2021 YT Jeffsy Core 3 29 Bike

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When YT launched the revised Jeffsy platform in 2019, we were on hand for our First Ride report from the press camp. Since then we've tested the $2,399 Jeffsy 29 Base model and again, found it to be a stand-out performer, especially for the price. When YT released their latest Jeffsy Core offerings earlier this year, that Core label had us grinning. We have a test pilot who is the very type of rider that YT’s marketing efforts embrace. Young, eager to hit massive jumps without much regard for personal safety or equipment, Logan Brown is not the typical product reviewer and would be the perfect punisher to test out just how Core this Jeffsy iteration is.

Highlights

• Full carbon frame
• 29-inch wheels only (alloy has 27.5-inch option)
• 150mm (5.9-inches) of rear wheel travel // 150mm (5.9-inches) fork travel
• V4L, Horst Link suspension design
• Tapered headtube
• Internal cable routing
• Five year warranty
• FidLock, proprietary water bottle
• DUB Pressfit bottom bracket with ISCG tabs
• Integrated, rubber molded frame protection on downtube, bb, and stays
• Clear frame protection in select areas
• Boost 148 rear spacing with 12mm through axle
• Measured weight (size large, no pedals): 31.87 pounds (14.45kg)
• MSRP $4,199 USD

We arranged to have YT send us a Jeffsy Core 3 29er to review, and we eagerly lined up Logan as the pilot. Once it arrived, we turned over the still-sealed box and sent Logan on his way, just as any YT customer would find themselves. Initially, Logan was a bit sad to have a 29er. He figured the 27.5-inch version would be easier to whip, flick and 360. As it turns out, that wasn't an issue. Let’s dig into how this 150mm-travel 29er performed on the trail, at the jump park, and under the abuse of lift-served laps.

Overview

For 2021 YT left the Jeffsy alone, only updating the colors and lineup. Moving to a simpler, Core, nomenclature, there are only three trim offerings. The Core 2 is the starting point at $2,999. Riders will get the same alloy frame as the prior Base model which follows identical geometry as the carbon frames. It merits a mention this is the only model offered with a 27.5-inch wheel option. A SRAM NX drivetrain and FOX Performance level suspension take care of the big stuff while DT Swiss M1900 wheels and Maxxis Minion DHRII tires round out things.

Next up is our test bike, the Jeffsy Core 3 with its carbon frame. 150mm of squish is handled by a FOX 36 Performance Elite fork and FOX DPX2 Performance Elite rear shock. SRAM's venerable 12-speed GX Eagle drivetrain takes over shifting duties and rounds out a kit that should be both durable, and still easy(ish) on the wallet at $4,199.

YT's big dog Jeffsy, the Core 4 gives riders FOX Factory versions of the 36 fork and DPX2 shock with a bump to SRAM's X01 Eagle drivetrain. The wheels also get a bit nicer with DT Swiss XM1700s and a star ratchet hub. Those upgrades come with a tab, however, as the Core 4 will set a rider back $5,199.

We really took a shine to the Jeffsy Base last year and felt like we had a read on it. Not wanting to go full baller though, we opted for the $4,199 Core 3 build. Every part on this bike should be up for some very heavy use, with no excuses.

First Impressions

The Jeffsy came right out of the box ready to ride. We slapped on the bars and wheels and it was good to go. This is what we would expect with YT being a direct-to-consumer brand. We cut down the 780mm bars 10mm on each side just to make it a bit more nimble. On the jump lines and flow trails, we rode the YT stiff to get some more pop out of the travel. We were under the 30% sag recommendation, getting the preferred feel closer to the 20% range. The flip-chip was set in the low (slack) position. That put the reach on our large at 470mm, effective seat tube angle, 77 degrees, head angle hits 66 degrees and chainstay length is 435mm for sizes small through large, stretching out to 440mm on XL and XXL sizes.

The cockpit on the YT felt right at home. This is a super solid bike in which one should feel comfy doing some big drops or hucks. The handlebar setup is clean, and SRAM's Matchmaker system kept the YT Postman dropper lever and GX shifter neatly tucked away. With the seatpost extended, the bike is ready for the climbs. Rider position may be a bit more over the front with a 50mm stem, but not so much that traction suffered on the steep stuff. With the 150mm Postman dropper slammed, the seat sits quite low, making it nice for over-the-seat tricks and getting weight over the back wheel on the descents. Other than making sure the flip-chip was in low and a slight shave of the handlebars, the Jeffsy Core 3 was pretty close to perfect out of the box.

