Chumba Slackr Hardtail Review: Re-Centering Hardtail Geometry –

John took a Chumba Slackr hardtail home from the 2024 MADE Bike Show to review. Since then, he’s squeezed every bit of riding potential on the bike before winter set in early in Santa Fe, putting it and himself through a multitude of rides in the Southern Rockies. Find out what epiphanies he’s had while riding this Austin, Texas-welded titanium hardtail below…

Named after the cult classic movie Slacker, filmed in Austin, where Chumba is based, the Slackr is a 150mm 29er hardtail, welded in-house at Chumba from US-made titanium.

Chumba Slackr Quick Hits

US-made titanium tubing, frame welded in Austin, Texas
Size XL reviewed here by a 6’2″ tall human with long legs and arms
Weight: 30 lbs, as reviewed here, with pedals and cages.
Sizes: S-XL (custom sizing available)
$4495 frame with your choice of internal or external routing, dropout inserts, seat collar, and one-color brushed finish with head tube badge.
As specced here $$$$$$, but with an XT kit, Fox 36 fork, and Industry Nine wheels, it would be $8500
Fork Travel: Optimized for 140– 150 mm travel suspension forks. 44 mm offset recommended.
PMW Sliding Dropout Options: Geared, singlespeed, SRAM Transmission (your choice of inserts comes w/frame)
Max Tire Clearances: 2.6” on a 36 mm rim

Made in Austin, Texas

Since my last visit with Chumba in late 2019, the brand has moved all of its titanium welding in-house, with Chumba co-owner Mark Combs laying down beautiful beads on each of its titanium offerings. A lot of builders have moved to titanium frames in recent years. While the process is more intense – requiring more prep work, purging, and two passes at each butted weld – it’s nice to offer both steel and titanium to customers as an option, depending on their budget.

While both materials can be engineered to achieve similar ride qualities, titanium requires no finishing and no rust-proofing, which is appealing to many people. Plus, when a brand uses US mil-spec tubing, they are making bikes essentially from aerospace cuttings and scraps.

Seeing Chumba grow over the years has been something I hold close to my heart. I first met Vince in 2014 when he brought the brand back after the original Chumba closed in the early aughts. They re-launched the MTB brand with 29+ rigid and hardtail bikes, focusing on singlespeed riding. I really dug the new Chumba’s no-nonsense approach to mountain biking.

Over the past decade, the brand has grown to offer road, gravel, mountain, and touring rigs. Bikes like the Slackr epitomize the brand’s in-house capabilities and balanced design ethos.

Technical Specs

Much like Chumba’s Sendero, Yaupon, and Terlingua SL frames, the Slackr is built from domestically sourced and certified aerospace grade 3Al-2.5V titanium tubing. It uses a 1.75”/44.45 mm straight downtube. This size tube offers the ideal strength, miter size, and clearance for suspension forks without compromising strength and durability.

The Slackr features a titanium chainstay yoke, what Chumba calls the Space Yoke, made in the USA from 6/4 titanium. These 3D-printed yokes are FEA strength-tested and heat-treated to aerospace specifications to ensure they withstand decades of heavy use. What’s unique about its design is that Chumba engineered these yokes to form some of the best tire clearances out there while still using beefy 22.2 mm chainstays.

These chainstays keep the rear end of the bike responsive and snappy while the large-diameter down tube helps the Slackr maintain its line. More on that later…

Chumba launched this bike with a UDH-compatible rear end courtesy of hooded titanium sliders by Paragon Machine Works (included in the standard pricing; many brands charge $300-500 extra for these). This allows owners the option to run the most modern mountain bike drivetrains like wireless SRAM Transmission, cable-actuated Shimano XT, or the simplest, singlespeed. Chumba uses a Paragon Machine Works head tube on the Slackr, offering a renowned strength-to-weight ratio that keeps the bike light.

