Kona Unit X Review: The Ultimate… Gravel Bike?

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With a compelling new geometry, 29 x 2.6” tires, and a 1×12 drivetrain, the Kona Unit X looks like a great bike for 1,400 bucks. We tested one to find out how it stacks up on the trail, bikepacking, and even as a gravel bike. Here’s the full review…

Although it’s yet to see its 20th birthday, the Unit might as well be a classic at this point. It’s been in Kona’s lineup since 2003 when it was released as one of the first production singlespeed mountain bikes on the market. It was (and kind of still is) Kona’s affordable, bare bones, cross-country-oriented, steel singlespeed staple. But it’s also something of an oddball niche experiment.

My first Kona Unit was a dark green 2010-ish fully rigid model. I bought it to punish myself after work a couple of times a week on our local suburban stacked singletrack. At that point in time, singlespeed mountain bikes were still a bit eclectic, though I suppose they always will be to the mainstream. Later, in 2016, Kona reinvented the Unit once more, again as a singlespeed. But this time it was adorned with mounts and provisions, and launched with a fantastic video featuring Erkki Putilla, an adventurous seafaring Norseman, who rode the Unit from his fishing boat into the Finnish forest for a simple, singlespeed bikepacking adventure. Building on this campaign’s success, Kona decided to stick gears on it and spin up a dedicated trail bikepacking version for 2018—the Unit X. Then, in 2020, it was revamped once again, and we were particularly excited about this model. Read on for a full review after several local overnighter trips, a lot of trail miles, and loads of…. gravel rides!?

  • Highlights
  • Angles: 68° Headtube, 75° Seattube
  • Chainstay: 430mm
  • Bottom Bracket: 73mm Threaded
  • Hub specs: 15 x 110mm (front); 12 x 148mm (rear)
  • Seatpost Diameter: 31.6mm
  • Max Tire Size: 27.5 x 3.0″ / 29 x 2.6″ (TBD)

To preface, just a couple of weeks ago Kona announced its 2021 Kona Unit X. Fortunately for us, aside from a new paint job, it’s nearly identical to the 2020 model, which is what’s reviewed here. To that end, this review is still 100% relevant!

There were quite a few exciting changes made from the 2019 model to the 2020 Unit X. Aside from that blingy “Gloss Champagne” paint scheme, the most visible update was Kona’s switch from 27.5+ to 29 x 2.6″ tires, a move I happily stand behind. I’ve been riding 29 x 2.6″ tires almost exclusively on trail bikes and longer bikepacking trips for the last few years and have been pretty stoked on the platform. It offers a good mix of traction and floatation without taking as much of a penalty on sidewall support and weight that’s often evident in larger 29 x 2.8 or 3.0” rubber. To be sure, 29 x 2.6” tires are usually a little heavier than 27.5+ tires (about 100 grams per pair, on average), but the rollover benefits of 29er tires is bar none.

Kona also ditched the 100/135 quick-release dropout standards in favor of BOOST-spaced thru-axles (148 x 12mm rear and 110 x 15mm front). This was another major upgrade that not only allowed a shorter chain stay, it also provided a little more front and rear tire clearance—it now comfortably fits 29 x 2.8” tires (which I tried) and appears as if it will fit 3.0” tires as well.

  • Kona Unit X Review
  • Kona Unit X Review

However, the most significant alterations to the 2020 Kona Unit X come from a shift in the bike’s geometry. Following modern trail bike trends, the 2020 Kona Unit X got a little longer and slacker. For starters, the headtube angle was slackened by a degree (68°) and the seat tube was made a degree steeper (75°). This clearly follows in the footsteps of Kona’s renowned Honzo lineup, and both are welcome changes to give the bike a more stable ride on downhills and what I find to be a more comfortable climbing posture as well. The bike is also significantly longer. The top tube was lengthened by a hair and the wheelbase increased by about 2cm, as did the bike’s reach. The stack height also got about 2cm taller, which (although still comparably short) falls in line with its dirt-touring prowess to give it a slightly more upright stance and make it more comfortable during long days in the saddle.

Kona Unit X Review

Additional tweaks include a significantly shorter chainstay length (430mm, down from 442mm). Another interesting feature on the 2020 Kona Unit X’s Reynolds 520 chromoly frame is the rather unique, dual-slotted sliding rear dropout, which allows it to be set up as a single speed or with a Rohloff. And there are plenty of mounting options, including three bottle cage mounts on the triangle (two inside and one under the down tube), front and rear rack mounts, fender eyelets, and three-pack cargo cage mounts on each fork blade.

Kona also dropped the bottom bracket by about 5mm, which was nullified on the complete with the larger diameter 29 x 2.6″ tires. Here’s the full geometry chart for reference (in millimeters).

