Reviewed by Steve Wentz and Brandon Turman // Photos by Lear Miller
Jamis has a long history of making decent trail bikes at good prices, and they’re taking aim at the popular “do-it-all” enduro/all-mountain category with the new 160mm travel Defcon series. This is the first long travel ride they’ve offered in years, and of course it’s accompanied by 27.5 (650b) wheels – something Jamis has been using since 2010, well ahead of most others. Visually speaking the Defcon 1 holds true to its name and looks like it could stop a nuclear threat with its robust tubing, big tires, and some of the burliest suspension available. Add in some Shimano Saint brakes typically reserved for downhill bikes and you’ve got a ride that stands out from the crowd, urging you to pilot it down the rowdiest trails you can find. We did exactly that during the 2016 Vital MTB Test Sessions in Phoenix, Arizona.
- Aluminum frame
- 27.5 (650b) wheels
- 160mm (6.3-inches) of front and rear wheel travel
- MP4 suspension with one-piece bell crank
- Tapered headtube
- Internal derailleur cable and dropper routing (non-stealth)
- Post mount rear brake
- Enduro Max sealed bearing pivots
- Threaded bottom bracket with ISCG05 mounts
- 142mm rear spacing with 12mm through axle
- Measured weight (size 19, no pedals): 31.5-pounds (14.3kg)
- MSRP $4,899 USD
Close inspection of the Defcon reveals some interesting tube shapes. Check out the top tube for an obvious example. These shapes are made possible by the use of SPF air forming, a high temperature process that allows for more work to be done to the 6061 aluminum tubes than traditional hydroforming. Jamis claims this process allows for optimized shapes and less weight.
Suspension duties are handled by a linkage drive single pivot “MP4” design with a robust bell crank to actuate the 216x63mm (8.5×2.5-inch) shock and control the leverage curve. The bike is on the more progressive side of the all-mountain spectrum with a reasonably low 2.54:1 average leverage ratio.
The absence of a bridge on the seatstays may throw up a red flag for some, though Jamis claims the design of the new one-piece bell crank raises frame stiffness to levels high enough to eliminate the bridge, creating great mud clearance and the ability to shrink the chainstays. They’ve also utilized oversized 10mm shock hardware, asymmetric chainstays, and sealed Enduro Max bearings at the major pivot points to improve lateral and torsional stiffness.
Cable routing is a mixture of internal and external options, with the rear brake remaining outside the frame for easier maintenance. The rear derailleur cable enters at the side of the headtube before popping out below the bottom bracket, and can be a bit noisy as it’s loose inside the frame. Dropper post routing runs along the inside of the top tube, and those wanting to run a stealth style dropper can use the optional front derailleur routing. Shimano’s new 1×11 drivetrain allows Jamis to ditch the front derailleur, but the frame is direct mount compatible if you prefer that setup.
Additional details include room for a water bottle inside the front triangle, a threaded bottom bracket (hooray!), ISCG 05 tabs, a post mount rear brake, and some basic rubber frame protection on the chainstay.
The Defcon comes in three versions priced at $2,799, $3,799, and $4,899. Curious about the unique spec we opted for the highest end Defcon 1, which sees upgrades to FOX Factory level suspension, Shimano XT drivetrain, Saint brakes, and a KS Lev DX dropper post over the mid level Defcon 2.
What you see is what you get when it comes to the bike’s geometry, as there are no high/low settings or head angle adjustments. You’re looking at a ride with a capable 66.5-degree head angle, pretty average length 435mm (17.1-inch) chainstays, and a slightly higher than normal 340mm (13.4-inch) measured bottom bracket height. Relatively short reach measurements resulted in our 5’8″ and 5’10” (1.73 and 1.78m) tall testers opting for a size 19 test bike, so be sure to reference the numbers carefully when choosing a size. The seat tube height may be an issue for some riders who prefer a longer front center.