On the Trail

Our YT Jeffsy saw all kinds of action during testing. Of course, we took it out to the foothills for plenty of trail riding. We also had some sessions at the jump park, as well as some lift-served downhill laps. Over the past months, it became our do-everything bike.

The Jeffsy is nimble and lively on the trail. Our tester has an affinity for 27.5s, and the Jeffsy’s feel of being more on top of the bike, rather than submerged in the bike, brought to light just how playful wagon wheels can be.

After experimenting with different configurations, the Jeffsy Core suited our jump and bike park riding preference with a firmer suspension setup. When set up in the 30% range, the bike soaked up the small and mid-sized trail hits quite well. That said, we preferred the stiffer settings to embrace the Jeffsy's more aggressive nature and while providing that extra pop for jibs and jumps. The FOX DPX2 is a reliable performer for most trail bikes. We did find that speeding up the rebound gave a more lively feel to the rear end and helped propel the bike when boosting sharkfin booters and hopping out of corners. Despite our firm settings, the bike kept its composure under braking and blitzing through the chatter.

Pedaling the Jeffsy uphill was an easy task. The balanced rider position was fantastic. When we got to really steep sections, the rear tire maintained its grip, and the bike just motored up the grade. We never felt the front end wander and appreciated the "trail" intent of this bike's nature.

If there was a standout characteristic of the Jeffsy, it would be fun. Downhills are always the best part of the ride and this bike just takes it to a new level. We found that in areas with steep jumps like the Boise Bike Park, the Jeffsy Core 3 carried speed and was still able to get loose; throwing it sideways and even spinning 360s. Although it took a little while to find the balance point, once we did, the Jeffsy would manual for days. We felt the Jeffsy handled both chunky sections and fast, flowy trails equally well. This 29er ate everything we put in front of it.

Parts Check

The build spec on our bike was fantastic. SRAM's GX Eagle drivetrain is a strong performer and worked awesomely. We did explode the rear derailleur on a rock, but that was our fault, not SRAM's. After a new hanger and derailleur, we were back on the trail with no more issues.

Fork - Our favorite component on this bike would be the FOX 36 Performance Elite fork. It was plenty stout for our abuse and gave us the adjustability we needed. Whether it was downhill laps at the gravity park or boosting really steep lips, the FOX fork did its job well.

Brakes - The SRAM G2 R brakes felt solid out of the box. Even on longer descents, they held their own. After a few weeks of riding, however, the rear brake got a little spongy. We did a quick brake bleed and it firmed right back up without a flinch throughout the rest of the test.

Wheels - The only weak piece of spec was the DT Swiss rear hub with its 3-pawl engagement. In sprints or powering out of corners, slapping gears, we noticed a delay and slam before driving forward. Because the Jeffsy is such a charger on the downhill, something small like this really stood out to us when we did have to put the power down. The M1900 rims, however, stayed strong and true regardless of endless attempts to ruin them with berm slaps and sideways landings.

Frame - It was a little ironic that the only thing to show immediate wear was the frame protection. The clear protective kit that YT includes started to peel off fairly quickly. We know this stuff is supposed to protect the paint but it has to stay on the bike to do that. Riders will want to get their own protective kit straight away.

What's the Bottom Line?

After a couple of months of some very hard riding, the YT Jeffsy Core 3 held its own, and we were impressed with the versatility of this 150mm-travel 29er. With only some peeling stickers, it seems the Jeffsy is up for the care-free nature of its target demographic. Should they become available sometime soon, we would once again give the YT Jeffsy two thumbs up.

About the Tester

Logan Brown - Age: 21// Years Riding: 1 year MTB, 8 years BMX, 18 years Moto // Height: 5’11” (1.8m) // Weight: 155-pounds (70.3-kg)

Despite riding downhill for a few years at 15 it was never something I really got into until recently. With a long history in 2-wheeled sports, I picked up MTB relatively quickly. In my short year I have a nice grab bag of tricks and I would like to say I know how to get rowdy and have a good time on a bicycle. I used to be against the climbing aspect of MTB but with my testing of bikes that are well equipped for the climb, I have come to love it. MTB has quickly taken over my life. When I have no plans I'll ride 2-3 times in a day just to put a smile on my face. I currently ride dirt jumpers and all kinds of trail/ DH bikes. It has been awesome learning tricks on the DJ and taking them to the big bikes.