YT Jeffsy CF Pro 27 first ride review

Thoroughly capable trail ripper

GBP £3,399.00 RRP | AUD $5,999.00 | USD $4,799.00
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Following on from its successful first foray into the world of big-wheeled trail bikes with the Jeffsy 29, YT has decided to expand its offering and deliver the same bike with smaller 650b wheels.


YT Jeffsy CF Pro 27 spec overview

  • Frame: Carbon fibre, 150mm (5.9in) travel
  • Fork: Fox 34 Float FIT4 Performance Elite, 150mm travel
  • Shock: Fox DPS Performance Elite
  • Drivetrain: SRAM X01 Eagle (1×12)
  • Wheelset: e*thirteen TRS+ wheels
  • Tyres: Maxxis High Roller II 3C MaxxPro EXO 27.5×2.4in
  • Brakes: SRAM Guide RSC, 200mm/180mm rotors
  • Bar: RaceFace SIXc 35, 780mm
  • Stem: RaceFace Turbine, 60mm
  • Seatpost: RaceFace Turbine 125mm dropper
  • Saddle: SDG Fly MTN
  • Weight: 13.05kg (28.7lb), large size without pedals

YT Jeffsy CF Pro 27 frame and kit

On the surface at least, there’s little that’s obviously different between this bike and the 29er version. But look closely at the geometry chart and you’ll spot a mixture of subtle and more significant changes.

For starters, the head angle is slacker, at 66.5 degrees in the low setting (a flip chip in the rear shock mount lets you switch between the high and low settings), and the chainstays are a touch shorter, at 430mm. The Jeffsy 27 also has a steeper 75-degree seat angle.

The Jeffsy 27 looks a lot like its bigger-wheeled sibling but offers a bit more reach
The Jeffsy 27 looks a lot like its bigger-wheeled brother but offers a bit more reach
Russell Burton / Immediate Media

Possibly the biggest difference, though, is the reach. The Large frame is 15mm longer from bottom bracket to head tube (horizontally) than its bigger-wheeled equivalent. It also has a healthy 15mm of bottom-bracket drop, which sits you deep into the bike.

Unlike its 29er counterpart, the Jeffsy 27 gets Boost rear-axle spacing (although not a Boost fork) and uses a metric-sized shock to deliver its 150mm of rear-wheel travel.

The BB92 press-fit bottom bracket will be more of a faff to work on than an external one, but I’m a big fan of the external hose routing for the rear brake, which makes maintenance that bit easier.

YT makes its own bottle and cage to fit the Jeffsy, though it’s sold separately. There’s even provision for a front mech, in case you’re adamantly against single rings.

Considering the price, the CF Pro 27 packs a lot in. Highlights include the SRAM X01 Eagle 1×12 transmission, with its massive 500 percent gear range, and e*thirteen’s sprightly TRS+ wheels.

Be careful when adjusting the height of the RaceFace dropper post in the frame though, because its cable tension seems to be easily upset, resulting in a potentially droopy post.

YT Jeffsy CF Pro 27 ride impressions

In terms of shape and purpose, the Jeffsy 27 feels very similar to its bigger-wheeled sibling, though a touch roomier when out of the saddle and flinging it about.

It’s a little more stretched out in the top tube too, which is a plus when hitting the climbs. That, coupled with the steep-ish seat angle and the lockout on the shock, means it’ll be your legs and lungs holding you back on the uphills, not the bike.

The suspension balance is good too, and, paired with the confident geometry, this makes it a seriously fun and incredibly agile trail machine that’s happy to be flicked in and out of turns, hammered along the singletrack or lofted over jumps, where it was progressive enough to deal with some seriously heavy landings.

It’s happy to take a beating too, although it can start to feel unsettled when the trail gets burly and churned up. But if that’s your thing, the longer-travel Capra may be what you’re after.

Instead, the Jeffsy 27 offers some impressive all-round credentials and is as happy being razzed about in your local woods as it is clocking up the trail miles, though the bigger-wheeled version does feel like it carries speed a touch better.


YT Jeffsy CF Pro 27 early verdict

Seriously fun trail bike that’s as happy pounding trail miles as it is sessioning turns in the woods.

Product Specifications


Name Jeffsy CF Pro 27
Brand YT Industries

Available Sizes S M L XL
Shifters SRAM X01 Eagle
Wheelbase (in) 47.24
Top Tube (in) 24.61
Standover Height (in) 29.61
Seat Tube (in) 18.9
Chainstays (in) 17.13
Wheelset e*thirteen TRS+ wheels
Weight (kg) 13.05
Stem Race Face Turbine, 60mm
Seatpost Race Face Turbine 125mm dropper
Brakes SRAM Guide RSC, 200mm/180mm rotors
Seat Angle 75
Saddle SDG Fly MTN
Rear Derailleur SRAM X01 Eagle
Head Angle 66.5
Handlebar Race Face SIXc 35, 780mm
Frame Material Carbon fibre
Fork Offset 4.2
Fork Fox 34 Float FIT4 Performance Elite
Cranks SRAM X01 Eagle
Frame size tested L