Vital Rides the All-New YT Jeffsy 29 37

Longer, lower, and slacker are all words that apply to the new Jeffsy 29 - but it also has revised anti-squat numbers and a steeper seat tube. All in all, it adds up to one very capable trail bike.

Vital Rides the All-New YT Jeffsy 29

INjust ten short years, YT has enjoyed the kind of success that you would usually expect from bigger, or older brands. Born out of one man’s desire to make high quality bikes affordable to more people, and firmly rooted in the gravity side of the sport, YT has managed to carve out an impressive market share for itself in both downhill/park and enduro. Three years ago, YT decided to get into the trail/all-mountain game as well, with the first version of the Jeffsy 29. At the time, the crew from Forchheim, Germany were aiming to build a “fun-loving and agile” 29er that would “change the way people thought about big wheels.” It’s probably fair to say that they succeeded, but the mountain bike market is not known for standing still and three years later, the original Jeffsy 29 was certainly starting to look dated in the geometry department. For 2019, the company went back to the drawing board, and the result has just been launched.


2019 YT Jeffsy Highlights

  • All new kinematic with increased anti squat
  • 10mm more travel and metric shock for 29er
  • Updated geometry
  • All new bearing and axle system - single sided access and longer lifetime
  • Better headtube stiffness then the predecessor - new "HeadBox" shape
  • Less mud pockets all over the frame
  • New integrated FidLock bottle and bottle cage system with 600ml volume
  • All new cable routing system
  • Fully integrated protection system with bolted down tube protection
  • Weight: 12.9 kg/28.4 lbs (CF 29 Pro Race, size s, without pedals, tubeless)
  • MSRP: 5299 € / £4799 / $5699 USD (CF Pro Race)
  • Availability: February 2019

Both the 27 and the 29er versions were updated for 2019, with the biggest changes applied to the 29er. Longer, lower, and slacker are starting to sound like gratuitous buzzwords by now, but when it came to the original Jeffsy 29 these changes were more than warranted. YT added ~ 25mm of reach across the board, lowered both the stand over height and the seat tube length, slacked out the head angle and even added 10mm of travel to the top-end version of the 29er.

Jeffsy 29 MK2 geo evolution
Jeffsy 27 MK2 geo evolution

The chain stays grow longer on the two largest sizes (with the addition of an XXL there are now 5 sizes to chose from), and YT also made the seat tube angle steeper. YT calls this concept “YT Tailor Made”, with the idea being that you can simply pick the reach you like to ride without too much concern for stand over height and seat tube length.

Jeffsy 29 CF Pro Race in "Deep Petrol"

The original 27-inch version was born a year after the 29er, and it was already significantly longer in reach. For 2019, YT still applied a number of the other changes such as a steeper seat tube angle, shorter seat tube and the introduction of five frame sizes.

Jeffsy 27 CF Pro Red
Jeffsy 27 CF Pro White

The original Jeffsy had a bit of a split personality. It was a very fast and fun bike as long as you were riding in the direction of gravity, and while it pedaled well enough to be a very versatile bike, it never really shone when you were putting down the watts. For 2019, YT decided to completely rework the anti-squat numbers in order to remedy this particular aspect of the bike’s handling. A 20-25% increase in anti-squat should translate to a more direct feel on the pedals and better efficiency on the climbs. There is also a flip chip that can be used to alter the bike's geo, raising the bottom bracket and making the seat tube and head tube angles slightly steeper for better ground clearance and further improved climbing capabilities.

Looking over the new frame in more detail, a number of improvements become apparent. Inspired by the work done with the YT Mob on the new Tues DH bike, all the hardware on the new Jeffsy can now also be accessed from just one side. This means the mechanics don’t need to walk around the bike when working on the pivots and bearings etc. The cable routing is now fully internal as well as fully guided, which means you only have to push the cables through from one end to have them pop out in the right place at the other end. The cable housings are held in place with a single clamp in the middle, another clever touch to make things easier to work on. On the topic of ease of use, YT turned to the company FidLock to help them make room for a slightly bigger water bottle in the frame. The bottle is held in place with a combination of a magnetic and mechanical system, which is easy to operate and takes up less space than a traditional bottle cage. The new bottle (specifically designed for the Jeffsy) holds 600ml of liquid, 100ml more than the previous version.

To ensure similar levels of stiffness with a lower frame profile, YT reworked the shape of the head tube (they call the distinctive shape “HeadBox”). The frame has also been made as smooth as possible in most places, which YT says will reduce the risk of mud accumulating in hidden pockets and similar. In terms of frame protection, the down tube guard now bolts on, and the swingarm guards extend further along the edges. The derailleur hanger now continues up along the seat stay, which offers a little extra protection against the chain coming in contact with the carbon at this particular point. All in all, the attention to detail and the level of workmanship are both very high on these new frames.

Note that YT did not manage to rework both the carbon and the alloy version of the Jeffsy for this launch, so at present the full alloy bike (“AL Base”) is still based on the MKI frame. To provide a more affordable alternative for those looking for the new frame geo in the meantime, YT has introduced a CF Comp version which features the same carbon front triangle as the full carbon version, with an alloy rear triangle.


