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Field Test: YT Jeffsy Core 1 - Where Value Meets Performance

May 23, 2024 at 14:40
by Mike Kazimer  


YT Jeffsy Core 1

Words by Mike Kazimer; photography by Tom Richards

The bright yellow YT Jeffsy Core 1 was one of the highlights of the Value Field Test, both literally and figuratively – that bright yellow paint job is hard to miss in the dark woods (there's also an all-black version available for the goths / vampires out there). We reviewed the higher end, carbon model when it launched at the beginning of this year, so we decided to bring in the entry-level version to see how much of a difference that much lower price tag makes.

The Jeffsy was designed with an equal focus on climbing and descending performance, although on the trail it does feel a little more descent oriented. All sizes roll on 29” wheels, with 145mm of rear travel and a 150mm fork.

Jeffsy Core 1 Details
• Travel: 145mm rear, 150mm front
• 29" wheels
• 65° head tube angle
• 77.9° seat tube angle
• Reach: 475mm (L)
• Chainstay length: 437mm (L)
• Weight: 36.3lb / 16.3 kg
• $2,799 USD (currently on sale for $2,249)
• More info: yt-industries.com

YT Jeffsy review

The Core 1's retail price is $2,799, although it's currently on sale for $2,249, making it an even more impressive deal. That gets you a RockShox Lyrik Base fork, a Deluxe Select+ shock, and SRAM DB8 brakes with 200mm rotors front and rear.

There's a 12-speed SRAM NX drivetrain, which gets a MatchMaker mount to attach the shifter to the brake lever, a small but useful detail that's often overlooked at this price. The Sun Ringle wheels are shod with a Maxxis DHF / DHR II tire combo, both in an EXO+ casing.

The Jeffsy is available in five sizes, from S all the way to XXL. Reach numbers range from 435 up to 515mm, which means the bike should fit a wide range of rider heights. The head angle sits at 65-degrees (it can be steepened to 65.6-degrees via a flip chip), a number that's become the norm for a modern trail bike. The chainstays measure 437mm on the S, M, and L sizes, and then bump up to 442mm on the XL and XXL in order to maintain a little more balanced ride.



The Jeffsy Core 1 weighs in at 36 pounds, making it the heaviest bike in this roundup. It also has what's arguably the burliest, most capable parts kit; personally, I'll take the extra weight if it means I don't need to hold back on the descents.

As for how the Jeffsy climbs, even though it's packing a few extra pounds it's still very manageable. The suspension feels more active than ultra-efficient, which is handy for finding traction on slippery and soft dirt. The steep seat angle comes into play here as well – the seated position is centered and fairly upright, making it possible to sit and spin up steep climbs without feeling like the front end is going to lift up and spit you off the back of the bike.

There is a lockout, and a very firm one at that, which can come in handy on paved road spins or long fire road climbs, but for the most part we were content to leave the bike in the open position.



Hands down, the Jeffsy was our favorite of the bunch when it was time to head downhill. Decently powerful brakes, suspension that actually works, tires with a good tread pattern, appropriate geometry - the Core 1 has it all, and it was very much appreciated.

At its core (no pun intended) the Jeffsy is an aggressive trail bike, one that feels right at home in rougher, more challenging terrain. That 145mm of travel isn't earth-shatteringly plush, but it does provide a good platform for pushing into while cornering, or getting popping off the lip of a jump. It's also accessible travel, meaning that it's possible to use it all when necessary, while also not needing to worry about bottoming out off of every little drop.

The geometry is long and slack enough to provide stability in the steeps, but the Jeffsy also remains very manageable on mellower terrain or at a more leisurely pace. YT found a nice balance with the geometry, creating something that can comfortably be ridden on everything from machine-built flow trails to chunky, extra-techy descents. In fact, the Jeffsy feels solid enough at speed that I wouldn't hesitate to bring take it into a bike park every once in a while, something that can't be said of most bikes in the price category.



Overall, the Jeffy's components are very well suited to the bike's intentions. There are a few areas that could be upgraded in the future, like going with metallic pads and thicker rotors to bump up the stopping power of the brakes even further, or possibly upgrading the fork damper to gain even more adjustability, but right off the bat there really isn't that needs to be changed.

I do want to shout out the YT Postman V2 post (a rebranded SDG Tellis V2) – the mounting system for the seat is one of the best around. The bolts are angled outwards, providing plenty of room to tighten or loosen the clamp to the seat rails without hitting the post with an allen key. It's one of those “Why did it take so long for someone to invent this?” features, making adjusting the seat angle a much less annoying proces.

Who's It For?

The Jeffsy Core 1 would be an ideal option for the rider who wants to continue to progress without being held back by their bike's frame or components. It's an aggressive trail bike that could easily be called into action for an enduro race or two, or even the occasional day in the bike park. It'd be an amazing first bike, but it'd also be an excellent upgrade for someone with a fairly basic, entry level bike that wants to get more serious about the sport.


