2017 KTM/Husky: Frame Flex

Explainer: How and why the new frames in the 2017 year-model enduro bikes from Husqvarna and KTM are designed with more longitudinal flex, but greater torsional rigidity.

Prior to KTM’s all-new 2017-model EXC line-up, the last time the Austrian manufacturer unveiled new-generation enduro models was five years ago. And central to those 2012 year-model machines was an all-new chromoly frame – a frame designed to be more torsionally rigid, but allow extra longitudinal flex. The objective? To produce a motorcycle with more stability at high speeds, but deliver a smoother and more compliant ride over bumps. In other words, KTM introduced their frame as an additional damping element to assist the suspension in absorbing hits. This was achieved via major changes to the frame tubing’s dimensions and architecture, and by the use of a ‘remote’ tower for the upper shock absorber mount.

The 2017-model enduro models from both KTM and Husqvarna extend that frame design philosophy further; much further! This time around, by making the chromoly tubing 6mm wider and 2mm lower, and altering its architecture significantly, the frame is 30% more flexible in the longitudinal plane and yet it’s 20% more torsionally rigid. These are radical changes in anybody’s language, and they’re graphically illustrated in the short videos below, which compare the flex of the 2016 (blue) and 2017 (white) frames through both the longitudinal and torsional planes.

Having recently tested both the 2017 KTM and Husqvarna enduro ranges at the Spanish and Swedish launches, respectively, we can confirm that the chassis on both brands’ new bikes is noticeably more agile at slow speeds and more stable and sure-footed ride at high speeds. Admittedly, both ranges come with an all-new WP fork and shock (and the Huskys also get a revised shock linkage), meaning it’s difficult to isolate the new frame’s impact on handling. But what we can say is that the combination of the revised 2017 frame and suspension significantly improves the bikes’ handling character. They’re plusher and more planted than their predecessors over small bumps, but a lot more capable of handling bigger hits without bottoming. In other words, they offer a broader operating range that makes them safer and more versatile. And versatility is a value attribute with any enduro machine.

For more on the 2017 Husqvarna machine, check out these recent articles:

• 2017 Husqvarna Range: Ride Impression
• 2017 Husqvarna FE450: Power
• 2017 Husqvarna FE450: Suspension
• 2017 Traction Control: Gimmick or Advantage

For more on the 2017 KTM machine, check out these recent articles:

• 2017 KTM EXC Range: Ride Impression
  
• 2017 KTM 250/300EXC: Jetting Specs
• 2017 KTM EXC Range: Pricing Revealed
• 2017 KTM EXC Range: Meet the Engine Guru