The YT Jeffsy needs little introduction. The original launched in 2016 with much hype and surprised a lot of riders, but it has gone on to be well received and helped to expand the German direct-sales company’s appeal into the lucrative trail bike market.
The pace of development in the bike world over recent years has been rapid, and so for 2019 the 150mm-travel Jeffsy 29 has been given a fairly major overhaul to keep abreast of the changing shape and capability of modern mountain bikes, but without losing any of the appeal of the original.
YT Jeffsy 29 CF Pro Race Details
• Intended use: trail / all-mountain
• Wheel size: 29"
• Rear wheel travel: 150mm
• 66º head angle
• Water bottle compatible
• Aluminum and carbon frame options
• Weight: 28.4lb / 12.9kg (CF Pro Race, SM)
• Size: SM - XXL
• Price: $5,699 USD (CF Pro Race)
Travel remains set at 140mm front and rear on all models except the range-topping CF Pro Race that's pictured above, which gets a boost to 150mm front and rear. A more significant change is geometry that's been stretched out and slackened off, with a size large now getting a 470mm reach. Other numbers include a 66-degree head angle and 77-degree seat angle, along with revised suspension kinematics, internal cable routing, ISCG 05 tabs, space for a bigger water bottle, and a choice of aluminum or carbon fiber frames.
The Jeffsy 29 starts at $2,299 USD and rises to $5,699 for the range-topping 29 CF Pro Race that I got to ride over two days in Portugal. It’s generously equipped: Fox 36 and DPX2 shock and Transfer dropper post, Shimano XTR rear mech and shifter, SRAM Guide RSC brakes, e13 wheels, tires, cassette, crankset, and chain guide, and a Renthal handlebar and stem. All very nice equipment and nothing you’d want to change, save for perhaps some things here or there that boil down to preference.Frame Details
The overall silhouette of the new bike is largely reminiscent of the original, which is no bad thing as it’s a solid looking machine and clearly a YT, and very much a mini-me Capra. It’s available in carbon fiber or aluminum, and there’s still the same Virtual 4 Link suspension, YT's take on a Horst Link design with a Metric shock sandwiched between the downtube and seatstays. Pivot hardware has been updated with custom Acros sealed and covered bearings to provide better durability and protection against the elements, and all the bolts are accessed from the non-driveside so maintenance is much easier.
To improve the stiffness of the frame, the headtube has been bolstered with a boxier shape where it flows into the toptube. YT resisted the lure of internal cable routing with the original Jeffsy but has relented and tucked all the cables inside the frame for the new bike. It’s very neatly done though, with an easy access point under the downtube and neat rubber cable clamps to keep the housing firmly in place and prevent unwanted rattles. I like that attention to detail.
There are now ISCG 05 tabs so you can run a bash guard; you couldn’t on the original. The frame is 1x only, allowing the bottom bracket and main pivot area to be optimized for maximum stiffness, but YT has stuck with a press-fit bottom bracket that I know will upset some people who are hoping threaded shells will take over the world again. There’s frame protection on the downtube which is bolted into place so it won’t peel off, and to protect and dampen the annoying sound of chain slap, the chainstay is generously wrapped with a durable rubber material.
“But does it take a water bottle?” is a pressing question for all new trail and enduro bikes these days (how times have changed). Yes, you can fit a bottle at the bottom of the downtube with a capacity upgrade from 500 to 600ml, so no excuse for running dry. YT has partnered with Fidlock to provide an optional magnetic bottle, but a regular cage and bottle can be used instead.Suspension and Geometry
The Virtual 4 Link remains from the previous Jeffsy, the company's own take on a Horst Link setup. The shock is driven directly by the seatstays with a short link mounted to the seattube to control the motion and provide added stiffness. Where the majority of the range stick with the same 140mm travel front and rear via a 210x50mm shock, the range-topping CF Pro Race model I rode gets 150mm at both ends courtesy of a longer, 55mm-stroke shock. YT has also focused on refining the kinematics and has increased the leverage ratio and anti-squat to provide extra progressiveness and support when pedaling and handling big impacts.
Geometry has been a big area of focus for YT, as it is for any new trail bikes these days. And yet, it's longer, lower and slacker. How did you guess? The five sizes experience an increase in reach with a slacker head angle, steeper seat angle and improved standover. The size large features a 470mm reach, 66-degree head angle, 77-degree seat tube, 1215mm wheelbase, and a shorter 435mm seat tube so longer dropper posts can be fitted. You still have the ability to adjust the geometry by flipping a small chip located where the shock is bolted to the seatstays, which has the effect of adding half a degree to the angles.
Chainstays are size-specific, 435mm on the small and 440mm on the XXL, a trend we’ve seen from a few bike brands and it’s one that makes good sense. Bikes are equipped with 44mm offset forks, another trend that is buzzing through the industry at the moment.
