From the SRAM Press release.

roam 40 cutTHE RELENTLESS PURSUIT OF BALANCE

RISE HIGHER. ROAM FARTHER. RAIL HARDER.

You don’t win by being the lightest. Or the stiffest. Or the toughest. You win by being the fastest. And that takes a wheel designed specifically for the modern mountain biker. At SRAM, we start with the demands of the terrain and work forward from there—carefully balancing each wheel’s design around five key attributes: weight, inertia, engagement, stiffness and durability. No matter where you ride, SRAM wheels will take you further. RISE higher. ROAM farther. RAIL harder.

RAIL HARDER

Ready to attack, easy to maneuver. Built for aggressive All-Mountain descents, RAIL wheels balance the strength and stiffness you need with the lightness to climb quickly back to the top.

SRAM RAIL 40 WHEELS

With WIDE ANGLE™ rim design providing superior stability, RAIL 40 can withstand the most aggressive All-Mountain / Enduro riding by setting a new benchmark for stiffness in its category. Featuring the perfect balance of strength, lightweight and width for enduro terrain, RAIL 40 delivers high performance ride quality all the way down.

TECHNOLOGIES

  • SOLO SPOKE™
  • TAPER CORE™
  • WIDE ANGLE™
  • SPEEDBALL™
  • DOUBLE TIME™
  • XD™ DRIVER BODY
  • BOOST

FEATURES / BENEFITS

  • Available in 27.5” and 29”
  • Lightweight but strong aluminum rim, asymmetrical profile with TAPER CORE™ technology. Welded joint
  • UST Tubeless
  • WIDE ANGLE™ profile—23mm
  • SOLO SPOKE™—double butted spokes
  • DOUBLE TIME™ ratchet mechanism for durable, quick engagement—SPEEDBALL™ bearings
  • Convertible axles:
    • Front Hub: QR 9×100, QR Torque Caps, 15×100, 15×100 Torque Caps, 20×110, 15×110, 15×110 Torque Caps
    • Rear Hub: QR 10×135, 12×135,12×135 XD, 12×142, 12×142 XD,12×148, 12×148 XD
  • Available in XD™ or 10-sp driver body
  • BOOST 148 compatible
  • Weight: 1810g (27.5”), 1900g (29”) Wheel pair in lightest configuration

TECHNOLOGIES

DOUBLE TIME™

Ratcheting up the smarts. This straightaligned, 4-pawl design turns the 26-tooth ratchet ring into 52 points of contact. The result: smooth 6.9-degree engagement without reducing tooth size or offsetting internal geometry—which means serious long-term durability.

SPEEDBALL™

The only adjustment they’ll ever need was made back at the factory. Every part of the ball bearing comes from the exact same supplier—which means that each bearing bore can be precision machined to fit the bearing race exactly. With tolerances this tight, the days of adjusting play after every ride are over.

SOLO SPOKE™

With SOLO SPOKE™, you’re never wrong. SRAM wheel design eliminates the need for different spoke lengths—one size fits the entire wheel. This identical-length design means no longer wondering whether you have the right front/rear/drive-side/ nondrive-side spoke handy.

TAPER CORE™

Strong in the right places. The sidewalls of SRAM rims are reinforced along the wings to withstand major impact. But the sidewalls then taper in along the center—reducing overall mass. The result is a very light rim with excellent dent resistance.

WIDE ANGLE™

Take corners as fast as you want. SRAM wheels have a wider rim profile without significant added mass. This profile holds tire shape better, preventing tire roll and giving you superior

comfort and traction around corners.

XD™ DRIVER BODY

XD™ is a cassette driver body design that allows the use of a 10-tooth small cog and provides an improved interface with the cassette.

BOOST

BOOST is a new wheel and drivetrain specification that provides: increased wheel stiffness and durability, better riding efficiency and bike handling precision, improved frame geometry with shorter chain stays, wider and stiffer suspension pivots, wider range of chainring options, more clearance for bigger tires.

MSRP in USD seems to be around $650.00 a set depending on the axle/driver configuration.