On The Trail
From fast XC loops to downhill bike worthy descents and climbs that require trials skills, Phoenix, Arizona’s South Mountain trail system offers everything required to throughly test a bike claimed to do it all. We rode Javelina, Mormon, National, Holbert, and Geronimo a number of times. The FOX Float X Factory Series EVOL shock was set to the recommended 30% (19mm) sag value before heading out the door.
Pointed uphill it quickly became clear that the Defcon certainly won’t be the first one to the top. The rig is heavy, lacks a snappy pedal response with a 1X drivetrain, and is difficult to keep the front end down on steep climbs even with the seat slammed forward in the rails. While the geometry chart lists a reasonably steep 73.5-degree effective seat tube angle, the much slacker actual seat tube angle creates lots of rearward weight bias and a long effective top tube length. Riding the Defcon uphill while seated felt like we were pedaling in a lounge chair: it was soft, comfortable, stretched out, and not all that fast.
Standing up only accentuates the bike’s mushy feel. Hopping up a technical trail features that require an immediate pedal afterward, you often get the sense that there’s nothing there when putting that first pedal down to maintain your speed and balance. While equipped with the stock 32-tooth chainring, very low anti-squat values make it require the use of the shock’s firmest compression setting to add any sense of pedaling efficiency.
The bike climbs best when you’re able to maintain momentum, and rewards a charge in fast and keep the RPM up approach. Should you lose that momentum, however, it can be difficult to get back up to speed as it’s quick to rob your power. This realization lead to us sprinting into many climbs, which made for one hell of a workout and a big challenge. It also left us literally gasping for air at times, as it requires far more energy than the competitors even with the shock in the firmest setting. The feeling is a bit like riding your downhill bike uphill with the compression knob cranked all the way in, and it has a similar bouncy attitude as you gently bob your way through technical features.
What surprised us was how the bike’s ultra plush feel could actually benefit us on the climbs. Given enough leg strength it felt as though we could motor up anything. While it took an extreme amount of will power, there were a couple particularly tough climbing sections on National trail that we successfully navigated aboard the Defcon 1, like this:
To make this happen, we chose the open compression setting to allow for maximum traction at the wheels. It certainly wasn’t efficient, but it can be done.
The slightly high feeling bottom bracket allowed us to keep the cranks turning over more rocks and undulations than we expected, though under really hard efforts the bike’s tendency to blow through the travel – in combination with long 175mm cranks – lead to us smashing more rocks than any other of the 17 bikes in Test Sessions. The bike would be far better off going uphill in the little ring of a 2X drivetrain which would result in higher anti-squat values, though if you make the switch you’ll want to keep the big ring as small as possible to maintain some level of sprinting performance when it’s time to put the hammer down on the descents.
Once we got to the top of the trail, wiped the sweat from our eyes, and recovered from the endeavor, we were excited to see if the all-out spec and aggressive looking numbers added up to a good descender. That hope quickly faded, however, as the first few downhill sections immediately revealed a less than capable feel.
Confidence in the frame’s length, 66.5-degree head angle, stout FOX 36 Float fork, and a reasonably short/wide cockpit got us to consider lines we’d normally save for our downhill sleds, but upon landing the flexy rear end, Vittoria tires that folded easily, and surprisingly unsupportive suspension lead to several sketchy situations and nearly kept us from really uncorking it. While smashing turns or navigating tight switchbacks and powering out, we could hear and feel the back end creaking and flexing, and the tire would occasionally rub on the inside of the seatstay. The rider that’s brave enough to let it go in truly heinous terrain had better hang on tight, as this buckin’ bronc is difficult to keep under you at speed. We were foolish enough to give it a try, and we haven’t been that scared on a bike in a long time.
