Review: YT Jeffsy CF Pro

YT Industries are best known for their freeride legends Cam Zink and Andreu Lacondeguy, and also have top downhill racer, Aaron Gwin on their books. The launch of the mini-downhill Capra enduro bike made waves with its excellent performance paired with a great value offering. A mid-travel 29er trail bike might not fit YT’s image but it makes complete sense for them to approach this huge market. In reality, most people simply can’t or don’t want to ride like Lacondeguy or Gwinn.

YT Industries did a great job with their somewhat strange “

” advertising campaign leading up to the announcement of the bike. The campaign set the internet abuzz, discussing what the final form of Jeffsy might be. My guess was a trail bike but I had expected to see it fitted with a 27.5 wheel size. Going 29er might be seen as a bold move but it’s something we’re seeing more and more of.

The frame

The Jeffsy is a 140mm trail bike designed around 29-inch wheels. While the Jeffsy looks similar to the Capra, it does appear as if the bigger brother hogged all the food, giving the Jeffsy a more slender build. Unlike the Capra, there is no strut between the down tube and seat tube supporting the linkage. The rocker link bolts are also very neatly hidden under the seat stay. This has freed up some space in the front triangle to fit a small water bottle. The mounting and bottle can be added to the bike at checkout and did not come with our test bike.

The Jeffsy makes use of the same Virtual 4 Link suspension found on the longer travel Capra and Tues. The design uses a pivot just in front and below the rear axles with the seat stays connecting to the seatpost with a short link on their way to the shock mounting. As expected from a YT bike, the suspension travel is progressive with easy movement through the mid travel and support ramping up close to the end of the range.

The Jeffsy is bang up to date making use of Boost 148 rear axle spacing. Interestingly, YT has decided not to go Boost on the front axle, meaning the front wheel is not as stiff as it might have been. Not that I noticed any unnecessary flex, to be honest. Cable routing is mostly external with the exception of the path through the down tube for the rear derailleur. The drive side seat stay comes with a useful integrated slap guard. There are no ISG mounts for a bash guard but in single chainring mode, the front derailleur mounts are suitable to run an upper chain guide.

Geometry

The Jeffsy’s geometry can be adjusted using a flip chip that changes the bottom bracket height, head angle, and seat tube angle. In the high setting, the head angle sits at 67.6°, bottom bracket drop is 24 mm, and the seat tube angle is 75,3°. In the low setting, the head angle slackens by 0.7° to 66,9° with the seat tube angle at 74,7° and the bottom bracket is lowered by 8 mm. The idea is to have a better climbing, more agile turning bike with better clearance in the steep setting. Flipping the switch should turn the Jeffsy into a slightly more capable bike for rowdier trails, but makes it a touch more sluggish on the ups.

The Jeffsy flip chip found on the shock mount in the seat stay is used to adjust the geometry.

The flip chip forms part of the shock mounting at the end of the seatstays. To change it between modes requires the removal of the mounting bolt. While a relatively simple task, it does take a couple of minutes and is not ideal for constant changing on a ride.

While the reach on a large Jeffsy is modern at 445 mm, the number isn’t pushing boundaries. Chainstay length varies depending on the frame size with small and medium frames measuring 435 mm and large and extra large bikes sporting 440 mm chainstays. YT do this to balance the change of the upsized front triangles and keep the bike feeling as it is designed to.

Components

The Jeffsy CF Pro is the range topping model constructed with a full carbon frame, Fox Factory suspension and a SRAM single chainring drive system.

Shock: At the centre of the suspension system is the Fox Float DPS Float Factory shock with EVOL extra volume. It proved to be up to the task with sensitive and smooth travel throughout testing.

Fork: The Fox 34 plays a difficult role as a trail fork filling the gap between the purpose built 32 and 36 forks. While not as light as an XC fork, it’s also thinner than the beefier 36 all mountain fork. There is, however, little sign of compromise in the 34 and I was able to confidently take on any piece of the trail without the fork feeling out of its depth. I know there will be those that cry out for a 36 on this bike but I really did not see the need.

Drivetrain: The SRAM X01 drivetrain with a Race Face Next SL crankset is not an uncommon combination and has proved to be reliable. The top of the range Jeffsy CF Pro was revealed just after the announcement of SRAM’s 12 speed Eagle groupset, meaning it was a tight squeeze to specify the bike with these components. This, however, has been addressed and the updated CF Pro now boasts X01 Eagle components.

Wheelset: The wheelset is a carbon pair of DT Swiss XMC 1200 Spline. The wheels proved to be tough with predictable steering and excellent power transfer. The carbon rims played a huge part in the feel of the bike. The inner rim width is 24 mm which some might expect to be too narrow but in reality, I never felt like I needed anything wider.

Tyres: At Bike Hub, we like the Onza Ibex. It provides good, reliable grip with a sturdy casing that can take a beating. In the 2.4 inch size on the Jeffsy, the Ibex allows you to explore the boundaries of the bike and your skills without fear of the tyres letting you down.

Brakes: The SRAM Guide Ultimate brakes are the top tier in the Guide range. They offer lightweight with powerful braking and a comfortable lever. Out on the trails, however, they felt very similar to the heavier Guide RSC and RC models which is not to say the Ultimate’s are bad, rather that the lower model Guides are outstanding.

Controls: The Renthal Fatbar is a reminder of the gravity roots of YT Industries and signals the type of riding this bike is built for. The 780 mm width and 30 mm rise is spot on for my tastes and is paired with suitable length 60 mm stem in the large and extra large sizes (the medium and small get 50 mm stems). The CF Pro features a RockShox Reverb with a healthy 150mm of travel, the small size is a bit shorter at 125 mm.

