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 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.