Manitou’s Marvel Pro and Real Custom Tuning – Eurobike 2011

Available in 100mm and 120mm travel options, Manitou’s Marvel Pro is their top tier XC fork. Inside you’ll find a damper that combines Manitou’s proven TPC damper with the pedalling performance of the Absolute+ piston and shim configuration. TPC refers to the fork’s Twin Piston Chamber – two pistons, one compression and one rebound, in a serviceable cartridge that lowers weight through oil volume. Manitou pioneered the two piston design in mountain bike suspension (later on developing the TPC+ system that uses a third floating piston as well) that you can now find inside of many other forks.

This is then combined with the Absolute+ damper to create a system that offers a firm pedalling platform early in its stroke, but that also opens up quickly to let the suspension work over the terrain. The 32mm stanchion Marvel Pro is available in both QR and 15mm axle versions. The fork’s price of $699.99 USD price puts it well under the competitions high-end offerings, but only time on the trail will show how it compares in performance. Stay tuned, we have our names a Marvel Pro for testing.

Manitou Marvel Pro details:

  • 100/120mm travel options
  • ISO Air spring
  • TPC Absolute+ damper
  • Adjustable compression (to lockout), rebound and air spring
  • 32mm stanctions
  • QR15 hex thru-axle or 9mm QR lowers
  • White or black lowers
  • Tapered and straight 1 1/8th steerer options
  • Weight: 3.5lbs
  • MSRP: $699.99 USD (tapered steerer, QR15 axle)

15mm HexLock thru-axle: Manitou’s QR15 HexLock thru-axle uses a 90 degree quick release lever to disengage the axle from the lowers. The silver dial adjusts the tension once the QR lever is tightened down. Adjust it once and it is set from then on in. The photo above clearly shows the axle’s hex shaped clamping zone that resists twisting. The recessed dropouts on the Marvel are shaped so that the tension adjustment – the anodized grey aluminum dial assembly on the axle – sits mostly inside the lowers, with only the dial itself exposed. The opposite side uses threaded insert for the axle to tighten into that is also replaceable if damaged.

Absolute+ damper: The compression damper ()above left() used within the Marvel Pro fork employs a digressive shim stack to provide a specific amount of low speed compression damping early in the stroke. This provides a firm pedalling feel at the top of the fork’s travel to keep it from bobbing under power. The large black tube just above the piston is a closed cell foam compensator that does the same job as an IFP (internal floating piston), but without the added friction of an air spring seal, in that it compensates for changes in the oil volume as the rebound damper rod enters and exits the cartridge. Without it the fork would require an air gap in the cartridge, something that can lead to foaming oil and inconsistent damping.

How it works: A digressive damping curve means that once the oil pressure (which creates damping force) climbs high enough to engage the shim stack, the opening of the shims is drastic enough that any further increase in stroke velocity does not add any appreciable increase in damping force. This is differentiated from an orifice damper in which damping force climbs exponentially with stroke velocity, or a standard linear shim stack where damping force climbs linearly with increase in stroke velocity. This was first used on race cars and motorbikes to prevent chassis roll when braking or changing direction, but still allowing the suspension to absorb the ground below. It is accomplished by preloading one or more of the shims so that they are flexing in the opposite direction of the oil flow before entering the travel.

Manitou achieves this by shaping the compression piston (bottom right in the above photo) in such a way that the outside edge of the bottom shim rests on a raised lip and is flexed down – preloaded – by tightening the piston bolt. This preloading requires more oil force to flex the shim at first, giving the damper its platform feel. Once oil pressure (damping force) climbs to a level that matches the preload of the shim, the outer edge of the shim will lift off the lip, rapidly releasing that pressure. With the right shim stack, the system can handle high stroke velocities with little or no increase in damping force. The really neat thing with a digressive shim stack, and what Manitou have done on their Absolute+ damper, is the ability to actually tune the exact amount of damping force change that you want by altering the amount of preload and shim thickness in the very same way that you would tune a standard shim stack.

True custom tuning: Manitou is bringing custom tuning to the masses in 2012 with their Absolute Plus Tuning Kit. Unlike the motocross world where riders can open up and alter their suspension, supplying shops and consumers with the means to alter their fork’s damping by changing the shim stack has not been something that the mountain bike industry has embraced. While some may argue that the average consumer is likely to do more harm than good by messing about within their fork’s damper, this certainly shouldn’t keep those who know, or who want to know, from doing the job.

Thankfully, Manitou agrees. Not only does the Absolute Plus Tuning Kit come with all parts that are needed, including shims, pistons and other assorted bits, it also comes with a detailed booklet that provides a number of different shim stack suggestions and corresponding dyno charts to show you exactly what to expect. This allows you or your shop to explore nearly endless custom tunes in order to find the right setup for your style and terrain. We picture suspension nerds and wannabe suspension nerds everywhere jumping with joy right now.

Visit the Manitou website to see their entire lineup.

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