YT’s 29er Jeffsy won BikeRadar’s Trail Bike of the Year contest in 2018, and so it’s 2019 revamp was eagerly awaited. It’ll not take a genius to guess at some of the new bike’s facelifted details - yes, it’s longer, slacker, lower and steeper in all the right places. But has it retained its characterful ride? Read on to find out.
- YT have updated the award winning Jeffsy for 2019
- Shimano's new XTR groupset is refined in every detail
- We've designed the mountain bike of the future
The YT Jeffsy CF Pro Race Frame
This new generation of Jeffsy comes with a carbon only frameset (alloy will follow at a later date), and being the Pro Race, the bike I rode had 150mm travel front and rear, controlled by a 4-bar linkage.
Geometry has been updated, following the rest of the trail bike pack with more aggressive, contemporary figures. The size Large I rode has a reach of 470mm, up from the very short 445 of the previous generation. The head angle has lost a degree of steepness, dropping to 66 degrees, while the seat tube is right up there at 77 degrees. YT has realised that more and more people are sizing up or down on their frame sizes, depending on size preferences, and so the seat tube on the Large is a relatively short 435mm, allowing the use of longer droppers, or riders to easily size up on frames.
Lowering the whole of the bike has compressed the front triangle a touch, however, YT still manages to fit a 600ml bottle in all frame sizes, though you’ll have to use their own bottle and Fitlock carriage system. This lowering is the result of the shorter seat tubes, and the re-working of the suspension’s kinematic, which also now gets metric length shocks. The suspension remains nicely progressive through its stroke, but now has around 30% increased anti-squat figures.
YT’s mechanics asked the team to develop linkage pivots that were all accessible from one side of the bike (save for the Horst-link driveside chainstay pivot, for obvious reasons) on the new Tues DH bike, and the latest Jefsy gets this too - in theory, you should be able to strip the bike down from one side of a workstand. There’s also neat cable routing, with the housing only clamped in one place.
The YT Jeffsy CF Pro Race's Kit
As the top of the line model, the kit on the Pro Race is pretty swish. Suspension is provided by Fox, with a 150mm 36 Grip2 fork up front and a DPX2 Factory rear shock. Fox also supply the Transfer Factory dropper post.
YT has a strong relationship with E13, and on this build they provide the TRS Race carbon wheelset and TRS Race (f) and TRS Plus (r) tyres in 2.35” width. E13 is also present in the drivetrain - their TRS Race cranks drive the chain over the 11 speed TRS Plus 9-46t cassette, and it’s all protected by a TRS Race SL chainguide. Shimano take the honours for the mech, chain and shifter, all M9000 XTR level.
Renthal provide the 50mm stem and 800mm Fatbar Carbon bars, ODI the grips, SDG the saddle and SRAM the Guide RSC brakes with 200/180mm rotors.
Our initial ride impressions
Simply put, the previous generation Jeffsy won Trail Bike of the Year because it was the most fun bike in the entire test. It was the bike that, whenever there was time for an extra run, was immediately picked up by the whole test team.
Technically speaking, it wasn’t the best bike there though. It didn’t climb with panache, it was short and relatively steep, and the seat tube was long, meaning sizing up wasn’t much of an option.
YT has addressed a lot of these issues though with the latest generation bike, and it shows on the trail.
Concerning suspension, the Jeffsy was always progressive, with the progression coming through nicely during its stroke giving a poppy, fun ride. However, the anti-squat figures were quite low, and so on the climbs the bike felt sluggish and slow, especially when combined with the slack seat angle and the draggy tyres.
This latest bike has a much peppier feel though, thanks to increased anti-squat figures and steeper set angle. While it’ll never win any XC races, it feels faster and more nimble when the trails climb, even with those same draggy tyres.
This increase in taughtness through the drivetrain also helped on the flatter trails I rode, with the bike maintaining momentum easier, and feeling more eager to accelerate out of turns. There’s still a fair bit of pop available, thanks to the progressive suspension, but with a longer bike, it’s not quite as playful as the previous generation, I feel.
As you’d expect though, the main benefits of that length come the steeper the trail gets. While the sticky tyres and low BB gave the original bike descending confidence, it wasn’t the most suited to loose, flat out trails, or carving gnarly corners. This has changed though now.
The head angle isn’t radical, but combined with the reach there’s plenty of bike out in front of you, so you can push the bike into corners, and trust the front wheel to do its thing. The composure from the Fox 36, with its latest generation GRIP2 damper is sublime too, whether on small or large hits, through tight rock gardens or railing berms - it’ll take a lot to really start to rattle this bike.
It’s not all song and games though - if I’m honest, I wish YT would stick with a single flavour drivetrain - the mix and match Shimano/E13 doesn’t have the smoothness of feeling that a bike like this deserves - there’s creaking, and small derailments when back-pedalled, and the shifting across the block isn’t quite as good as it could be.
Overall the new Jeffsy is an improvement on the old one - technically. The suspension still has that progressive composure, but now climbs better than it did, and this is all backed up by improved tube lengths and angles. I can’t help but think though that this additional competency and capability has stolen a touch of its fun-loving character.
I’ve only ridden the bike for two days, though I repeated trails a number of times which helps get a feel for the bike. I currently have a Jeffsy CF Pro on test for our Bike of the Year 2019 test, so I am getting to know the bike a whole lot better as we speak. Look out for a full review as the BOTY 2019 tests appear on BikeRadar in March.