Jamis Defcon Enduro Bikes

Securing the rear wheel to the frame by threading a 12mm axle into the rear drop-outs is not only safer, it’s stiffer. The rear wheel tracks directly in line with the frame, for more precise handling, so you can go faster with more confidence. The 142mm hub drop outs provide a self centering feature for the rear wheel for faster, easier installation.

The custom one-piece bell crank on the Defcon increases frame stiffness while allowing for the elimination of a seat stay bridge. The absence of a seat stay bridge provides more tire and suspension clearance while creating shorter chain stays and seat stays for even greater stiffness and better handling.

The custom frame tubes on the Defcon are made by SPF Air Forming. SPF is carried out at high air temperatures, where the tube structure is in its most ‘plastic’ and formable state. This allows more complicated shapes to be produced that cannot be made using traditional forming techniques. For example, whereas shape designs can be applied to 25% of the tube using hydroforming, SPF allows up to 90% manipulation. The result: more optimized shapes and less weight.

15mm thru-axle QR’s offer all the benefits of the 20mm thru-axle design (stiffness!) + the benefits of the standard 9mm QR system (quick wheel removal!) without any of the down sides. The weight of the 15mm system is similar to the classic 9mm system (thanks to the lightweight alloy axle & reduction in fork leg weight) , but it is nearly as stiff as a 20mm axle. The increase in stiffness improves steering & handling significantly. It also puts less stress on the fork’s internals, improving fork durability and performance.

Our 10mm shock hardware is NOT the standard from our rear shock suppliers. We have to pay more for it and our production lead times are usually increased because we specify it. But the increase in lateral and torsional stiffness for our frames and the rear shock durability and performance is worth every extra dollar and every extra delivery day.

USA made Enduro® Max sealed bearings sustain 40% more load capacity than standard radial bearings & provide more lateral support for the multiple forces associated with mountain bike pivots. MAX bearings use CRC Marine Grease that will not wash out or breakdown under extreme circumstances.

The leverage exerted by the Defcon mp4 suspension is progressive. There are multiple benefits to a more progressive suspension system. The rear shock can be tuned more linearly for a smoother, more plush ride without bottoming. Because the rear shock can be pumped to lower air pressures without performance detriment, shock and seal life are optimized and a greater range of adjustability is available.

The Defcon’s oversized chainstays are asymmetrical, with an elevated straight stay on the non-drive side and a dropped curved stay on the drive side. The drive side must be dropped and curved to clear the front derailleur and chain, but running the non-drive side straight from the drop-out to the BB pivot reduces weight while significantly stiffening the rear triangle laterally. There’s more tire clearance too.


160mmトラベルの、エンデューロ競技を得意とするフルサスペンションMTB、DEFCON(デフコン)。荒れた路面でのハイ スピードでも安定しているのは、車体のコントロール性を重視したジオメトリー、MP4による効率の良いペダリング性能、そして 後輪のグリップ力を確かに保つプログレッシブなサスペンションが相まみえた結果。タイムを刻む走りでも、楽しく走るために でも、オフロードの下りなら、このDEFCONの出番だ。

Jamis Defcon 1 Enduro Bike Jamis Defcon 2 Enduro Bike