RockShox 2011: Tweaks to Boxxer downhill fork

Retuned damper and adjusters; new spring for World Cup model

In contrast to the numerous changes to RockShox’s cross-country and trail forks for 2011, the company's long-travel line remains largely unaltered, with the exception of some tweaks to the Boxxer downhill fork.

The Totem and Lyric fork both carry over unchanged save for the new lighter Maxle Lite through-axle and additional colour options. Totem is in its fifth edition and with that comes a new sticker kit by yet another guest designer, this time Geoff McFetridge.

The Boxxer, on the other hand, gets a retuned Mission Control DH damper and new adjuster knobs, plus a new, lighter and stiffer Maxle Lite DH through-axle. The top-end World Cup model also gets a new Solo Air spring design.

“We're introducing a new tuning package to the Mission Control DH [damper] based off some work we've done with the BlackBox riders [parent company SRAM's elite development team],” said Jeremiah Boobar, RockShox's long-travel product manager.

“Basically we’ve changed the rebound piston to reduce the amount of compression force that it’s generating, which allows us to re-valve the compression assembly in such a way that each of the clicks has more resolution, so each click makes more of a difference and gives much more of a grounded feel with the front wheel.”

The mission control dh adjuster for the 2011 boxxer, pictured left, is refined for easier adjustment: the mission control dh adjuster for the 2011 boxxer, pictured left, is refined for easier adjustment
The mission control dh adjuster for the 2011 boxxer, pictured left, is refined for easier adjustment: the mission control dh adjuster for the 2011 boxxer, pictured left, is refined for easier adjustment

The Mission Control DH adjuster for the 2011 Boxxer, left, is refined for easier adjustment

For the World Cup model ($1,700), the Solo Air spring has undergone two design changes that should have a major impact on the fork’s performance. It features a new air equalisation design that uses a Schrader valve instead of a conventional port system, and the Solo Air spring assembly has been moved further down the fork leg to reduce stiction.

The old Solo Air assembly travelled past the lower crown into the upper tube under full compression and if torque specifications weren’t precisely followed, the tube could actually catch the air piston assembly. The new piston assembly doesn’t enter this space under full compression, so the fork should not suffer from friction or stiction in the latter part of its stroke.

Boxxer’s new solo air spring and schrader valve: boxxer’s new solo air spring and schrader valve
Boxxer’s new solo air spring and schrader valve: boxxer’s new solo air spring and schrader valve

Boxxer’s new Solo Air spring and Schrader valve

The previous boxxer solo air spring used a longer piston assembly to equalise pressure between the positive and negative chambers:
The previous boxxer solo air spring used a longer piston assembly to equalise pressure between the positive and negative chambers:

The old Solo Air spring used a longer piston assembly to equalise pressure between the positive and negative chambers

Friction is further reduced by replacing the main seal O-ring with a quad ring and Delrin backers rings. As well as making the fork more slippery, this should also prove more durable.

A Schrader valve, instead of a solid piston, is now used to swap air from the positive to negative chamber. This is said to give the fork a more solid feel. As the fork tops out, the Schrader valve is depressed and the air flows.

From the outside, boxxer looks unchanged for 2011: from the outside, boxxer looks unchanged for 2011
From the outside, boxxer looks unchanged for 2011: from the outside, boxxer looks unchanged for 2011

From the outside, Boxxer looks unchanged for 2011

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