Starting at $2,799, Updated Geo and Travel - YT Jeffsy First Ride 1

When YT launched the original Jeffsy in 2016, it made waves as one of the first 29ers that was designed to be fun to ride. YT has always taken pride in their “gravity DNA”, and they made sure that their first wagon-wheeler would not come up short of chops when the trail pointed down the hill. If you were around at the time, you probably remember the “I Hate Jeffsy” campaign, which also introduced the “your best friend” concept that has defined the Jeffsy ever since. Today, YT is launching the third generation of the Jeffsy, and we’re here to tell you all about it – keep reading to learn more and to get our first riding impressions straight from the wet and wonderful trails of England and Wales. But before you do, check out the new “Power of Friendship” campaign video just below:

YT Jeffsy MKIII Highlights

• 29-inch wheels
• Travel: 145(R) / 150(F)
• Carbon and alloy versions available
• Seat tube angle gets progressively steeper on bigger frame sizes
• Longer chainstays on XL/XXL
• Downtube storage “YT STASH” (carbon frame only)
• Shock mount flip chip for geometry adjustment
• YT Postman V2 dropper post (adjustable, travel from 125 – 230 mm)
• PF92 BB
• Fully guided cable routing on carbon models
• MSRP: from $2799 to $6499 USD

Initial Impressions

What should an all-mountain or trail bike be? It’s easy to fall into the trap of always wanting more, and we’ve often seen manufacturers gradually increase the travel of the various models in their range to the point that even the shorter travel bikes invariably turn into “mini-enduros”. This kinda defies the point of having different categories in the first place though, which is why we were pleasantly surprised to see that YT has in fact reduced the rear travel of the new Jeffsy, and paid as much attention to improving the climbing experience as to the downhill capabilities.

YT used several geometry tricks to arrive at their stated goal of “trail excellence”. While tightening up the handling of the bike thanks to the reduction in rear travel, they also slackened the head angle out to an even 65 degrees (in the low setting). For reference, that’s only one degree steeper than the current generation of the Capra, YT’s big-hitting enduro bike. To make the bike easier to live with on the climbs, the seat tube sits at an effective angle of 77.2 degrees (at average seat height) for ALL FRAME SIZES. This meant giving the larger frame sizes a steeper actual seat tube, so that the saddle would end up in the correct position even with a taller seat post. The new Jeffsy also gets longer chainstays for frame sizes XL and XXL to help preserve the front-to-rear balance of the bike. The reach numbers range from 435 to 515 mm, ensuring that pretty much everybody should have a shot and finding a good fit.

In terms of kinematics, YT settled on 105% of anti-squat at 30% sag, which then decreases rapidly as the suspension compresses to prevent pedal kickback deeper into the travel. The overall leverage ratio curve is quite progressive, as you would expect from YT, and it’s been given a little bit of extra end-stroke progression as well compared to the outgoing model.

Digging into the frame details, YT has left no stone unturned. The new Jeffsy marks the first time that YT has developed an in-frame storage solution, and they’ve done a good job with it (note: the alloy version has to do without the in-frame storage). The storage compartment is large, and will easily hold tools, spares, and a small pump inside a pair of water-resistant neoprene pouches (the new frame-mounted Crankbrothers TS2 Tube Stash, which features an integrated tire lever and tubeless plugs as well as a strap to hold a spare tube, is also included with the Core 4 and Core 5 builds, which is pretty rad).

The cover of the storage compartment is water-resistant, and sits away from the water bottle mount on the downtube. Separation walls on either end of the compartment ensure that your stash doesn’t end up lost inside the frame somewhere, and the cable guide tubes have been bonded to the downtube walls to make sure nothing gets tangled up either. There is also an extra accessory mount under the top tube if you really have a lot of stuff to carry on your bike, and the magnetic rear axle lever pops out to reveal a sturdy 6mm hex key as well.

To keep the bike quiet and safe, YT also revised some of the frame protection pieces. There’s a large skid pad under the BB area, which features an extra sound-deadening foam layer. The pad bolts onto the frame and can thus easily be replaced if worn or damaged. The chain stay protector has also been beefed up, and is equipped the obligatory ridged waffle pattern to help minimize chain slap noises.

Build Kits and Pricing

The new Jeffsy will be available in five different build levels, ranging from $2799 to $6499 USD. The two top-tier models feature SRAM’s new T-Type Transmission drivetrains, while the other three make do with the good old cable-actuated versions. Fox and RockShox handle suspension duties depending on the model, with Crankbrothers, DT Swiss, and SunRinglé supplying wheels (shod with a Maxxis DHF/DHR combo in MaxxTerra EXO+ throughout the range). All the bikes come equipped with the 2nd generation of YT’s own Postman dropper, which now sports an updated head design and a new, adjustable lever. The droppers are also longer now across all frame sizes compared to the outgoing Jeffsy models.

