If you like riding hardtails on rugged trails, Curve Engineering’s Klonzo MKII frame could become your new long-term partner. Like all of Curve’s bikes the Klonzo is built from titanium, which offers a winning combination of durability and ride compliance that other materials just can’t match.

Bikerumor has checked out some of Curve’s bikes before, including the MKII softail XC and the belt-driven 714 C2 road frame, but this the first enduro frame we’ve seen from the brand. Designed with highly technical terrain in mind, the frame is intended to accommodate a 150-160mm fork, and fits 27.5” tires up to 2.8” wide.

The Klonzo MKII was named after a trail near Moab, Utah that Curve’s Olivier Ollagnier recently visited and thoroughly enjoyed. There was a previous version of the Klonzo, but the new MKII model has been updated with more aggressive geometry.

Curve Engineering Klonzo MKII titanium enduro hardtail frame, side shot

The Klonzo MKII is made entirely from 3AL/2.5v titanium, and to deal with enduro levels of abuse the rear triangle features thicker tubing than Curve’s XC frames. Curve offers fully customized geometry to buyers, but also produces frames in stock configurations as well…

The standard Klonzo features a 66° head angle and a 74° seat mast. While top tubes are growing longer on trail bikes, the Klonzo may be ahead of the curve (pun!) with a size medium coming in at a lengthy 625mm.

Curve Engineering Klonzo MKII titanium enduro hardtail frame, yoke and BB

Curve’s simple and beefy looking chainstay yoke helps the frame fit wider tires while keeping the back end nice and short at just 422mm. The Klonzo’s standard rear end is Boost 148 spaced, but buyers can opt for a 142mm width if desired.

Curve Engineering Klonzo MKII titanium enduro hardtail frame, closeup

The frame uses a threaded 73mm BSA bottom bracket, and features internal routing for a dropper post. The rear brake and shifter cables run internally through the top tube, but are externally routed on the rear triangle. There is one bottle cage mount atop the Klonzo’s down tube.

Curve Engineering Klonzo MKII titanium enduro hardtail frame, front angle
*Images c. Curve Engineering

Curve says a size medium Klonzo frame weighs 2050g with the seat clamp and rear axle included. The Klonzo MKII will sell for $1983, with the option of full custom geometry plus your choice of frame finish (brushed or sandblasted). Customers can also pick their sticker colors, or have the logos sandblasted onto the frame. Stock frames are available in S/M/L sizes.



  1. I wish someone would make a “slack hardtail” designed around a 100-120mm fork. I guess you can just run a 160 with low sag, but I don’t think the 160 on a hardtail feels very balanced.

    • why?? surely if you want a slack hardtail its for stability in the steep stuff and very fast rough stuff, ergo longer travel forks are preferrable. short travel forks are normally for less rough terrain and more responsive steering, ergo tight headangled frame to suit. not to mention the weaker design off these forks like 30 or 32 mm stanchions and QR’s and the damping systems not designed to cope with big aggressive hits etc

      can’t think of anything more paradoxical than having a frame that can handle extreme terrain and yet
      having the first part of the bike that hits the rough stuff (wheel and forks) unable to cope with the impact.
      or a lightweight twitchy/responsive fork attached to a frame that turns like a barge

      160 feels very balanced if thats what the bike was designed for, having run slack hardtails with 160m forks since long before it was the fashion and being scottish enduro HT champ in 2014 i can assure you the theory works.

    • Sonder Transmitter. Designed around a 120mm fork. That said, I wish it could do a 130-140mm fork.
      Regardless, I love mine as it is.

    • Stif Morf is design around 130mm, perfectly happy to run a 120mm fork too. But these guys offer custom geometry for an upcharge, so you could have exactly what you want provided you’re prepared to pay a bit extra and wait for it to get made.

    • Duder…. Currently testing prototype V2 of @four5bikes LuckyNo5 titanium hardtail…. 67.5 with 100mm fork, blend of trail agressor and xc race. Adjustable rear end too.
      Custom geometry too. Long reach, short stack. Really loving it.

  2. “Engineering” in the title and they have hooded dropouts, a seat stay brake mount, and a yoke made out of plate. Also, increasing reach and front center shouldn’t really be called “more aggressive”. Then again, they miss the point of forward geometry with their super short rear center and STA anyway. This thing can’t climb well, which kinda erodes the ‘enduro’ moniker, no?

  3. This frame looks like it was made by Waltly Ti. Not that there is anything wrong with that — I have 3 Waltly frames that are excellent — but, if true, it’s a ~100% markup for the “Curve” name on the down tube.

  4. Nice. Been looking for a Ti hardtail for a while. Anyone know where I can get geo/price info? Seems like the website doesn’t work.

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