Last year's Trail Bike of the Year is back to defend its title

Product Overview

Overall rating:

Score 8

YT Industries Jeffsy 29 CF


YT Industries Jeffsy 29 CF (2018) review


Price as reviewed:

best full suspension mountain bike

Trail Bike of the Year in association with Alpinestars

Twelve months ago, Trail bike of the Year in the 29in category was the YT Jeffsy 29 CF. It’s back again this year to defend its title.

>>> 29in Trail Bike of the Year Winner: Vitus Escarpe 29 VRX

On paper looks every bit as well spcced as its predecessor, but a year is a long time in the bike business and there are plenty of new bikes challenging for that coveted crown.

yt jeffy 29 cf

YT Jeffsy 29 CF review

Price wise the Jeffsy 29 CF is £200 more than anything else in its class, but for the extra dosh you do get a full carbon frame, and that means front triangle, chainstays, seatstays and linkage. It’s nicely finished too and comes with armour at all the pinch points like the down tube, chainstays and BB area. Four sizes are available and to keep the handling balanced across the range YT uses proportional chainstays – small and medium fames get 435mm stays, large and XL bikes have 440mm.


Last year’s bike came with Fox Performance Elite suspension front and rear but this year YT has switched to a RockShox Pike RCT3 suspension fork and Monarch RT3 shock. Front and rear travel is the same at 140mm, but the fork offset is now 51mm, rather than 44mm so the bike is a little longer.

On the rear the Jeffsy 29 CF still has adjustable geometry, which is accessed via a flip chip located on the tip of the seatstay assembly. There are two settings – low/slack or high/steep. You can flip the chip mid-ride but you will need two 5mm Allen keys to do so.

Very few manufacturers bother to fit the bigger 31mm Torque caps to mate with RockShox dropouts. These increase steering precision but the ones on the E13 wheels are loose fitting so constantly fell off when we tried to get the wheel in and out.


YT bucks the SRAM Eagle trend and fits a Shimano shifter and derailleur with E13’s new 11-speed, 9-46t cassette. This has a whopping 511% gearing range so the jump between the upper and lower gears is bigger than on a SRAM Eagle cluster. The overly all gearing is higher though and combined with a 32T chainring up front, the resulting lowest gear is actually harder to push. We’d definitely consider swapping to a 30T if you struggle with fitness on the climbs.

Following the current trend of more drop, YT has fitted a 150mm E13 TRS dropper post to the size L Jeffsy, but unfortunately, we ran into a sizing issue with the longer post. That’s because increasing the drop means there’s more post in the frame but on the Jeffsy the upper link pivot interrupts the seat tube about half way down so it will only go so low. On our large test bike there’s about 25mm lower shaft exposed, which means it’s like riding a 170mm post and at full extension we really struggled to reach the pedals. With infinitely adjustable posts, like the RockShox Reverb, you can just drop it a bit to compensate, but the E13 TRS dropper with three pre-set heights we actually had to drop the post to the second (110mm) position and extend the post in the frame to get the correct saddle height. YT does offer the Jeffsy 29 CF with a 125mm post, which may be the only choice if you’re average height.


Compared to last year’s bike, the new Jeffsy 29 CF is every bit as well dressed and even comes with a few upgrades like a better fork and rear shock. However, the geometry is starting to look a little dated – the bike has the shortest reach, the steepest head angle and the highest bottom bracket height for its travel. It’s still nippy and efficient but the sizing is just too short and the fit is made worse by the lack of infinite adjustment in the dropper post. That’s not particularly the fault of the post, it’s just the two things don’t mesh very well together. The Jeffsy 29 CF has also put on about half a kilo since we tested it last year but that seems to be the case with all bikes that have gone to Boost spacing.

yt jeffsy 29 cf


Even though the Jeffsy 29 CF is £200 cheaper than the bike we tested 12 months ago, it still has an amazing frame and fantastic components for the money. Unfortunately, while the spec has moved on, the ride quality has taken a step back. We felt perched on the Jeffsy 29 CF and it felt nervous and edgy compared to the other three bikes in this test. The issue with the seat post also put the mockers on a lot of our rides because we were constantly worried about it firing back to full height.


Frame:Carbon 140mm travel
Shock:RockShox Monarch RT3
Fork:RockShox Pike RCT3 140mm travel
Wheels:E13 TRS 29 wheelset, E13 TRS 29x2.35in tyres
Drivetrain:Race Face Turbine chainset, Shimano XT r-mech and shifter
Brakes:SRAM Guide RS 200/180mm rotors
Components:Race Face Turbine R ??mm stem, 35mm Turbine R ???mm handlebar, E13 TRS+ dropper post, SDG Fly MTN R saddle
Sizes:S, M, L, XL
Weight:13.75kg (30.3lb)
Size ridden:Large
Head angle (low setting):66.9°
Seat angle (low setting):75°
BB height (low setting):340mm
Front centre:750mm
Top tube:616mm