Size
S
M
L
XL

ST LENGTH
370
420
470
530

TT LENGTH
582
610
637
675

REACH
425
450
475
510

STACK
588
597
606
615

STANDOVER
695
731
768
810

HT ANGLE
68.0
68.0
68.0
68.0

HT LENGTH
110
120
130
140

ST ANGLE
75.0
75.0
75.0
75.0

CS LENGTH
430
430
430
430

BB DROP
65
65
65
65

BB HEIGHT
310
310
310
310

WHEELBASE
1115
1144
1173
1211

FRONT CENTER
693
722
750
789

FORK LENGTH
470
470
470
470

FORK OFFSET
50
50
50
50

2020 Kona Unit X Build Kit

Highlights of the 2020 Kona Unit X include the relatively new SRAM Eagle SX drivetrain, which features a 11-50t cassette and a 32t chainring, yielding a 454% gear range and a relatively bikepacking-friendly 19 gear inches in the granny gear. Here’s the full build kit, with my opinions to follow.

  • Kona Unit X Review
  • Kona Unit X Review
  • FRAME MATERIAL Reynolds 520 Butted Cromoly
  • COLOR Gloss Champagne with Black and Dark Silver Decals
  • SIZES S, M, L, XL
  • FORK Kona Plus Fork 110mm spacing
  • CRANKARMS SRAM SX-Eagle
  • CHAINRINGS 32t X-Sync Eagle
  • B/B SRAM DUB 73mm
  • PEDALS Kona JS2
  • CHAIN SRAM SX-Eagle
  • FREEWHEEL SRAM SX-Eagle 11-50t 12spd
  • REAR DERAILLEUR SRAM SX-Eagle
  • SHIFTERS SRAM SX-Eagle
  • BRAKE CALIPERS SRAM Level T
  • FRONT BRAKE ROTOR SRAM Centerline 180mm
  • REAR BRAKE ROTOR SRAM Centerline 160mm
  • BRAKE LEVERS SRAM Level T
  • HEADSET TH ZST No.10
  • HANDLEBAR Kona XC/BC Riser
  • STEM Kona XC/BC
  • SEATPOST Kona Thumb w/Offset 31.6mm
  • SEAT CLAMP Kona Clamp
  • GRIPS Kona Key Grip
  • SADDLE WTB Volt Sport (Sport 250 size S)
  • FRONT HUB Formula 110x15mm
  • REAR HUB Formula 148x12mm
  • SPOKES Stainless Black 14g
  • RIMS WTB ST i30 2.0 TCS
  • FRONT TIRE WTB Ranger TCS 29×2.6″
  • REAR TIRE WTB Ranger TCS 29×2.6″

I don’t have a lot of complaints about the Kona Unit X build as a whole. You certainly get a great bike for the price, and no matter how much you dissect the components, it’s definitely much more than a sum of its parts. However, for the sake of a review, there are a few issues I had with the build kit. My biggest gripe is the fact that it didn’t have a dropper post. WIth the Unit’s trail-worthy geometry, it only seems fitting. Of course, that might up the bottom line by $60, but it would be worth it. I put my 150mm Crank Brothers post on for the duration of the review period. Another quibble is the rather narrow handlebar—760mm is just a little too small for me and I would have preferred a 780mm bar, which is a little more common on trail bikes these days. Lastly, I experienced quite a bit of chain slap with the SX derailleur. It quickly became clear that the lowest-end Eagle cassette definitely suffers from a weak clutch. Wrapping the chainstay with an old innertube would solve this.

Otherwise, there are a few componentry specs that I really liked, such as the 180mm front brake rotor. Also, the WTB ST i30 rims and tubeless-ready WTB Ranger tires are a match made for bikepacking. I’ve always been a fan of the Rangers and really liked the 2.6” versions. They’re fast and still offer a surprising amount of traction.

Kona Unit X Review
  • Kona Unit X Review
  • Kona Unit X Review

On the Trail

I was quite anxious to get this bike out on our local rowdy and rooty trails. I don’t ride fully rigid bikes as much as I used to, but there’s always a soft spot in my heart for the genre, and an overt curiosity as to how well they’ll handle singletrack. The Unit X has a lot of good qualities that you see in other rigid steel trail bikes—think Surly Krampus and Tumbleweed Prospector—with a few modernized tricks, like a longer stance and steeper seat tube angle. On the trail, the Unit X felt very comfortable and stable. It was surprisingly sprightly, too, despite the fact that it weighs north of 30 pounds (31.1 to be exact, or 14.1kg). I’m not quite sure where the extra calories are on this bike, to be honest. Perhaps they just add up with heavier hubs, cockpit components, and lower grade parts and bits. But I definitely don’t think it’s a heavy tubeset. In fact, I was very impressed with how comfortable the Reynolds 520 frame felt. I wouldn’t say it was springy, but it’s clear that it’s not overbuilt. The rear end was more compliant and soft than other bikes I’ve tried recently. It was quite nice, zingy even, and kind of reminded me of my old Moonlit Swamp Krampus. With a lighter wheelset and a few parts upgrades, I have no doubt that it would feel all the more spritely and playful.

