Chumba Ursa 29+ BC Review

Brent Knepper shares his thoughts on how this 29+ bikepacking rig fared…

I’m that person who has to pop a wheelie on every bike they ride. It’s a compulsion. How well I can kick back on the rear wheel is indicative of how fun the bike will be; a byproduct, I guess, of so many years dinkin’ around on bmx bikes. It’s a habit that’s annoyed my past bike shop bosses, and delighted onlookers at cx and mtb races. I suppose those wheelies were reminders that no matter how long the day was working on rusted hybrids, or how miserable the weather was in a race, that bikes are fun- you know, if you wanted to get metaphorical about it. So when I got to borrow one of Chumba’s Ursa 29+ BC bikes for a recent adventure, y’all can guess the first thing I did once I had it built up.

The “BC” in Chumba’s Ursa BC stands for “Backcountry,” and over four days I rode this bike through some of the most challenging terrain I’ve had the privilege to experience- dirt roads connecting single track, rough cattle trail, and (slightly) better equestrian trail through the Eastern Sierra.

The bike showed showed up with Wanderlust frame bag, seat pack, handlebar roll, and stem bags in de rigueur camo, matching the True Temper, US-made steel frame’s desert-tan color. The frame reps Texas hard with show-bike-level details in brake bridges and paint, but still has plenty of utilitarian features like Paragon sliding dropouts and braze-ons galore for all your rack and bottle cage needs. As a foundation, the Ursa left me feeling confident about that little task of completely relying on it in remote wilderness for days.

This said, when the bike came in, I was surprised by the amount of fancy parts on it. Carbon fork and bars, Thomson everywhere, and super-buzzy Hope hubs all held up by 29×3” Maxxis Chronicles, set up tubeless with Orange Seal, comes together as a bike I’d call “crazy light”. Unloaded, it has that great whip-shit quality of a full-rigid xc bike, but with the monster-truck confidence (and weight) these mondo tires offer. Kinda like a giant bmx bike, and just as fun feeling. It would be interesting to see how all this would translate once I stuffed the bike’s bags with the 30lbs of food and gear for a week of self-supported riding through the mountains.

So, my main experiences with 29+ before this bike are with the Surly Krampus and those swooshy Jones frames. The Chumba has many of the trail-bike qualities of the Krampus, especially that “lean back and party” feeling (reminiscent of 26” downhill bikes of the late oughts) that I’ve always felt is missing in the Jonesie, and in a lot of 29ers in general.

The frame is full of intentional moves, and two days into my Eastern Sierra adventure Chumba’s geometry choices really shined. See, I like to descend fast. It makes up for my slow climbing. And the way this bike obliged when stuffed into rutted, sandy corners out there just to spring back out and skip over step-ups and rock gardens made me forget at the time I’m on a 50lb bike. That alone is a lot to ask, and this responsiveness isn’t accidental. The 29+ tires, 150mm rear spacing, and DH-width bottom bracket make for a bike that I don’t think twice about leaning over and getting loose on, and these standards also allow for a great amount of clearance between the tire and chain line – yes, even with a front derailleur.

But there’s always trade offs, right? The advantages of big tires come with a weight penalty. 29+ tires, much like fat tires, love momentum- assuming you have the strength and/or gearing to spin them up. Luckily, the wide hub spacing and DH bottom bracket that stabilize so much on the downhills do a great job of transferring power in the climbs. Chumba really cherried out the particular model I was on with all their available upgrades. While I loved the weight when pushing the bike up steep, loose-sand trails that seem to proliferate in the Sierras, the stiffness of all that carbon up front takes a toll on you while muscling the bike around on long descents. It’s the classic rigid mtb dilemma, with only the volume of the huge wheels to take the edge off.

An easy solution would be to stick with Chumba’s standard option of a Surly steel fork. In addition to the more forgiving ride, the Surly fork would let you mount more bags on the bike – fitted as they are with mounts for Anything Cages and the like. I could definitely have benefitted from a set; instead I was overstuffing the Wanderlust handlebar roll the entire time. Turns out that wasn’t the smartest idea. The roll I was using is an early one made for the team, marked by someone’s attempts to add a few extra stitches in brown thread – stitches my downhill indulgences would end up ripping out. I felt bad for wrecking a bag that wasn’t mine, I’ve been told production bags have way heavier stitching. Anyway, something goes wrong on every tour for me, it keeps things interesting, so a bag mount ripping isn’t that catastrophic. Luckily, the accessory bag that comes with the roll has it’s own handlebar straps, and did such a good job at holding up the jeopardized side that I didn’t actually notice things were wrecked until the last day.

