YT Jeffsy 29 Core 3 review

The YT Jeffsy 29 is positioned as a lighter-weight, shorter-travel cousin to the ever-popular YT Capra and marketed as “your best friend” for enjoying both the ups and the downs.

It's an all-round package with solid spec from a brand famous for offering value for money.

YT Jeffsy 29 Core 3 frame and suspension

Formed in that now-synonymous YT Industries shape, apart from the entry-level Core 2 Jeffsy, all other models are sculpted in carbon fibre throughout.

The sinuous carbon lines integrate fully internal cable routing and are protected by a replaceable rubber down-tube guard, as well those for chain slap or suck on the rear stays.

Double-sealed bearings are intended to keep out the worst of the grime, and an easy-to-rotate flip chip in the lower shock mount affords some geometry adjustability.

With space in the front triangle tight, and the ability to carry a water bottle now a deal-breaker for many, YT has come up with its own short but stout Thirstmaster 4000 600ml bottle, that as an optional extra can be snapped into place beneath the shock with the elegant Fidlock system.

At the rear, there’s 150mm of travel, which is matched by the fork up-front.

It’s modulated through YT’s Virtual Four Link (V4L) suspension platform, promising all the usual buzz words of sensitivity, mid-stroke support and progression.

YT Jeffsy 29 Core 3 geometry

With five frame sizes on offer, most should be able to find a Jeffsy that fits.

At a fraction shy of the 6ft mark, I opted for the large, which measures up to a middle-of-the-road 470mm in the reach.

Chainstays are a compact 435mm, but these grow to 440mm on the XL and XXL sizes.

Low standover heights throughout make it easy for riders to up-size should they choose to.

The ability to rail turns is ensured by a bottom bracket that’s dropped 32mm below the axles, although with the flip chip this can be raised to -24mm.

Given the bike’s genetics, the adjustable 66/66.5-degree head angle stands out for being on the steeper side.

YT Jeffsy 29 Core 3 specifications

The Jeffsy Core 3 is one of those bikes that leaves little need for upgrades, save for the tyres, which I found hard and unforgiving in the Maxxis Dual Compound rubber.

The GRIP2-damper equipped Fox Float 36 Performance Elite fork provided supple but well-controlled suspension action, as did the Float DPX2 shock its paired with.

The wide gear range of the SRAM GX Eagle drivetrain was a welcome help on the hills and shifting was near-flawless throughout the 12 months I had the bike.

Equally impressive were the DT Swiss M1900 Spline wheels, which needed next to no attention with the spoke key, despite some wayward impacts.

YT’s own-brand Postman dropper post proved reliable and pain-free to change cables, but longer drops for each size of bike would make it better in my opinion.

YT Jeffsy 29 Core 3 ride impressions

With the luxury of this being my test bike for BikeRadar's sister magazine Mountain Biking UK over the last year, I’ve had the opportunity to subject the Jeffsy Core 3 to a whole host of different riding styles and conditions.

On the whole, it performed admirably, even during unwise forays into the big jump lines of the Welsh bike parks.

Its shortfalls amount to a little more than desired pedal-bob from the rear end and a head angle that cries out to be a degree or so slacker.

YT Jeffsy 29 Core 3 climbing performance

On mid-travel trail bikes such as this, climbing performance is paramount in order for longer stints in the saddle to not feel like a chore.

On the whole, the Jeffsy eats up the miles with ease, the 77 / 77.5-degree effective seat tube angle situating you nicely over the bottom bracket on most gradients.

There’s ample traction from the Maxxis Minion DHR II tyres for getting power down on loose or muddy ground, and the harder-compound rubber – while not the best for descending – avoids that all too familiar sluggishness inherent with a lot of harder-hitting trail bikes and enduro bikes.

Where it does feel as though you’re putting in more watts than desired is during hard efforts out of the saddle.

The trade-off for the Jeffsy’s highly active V4L suspension seems to be some quite noticeable squatting under power, a trait that made me flick the Fox DPX2’s 3-postion lever to ‘firm’ for nearly all big climbs.

Fortunately, the shock’s climb lever made this an option, though, and combined with a ‘medium’ mode, it’s easy to choose a setting for undulating ascents as well as prolonged lung-busting grinds.

Speaking of undulating trails, I’d have welcomed a longer-drop seatpost than the 150mm-travel YT Postman specced on my bike, especially as the seat tube has the internal clearance for something over the 200mm mark.

And on the subject of sitting down, the SDG Belair 3.0 saddle is worth a mention for being supremely comfortable (in my opinion at least), offering an optimum balance of flex and support.

YT Jeffsy 29 Core 3 descending performance

The Jeffsy 29 Core 3 is a bike that you’d be hard-pressed to have a bad time on.

Jumping onboard, it feels as if everything is where it should be, and the low bottom bracket positions you reassuringly ‘in’ the bike, so the confidence to throw it into a turn is there from the outset.

Of the two geometry positions offered by the flip chip, I ran the bike in the low setting almost 100 per cent of the time, and while this felt great in terms of centre of gravity, it still left me wanting a slacker head angle.

While 66 degrees isn’t outrageously steep, on a bike that’s kitted out for attacking rough terrain and urges you to lay off the brakes when veering into faster or steeper ground, I wished I had the reassuring stability of my front wheel further out in front.

This does, of course, only become a factor at the more extreme end of the bike’s remit. For general all-mountain stuff, trail centres and the like, the nimble movement afforded by the compact geometry makes this a quick-handling 29er for slower-speed techy business.

I certainly had no complaints about the suspension either, which feels generous for 150mm.

It’s sensitive off the top and then ramps up through its stroke to handle some pretty sizeable hits.

The Fox dampers do a good job of controlling this, and the independent high- and low-speed adjusters on the fork came in useful for increasing the fork’s support and preventing it from diving away to further steepen the head angle.

When it comes to grip, I’m a long-standing fan of the Maxxis Minion DHR II tread pattern, both front and back, but on the Jeffsy, the harder Dual-Compound rubber, in contrast to the 3C durometers I’m used to, felt a little unpredictable on the front wheel, glancing off obstacles rather than conforming and gripping.

It’s a good choice at the back for durability and rolling speed, but a softer-compound front tyre would be a welcome change.

Also put to the test in descending were the SRAM G2 R brakes, which have reliable modulation and bite point, and ample power for most trail situations, but can feel under-gunned on prolonged gravity attacks.

As someone who’s fairly light in stature, it’s almost certain that heavier riders would notice this more.

YT Jeffsy 29 Core 3 bottom line

As a general trail riding go-to, the Jeffsy is an excellent bike.

Although the tyres may be a little hard and the seatpost travel a little short in general, the build kit is bang-on.

It’s a bike that’s more solidly positioned in the trail/all-mountain category though, rather than leaning towards enduro trends. Riders from a gravity-focused background will likely pick up on my feelings about the slightly conservative head angle.

Having said that, if you’re looking for a dependable all-day ripper that’ll eat up nearly everything you can throw at it, you won't go far wrong with the Jeffsy 29 Core 3.