While the bike is indeed progressive, it feels like it is barely so. The plush suspension gobbled up medium sized consecutive hits like few trail bikes can, though a distinct lack of support in turns, g-outs, and off jumps creates a ride that feels best at speed with the rear shock in the firmer compression settings. Even in the firmest setting the bike doesn’t provide the support it needs as it uses too much travel too quickly, which is indicative of a possible need for a firmer tune. A volume spacer will also help in this regard – there wasn’t one in the shock when we looked – and Jamis is considering this in the future as a change to the OEM tune. Simply upping the air pressure did not resolve the issue.
Here’s the rear end in action:
Almost out of necessity, after a few rides we decided to stop trying to push the bike into extreme situations and instead just ride casually and have fun. The Defcon 1 was great for that. The bike sagged enough to help create that feeling of being ‘in’ the bike, which allows you to set it into corners and not feel too far off the front or the back. At slower speeds the front and rear suspension feels balanced and smooth, it tracks well over undulating terrain, and handles chatter particularly well. The addition of compression damping at slower speeds can make it a bit harsh over small and medium sized bumps, however, and it felt like there was just enough hesitation to fold over the tires a bit, allow for some deflection, and transmit a bit too much of the trail back to the rider. While it’s unfortunate that this isn’t a true do-it-all bike in the traditional sense, it is possible to just run the Defcon in the open setting, be chill, and have some mid-paced fun with it for best results.
The Defcon 1 build serves up several high end components that have proven themselves individually and in the right application. How a bike rides is a function of the parts as a whole, however, and in this instance a few of the less common choices let the bike down in a big way.
At first glance the Vittoria tires are meaty, and even sized well with a 2.4-inch Goma front matching to a 2.3-inch Morsa rear. Unfortunately this pair left much to be desired, as cornering traction on the loose over hard conditions was very poor front and rear, especially when we’d push into the bike through a turn. We also spun out pretty often while climbing. The large volume and light casing adds to the instability of the bike, and we found they require a minimum of 32psi due to poor sidewall support when mounted to the chosen rims. Braking traction was good, however. In our followup with Jamis we learned that the rear tire may have been a pre-production model with an overly soft compound, though Jamis was unable to verify.
Some of that performance is the wheel and tire combo though. We applaud Jamis for going out on a limb to spec unique and eye catching Loaded Precision parts around the Defcon 1, but we’d be happier with a more stout wheelset for this application and possibly some money saved in the end. The tubeless X-Lite X30 wheels retail for around $600, and for that price there are lots of better options. It isn’t a bad wheelset, but quad-butted spokes and super lightweight rims don’t really have their place on this rig. After our test the rear wheel needed a good truing, and was in close to the worst condition of all the wheels we rode in Phoenix.
We feel the bike could be vastly improved with a better wheel/tire combo, adding stability where it really counts. Even narrower tires with a slightly stronger casing could improve the overall descending capability. There was one instance in particular where we came off of a small drop and burped the rear tire nearly off the rim. The bead leaked for a few seconds, but then the area was moist with sealant and quickly repaired itself. It wasn’t the small leak that was the problem, that was just another instance where the Defcon 1 would be otherwise stable save for the fact that the tires would fold over and throw our weight sideways. All of that could have been avoided with a more fitting wheel/tire combo.
Attached to the rather confused wheelset are Shimano’s top of the line stoppers in terms of power, the Saint M820 hydraulic disc brakes. Combined with Ice-Tech pads and 180mm rotors they slow the heft of the Defcon 1 down without any issues. In a sustained bike park setting they’d do really well, too.
Shimano’s 11-speed XT drivetrain shifted nicely under some high torque applications. While less than SRAM’s 1X cassette, the range on the 11-42 tooth cassette was acceptable on a bike where top speeds were limited for other reasons. The 32-tooth front ring provided enough of an easy gear to truck up and over most ascents. We did lose the chain twice, however, which means you’ll want to invest in an upper chainguide. We were expecting more noise as the built-in chainstay guard isn’t the most robust, but the clutch mechanism kept things pretty quiet. If it were our bike, we’d add a bit of 3M Mastic tape to the exposed areas.
