Tons of fun and will flatter any rider, no matter their ability.

Product Overview

Overall rating:

Score 10

YT Industries Jeffsy CF Pro



  • Amazing ride quality, mind blowing spec.


  • Fork is a little harsh.


YT Industries Jeffsy CF Pro 29 (2017) review


Price as reviewed:

best full suspension mountain bike

Trail Bike of the Year in association with Alpinestars

Just over a year ago the YT Jeffsy 29 was launched and it has been one of the most talked about trail bikes ever since. And for good reason.

The Jeffsy CF Pro 29 tested is costs £3,400, but for that you get a full carbon frame, Race Face carbon handlebar, 150mm RockShox Reverb dropper post, E13 wheels, Fox Elite suspension, Onza tyres, SRAM disc brakes and the icing on what is already an incredible cake, a full SRAM Eagle XO1 12-speed groupset.

We could waffle on about the quality of the spec for most of this test but the Jeffsy is more than the sum of its parts – the frame is a gem too.

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The outline of the Jeffsy looks similar to YT’s enduro bike, the Capra, but it’s much sleeker. YT has saved weight by removing the ISCG mounts on the BB and the brace between the seat tube and the down tube, which also allows YT to shoehorn in a bottle cage and mini water bottle (called a Thirstmaster 3000); a handy addition in our book.

Where the shock mounts to the seat stays, YT has flip chips for adjusting the geometry. There are two settings – low and slack for shredding, or high and steeper for getting up the hills quicker or riding tight trails where you need more ground clearance. The best thing is you can flip the chips trailside with nothing more than a multi-tool.

There are four frame sizes, including an extra large, and they have proportional chainstays. This means the small and medium use 435mm stays, while the large and XL bikes are 5mm longer. Why go to such lengths? Because YT wanted to keep the handling balanced across the entire size range.

yt jeffsy 29

Integrated Flip Chip in the shock mount slackens the angles by ¾ of a degree and lowers the bottom bracket by 8mm


For the Jeffsy CF Pro, YT has selected Fox’s stealth black Performance Elite range – the rear shock is a Float DPS and the suspension fork is a 34 Float. The latter has a shorter 44mm offset, adjustable Fit4 damper and isn’t Boost. Travel is fixed at 140mm front and rear.

yt jeffsy 29

Race Face cockpit is top notch but the 35mm Turbine stem is the older, more flexible design


The specification on the YT Jeffsy CF Comp 1 is truly stunning and there are loads of highlights but one of the things has to be the Race Face Six C 35mm bar. It’s the only handlebar on test that’s 780mm wide and this really makes a massive different to the control and comfort – we wish it’d been fitted to all of the 29er test bikes.


The first thing you noticed about the Jeffsy is its raw acceleration. In fact, it caught us out a few times coming into a particularly steep rocky chute on our Surrey Hills test loop. So we were thankful the bike has a 200mm rotor on the front because there were more than a few occasions were we needed to scrub speed quickly.

yt jeffsy 29

Integrated protectors on the downtube and chainstays ward off carbon damaging rock strikes and chain slap

Away from the steeper trails, the Jeffsy is fast rolling but it’s also extremely playful. Thanks to its poppy, progressive suspension it’s incredibly easy to get off the ground and on trails littered with jumps and berms, it’s like an off-road version of a Ninja Warrior, leaping from one obstacle to the next. It never gets too deep into the travel, but there’s still plenty of cushioning for smashing through rocky terrain.

To put the Jeffsy’s trail centre credentials to the test we spent a couple rides hammering around Swinley forest. Normally, it’s a bit of effort bashing out a loops on the Blue trail, but the Jeffsy was able to breathe a new lease of life into them. The only fly in the ointment was the Fox 34 fork; it just didn’t have the suppleness to deal with the small vibrations you get on typical trail centre singletrack. We couldn’t help feel a RockShox Pike, with it’s greater sensitivity would have been a better fit.

Normally, we just want to get the climbs over with, so we can get to the fun bit quicker, and the Jeffsy allows you to do exactly that. With its upright riding position, supportive suspension and wide range Eagle gearing the Jeffsy is almost as quick uphill as it is on the singletrack.

yt jeffsy 29


If we ignore the specification for moment and just consider the ride quality, the Jeffsy CF Pro is one of the fastest 29er trails bikes we’ve tested. It has a turn of speed that literally takes your breath away. It’s also tons of fun and will flatter any rider, no matter their ability. Just don’t think of it as and Enduro bike, as it can get a bit out of shape on steeper rougher tracks. The flip side being that it’s incredibly agile and with 140mm travel it can still punch its way out of most skirmishes. Mesh this standout ride quality with the parts adoring the Jeffsy CF Pro, and you literally have one of the best pound-for-pound 29er trail bikes on the market today.


Frame:Carbon fibre, 140mm travel
Shock:Fox Float DPS Performance Elite
Fork:Fox 34 Performance Elite, 140mm travel
Wheels:E13 TRS+ wheelset, Onza Ibex 29x2.4in tyres
Drivetrain:SRAM Eagle XO1 chainset, r-mech and shifter
Brakes:SRAM Guide RSC 200/180mm rear
Components:Race Face SIXC 780mm bar Race Face Turbine 60mm stem, RockShox Reverb Stealth 150mm post, SDG Fly Mtn saddle
Sizes:S, M, L, XL
Weight:12.96kg (28.57lb)
Size ridden:Large
Rider height:5ft 11in
Head angle (low setting):66.9°
Seat angle (low setting):74.5°
BB height (low setting):345mm
Front centre:735mm
Top tube:616mm