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.
The only bummer would be that it will probably take another while for the new frame to become available in aluminium too. Then again that's understandable and not unique to YT. If I want a silent Shimano freehub now I'll need to buy XTR. It will take another few years for them to sink down to my level (XT/SLX/Zee).
I'm surprised to see though that people can tell right from reading this article that 140mm wouldn't suffice, the Capra would be too much and the 150mm would be ideal. I would think that when I come unstuck with 140mm travel, getting 150mm out of the same bike isn't going to help me much. Haven't tried though. Does anyone here have experience with adding 10mm of travel and does it even make that much of a difference?
@freebikeur: well it isn't as easy to increase the travel of the fork
It is if its a Pike.
"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."
I'd love to see in depth tests covering both the high and low end specs in a range, so buyers will know whether it's truly just a bit of lighter weight and better brakes and shifting, or whether the low end bike rides qualtatively differently.
140mm except 150mm for top model. Why?
If your articles avoid real questions and opinions are manufacturer-approved, then what value is it providing to any of your readers?
2012-2017: Hyper Neon Dance Dance Revolution Max Extreme
He used to shred the Santa Monica hills between pipe sessions.
Oh, and no one said you had to watch the ad, but ya did, and here you are, adding to the conversation.
I'm on board with the concept of paying a Hollywood actor to push the bike, but in this case it was a boring old dude just talking, and the script wasn't exactly profound.
I would have been more into it if they got a hot chick like that one from San Andreas and Batwatch to do it.
The Ibis has a too linear leverage ratio, which tends to provoke a lack of progressiveness at the end of the travel for heavy/aggressive riders. That was the first complain that appears among riders after the Ripmo was released and I'm sorry, but on a bike of this price it's quite of a bummer...
Give me any Ibis or any YT and I’ll shred anyone of ‘em.
Oh and yeah I love my Mojo 3. Been riding it 2-1/2 years now and the paint still looks good. :-)
My Ripmo looks like a work of art.
The fundamental physics of damper is the conversion of kinetic energy to heat through a fluid medium (i.e oil). Yes that 'tiny volume' of oil is creating almost all the heat. No heat = no suspension. The seal friction is pretty minimal.
The fundamental mistake you are making is assuming the temperature of a shock is directly related to how much heat is being generated. The main difference between different types of shocks is their ability to dissipate heat. The issue isn't how much heat is generated it's how it is how effective a shock is at transferring that heat to the surrounding air.
The weak point of air shocks (especially inline) is that the air sleeve surrounds the damping circuit as the shock compresses and insulates it. The oil is heating up the air sleeve as this is the only path to disapate heat. In a coil shocks the damping circuit is inside the threaded shock body and there is a much more direct path to transfer heat outside the shock, thus cooler temps. Piggybacks are great for any type of shock as they provide a much greater surface area for heat transfer, but they make a bigger difference for air shocks.
A simple test of pumping up a road bike tire and then holding the valve will prove that to you, and that's only 100 PSI. Now think about 200 to 500 psi multi-second cycles for minutes at a time.
Repeatedly compressing air generates a lot more heat than repeatedly pushing oil through damping circuits.
I'm not discounting what these guys are saying, it's definitely a factor, but compression of air is the dominant cause.
Of course a top end bike with top end suspension rides well. Is that great suspension hiding flaws in the frame design that would be exposed by cheaper, less adjustable suspension? The only way to know is to ride the lower spec options.
Surely spec'ing the same components they already have on the lower models but with the longer stroke shocks wouldn't have even affected the price, so why not give them the extra travel too?
Just seems like an artificial way of putting the top model on a pedestal
To be fair, we are talking about 1.5mm difference in shaft displacement at sag here (30% sag @ 15mm shock stroke 140mm or 16.5mm for 150mm version) so minutia haha.
I am changing my shock on my 2017 Jeffsy to get 160mm (27.5 version) for this exact reason: more margin for error without a real downside.
Times have changed. The 27.5 and Alu bikes are still incoming. Sure they will be visited when they are available.
So, my question is does the bike come with a shuttle or do you have to provide your own? Some more uphill trail riding and level stuff would have been good to know about but that is YT's doing. I'm sure PB will provide the goods on a long term review.
But honestly, I could not give much damn. My next bike will surely be 150-170 29er. I will buy a used E29 or Yeti 150.