The suspension components are very good, and we’ve enjoyed our time on the latest generation FOX 36 Float fork and Float X EVOL rear shock. The Kashima coated suspension requires very little breakaway force and both items are very adjustable. As mentioned before, the rear shock will require additional tuning for most riders.
Rounding out the build is a roomy cockpit complete with bright blue 760mm (29.9-inch) wide Loaded Precision AMX riser bars and a 45mm AMX Trail stem.
Long Term Durability
While the burly looking frame appears as though it’s built to withstand some abuse and features Enduro Max bearings for strength and long life, the creaking noises we heard and felt in the rear end are a bit concerning. Torque specs are located on each pivot point for easy service.
Given our experience with the wheels they seem to be under-gunned for the intended purpose of the bike and would likely see a premature demise. Our test bike was also covered in paint chips after a relatively short amount of use, though Jamis indicated the powder clear coat process may have been skipped on the “pre-production demo.” Jamis backs the frame with a two year warranty and 25% off crash replacement program.
What’s The Bottom Line?
2006 called. They want their bike back.
The Jamis Defcon 1 slots into the mid to upper end of a market filled with lots of good competition, and for just under $5,000 buyers shouldn’t have to put up with an overly heavy build, outdated suspension design, poor pedaling performance, a shock that needs additional tuning, flexy rear end, and some oddly chosen parts that really hamper the ride. In this configuration it’s also difficult to identify who this bike would be
safe best for, because as speeds increase the bike shows some very odd and unstable handling traits.
That said, the geometry is decent, the travel is right, and the thing can make it to the top given an extreme amount of volition. If someone is just getting into the market for a bike that can do most descents, be taken to a bike park here and there, and do some shuttle assisted XC, the Jamis Defcon 3 at $2,799 could be worth a look. For that price, you still get long travel, a dropper post, two chainrings to make climbs less painful, and a chassis worthy of a few upgrades to fit your exact style. Just be sure to swap out those tires…
Visit www.jamisbikes.com for more details.
Vital MTB Rating
- Climbing: 1.5 stars – Poor
- Descending: 2 stars – Mediocre
- Fun Factor: 2.5 stars – Okay
- Value: 2.5 stars – Okay
- Overall Impression: 2 stars – Mediocre
Bonus Gallery: 30 photos of the 2016 Jamis Defcon 1 up close and in action
About The Reviewers
Steve Wentz – Age: 31 // Years Riding MTB: 20 // Height: 5’8″ (1.73m) // Weight: 180-pounds (81.6kg)
“Despite what it looks like, I’m really precise and calculated, which I’m trying to get away from. I’m trying to drop my heels more and just let it go.” Steve is able to set up a bike close to perfectly within minutes, ride at close to 100% on new trails and replicate what he did that first time over and over. He’s been racing Pro DH for 13+ years including World Cups, routinely tests out prototype products, and can squish a bike harder than anyone else we know. Today he builds some of the best trails in the world.
Brandon Turman – Age: 29 // Years Riding MTB: 15 // Height: 5’10” (1.78m) // Weight: 175-pounds (79.4kg)
“I like to have fun, pop off the bonus lines on the sides of the trail, get aggressive when I feel in tune with a bike, and really mash on the pedals and open it up when pointed downhill.” Formerly a Mechanical Engineer and Pro downhill racer, Brandon brings a unique perspective to the testing game as Vital MTB’s resident product guy. He has on-trail familiarity with nearly every new innovation in our sport from the past 5-6 years and a really good feel for what’s what.
About Test Sessions
Four years ago Vital MTB set out to bring you the most honest, unbiased reviews you’ll find anywhere. That tradition continues today as we ride 2016’s most exciting trail, all-mountain, and enduro bikes in Phoenix, Arizona. Reviews can be accessed 24/7 in our Product Guide. Test Sessions was made possible with the help of Rage Cycles. Tester gear provided by Troy Lee Designs, Royal Racing, Smith, Fox Racing, Race Face, Easton, and Source.