YT Industries recently brought a Jeffsy fleet to Santa Cruz, California, and invited Mtbr to cast our verdict: love or hate. (If the former, then an #ILOVEJEFFSY social media post would be in order). Both Markus Flossmann (CEO) and Stefan Willared (CTO) were on hand to talk about the bike's design, answer questions, and provide some colorful commentary about our riding while we tried to look good for the camera. Fortunately the location was our home base, so we got to ride Jeffsy on familiar territory. Continue reading to learn our final verdict on this new 140mm 29er trail bike.

Jeffsy CF Pro. Photo by Ale Di Lullo

Jeffsy CF Pro (click to enlarge). Photo by Ale Di Lullo​

We've already posted a first-look at the Jeffsy, which covers general information about the bike's geometry, builds, and target use. So we'll skip the rehash except to say that the Jeffsy is a bit less than I generally ride (29er with 160mm travel). Now on to on-trail performance of the Jeffsy Comp 1 (white bike), which is what we tested. The red frame rig in some of the photos is the CF Pro.

Jeffsy CF Comp 1. Photo by Ale Di Lullo

Jeffsy CF Comp 1 (click to enlarge). Photo by Ale Di Lullo​

The Jeffsy looks quite similar to YT Industries' other two bikes, the Capra and Tues, which is a very good thing. The main difference is the link now attaches to the seat tube instead of downtube. Additionally, the downtube takes a less direct path to the bottom bracket, which improves aesthetics and provides a location for a water bottle cage. Cables are routed both internally and externally, with the rear derailleur cable traveling inside the downtube and chainstay, dropper cable inside the seat tube, and other cables external, secured to the frame using integrated mounts with zip ties.

2017 YT Jeffsy 2017 YT Jeffsy

Cable management and routing, down and seat tubes (click to enlarge). Photos by Ale Di Lullo

Utilizing the 148mm boost rear hub standard has allowed frame's designers to improve the chainline for these large wheeled trail machines and add additional stiffness, particularly useful with the larger wheel diameter. An additional 3mm on the drive side might not sound like much, but given the clearance, it makes a huge difference. Boost is only in the back though, with the front retaining 100mm hub spacing.

SRAM and Race Face drivetrain. Molded chain stay protectors. Photo by Ale Di Lullo

SRAM and Race Face drivetrain. Molded chain stay protectors (click to enlarge). Photo by Ale Di Lullo​

The bikes all look amazing, with the paint on the alloy version being particularly eye-catching (more of a flat look rather than glossy). Keeping the finish looking flawless is easier now, and there's no more need for old inner tubes being wrapped around the stays. YT added not one, but three molded rubber protectors, located on the lower downtube and inside both the chainstay and seatstay.

Additional frame protection for chain drops was a stroke of genius. Metal pieces are located outside the cassette on the seatstay, on the front edge of the chainstay and on the upper portion of the bottom bracket - all the points of contact from chain drops. My personal bikes have scars in those areas, so I'm excited to see something functional to address it (that I didn't hack together in the garage and have to worry about falling off and getting sucked into somewhere it shouldn't be).

Continue to page 2 for more on the YT Jeffsy »



Chain drop protection. Note the silver metal pieces on the left side of the chainring and the top of the bottom bracket. An additional protector is located inside the rear chainstay. Photo by YT Industries

Chain drop protection. Note the silver metal pieces on the left side of the chainring and the top of the bottom bracket. An additional protector is located inside the rear chainstay (click to enlarge). Photo by YT Industries​

Clutch-style derailleurs have minimized chain drops for most, but they still happen. I experienced one during this ride during some rowdy play. Fortunately, the E-Mount provides a simple and efficient method to add an upper guide to the bike. ISCG tabs are not included, but when using an upper-only guide, are overkill. Given the minimal weight, there is little reason not to add an upper guide. A RockShox Reverb with 150mm of drop is standard.

RockShox Reverb dropper post. Photo by Ale Di Lullo

RockShox Reverb dropper post. Photo by Ale Di Lullo​

After thoroughly enjoying my previous time on the Capra, one daily gripe was no water bottle holder. YT addressed this on the Jeffsy, however, these water bottles are special. Not surprisingly, they hold exactly one pint and are available from YT. They come is a set including bottle holder plus two water bottles for $50.

Water bottle holder and bottle. Photo by YT Industries

Water bottle holder and bottle (click to enlarge). Photo by YT Industries​

The Jeffsy I rode was the CF Comp 1 build which includes RockShox suspension and fewer carbon components than the Pro build. Consequently, the listed weight is 2 pounds higher (28.2 for Comp 1 versus 26.2 for the Pro).

RockShox Monarch shock. Photo by Ale Di Lullo

RockShox Monarch shock (click to enlarge). Photo by Ale Di Lullo​

All test bikes were in the low flip-chip setting (66.8-degree head tube angle) and I had zero reason to wish for it to be steeper. Maybe if the terrain was totally flat...or just curiosity's sake. But not on a first ride.

