If you're in the market for a 29er trail bike the YT Jeffsy 29 CF Comp is where it's at

Product Overview

Overall rating:

Score 9

YT Industries Jeffsy 29 CF Comp


29er Trail Bike of the Year: YT Jeffsy 29 CF Comp


Price as reviewed:

best full suspension mountain bike

Trail Bike of the Year in association with Alpinestars

This year, the YT Jeffsy 29 CF Comp is back with a vengeance, a new frame, new geometry but the same keen pricing and 140mm travel.

>>> Trail Bike of the Year 2019

Two years ago, the YT Jeffsy was our winning 29er bike. Last year, because things had moved on a lot we dropped it down to an 8 rating.

yt jeffsy 29

YT Jeffsy 29 CF Comp review

For £3k you get a carbon front triangle, adjustable geometry, top-quality components and Fox suspension. On paper, it looks way better than the previous model, but can it deliver where it counts?

Before we get to that however, we should point out that we’re testing a size extra-large and this might sound like it’s a big bike, it doesn’t look too big or ride that way. Yes, it has the longest reach in test but in every other aspect it’s similar to the other bikes.

yt jeffsy 29

Cable routed neatly through gusseted head tube junction


For 2019, YT has switched to Fox 34 Float Performance Elite suspension fork on the Jeffsy CF Comp, which is basically a Factory fork but without the Kashima coating. It feels great over small bumps and deals easily with big G-outs, but the 34 is not as stiff as the 36 fitted elsewhere.

The Jeffsy CF Comp has 140mm travel at both end and rear suspension ramps up quite a lot, which means it pedals great and there’s plenty of pop when hitting jumps, but you do feel a little short changed on square-edge hit compared to the Scott Genius and Commencal Meta TR 29.

yt jeffsy 29

150mm-travel E13 TRS dropper post with three pre-set heights


Once again YT flips Eagle the bird, fitted instead an E13’s 11-speed, 9-46t cassette. And while there’s a bigger jump between the upper and lower gears than with a SRAM 12-speed cassette, there are less options in between. Running a 32T chainring means the lowest gear on the Jeffsy is actually hard to push on the steepest climbs, and we’d definitely consider going down to a 30t ring.

Also making a return appearance is the 150mm E13 TRS dropper post. We still have a little bit of a sizing issue with this set up because it has a deep collar, so it’s like riding a 170mm post in terms of overall height. And with three pre-set heights, you can’t just drop it 10mm, you have to drop it 50mm to its second position.

yt jeffsy 29

Bigger Thirstmaster 4000 water bottle with a magnetic attachment – locates quickly and is held securely. Fox DPS Performance Elite shock with 140mm of progressive travel


A stiff frame, really progressive suspension and the lowest weight of any bike in test results in one outcome – the Jeffsy leaves the others for dead on the climbs. It instantly gets a half wheel ahead because there’s no need to reach down to flick the Pro Pedal lever on, and all you need are a couple of quick cranks and the YT is off in the distance.

On the downhills the YT doesn’t quite feel as planted as the Commencal but with a massive 494mm reach measurement you are really centred on this bike, and never feel like you’re going to get pitched over the bars or have to get your arse right back over the rear wheel on steep stuff.

Once we changed the tyres the Jeffsy held a good line on loamy and groomed trails, but on wet roots the back end does step out suddenly. So it lack the ride feel of the Scott Genius and to an extent the Commencal, so you do have to make more corrections to line choice in lumpy terrain. How much of at is due to the shock tune or frame stiffness is hard to say, but it’s a compromise were happy with, given how well the Jeffsy pedals.

We initially ran the stock 60mm stem on our XL test bike but switched to a 35mm mid test. The steering felt more direct with the stubby stem, but there were testers that preferred the longer stem. An in between size would be a good compromise and we’d like to see this, and other upgrades, offered on the YT website, that way we swap parts at source. For example, there’s only a £100 difference in the retail price between the Fox 34 and 36 Performance Elite forks, so if we could upgrade we’d definitely tick that box.

yt jeffsy 29

Two-position flip chip takes half a degree off the head angle and 8mm off the bottom bracket height in the low setting


Every year we’ve tested the YT Jeffsy, we’ve said that you do get a ton of bike for your money. And that’s truer than ever. The Commencal and Vitus both have similar builds, but as a trail bike the new Jeffsy is a more balanced package and is that much lighter too. There are a couple of things we’d don’t like – the fixed position seatpost, clunky shifting and fork flex – but the Jeffsy is our 29er Trail Bike of the Year because it’s the most versatile bike here. It’s light enough to ride all day, but you and still smash the descents in a bike park.


Frame:Jeffsy carbon/aluminium, 140mm travel
Shock:Fox DPS Performance Elite
Fork:Fox 34 Float Performance Elite, 140mm travel
Wheels:E13 TRS wheelset, E13 TRS Plus 29x2.35in tyres
Drivetrain:E13 TRS 32t chainset, Shimano XT r mech and shifter
Brakes:SRAM Guide RS 200/180mm rotors
Components:Renthal Fatbar 800mm, Renthal Apex 50mm stem, E13 TRS+ 150mm post, SDG Fly MTN R saddle
Sizes:S, M, L, XL, XXL
Weight:13.82kg (30.47lb)
Size ridden:XL
Head angle (low setting):66.3°
Seat angle (low setting):70.7°
BB height (low setting):335mm
Front centre:810mm
Top tube:637mm