On The Trail

YT invited us out to Southern Portugal to test the new Jeffsy. The terrain here offers up a good variety of enduro-style trails, showcasing an assortment of natural features augmented by the handy shovel work of the local community of riders and MTB tour operators. With runs ranging from 5-20 minutes in length and a good mix of shuttling and climbing, we were able to get a good idea of what the changes on the new Jeffsy add up to. All our testing was done on the 29er, as this bike is where YT made the biggest changes for the 2019 update and this is what they wanted us to experience. 

Simply put, we never really felt that there was something this bike couldn’t do, but we also really appreciated just how much fun it was to ride when things were not at their most hectic.

To start things off, we set the bike up according to YT’s recommendations, and right off the bat, we were struck by just how easy it was to get along with the new Jeffsy. We definitely have a soft spot for today’s long-travel enduro bikes and their super slack geos, but there is something to be said for the versatility of a more “modest” 66-degree head angle and big wheels. Simply put, we never really felt that there was something this bike couldn’t do, but we also really appreciated just how much fun it was to ride when things were not at their most hectic. Of course, since we rode the Pro Race version we had the benefit of the ever-capable FOX 36 Factory up front, which adds a certain sense of security to the whole package, but we think the regular 140mm bike should be just about as capable. 

On the way back up the hill, the new Jeffsy’s geo changes became readily apparent. We were able to test the bike both in size L and XL (for a 1m84/6’0” tester), and in both cases the 77-degree seat tube angle left us sitting in a good spot “above the pedals”. The increased amount of anti-squat also seemed to do its job and although it is always hard to judge a bike on trails you’ve never ridden before, the new Jeffsy feels distinctly less sluggish than the old one when things point up the hill.

When things took a rowdier turn, the new Jeffsy impressed us with its poise. The word that we keep coming back to when looking to describe the new bike is “balanced”. It really feels like YT struck a great balance between “enduro light” and “trail”, the result being a bike that is every bit as happy being thrown in at the deep end of an enduro stage as it is racking up the miles on a long XC ride. There is enough pop to make the bike playful and lively, but not to the point of making it harsh over high-speed chatter and on rougher trails.

Build Kit

We rode the top of the line CF Pro Race, which as usual with a direct-sales brand offers up a very impressive kit list that is particularly good value for the price:

The FOX Factory 36 and DPX2 are widely considered to be among the class leaders and this was once again readily apparent when riding the new Jeffsy. Supple, smooth, yet with enough support and progressivity for the rowdiest trails, there is not a lot more we could ask for.

The e*thirteen TRS Race Carbon wheels are stiff and offer great engagement, which adds up to a snappy ride. The e*thirteen tires are very confidence inspiring and provide plenty of traction and cornering grip, but they are also not very fast-rolling. Depending on the type of terrain you ride, you may want to consider switching to something with more rolling speed to really get the most out of the new Jeffsy’s improved pedaling capabilities.

YT has stuck with the e*thirteen cassette mated with a Shimano XTR shifter and derailleur for 2019 (although they have gone with a SRAM Eagle transmission on the CF Pro). With 9-46 teeth it provides as much or more range than competing 12-speed systems and a lower profile and weight. Shifting is smooth and crisp and we had no issues with chain retention during our time on the new bike.

SRAM Guide RSC brakes provide plenty of modulation and more than enough power for most if not all the kind of riding you’d expect to be doing with a trail/all-mountain bike.

Carbon cranks and a carbon Renthal cockpit help keep the weight in check and provide a little extra bling, just as you would expect on the top of the line model.

We’re big fans of the FOX Transfer dropper, and it was its usual smooth and reliable self during this test as well (although we do much prefer to run it with the Race Face remote as opposed to the FOX version). With YT’s “Tailor Made” geometry approach, we had more than enough room in the seat tube for the 150mm version specced here, but many riders will also be able to fit a longer post (on that topic, there may be some news from FOX dropping soon…). 

2019 YT Jeffsy 29 CF Pro Race Spec

For more information on the new Jeffsy and to check out the full range, head on over to

About The Reviewer

Johan Hjord - Age: 45 // Years Riding MTB: 13 // Weight: 190-pounds (86kg) // Height: 6'0" (1.84m)

Johan loves bikes, which strangely doesn’t make him any better at riding them. After many years spent practicing falling off cliffs with his snowboard, he took up mountain biking in 2005. Ever since, he’s mostly been riding bikes with too much suspension travel to cover up his many flaws as a rider. His 190-pound body weight coupled with unique skill for poor line choice and clumsy landings make him an expert on durability - if parts survive Johan, they’re pretty much okay for anybody. Johan rides flat pedals with a riding style that he describes as "none" (when in actuality he rips!). Having found most trail features to be not to his liking, Johan uses much of his spare time building his own. Johan’s other accomplishments include surviving this far and helping keep the Vital Media Machine’s stoke dial firmly on 11.

Photos by Daniel Roos and Johan Hjord

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