YT set shock pressures based on suggested sag, and I set tires at 29psi front, 30psi rear (I'm 6' and was on a size large frame). After riding, we'd increase the shock pressure by a few psi plus add a couple more pounds to the tires. The reason being is that I ride heavier than my weight of 200 pounds, which caused a tire pancake at the limit of the travel. Good thing we were riding on wonderful Santa Cruz loam.

Debriefing with Stefan and the YT crew. Photo by Ale Di Lullo

Debriefing with Stefan and the YT crew (click to enlarge). Photo by Ale Di Lullo​

On Bike Analysis

After setting the bikes up, we headed to the local trails. This was a first-ride and one day only, so a bit brief. However, the familiar trails were a nice perk, because I could ride at full speed and get a feel of this bike's capabilities.

Initially, the cockpit felt a bit small while seated. This was mostly due to the bars being narrower than I prefer (760mm), combined with a slightly shorter than stock stem (50mm vs. stock 60mm on large). After spending a little time on the bike, that short cockpit feel dissipated and pedaling went smoothly. For my personal taste, I'd install a shorter stem and wider bars. The Jeffsy was easier to pedal than the Capra, which did fairly well itself. 175mm cranks do improve the pedaling feel, and zero pedal strikes were experienced even with the low bottom bracket.

Entering some slick roots. Photo by Ale Di Lullo

Entering some slick roots (click to enlarge). Photo by Ale Di Lullo​

During hard pedal strokes on climbs, the nose initially got a tad light, but that was easy to prevent. The stock 32t front ring is a bit steeper than many ride on a 29er with 1x setup, yet the bike's weight combined with pedaling performance made it reasonable. I tried climbing with the shock open and closed, finding minimal pedal bob when left completely open, but closed was preferred. Little technical climbing was done during this ride.

Continue to page 3 for more on the YT Jeffsy »



Splitting the trees. Photo by Ale Di Lullo

Splitting the trees (click to enlarge). Photo by Ale Di Lullo​

The surprising part of riding the Jeffsy is how fun it was even on flat terrain. Hard pedaling absolutely jets the bike forward. It pops out of corners, especially when using the proper body position - low and a tad back. After that, the Jeffsy threaded between trees and was surprisingly nimble. YT selected a reduced fork offset compared with similar 29ers, which improves the feel in tight turns and at slow speeds, reducing the "long nose" that large wheels with relaxed head tube angles can produce. I've generally seen ~51mm offset used on similar bikes, whereas Jeffsy is fitted with a 44mm offset fork. That reduced offset also means the rider needs to be disciplined about keeping weight down and back.

Fork Offset: 44mm. Photo by Ale Di Lullo

Fork Offset: 44mm (click to enlarge). Photo by Ale Di Lullo​

Next it was time to use gravity rather than fight it. The beauty is how the Jeffsy utilizes its travel, which feels bottomless as the effective spring rate ramps up. That's a good thing, because it loves to be launched. The rider can generate quite a bit of pop with the supportive geometry. When combined with the light weight, I was flying higher and farther than on my normal bike.

Launching into a fun root section. Photo by Ale Di Lullo

Launching into a fun root section (click to enlarge). Photo by Ale Di Lullo​

With the Jeffsy marketed as a bike that likes to have fun, I definitely leaned into it during the test ride and experienced zero mechanical issues. Stefan commented that the rear tire kept getting wider and wider as the bike approached the limit of its travel. Onza Ibex 2.4 tires fit without issue and performed decently, tending to drift a bit mid-corner. Personally, I'd switch to my normal tires, Maxxis DHF/DHR II.

The SRAM Guide brakes worked without issue. My personal preference is Shimano, but I'm left with zero faults after this ride. The combined Race Face/SRAM drivetrain performed similarly, generating zero complaints. One dropped chain was experienced during the ride, which would be prevented by an E-Mount guide.

SRAM Guide brakes provide stopping power. Photo by Ale Di Lullo

SRAM Guide brakes provide stopping power (click to enlarge). Photo by Ale Di Lullo​

When the trails got steep, root covered, and off camber, this bike allowed for a great big smile and little braking. We launched into some chunky roots and I expected to feel more flex, especially with the stock wheels, yet had zero issues. The DT Swiss alloy wheels performed well, which was a nice surprise. When the rear tire got loose, the Jeffsy drifted in a clean and controlled fashion, even through roots.

Grabbing a little brake, before heading into the roots. Photo by Ale Di Lullo

Grabbing a little brake, before heading into the roots (click to enlarge). Photo by Ale Di Lullo​

Bottom lime, the Jeffsy could easily serve as my daily go-to bike, capable of generating big smiles both downhill and uphill. Indeed, YT delivered with the Jeffsy, and yes, #ILOVEJEFFSY. For more information visit www.jeffsy.com.