Singletrack.com's Lennard Zinn says Scott's new Genius LT for 2011 manhandles downhills, yet with full lockout and only weighing 28.5
The new Scott Genius LT (Long Travel) for 2011 can be a giant, pillow-like bike for manhandling steep, rough downhills, yet with full lockout and only weighing 28.5 pounds, you can ride to the tops of those downhills relatively quickly without resorting to a chairlift or pushing on foot.
The bike’s intermediate Traction mode negotiates everything else between full-out climbing and full-out descending. It has a higher travel-to-weight ratio than either the Scott Ransom or Spark, and the same as the Genius, winner of marathon world championships.
The Genius LT is aimed more at downhill riding than the Genius, which maxes out at 150mm (5.9 inches) of travel, and I had the pleasure of riding the LT on lift-service downhill trails in Deer Valley, Utah, including ones with manmade stunts, and on the Mid-Mountain cross-country trail.
The Genius LT is the world’s only 185mm-travel (7.3-inch) bike with front and rear lockout. And the single Twinloc handlebar-mounted lever controlling it is very slick. It has three positions: Full (185mm-travel) mode, 110mm-travel (4.3-inch) Traction mode, and locked out front and rear.
The smarts of the Genius LT lie within its three-barrel Equalizer 3 rear shock, developed jointly by Scott and DT Swiss. This is the latest generation of the Genius TC “Triple Action” shock that wunderkind Peter Denk, who has moved on to designing for Cannondale, came up with for the original Genius on which Thomas Frischknecht won the 78km World Mountain Bike Marathon Championships in August, 2003. That course in Lugano, Switzerland required over 9,300 feet (2857m) of climbing and descending and showcased the true dual nature of the Genius, which at that time was unprecedented.
After having worked together with Scott USA since 1995, Denk and his partner, Thomas Fuderer, the founders of Hot Chili bicycles and now of Denk Engineering GmbH of Freiburg, Germany announced the end of their relationship with the introduction of the long-travel Scott Gambler downhill bike in the fall of 2007.
The Flip of a Switch
With all of these different settings at the flip of a switch, you may assume that setup of the Genius LT would be a bear, but Scott has made setting it up very easy. The Equalizer 3 shock has step-by-step setup instructions right on the side (see photo). Step 1 is to set the air pressure in both positive air chambers (which is done with a single, black Schrader valve). Step 2 is to set the air pressure in the negative air chamber (with the silver-colored Schrader valve). Rider weight and associated air pressure are clearly written on the side of the shock, and reading glasses are not required to see the numbers, either.
The air pressure required by this shock is high: 13.5 bars (196psi) is recommended for my 80kg (176-pound) weight, for instance. Step 3 is to set the rebound damping on both the taller, traction-only TC cylinder and on the more plush circuit only utilized in the Full, 185mm-travel, mode. Instead of counting clicks, the stops are all numbered. These two rebound damping adjustments must be set within one click number of each other or in the Full mode, the shock could be damaged if one damper is open wide and the other is tightened down to greatly constrict the oil flow.
It’s hard to measure the sag with a pull shock, but Scott makes that very easy as well with and indicator pointer that moves along a graded scale. Sag increases from 20 percent in the Traction mode to 30 percent in the Full mode with a flip of the Twinloc lever (and, of course, to no sag in Lockout mode). Similarly the bottom bracket is a half-inch lower in Full mode (12.7 inches) than in Traction mode. And by flipping a chip on the shock mount, you can change the bike from a low position, with a lower bottom bracket (359mm) and slacker head angle (66.3 degrees) than the 165mm-travel Scott Ransom, to a higher position with the same head angle (67 degrees) yet higher bottom bracket (367mm) than the Ransom.
And with 20mm more travel than the Ransom, the Genius LT has the same standover height. [The Ransom all-mountain bike has a TracLoc lever which flips the Equalizer TC shock between Lockout mode, Traction mode (90mm, or 3.5-in.) of travel, and Full (165mm, or 6.5-in.) travel mode.]
The diagram shows the oil flow through the Genius LT’s Equalizer 3 shock in its three modes. In Lockout mode, oil is blocked from moving out of the shock’s central cylinder above the negative spring through either of the other cylinders and their damping circuits. In Traction mode, oil cannot pass through the damping cylinder above the larger air spring meant for downhill riding; it can only pass through the more cross-country-style damping circuit above the smaller of the two positive air chambers. The smaller air volume ramps the spring up faster than a bigger chamber. In Full mode, oil is free to move through the damping circuits above both positive air chambers. The air pressure is the same in both chambers, resulting in a very large total air volume and hence slower ramp-up in spring rate. Much of the damping is now handled by the damper in the fatter air chamber, and that one is designed to be far more plush.