It was a short flight out to the Algarve, Portugal, to see the covers pulled off the new bike and put it through its paces. Sunny, mild, and dry trails in December when it’s freezing cold rain and quagmire trails at home? Yes, please! The terrain provided the ideal place to test the new bike, with mostly natural trails with a few man-made additions running on super tacky dirt with the grippiest rocks I’ve ridden in a long time, and a real variety of fast flowy singletrack to rough rocky chunder. It’s the natural trail bike environment, the sort of place this bike was designed for. And it was a hella lot of fun, too; I can strongly recommend the area for riding if you want a winter escape.
Setting up the bike was a breeze. YT has developed this cool bike stand/jig for getting a rider properly set with sag, handlebar and brake lever angle all taken care off. I followed the recommended settings, which is 30% in the rear shock achieved with 200psi with a 0.4 spacer, and 65psi in the fork with one spacer and the high and low-speed compression set three clicks from fully open. I fiddled with the fork pressure a few times but the settings worked well during the two days of testing.Climbing
Okay, I’ll admit it, we didn’t do a whole lot of climbing. We had shuttles whisking us to the top of the hills on both days which gave us more time on the descents, but despite this there were still trails that required a reasonable amount of pedaling - they don't just point you straight back down the hill again, but curve and twist through the many hills in this region.
When traversing across and up the hillside you're immediately struck by just how cleanly and efficiently this bike pedals. Okay, it’s not XC bike-rapid but it really shone on the climbs and undulating trails with lots of elevation and speed changes and never felt sluggish or reluctant to point its wheels up the hill. The suspension provides stacks of support at the sag point when you are pedaling, so much so that you can leave the shock open all the time. Not once did I feel compelled to flick the 'Mike Levy Cheater Switch,' and I like that. You can just concentrate on riding the bike and not worrying/forgetting what setting the shock is in.
What the Jeffsy does clearly lack is outright small bump sensitivity compared to some rivals, like the Stumpjumper I rode earlier in the year. To be fair, I didn’t get to ride enough really challenging climbs covered with roots or rocks to really see how the suspension copes with tricky pitches that require suspension to be fairly active and deliver necessary traction to let you up to the top without dabbing or waving the white flag.
The fit of the large-sized bike was perfect for comfortable pedaling, too. The steepened seat angle puts you in commanding position to maximise your speed on pedally trails, and the reach to the handlebar was just right; generous without being overly stretched. It's also clear that the low weight of this spangly top-end build certainly helped in the pedaling and climbing department.Descending
Oh my God, the YT Jeffsy was crazy fast and so much fun on the descents. It’s a playful and lively bike with plenty of pop so you can get as much airtime as you desire or tuck low racer-style and carry warp speed through corners. The geometry changes are well received, perhaps not the most progressive of the current crop of 29er trail bikes but, for what it’s worth, I found the numbers to hit a good sweet spot for my 5'11" frame.
I was able to move the bike around the trail and through the corners with a good amount of agility present, but when it came to steeper drops I felt comfortable behind the 66-degree head angle and 470mm reach. There are two larger sizes, and with shorter seat tubes than before, there is the option of sizing up if you need.
When it came to dealing with the varied trails we spent our time on, with everything from steep rock slab drops to fast pinball alley-style loamy singletrack through the most spectacular landscape, there is a stack of stability present in how the Jeffsy conducts itself. It feels really composed when ram-raiding through rocky gulleys and smashing into rocks and drifting through beautifully manicured catch berms, yet it’s nimble and agile enough for picking its way through the most annoyingly tight corners. It’s an easy bike to get through the turns, with good weight balance and steering is light and agile enough to let you put the bike where you want it with precision.
The progressive suspension helps to give the Jeffsy its playful character. When it comes to bigger drops, there’s no hint of coming up short on travel or harshly bottoming out; it’s very well controlled. Many an occasion it displayed the sense of a much bigger bike in how calmly it dealt with everything - it would be interesting to see how the shorter travel 140mm Jeffsy compares to this 150mm range-topper. The firm suspension doesn't deliver the magic carpet sort of ride that some bikes do - it does flatten the trail - instead, it's much more engaging and involving with more information feedback. You ride the Jeffsy instead of just hanging onto it.
I had no issues with the build kit on this range-topping bike, although this was only a short introduction. The gears shifted with sweet precision and there’s all the range I needed, the brakes were powerful, and the tires grippy on the strangely tacky dirt and rock features of the local trails. Using the optional Fidlock magnetic bottle takes a little practice to perfect, but it does work well and nobody lost a bottle during two days of riding. I’d like to swap it out for a regular cage and bottle for comparison, though.
The launch of the original Jeffsy 29 was a bold move by the small company, but this category of big-wheeled trail bike has really blossomed in recent years and the changes YT has enacted on this latest version definitely make it a contender. If you want fun and fast, the first impressions of the updated Jeffsy show that it clearly delivers. I can’t wait to get a longer, more in-depth ride on the new bike on my own trails.