E.g. a 2013 Kona Process had a 64 deg HA, 2013 Trek Session 63.6 deg HA, 2014 Nomad 65 deg HA which are still acceptable today.
Looks like we settled some years ago on 62-64 DH, 65-66 Enduro/AM, 66-67 Trail and it hasn't really been changing as much as people believe.
Reach and SA are a different story though.
For example the Jeffsy CF Pro Race has 450mm reach in size M, the CF Comp 454mm also in size M and the AL version has only 424mm reach?! Why?
I think this is a big mistake, if this is real. What if somebody an AL version? This person'll get a newly hyped bike, with old timer geo?
The slacker HA (160mm fork) shortens the reach a bit- still the same frame
But still don't get whats up, with the carbon version, ok I do. So the CF comp works with 140mm travel f&r, the CF ProRace uses 150mm f&r. The two frames are the same, but the specs are different. So the CF Comp uses shorter shock.
A 29" trail full suss with 140mm travel is really capeable and YT says the Jeffsy is for trail/am. But we know the lads, they're going to put a 160mm fork on it and bigger shock (or buy ProRace version) and when this comes to life, the bike is no more will be a trail bike but enduro.
This is good in one way, cuz' the bike is more tuneable but I think this has the cons in other way, cuz' the bike loses its original funcionality. Maybe.
Its the same in the Stumpjumper Evo
The CF Comp has 140/140 travel while the CF PR has 150/150 and there are the geo chart what says difference btw the two models.
I never sad if this'd be a problem, just interesting.
The forks are 10mm more travel on the Pro Race hence the geo changes as I explained above. Most forks you can change the air shaft for ~$40ish to get the extra 10mm.
Pretty identical except for 150mm travel compared to 145 on ripmo
32mm is flexy XC stuff and makes no sense unless you are racing XC and shaving every gram to improve climbing times.
In summary: move to BC.
Sounds hella fun there though
It is the consequence of steeper seat angle, but still..
And apparently the reach and stack also depend on wheelsize. Didn't expect that. I read this review (link below) a few days ago about the 27.5" model and reach was slightly longer. I would have expected the head tube angle to be slacker on the smaller wheel size model but apparently it is the other way around for this bike.
Reach is what matters on a mountain bike because it determines your standing position, you know, the one you take when you're riding down the trail.
The steep seat angle you mention is what will help you on seated climbs if you're so worried about your fire road grinding.
And as others mentioned, the bike is significantly longer overall (i.e. in the wheelbase, which matters for handling unlike HTT).
That said, considering all the rage about steep seat tube angles and dropper posts that allow you to raise the seat with the flick of a switch, I acknowledge that seated pedaling is very important for more than a few. So yeah, different people and all that. Just remember that what applies to you doesn't go for everyone.
So yeah, frame geometry is by no means simple. Even the numbers won't tell you the whole story. I'm personally always interested in the difference between standover and bb height as that basically implies how much room you've got over the bike. My hardtail is pretty much standard geometry except for the seattube. I decided 400mm should be sufficient even if I want to get a 400mm seatpost (with 100mm min insertion) up to XC height. Looks funny, but good enough should I ever desire to do so. But I wanted to have the top tube so low that the back of my knee would be above the top tube even with the cranks level. I thought that would give me the freedom to ride (and most specifically, corner) the way I like to. I measured, calculated and decided the top of the top tube should meet the seattube at 320mm above the center of the bb, measured along the seattube. That's what I asked for, that's what I got and it worked out exactly the way I wanted. But yeah, what I meant to point out is that sometimes you really need to do your own measurements and calculations to decide what sizes you're after.
Besides, your point makes sense as opposed to @pulDag's which I was responding to. What you're saying is that long reach works best with a steep STA to a) get the rider's weight when seated forward for climbing and b) keep the TTL in check so you're not too stretched when seated. It's true and bike manufacturers clearly take this into account seeing how most new long reach bikes have steep STAs.
The other guy insinuated that we're somehow being 'lied to' and the long reach bikes are in fact too short for his liking because the steep STA shortens the TT. I got the impression that he thinks riders are kind of stupid and buy long reach bikes in hope of getting a more stretched seated position. Which is obviously false as the actual reasons are standing position and overall handling improvement.
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