Kona Unit X Review
  • Kona Unit X Review
  • Kona Unit X Review
  • Kona Unit X Review
  • Kona Unit X Review
  • Kona Unit X Review

Unfortunately, I didn’t get to try the Unit X with a suspension fork. The frame is designed for a fork with 100mm of travel, which is a little small for my liking. Not to knock it before I try it, but if I had one wish for this bike, it’s that Kona would revamp it around a 120mm fork—that might just be perfection. I think you could easily get away with running a 120mm fork on it, but as intended, the frame’s 65mm bottom bracket drop gives it a nice in-the-bike feel and keeps it nimble in the corners, which I really liked. Bumping up to a longer fork might tarnish those qualities a little.

Following in the footsteps of the Sutra LTD, the Unit has a surprisingly low stack height for a dirt-touring rig. This firmly planted the front wheel, and coupled with the Unit X’s relatively heavy build, made it a little challenging to lift up the front end at times. Even so, like the Sutra LTD, I felt like the Unit X was very well balanced. And, the shorter fork, low stack, and steep seat tube gave it an ibex-like climbing prowess. There’s one local downhill that I like to occasionally ride in reverse on weekday afternoons. It has two super steep pitches with roots and rocks that require some finesse to clear. It’s not uncommon that I make it over one of them and spin out on the other. The two times I climbed it with the Unit I cleared both pitches. It’s also comfortable and efficient in the climbing position, both on steep technical climbs, and even on longer dirt road and gravel ascents.

Speaking of gravel, as the title suggests, there were multiple occasions when I was preparing to roll out on a gravel/doubletrack ride, and I grabbed the Kona Unit X over three drop-bar bikes that I had at my disposal. Despite its chunky 31-pound weight, it simply felt at home on these types of rides. It tracked beautifully, felt incredibly stable, and it was quite fast, too. Moreover, it simply felt comfortable. The relatively long geometry and steep seat tube fit me well and weren’t at all tiring to pedal for long rides.

Kona Unit X Review
  • Kona Unit X Review
  • Kona Unit X Review

While Out Bikepacking

Barring a couple of caveats, the previous two paragraphs adequately summarize why I think the Unit X makes a great dirt-touring bike. Namely, it checks off a lot of mandatory provisos that are required of a bike for such a task: speed, stability, comfort, versatility, and the “at home” feel that’s priceless for a bike that will be ridden day in and day out on a long tour.

The Unit X also has a lot of features that fit the category: rack mounts, plenty of bottle bosses and accessory mounts, and sliding rear dropouts to enable subtle geometry shifts and the potential to run an internally geared hub… or take it back to its roots and make it singlespeed.

During the overnighter bikepacking trips I took with the Unit X, it performed as expected. I suppose there are some caveats. Namely, I would prefer the rack mounts to be a hair lower on the seat stays. Not a deal breaker, but something I noticed. Also, on one particular bike-glamping trip when I was carrying a camp chair, a six-pack of beer, too much food, and fishing gear, along with a lot of other extras, I noticed that the frame felt a little on the flexy/noodly side. Really, this is another non-issue as I think the tubeset is really well balanced for trail riding and bikepacking, but if you’re thinking of a bike that can be loaded with four panniers and a full touring load, this might not be the one.

  • Kona Unit X Review
  • Kona Unit X Review
  • Kona Unit X Review
  • Size Tested Large
  • Actual Weight 31.1 pounds (14.12 kg)
  • Place of Manufacture Taiwan
  • Price $1399
  • Manufacturer’s Details KonaWorld.com

Pros

  • Incredibly versatile geometry that’s equally at home on the trail as it is on gravel roads
  • Great value for the complete
  • Slotted dropouts can be used for singlespeed or IGH conversion

Cons

  • Minor build kit gripes, including narrow 760mm handlebars, no dropper post, and shoddy Eagle SX derailleur that doesn’t work so well with a small chainring due to its weak clutch

Wrap Up

The Kona Unit has always been something of an enigma, and as Kona suggests, it’s a bike they’ve kept in their lineup because people liked it for a lot of unknown reasons. Whether you see the Kona Unit X as some sort of an adventure rig, a do-all bike, or a cult favorite rigid steel oddball, you’re exactly right. It’s a bike that can’t be pigeonholed and truly works well for a lot of different surfaces and scenarios. If you want to ride the Unit X on a long stretch of backcountry gravel while taking in scenery, it’s quite comfortable and tracks extremely well. And if you want to get loose on chunky singletrack, it won’t disappoint there either.

Generally speaking, I had some minor gripes with the build kit, but overall it’s pretty solid, and I wouldn’t hesitate to take it as is on a dirt tour almost anywhere. It’s a little hefty on the scales, but for $1,400 it’s a pretty good deal. If Kona kept that price tag and threw in a dropper post, it would be even sweeter. Either way, the Unit X remains one of the more affordable, well-appointed options on the market. Most of all, rigidx steel bikes like the Kona Unit X epitomize how bikepacking rigs came to be, and Kona made a lot of excellent changes that represent how these bikes should continue to evolve.

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