERY
Specialized just introduced a new adjustable-height seatpost available aftermarket, not just on its bikes. Called the Command Post BlackLite, it is a lighter version of the three-position mechanical Command Post currently available on all Specialized all-mountain Enduros except the Enduro Comp.
The Enduro’s Command Post has 125mm of travel, whereas the BlackLite is lighter and has two additional travel options, namely 100mm and 75mm for the weight-conscious rider who also wants on-the-fly seat height adjustability.
The three seat-height positions are:
1. Climbing: This position is intended to be normal road/cross-country seat height for optimal power and leg extension when climbing or riding on smooth surfaces.
2. Cruiser: Dropped down by 35mm, this height is intended for technical riding, to enhance maneuverability without sacrificing power.
3. Descending: Depending on the model, full drop goes down by 125mm, 100mm, or 75mm, getting the saddle out of the rider’s way for challenging drops.
The BlackLite Command Post is 100 grams lighter than the current Command Post and weighs in at 501g, 531g, and 547g in the three travel lengths – definitely at the low end of seatposts of this type. Specialized had improved the bushings, seals and the mechanical locking mechanism, cut weight by removing material, especially from the lower tube, and by bonding the seatpost head, and it has sharpened the post’s appearance.
The BlackLite with 125mm of adjustable travel is for riders who really want to be able to drop their center of gravity and get their saddle completely out of the way. Weight weenies can choose 75mm or 100mm options. A quick-release engagement cable on the seatpost head simplifies setup and removal. All Command Post BlackLites are available in 30.9 and 31.6mm diameter.
Some riders complain of the difficulty of hitting the middle position with the current Command Post. You had to push the post below the middle position and then let up on it to click into the middle stop. This is something hard to do at speed on bumpy, technical terrain.
Specialized’s Director of Suspension Technology, Mike “Mick” McAndrews, the former chief suspension engineer at RockShox with more than 30 years of working with top motocross and MTB teams, addressed this when designing the post.
“We improved the internal design so the collet slides easier between positions. This makes for smoother action and improves a rider’s ability to hit the middle position on the down stroke (providing they use a fanning motion on the lever). The collet now has a hard chrome finish (as this runs on the ID of the main tube) as well as the contact area of the tube ID has been reduced by 50 percent due to the longitudinal lightening grooves we use on the new BlackLite design.”
Availability: Late spring/summer 2011
Drop options: 75mm, 100mm, 125mm
Weight: 501g, 531g, and 547g
Diameter: 30.9 and 31.6mm
Why a mechanical and not hydraulic system?
All on-the-fly, adjustable-height seatposts have a spring to return the seat to the desired height, but they have a position-holding system or they would be suspension seatposts. Many “dropper” seatposts, including the Specialized posts, use an air spring to raise the saddle, and hydraulic ones hold the seat height in place with hydraulic pressure. Specialized claims that when the rider is sitting on a column of (uncompressible) oil, the O-rings sealing the oil chambers tend to bulge or fail under the pressure, resulting in inconsistent saddle position. The Command Post BlackLite, like other remote systems, utilizes a standard derailleur cable to free the post. But unlike hydraulic posts, which open an oil port when the handlebar-mounted lever is depressed, the Command Post’s cable instead releases a mechanical collet, allowing the post to slide up and down. The rider’s weight drops the post, and an adjustable air spring returns it. Once the lever is released, the collet locks into one of three machined slots, securing the post in place in one of its three positions.
A dual keyway is meant to eliminate side-to-side play, and the air chamber has a dust wiper and Dual-Lip X-Ring seal meant to prevent air leakage over the long haul.
Even though McAndrews says, in general this hasn’t been a problem with the Command Post design, I’ve heard complaints of lateral saddle movement with them.
“Our design has a unique feature to prevent this,” McAndrews says. We use our two alignment keys (Ed. note: i.e., steel tabs that slide in alignment grooves) as the contact points for top-out. The top-out washer these keys mate with is backed with a small bumper, but this constant tapping of the keys to this washer slightly flares the top portion of the keys with each tap. The keys are then ‘re-sized’ the next time the post moves down. This constant flaring, re-sizing, flaring, re-sizing keeps the running clearance tight and slop-free.”
As someone who has remote-activated adjustable-height seatposts on my own mountain bikes, I believe that anyone taking on rough and steep trails, from cross-country racers to chairlift-riding gravity-driven riders, can benefit from on-the-fly remote saddle height adjustment.
Readers can send brief technical questions directly to Lennard Zinn.
Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of numerous books on bikes and bike maintenance including the pair of successful maintenance guides “Zinn and the Art of Mountain Bike Maintenance” – now available also on DVD, and “Zinn and the Art of Road Bike Maintenance,” as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”
Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn.
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