The brand’s in-house anodizing finishing allows for a variety of options ranging from solid color to tie-dye. This Slackr features Chumba’s tie-dye with a crisp-edge finish. The head badge is a standout finishing feature on the Slackr in its subtle and minimal detail.

I selected the size XL frame as a 6’2″ 190 lb human with long arms and long legs

Geometrically Centered

The Slackr geometry numbers, as discussed in this review, are represented by 20% sag. I’ve seen similar hardtails with steeper seat tube angles, coming in at sagged numbers of 77º or more. While I appreciate the climbing efficiency gained with steeper seat tubes – remember, even 1º can make a big difference – I’m more drawn to bikes with a 76º sagged seat angle.

For beginners, if you’ve sized your bike according to a top tube length, a steeper seat tube angle pushes the top tube towards the front of the bike more, increasing the wheelbase accordingly. This is why it’s best to size a bike off the effective top tube length, not reach. The latter is unaffected by seat tube angles.

Bike geometry is a game of millimeters and fractional degrees. Every single adjustment causes ripple effects. Over the past decade, hardtail geometry got steeper, slacker, and lower, but bikes like the Slackr prove you can accomplish mostly the same ride quality with a slightly dialed-back geometry.

Build Spec

Chumba offers all of its models to be built with the brand’s Custom Bike Builder, allowing the customer to select from their favorite drivetrain and components. Chumba can also work one-on-one with a customer to tailor their build kit to be as budget or bling as their budgets allow.

This Slackr was built as a show bike with flashy components, the latest in SRAM Transmission electronic shifting, those bomb-proof new M6 wheels from ENVE, TRP brakes, 5 Dev alloy cranks, a Cane Creek Helm MKII fork, and some blingy titanium bars from Thomson.

Personally, I prefer to review bikes with lower-tier groupsets, mainly because it takes some sting out of the price tag of a review product, but it’s also easier to “feel” a bike through lower-end componentry, removing the rose-colored lens effect of riding the highest-end parts spec.

I would have been more than happy with Shimano XT and aluminum Industry Nine wheels, but it’s kind of nice to be able to rally an all-mountain hotrod specced with top-tier componentry, too. ;-)

When I asked Vince from Chumba about the high-end build kit, he remarked:

“It was a Made show bike so it got the bling! We kinda figured we need to show people what we are capable of providing, and then anything below that is possible.”

Vince also noted that if you want to go even more over-the-top with the parts spec, Chumba can do that too. Or if you’d like the Slackr in a more affordable chassis material, they can make you a steel Slackr upon request.

One unfortunate note during the review is that I smashed the rear derailleur on a rock, and let me tell you, regardless of all those videos of people standing on a Transmission derailleur, the cage bent quite easily. I’ve spoken about this a bit before, but the T-Type mechs are larger than their cable-actuated predecessors and sit outboard a bit more, too. Of course, this was a rider error (oooops!), but I’ve smashed on this particular rock before without such results in product performance. ¯\_(ツ)_/¯

Maybe it’s just personal bias, but I still prefer cable-actuated SRAM to the new T-Type.

Blasting a favorite hip at Mach 10. Photo: Cari Carmean

Riding Experience

Last year I sold my Moots Womble, much to the dismay of the Necronomicog. It wasn’t because the bike wasn’t excellent; it’s just that it wasn’t what I wanted it to be in its current form. I wanted a little more travel, a slightly steeper seat tube angle, and a much slacker head angle. Some of my other notes included a chainstay yoke to eke out a little more tire clearance. I’m in no hurry to get a new hardtail – I still have my trusty Retrotec – but I have been eagle-eying what brands are cooking up in the space.

When the Slackr was announced, I began to froth. It checked all those boxes and had sliding dropouts for if I’m ever inclined to ride our trails here singlespeed again. While it looked rowdy, it still looked like it could rally without being overly cumbersome and wouldn’t be all wheel-floppy on climbs.