The carbon front end of the Genius LT is molded as a monocoque (single piece) with Scott’s “Integrated Molding Process” IMP5 technology. IMP is a method Denk came up with to fully pressurize the carbon layers without wrinkles. Wrinkles weaken the structure, since tension will try to unfold the wrinkle in the fabric rather than pulling on straight fibers, and excess resin will collect in the wrinkle, creating a more brittle area.
In IMP, a foam block in the shape of the shape of the inside of the main frame is dipped in liquid latex and allowed to dry. Instead of laying pieces of pre-preg carbon fabric inside of a concave mold (which is then closed around a bladder that is subsequently inflated inside, creating opportunities for wrinkles to form), workers wrap the carbon layers over the latex-dipped foam block, and the whole thing is put inside of the mold. The latex covering the foam is inflated to high pressure inside of the mold during heat curing, squeezing the wrinkle-free layers tightly together.
The number in IMP5 indicates the number of separate pieces included in the single monocoque carbon structure that would normally have to be lashed together in a multi-piece, tube-to-tube construction. In contrast to the Ransom, which has five separate carbon parts and an aluminum bottom bracket shell/main pivot in the main frame attached by tube-to-tube construction, the Genius LT has a single piece incorporating all of these.
The advertised frame weight of 2.8kg (6.2 lbs.) includes the 500-gram shock.
The bottom bracket is a press-fit BB92. The main pivot is 17mm in diameter, and the linkage pivots are 15mm for great torsional stiffness. The hollow aluminum link is also very stiff and light.
Inserts in the dropouts can be interchanged to fit a rear wheel with a 142mm overlock dimension and a 12mm through axle, a 135mm X 12mm through axle, or a 135mm X 10mm quick release. A direct post mount on the chainstay for the rear disc brake eliminates the weight and added flex of a bolt-on adapter. Greater tire clearance than the Ransom, improved cable routing (there are a lot of cables on this bike with dual lockout cables, brake hoses and derailleur cables), a plate to prevent chain jam between the inner chainring and the bottom bracket, and mounts to hold a full-size water bottle round out the package.
The bike ranges in price from $6800 for the Genius LT 10 to $2950 for the LT 40.
For a bike with this much available travel, it climbs incredibly well on smooth trails, and it rides undulating terrain with aplomb. When the ups get steeper and the downs get steeper and rougher, it is as easy as shifting a derailleur to switch between Lockout, Traction and Full mode while rolling along at speed.
It also deals with rough downhills like a dream for a rider who does not huck big drops or encounter lots of good-size hits in rapid succession. Since I don’t go off drops of any significant height and don’t ride as fast as the guys in full pads on closely-spaced bumps, I love this bike as is. But if you were to ride really fast over lots of bumps or take huge drops (like I almost did on one manmade stunt; I guess I was too focused on the trail to notice the not one, but three signs saying “DROP” on them), I think you would run into a fundamental contradiction within the Equalizer 3 shock.
Due to the shared damping circuit in the Full mode, the damping will always be a compromise between climbing and descending performance. If you tighten up on the rebound so it climbs better in Traction mode (when it is only using one rebound circuit), you will also tighten up the rebound in descending mode. You must adjust both rebound adjusters in tandem, so they are not separated by more than a click in adjustment, as I explained above. A slow rebound for climbing is fine, but too slow a rebound on successive bumps will cause packing in (progressively reduced travel). Furthermore, the compression damping, which you cannot adjust, also is not separate in the two modes. So a lot of compression damping to counteract pedal-induced bobbing will be too harsh when landing a big drop; you want to move deeply into the travel but quick in that situation!
The low compression and rebound damping to get decent downhill performance would then compromise pedaling performance in the Traction mode. And while full lockout is great on smooth climbs, it’s inefficient for rough ones (since your center of mass will be going up and down over every bump, rather than moving along parallel to the slope while the bike absorbs the bumps), so you need the Traction mode to also work for climbing.
All in all, this is a great bike, but it needs a bit of an improvement in damping in the rear to realize its full potential. Also, in really muddy conditions, the tire would throw lots of junk on this hi-tech shock.
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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