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YT Jeffsy 29 Core 3 review

A versatile all-rounder from one of the original direct-sale brands

Our rating 
4.0 out of 5 star rating 4.0
GBP £3,749.00 RRP | USD $4,199.00 | EUR €4,199.00 | AUD $6,799.00
+ £19.90 bike box + £100 shipping + £85.50 import fees
Pack shot of the YT Jeffsy 29 Core 3 full suspension mountain bike

Our review

An excellent complete package that makes fun of all but the gnarliest descents, thanks to a head angle that feels too steep
Pros: Predictable ride quality; a solid suite of parts; great for riding just about any terrain
Cons: Conservative head angle; a good price, but the outrageous value YT’s reputation was built on isn’t there
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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.

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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

The DPX2 shock has plenty of external adjustments.
Steve Behr / Immediate Media

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.

There’s just enough space for YT’s own water bottle beneath the rear shock.
Steve Behr / Immediate Media

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

Even with a geometry flip chip, the head angle could have been a bit slacker.
Steve Behr / Immediate Media

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.

Seat angle (degrees)77 / 77.577 / 77.577 / 77.577 / 77.577 / 77.5
Head angle (degrees)66 / 66.566 / 66.566 / 66.566 / 66.566 / 66.5
Chainstay (mm)435435435440440
Seat tube (mm)400415435460485
Top tube (mm)572593615638660
Head tube (mm)100105110120125
Bottom bracket drop (mm)32 / 24 32 / 24 32 / 24 32 / 24 32 / 24
Bottom bracket height (mm)344 / 352 344 / 352 344 / 352 344 / 352 344 / 352
Wheelbase (mm)1,1741,1961,2181,2471,269
Standover (mm)706702701693694
Stack (mm)618622627636640
Reach (mm)430450470490510

YT Jeffsy 29 Core 3 specifications

SRAM’s GX Eagle drivetrain is genuinely hard to fault.
Steve Behr / Immediate Media

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.

Fox’s 36 fork has proven to be a great performer.
Steve Behr / Immediate Media

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.

It rolls on DT Swiss wheels, adding to the fully branded finishing kit.
Steve Behr / Immediate Media

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

It was a true jack of all trades, at home pedalling and jumping.
Steve Behr / Immediate Media

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

It hooked turns, but would benefit from a slacker head tube angle.
Steve Behr / Immediate Media

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.

The dual-compound Maxxis rubber is great for reducing rolling resistance, but less capable when conditions deteriorate.
Steve Behr / Immediate Media

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.

YT’s suspension kinematics are renowned for their progressive nature.
Steve Behr / Immediate Media

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.

The YT-branded Postman dropper was reliable.
Steve Behr / Immediate Media

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

For a 150mm-travel bike, it loved to get sent.
Andy Lloyd / Immediate Media

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.

The Jeffsy was great fun to blast about on.
Andy Lloyd / Immediate Media

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.

There were no problems getting airborn on the Jeffsy.
Steve Behr / Immediate Media

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

The Core 3 comes at a good price, but doesn’t quite represent the value YT bikes are usually known for.
Steve Behr / Immediate Media

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.

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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.

Product Specifications


Price br_price, 5, 3, Price, AUD $6799.00EUR €4199.00GBP £3749.00USD $4199.00
Weight br_weight, 5, 6, Weight, 14.68kg (L) – without pedals, Array, kg
Brand br_brand, 5, 10, Brand, Yt industries


Available sizes br_availableSizes, 11, 0, Available sizes, S, M, L, XL, XXL
Brakes br_brakes, 11, 0, Brakes, SRAM G2 R, 200mm rotors
Cassette br_cassette, 11, 0, Cassette, SRAM XG-1275, 10-52t
Cranks br_cranks, 11, 0, Cranks, SRAM Descendant, 32t
Fork br_fork, 11, 0, Fork, Fox 36 Float Performance Elite, 150mm (6in) travel
Frame br_frame, 11, 0, Frame, Carbon fibre, 150mm (6in) travel
Grips/Tape br_gripsTape, 11, 0, Grips/Tape, ODI Elite Motion V2.1
Handlebar br_handlebar, 11, 0, Handlebar, E13 Plus 35, 780mm
Headset br_headset, 11, 0, Headset, Cane Creek 40
Rear derailleur br_rearDerailleur, 11, 0, Rear derailleur, SRAM GX Eagle
Rear Shocks br_rearShock, 11, 0, Rear Shocks, Fox Float DPX2 Performance Elite
Saddle br_saddle, 11, 0, Saddle, SDG Belair 3.0
Seatpost br_seatpost, 11, 0, Seatpost, YT Postman MMX remote (dropper)
Shifter br_shifter, 11, 0, Shifter, SRAM GX Eagle
Stem br_stem, 11, 0, Stem, E13 Plus 35, 50mm
Tyres br_tyres, 11, 0, Tyres, Maxxis DHR II EXO TR Dual Compound 29x2.4in
Wheels br_wheels, 11, 0, Wheels, DT Swiss M1900 Spline