I’m drawn to bikes like the Slackr. They are great all-day pedalers. And they are usually pretty comfy sitting in on a long fire road or a techy singletrack climb.

Side hit speed scrub. Photo: Cari Carmean

Vince reached out shortly after the release and asked if I wanted to review one. Of course I obliged, and after this year’s MADE show, I took the Slackr home to Santa Fe. Once I got the Cane Creek Helm MKII fork dialed in, I really began to vibe with the bike. It’s not often that I say this, but the honeymoon and new bike feelings I initially had with the Slackr are still as strong as they were on day one.

Coming from the Womble, the Slackr feels more like an all-mountain trail rig trying to be an XC rocket, as opposed to the Womble feeling like an XC bike that I rode like an all-mountain trail smasher. The Slackr’s ability to aid in my riding tech terrain really impressed me. It never felt like it was in over its head and there was literally no adjustment to my riding style throughout the review process.

This summer, my riding felt like it was laced with piss ‘n’ vinegar, and the Slackr rose to the occasion.

Into the void of steep Atalaya chunk. Photo: Spencer Harding

However, one riding sensation that I couldn’t shake was that the Slackr, with its beefy 22.2 mm chainstays and robust 44.45 mm downtube did feel stiffer than I had imagined it would; not in a bad way, as the Womble could get a little too noodly in chunky terrain. Instead, the Slackr felt aligned with its trail prowess. While it still has a calm and assertive demeanor, if you really crank on it through chunky stuff, the flex you do feel is welcomed, especially on long rides. After long descents, I never felt overly walloped.

Climbing sprightly. Photo: Spencer Harding

Climbing

Here’s where the more even-keeled geometry really comes into play. Our climbs, like most Western places, are straight up for miles. We don’t have a lot of climbs that traverse unless you use the XC trails in town as connectors to the bigger mountain rides, which I did from time to time. That’s where the Slackr’s slightly slacker seat tube angle really brings comfort.

With a slacker seat angle, my hips are allowed to deflect more. Since I’m a very leggy person, with a 36″ inseam on my 6’2″ frame, I am a lot of leg. Steep seat angles in the 77-78º range can get uncomfortable on longer rides for me, both on my butt (because the steeper the seat angle on a hardtail, the more directly the impacts on the rear wheel travel up through the seatpost), but also in my hips from pushing hard up steep pitches.

Keep in mind less than a degree in seat tube angle might not seem like much, but degrees do make a big difference.

Ascending Atalaya, photo Spencer Harding

The Slackr was just slack enough in the seat angle to allow me to scooch backward on the saddle while traversing across flat terrain, essentially slackening the effective seat angle, and scooch forward enough on the nose of the saddle to get my weight closer over the bottom bracket on steep, techy switchback climbs, steepening it. It’s harder to achieve this as the seat angles get steeper into that 77º or 78º range.

When it came to faster-paced lunch rides, where I always try to spike my heart rate and maintain that for longer periods of time, I really liked the bike’s even-keeled geometry. I would call it “mild-mannered” in this regard, but that underplays its capabilities while descending.

For a while, I couldn’t think of what to call this review, but I kept feeling the word “centered” during my rides, so it stuck. This bike just feels centered and appropriately balanced.

Locked on. Photo: Cari Carmean

Descending

After the first descent on my favorite lunch ride here in town, I texted Vince from Chumba, “Bike fucking rips, man. Well done. Best titanium hardtail I’ve ridden.”

I don’t know what it’s like to design a bike, to literally make it in-house, and then send it off with some kooky bike nerd/wannabe journalist, waiting for their opinion to be posted online where thousands of people will read their thoughts. But I do know that I’d appreciate a text like that. It’s true, too.

I’m opinionated about many things, including hardtails, as they are my favorite bikes to review. I want them to be nimble and accurate while still being able to take a beating on the trail, and in these regards, the Slackr didn’t slack off at all. It delivered.

