Issue #029, Review - September 22, 2017

YT JEFFSY AL ONE 27 Review

For a while nobody knew who JEFFSY was. Just when we had accepted ‘he’ was a great 29er, YT went and dropped a 27.5” version and everyone’s heads just exploded. While we would argue that it’s nice to have a choice, can the YT JEFFSY AL ONE 27 live up to the high standard set by the award-winning 29er?

YT JEFFSY AL ONE 27 | 150/150 mm (f/r) | 13.50 kg | € 2,599

For an overview of the test fleet head to the group test: Seven trail bikes around 3.000 € in review

Starting with the spec, even though we have grown used to the impressive buying power of the direct sales brands, at just €2,599 even we were surprised to see a Pike Solo Air RC and RockShox Deluxe RT rear shock. That’s a great start to any build! The good news continues with a SRAM X1 1×11 drivetrain and the ever-reliable SRAM Guide RS brakes, which although noisy in the wet, are trustworthy stoppers. Full points to YT for fitting big 200/180 mm rotors for maximum control – important for a bike this fast. All the finishing kit is high end too: the SDG Fly Mtn seat is superb, as are the Sensus Lite grips. The 60 mm (50 mm on S/M) RaceFace Turbine stem and 770 mm handlebar feel great, in tune with the bike, and the new 35 mm standard provides a dose of stiffness and confidence.

The geometry of the aluminium YT is an exercise in balance: enough reach without being long, slack enough without being lazy. The result is that you can hop onto the 13.5 kg 150/150 mm bike and instantly feel at home. No matter if you are hauling up a steep mountain climb, hooning down a crazy trail, or sending the local jumps, the JEFFSY is ready. The 75° seat angle and V4L Virtual 4-Link rear suspension is very efficient on the climbs, stable and supportive, but when asked, it delivers its travel effectively and the progressive end stroke gives plenty of pop to rack up some air time. The RockShox Pike and Deluxe are a potent package; with some adjustment of bottomless tokens, in no time you are howling with joy as you rally down the hill, the excellent Maxxis High Roller II tires delivering huge grip. The bike is damn near perfect, but not quite.

The DT Swiss M1900 Spline wheelset accelerates well, but the 22.5 mm internal width is a bit narrow for good support at lower pressures, and the mixture of boost rear end and non-boost fork will make replacement more difficult in the future. The e*thirteen TRS dropper is a great post, but the insert depth is longer than most and cannot be fully inserted into the frame. This frustrated some of our hobbit-legged testers who could not size up for increased reach – keep that in mind if you are borderline.

**Helmet** Fox Metah | **Shorts** Alpinestars Vector | **Jersey** Alpinestars Vector LS

The YT JEFFSY AL ONE 27

Fork RockShox Pike RC 150 mm
Rear shock RockShox Deluxe RT 150 mm
Brakes SRAM Guide RS
Drivetrain SRAM X1
Seatpost e*thirteen Dropper Post
Stem Race Face Turbine
Handlebar Race Face Turbine 35
Tires Maxxis Highroller II
Wheelset DT Swiss M100 Spline
Price € 2,599

**Making The Difference**
At this price point, good tyres are everything. YT gets it right by fitting the excellent Maxxis High Roller II 2.4” tyres.

**Short Leg Blues**
The e*thirteen TRS dropper is a great post, simple and effective. However, the long insertion length does not fit fully in the frame, limiting use for shorter riders.

**Neat Integration**
T did not have enough room for a full-sized bottle, so they built their own. Neat and appreciated… but it is an expensive bottle.

The geometry of the YTJEFFSY AL ONE 27

Size	S	M	L	XL
Seat tube	410 mm	450 mm	480 mm	520 mm
Top tube	573 mm	602 mm	625 mm	648 mm
Head angle	66.5 / 67°	66.5 / 67°	66.5 / 67°	66.5 / 67°
Seat angle	75.0 / 75.5°	75.0 / 75.5°	75.0 / 75.5°	75.0 / 75.5°
Chainstays	430 mm	430 mm	430 mm	430 mm
BB Drop	15/9 mm	15/9 mm	15/9 mm	15/9 mm
Wheelbase	1138 mm	1169 mm	1200 mm	1224 mm
Reach	415 mm	440 mm	460 mm	480 mm
Stack	584 mm	597 mm	611 mm	620 mm
Wheelsize	27.5″	27.5″	27.5″	27.5″

The YT JEFFSY AL ONE 27 is more versatile than a Swiss Army knife; good at everything, it has few weaknesses.

Conclusion

The JEFFSY is the definitive trail bike: with fun at its core, it shreds towards the horizon while cheekily flipping the bird to far more expensive bikes. All the bikes in this test are great, but the JEFFSY is fantastic. The YT JEFFSY AL ONE 27 wins this test with ease, but be warned, you will be left with a tough decision: 27.5” or 29”?