Since we received the Jeffsy CF Pro for review, YT Industries refreshed the specifications across the range. The new CF Pro model underwent a number of component changes including X01 Eagle, Guide RSC brakes, E*Thirteen TRS+ wheelset, and Fox Performance level suspension. YT also introduced a CF Pro Race model which now takes the place of the CF Pro at the top of the range.

Specifications:

• FrameJeffsy Carbon 29″
• ForkFox 34 Float Factory
• ShockFox Float DPS Factory
• HeadsetAcros AIX-326
• CranksetRace Face Next SL
• Bottom BracketRace Face
• Rear DerailleurSRAM X01
• ShiftersSRAM X01
• CassetteSRAM XG 1175
• ChainSRAM PCX1
• BrakesSRAM Guide Ultimate
• DiscsSRAM Centreline 200mm / 180mm
• GripsRace Face Love Handle
• WheelsetDT Swiss XMC1200 Spline
• StemRenthal Apex
• HandlebarRenthal Fatbar Carbon Black
• SeatpostRockShox Reverb Stealth
• SaddleSDG Circuit
• Frame sizesS / M / L / XL
• Claimed weight11,9 kg

Building the bike:

While you can buy almost anything online these days, new bikes are still generally an exception. YT Industries are one of the few bike companies taking advantage of this retail channel and sell their bikes direct to the public through their website.

This does, however, mean that you need to unbox and build the bike yourself. While I can’t think of a better way to get to know your new bike, I acknowledge that not everyone has the time, skills, or interest for the job. Thankfully, YT Industries have given this a lot of thought and have made the process (almost) fool proof.

When you cut the tape and open the box, an instruction manual sits on top. The manual is very clearly written with picture examples to guide you through the build. Pulling the bike out the box, you’ll notice that it can stand freely on the cardboard cut-outs attached to the front and rear axles, creating a bike stand to build the bike. YT have done their best to set up the bike in their factory but they leave the fitting of the wheels, rear derailleur, handlebar, and pedals (not included) up to you. Some adjustment might be needed to the brakes and shifters to get your preferred angle of attack.

The tyres came inflated with tubes – understandably leaving sealant in the tyres while in storage is not really an option. Conveniently, a full conversion is not required, as the rims arrive with tubeless tape installed and there are two tubeless valves included in the box. So all that is required is to remove the tubes, insert the tubeless valves, and throw in some sealant.

On the trail

Even for a trail bike, the Jeffsy flies up the climbs. YT managed to restrain the urge to go super slack and long with the geometry. You do not feel stretched out on the Jeffsy with a more upright position than some other bikes, giving you a good position for pedalling. It’s a bike that you can easily spend all day riding without feeling uncomfortable.

The suspension provides a good pedalling platform even when fully open. I switched between the open and medium shock compression on technical climbs but did prefer the firm setting when climbing long jeep track ascents.

Trail bikes need to set themselves apart from slacker, longer travel all-mountain bikes in their ability to climb, and the Jeffsy impressed in this department. For what it’s worth, I managed a number of Strava PRs climbing at Jonkerhoek, a regular test ground where I’ve done a significant amount of riding on cross-country climbers.

YT are known for their great descending bikes and the Jeffsy is no different. But instead of just creating a mini Capra, the Jeffsy has a unique feel and character: one more suited to trail riding. Where the Capra has the ability to dumb down the trail, and requires fast speeds to feel lively, the Jeffsy requires a lot less to start feeling exciting. The Jeffsy manages to communicate a sense of consequence- a little reminder that your actions on the trail have meaning. There is a sense of achievement that comes with this, which I really like.

In the South African context, this bike makes perfect sense. Don’t get me wrong, the Jeffsy has the ability to dispatch with the most demanding trails and can pull you out of some sticky situations when mistakes happen or skills are lacking. But, at the same time, it is also endless fun on the most mundane trails. The Jeffsy transformed the Constantia Greenbelts for me, with the springy suspension encouraging me to boost every root or mound of dirt in sight. I simply wanted to ride the Jeffsy on every and any trail. This for me is the magic of the Jeffsy.

Many sceptics will probably point to the 29-inch wheels, so let’s address that. The bigger wheels rolled superbly over rocks and roots, and the bulky tyres paired with the large circumference wheels created mountains of grip. It is often said that the downfall of big wheels is agility in cornering, but the Jeffsy proves otherwise. While I do concede that this may be true in some cases, modern geometry frame design is starting to close the gap on smaller wheels. Also, in the context of South African trails, with significantly less steepness and more open, flowing trails than you might find overseas, the benefits of large wheels on mid-travel trail bikes is a no brainer.

Flipping the chip to change the geometry had a real impact on the characteristics of the bike. In high mode, it was notably better at climbing with some detriment to my confidence on more technical terrain. In the low setting, climbing was less sharp when accelerating up short punchy climbs on single track, but grinding out open climbs felt much the same. The slacker angles in the low setting improved descending over drops and rough terrain but the bike remained agile in the turns.

For reference, I started out with the chip on the high setting but ended up leaving the bike on low setting. I’m a rather fit rider, so I figured I would play to my strengths and go with the benefits of slacker geometry to help me through some of the gnarlier sections. But that said, I would be happy to ride in either mode for most trails.

Conclusion

In my reviews, I try to not get too carried away with emotions but with it being Valentine’s Day, I’m allowed to make an exception. I really love Jeffsy! The bike strikes a remarkable balance between an all day kilometre eater, and big mountain shredder. No matter where you point the Jeffsy, it manages to excite. The Jeffsy has gone straight to the top of my “if you could have only one bike” list.

Long term test bike

YT Industries have provided us with a Jeffsy CF Comp 1 for long term review this year.

Iwan Kemp will be riding it during this time and reporting back with an in-depth review in the second half of the year. I’m interested to see if he enjoys it as much as I did.