On The Trail

YT invited us out to not-so-sunny Southern England to test the new bike in person before today’s launch. We even got to meet the real-life Jeffsy, a Forest of Dean legend known to all as the most helpful and friendly guy around – the perfect namesake for a bike that wants to be your best friend. The weather turned out to be decidedly less friendly on this occasion, but in the UK this is par for the course so we battened down the hatches and got on with it regardless. The first day had us sample some of the Forest of Dean goods, with a fair amount of climbing and some quite slippery trails on the menu. We immediately noticed that the new Jeffsy is a great climber, putting you in pretty much the perfect position over the pedals to grunt out the miles. Pedaling response is excellent and the bike feels very lively when gaining altitude.

One thing that sets a good all-mountain or trail bike apart from a pure enduro bike is the ability to carry speed over undulating terrain. This is one area where the changes made to the new Jeffsy really paid off, as the bike is quick to pick up the pace and loves nothing more than pumping and popping around to make the most of the more mellow sections of trail. Without being able to ride the two bikes back-to-back we don’t want to get carried away here, but it did seem to us that the new version feels significantly more alive than the outgoing model could sometimes do.

When things got more serious, the new Jeffsy showed us that it is more than ready to take on heavier terrain as well. Despite sporting a few millimeters less travel in the rear, the bike makes good use of what’s available and never felt overwhelmed despite us ending up in some hairy situations on the new-to-us trails now and then (our second day of riding had us head down to Cwm Carn in Wales, to take on some more serious elevation and steeper, rougher tracks). The slacker head angle really helps give the bike a more confident feel, further underlining the “this-bike-is-your-best-friend” theme behind the design choices.

Build Kit

We rode the top-of-the-line Core 5 model, which comes equipped with high-end parts and retails for $6499 USD (EUR 5999 in Europe). Here are a few observations on the kit list:

Suspension

FOX Factory 36 fork and Factory Float X shock is a great combo, which we had no trouble finding a good set-up with. In light of the nasty conditions, we ran slightly lower pressures than usual which provided us with the comfort and grip needed to deal with the more slippery surfaces.

Transmission

Shifting on the Core 5 is handled by SRAM’s new wireless T-Type Transmission, which we’ve had a lot of good things to say about in previous testing already, whether in GX or as featured here, XO trim. Crisp shifts under power and easy operation sets this one apart from its mechanical predecessors, and it performed flawlessly during our two days of riding here.

Brakes

SRAM’s Code RSC is a solid choice when it comes to slowing down. The RSC lever provides a more refined lever feel compared to the regular R version, and it has proven itself capable in any riding setting over the years by now.

Dropper Post

YT has updated their in-house Postman dropper to V2, and it looks like they’ve made some good changes here. The post’s head is more refined and should perform better over time according to YT, and the travel of the post can be adjusted with shims. The lever is also now more sophisticated, offering more adjustability. We found this new lever to be a marked improvement over the old one on the trail.

Wheels and Tires

The Crankbrothers Synthesis wheels feature different rims and builds in the front and the rear, to provide more compliance up front and more strength and stiffness out back. We’ve had good experiences with these wheels before, and they performed as expected on this bike as well. The Maxxis DHF/DHR II combo is tried and trusted, and the updated EXO+ casing has proven itself more resistant to pinch-flatting making it a great choice for a bike in this category.

Finishing Kit

A Renthal alloy cockpit equipped with ODI grips is ready for anything you might throw at it (note: we swapped the grips for this tester’s favorites, which is something we often do when testing a bike to eliminate a few more variables from the equation). A nice touch: the Core 4 & 5 models come with the Crankbrothers S.O.S. TS2 Tube Stash included, which features an integrated tire lever and tubeless plugs as well as a strap to hold a spare tube.

What’s The Bottom Line?

A bike is defined by its character, and designing a bike is about how the geo and the parts involved add up to a certain riding experience. The all-mountain category is perhaps the most difficult category of them all to design a bike for, because it involves so many potential trade-offs. YT went about the redesign of the Jeffsy with intent, and they have delivered what amounts to a really strong contender in our opinion. By reducing the rear travel slightly and reshaping the anti-squat curve, they’ve made the bike easier to climb and better at carrying speed over undulating terrain. At the same time, they made the head angle slacker to make sure the bike remains calm and confidence-inspiring in the rough stuff. Other highlights include size-specific seat tube angle and chain stay length, and the frame has also gained a very usable in-frame storage compartment to really keep up with the Joneses. Your new best friend? Could well be!

For more information head on over to www.yt-industries.com.

View key specs, compare bikes, and rate the new YT Jeffsy in the Vital MTB Product Guide.

About The Reviewer

Johan Hjord - Age: 50 // Years Riding MTB: 18 // Weight: 190-pounds (87-kg) // 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 200-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 Johan Hjord and Jacob Gibbins/YT