When a company nails that, and it’s obvious right out of the gate, I’m going to congratulate them, dammit!

Grass blades fooling auto-focus sensors. Photos: Spencer Harding

Dialing the enthusiasm back a bit… phew. Sorry!

In between bike reviews, I usually jam all my MTB rides on my Murmur. Even if I’m slightly over-biking, there’s something nice about a familiar bike that acts as a palate cleanser between review bikes, and it’s the bike I’ll grab to ride 99.9% of the time when it comes to upper-mountain rides in the summer. So, the Slackr was an interesting juxtaposition between a 160/140 mm full suspension platform and a 150 mm travel hardtail. Usually, a dialing-back period happens in this transition, but with the Slackr, I poured more vinegar into my riding style. Riding it the first few times was like playing chicken with the bike’s and my abilities, squaring off to see which would back down first.

I feel really lucky to have this bike during my peak fitness because I could really push both it and myself more, rather than using the bike as a tool to get me into riding fitness again. When you’re fit, riding a bike like this feels like a power-up and allows for your riding to evolve. On that note, my first wreck of the year came on the Slackr last month, indicative of me pushing my abilities harder than normal as I took a corner a little too fast and lost my line into a pile of rocks.

Sorry for the scratched brake levers, team!

Glissading the steeps of Atalaya. Photo Spencer Harding

Switching back and forth between the Slackr and the Murmur allowed for some interesting comparisons and unexpected observations. What was surprising is I didn’t feel much faster on the Slackr than my Murmur, except in very chunky and steep terrain, where having a rear shock offers seemingly endless rear traction. At the same time, I’d rarely want to take a hardtail into this sort of terrain anyway. But in everything else, it truly was a well-honed tool for the job.

The Slackr gobbled up ruts and roots, turned on a dime, and charged effortlessly through our monsoon rain-ravaged, chunder-spewed mountainsides. It was in these high-speed luge-like situations where the Slackr kept right up with my intuition. Running the dropout all the way back gave the rear center a planted feel while keeping the front of the bike more nimble and easier to command and just… straight up plow! But I found that I liked the flickability and snappy responsiveness with the wheel slammed all the way forward. It manualed and jumped with ease, making my lunch ride all the more fun.

Tongue out, tail down. Photo: Cari Carmean

150 mm travel hardtails are great for honing descending skills. They keep you honest while offering much-needed compliance in the chunky stuff with a longer travel suspension fork. The Slackr is one of the most playful platforms I’ve had the honor of riding. It’s snappy yet planted, it plows yet it responds to input, and it just looks damn good, albeit at a made-in-the-USA price point.

TL;DR and the Wrap-Up

While I’d argue that a full-suspension bike allows the rider to engage with more of the trail, there is a special place in my heart for trail-capable hardtails – so much so that I cannot imagine life as a cyclist without one in my stable. What Chumba did with its Slackr is look at where brands are currently offering their super progressive rowdy hardtails and dial it back a notch. In doing so, they made the most capable and playful hardtails I’ve ever ridden.

Its geometry is even-keeled, centered, and mild-mannered on paper. Still, its climbing agility and descending prowess are enough to shift the mindset of the most incredulous full-suspension devotee. The frame construction mirrors its riding demeanor, with impeccable welds and a “lifetime bike” pedigree, all done in-house at Chumba’s Austin, Texas-based facility.

Look, titanium bikes might feel bougie, and for sure, the price tags reflect the cost of construction, but I’d argue one might go through a number of carbon full suspension bikes in the same time period they could be enjoying just one bike like this. In the dream bike category, the Slackr is in a class of its own.

If my bank account allowed, I’d be buying this frame from Chumba, replacing the drivetrain with a cable-actuated system, and call it good for years. When it comes to a made-in-the-USA titanium hardtail, it doesn’t get much better than this.

And if the Slackr premium price is too high for you — understandably, it is for me — Chumba can make it from steel for you, too!

Pros