In fact, when it comes to gear, Chumba offer plenty of choices. I was sent their medium Ursa 29+ Backcountry to go get rutty on, with their upgraded cockpit, dropper seat, and hydraulic brakes. Their stock model comes with a Surly steel fork, aluminum thomson bar and Elite post, bb7 mechs with Paul levers, and includes the Wanderlust frame bag, all for $3595. Their ZULU Handlebar bag ($135), seat bag ($135), and stem bags ($39 a pop) also came along so I could get the full Wanderlust Bags experience.

When it came to negotiating technical bits, I thought the Thomson dropper post fitted to the Ursa might be a game changer. Perhaps it’s a great addition for taller folks – but my short, weird body, on a medium frame, put the seatpost height in a spot where dropping the saddle, with a seatpack strapped on, made for a fun emergency brake on the rear tire at best. And unfortunately, it was just another place to develop creaking with all that extra wiggly weight back there.

Developments like carbon and dropper posts are really pushing how maneuverable mtbs can be. And to be fair, it’s pretty curmudgeonly to focus my critiques on these things. Truth is, I’m just impatient. I see how well this tech works in other niches. But in my opinion, it falls short for bikepacking. More people are dropping more cash on bikes that can ride up mountains with campin’ gear, so it’s really just a matter of time before we get versions that cater to our specific needs. Like I said, Chumba has more traditional parts options for their Ursa BC. The fact they off more advanced tech, and are happy to try it out, is a sign they’re invested in the future of this niche.

Pros

• Trail geo lets this bike get twisty.
• The MUSA (Made in the USA) frame is packed with details that look cool, are practical, and will help you stand out from all those bass boat green 29+ bikes.
• Wide hubs and DH-spec bottom bracket keep it stable if ya get too twisty, and really help transfer power to the rear wheel from those blasted quads of yours.
• Available carbon upgrades keep the bike light for pushing up miserable trails.
• 29+ wheels are huge and cool, roll over everything, and the Maxxis Chronicles are super grippy.

Cons

• Sometimes fancy parts are too fancy, and make the ride quality a little less ideal than their heavier ferrous and non-ferrous (ti/alum) cousins.
• Don’t take worn out bags out into the wilderness, or at least bring a sewing kit (jeez, Brent).
• 29+ wheels are huge and heavy, slowing down everything (except descents) – this is just part of the deal with big tires for now.

Build Kit

The following is based around an oversized True Temper and double butted 4130 tube set with PMW sliding dropouts.

• FRAME: CHUMBA USA Select Steel Frame
• FORK: MRP Rock Solid 490 w/15mm Thru Axle
• HEADSET: Cane Creek 110
• STEM: Thomson X4
• HANDLEBAR: Thomson MTB Carbon
• SEATPOST: Thomson Elite External Dropper 31.6mm
• SEAT: Raceface Aeffect
• GRIPS: Raceface Strafe
• BRAKES: Shimano XT Hydraulic, Ice Tech Rotors
• SHIFTERS: Shimano XT
• FRONT DERAILLEUR: Shimano XT Dyna-sys
• REAR DERAILLEUR: Shimano XT Dyna-sys Shadow Plus (w/clutch) 10 speed
• CRANKS & CHAINRINGS: Raceface Respond with Turbine Rings 36-24T
• CHAIN: Shimano XT
• CASSETTE: Shimano XT 11-36 10 speed
• FRONT HUB: Hope Pro Evo
• REAR HUB: Hope X2 Evo, 150x12mm thru-axle rear
• SPOKES: DT Swiss Comp
• RIMS: 29+ Surly Rabbit Hole 32h
• TIRES: Maxxis Chronicle 29 x 3.0 EXO Folding 120 tpi
• RACK MOUNTS: rear
• WATER BOTTLE MOUNTS: 2 inside main triangle, 1 below downtube
• NOTES: PMW Stainless Steel Sliding Dropouts w/replaceable inserts, 83mm bottom bracket

Wrap Up

If you’ve skipped past my novelization of whether or not this bike is cool, here’s the wrap up: The frame is a trail bike foundation with bikepacking amenities. Adding in modern tech like carbon and dropper posts, while fun unloaded on the trails, have some quirks once weighed down with food and camp gear.

But what matters most to me with this bike is how much went into keeping this bike fun, responsive, and capable of popping hella wheelies. Loaded or unloaded, Chumba’s Ursa 29+ just rips.

• Size Tested Medium
• Sizes Available S/M/L
• Weight (as tested) 29.75lbs/13.49kg
• Price (as tested) $3,970.00 (w/dropper add $350)
• Contact Chumba USA
• Recommended Uses A trail bike foundation with bikepacking amenities.

Rider’s Background

Years of riding bmx bikes influences my bike handling style, which played favorably for the crowds while I competed in CX and MTB races. The truth, though, is I’m just not the competitive type and I hate driving a car to go race in circles. I just want to go ride bikes off road and have fun! The dirt road touring and bikepacking scene have become a welcome home for these inclinations, and I share my stories of getting out, getting lost, and keeping things low-impact and earth-friendly on my site Everything Will Be Noble.
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