+ Excellent value (even more so when it's on sale)
+ Very capable descender, while still remaining manageable on mellow terrain
+ Wild or mild paint options


- On the heavier side for a trail bike

Pinkbike's Value Bikes Field Test is presented by Ride Concepts

Author Info:
mikekazimer avatar

Member since Feb 1, 2009
1,760 articles

  • 132 2
 Pros: very competent at going down. Just like pinkbike.com.
Too soon?
  • 39 0
 I literally had to do some work. Won't somebody think of the gapers.
  • 5 0
 pinkbike.com says [object Object] whatever that means
  • 52 2
 lol we deserve this, sorry for your increased productivity. In our defence it's scheduled maintenance that we've had a banner up warning about for several days. Smile

(I think there is still some post-maintenance weirdness happening on the site, so please continue to make fun of us while the dev team sorts it out)
  • 4 0
 @brianpark: Well can’t say you increased my productivity. I simply put a note on my computer the site is down so I’m taking my break early and went for a ride.
  • 19 0
 You cant blame Pinkbike for that, its not their fault their servers are now Outside..
  • 3 1
 @DizzyNinja: thats the string representation of an object
  • 1 2
 @marshall1234: we can blame pinkbike for their flawless and v ery modern ui though
  • 4 0
 @brianpark: the dev team, so you have 2 people, probably including one intern?
  • 1 1
 @brianpark: didnt they test the update before it went live?
  • 2 0
 @brianpark: I don't know if it's a caching issue, but I swear that maintenance banner has only just shown up for me (it was probably there all along and I was just so incensed by scaffolding that I didn't notice it). And possibly it now needs removing again? Also, nice hamburger!
  • 2 0
 @brianpark - Also, while on the subject of UI design, is there any chance the Fantasy League tags next to people's names could be some other colour than 'look at me'/'danger'/'very important' red? It tricks my brain into looking at the tag rather than the username every time and, for me anyway, makes the page harder to read. Could they be yellow say?
  • 1 0
 @brianpark: a lot of pictures of little blue question marks in this review ;-)
  • 47 2
 All mountain bikes should be available in powder-coated yellow. Fight me.
  • 49 1
 Toss a red fork on there and you can go full ronald mcdonald
  • 38 0
 McDonalds does in fact have a BMX background
  • 12 0
 @n8shearer: I googled it and came up with this bit of TV advertising gold www.youtube.com/watch?v=Yw0uRqBPevQ . Apparently Lopes is one of the riders!
  • 3 0
 @Woody25: pretty sure Steve Veltman raced for them as an amateur too. Highly underrated, he rose to number one pro and it’s hard not to see how his riding style has influenced BMX racing as we know it today. He, as well as others who rode for Boss/ L&S, were early pioneers of manualing anything on the track and pulling the pack in the process.
  • 1 0
 taxi cab yellow bikes>>>
  • 1 3
 The only yellow I want is from the sun, some fruit, and an 80's Lamborghini Countach. Otherwise, get it out of my eyeballs.
  • 1 0
 You don’t have to go back too far to see the McDemo days
  • 41 0
 Easily the best bike on test
  • 17 2
 no doubt, this is a very weak lot of budget trail bikes
  • 22 1
 Less than 3 pounds heavier than the Haro hardtail. Not sure if that makes the con a reach or instead highlights how portly that Haro is...
  • 8 3
 Both overweight
  • 14 1
 @tadabing: just like me
  • 4 0
 @catamplifier: only makes you faster downhill
  • 2 0
 @Mac1987: ye, you can also cook some nice meat on brake discs after the ride Smile
  • 16 1
 Damn, that's a pretty solid value, as in, you get good value for your money, as opposed to a cheap bike. I'd have a really hard time recommending something like the Giant over this to a newbie.
  • 6 6
 Being able to go to a local LBS for the bike might be valuable to a newbie (especially if it's a good shop)
  • 8 0
 @Mac1987: Agreed. Here's the thing, though - in any town that actually has a decent LBS ecosystem, you'll usually find one or more of them happily service DTC bikes. They advertise that, and they gladly work with people. For one, those customers don't expect freebies or special treatment for having bought their bike there, they just want to get honest service at honest prices. Selling bikes is an iffy proposition - expensive inventory and floor-plan interest, everyone expects a deal, and in a market that's no longer buoyed by once-in-a-generation bubbles like during the pandemic, there's always someone blowing out old inventory killing everyone else's margins. Service, however, tends to be a steady revenue stream with decent margins, and allows opportunities for up/cross selling parts and accessories and soft goods.
  • 3 0
 @g-42: very true. Unfortunately, there still remain a lot of areas where there is a brand dealer with decent support and a small shop that sells only city bikes here in the Netherlands. But if a good LBS is available that's brand agnostic, that's probably the best option.
  • 2 0
 @Mac1987: What's stopping them?
  • 1 0
 @g-42: I just don't see this. I've not had any issue with a bike shop doing work on a bike regardless of if its DTC or not. As a bike shop, why would you turn custom away?
  • 1 0
 @grotesquesque: nothing if they buy a brand that's sold by a local LBS. If they buy DTC, you need a good LBS that services other brands.
It was a response to the comment "I'd have a really hard time recommending something like the Giant over this to a newbie". I pointed out why for some people Giant might still be a better option, selling fairly priced good performing bikes from brick and mortar stores with good support.
For others who do their own maintenance or have a good brand agnostic LBS, the YT can be the better option.
  • 14 0
 The Jeffsy is a great bike at any price point. My buddy got one for his wife, liked it so much that he sold his Capra and bought another for himself.
  • 7 0
 I got one for my wife and it's funny, so fun to ride that i'm about to sell my capra too for a jeffsy. More on the funny side than a capra.
  • 7 0
 Funny, I want to buy one for my wife too. Unfortunately the only way she could test how 29er works was by trying a Hightower and now I have to convince her that 25% cheaper Jeffsy will be as good if not better Smile
  • 34 0
 Funny, I want to buy a Jeffsy for this guy's wife too, but then I rode it and now I bought another one to give to the other guy's wife. Then I bought another one to give to the third guy's wife. Funny
  • 1 0
 @lkubica: Try a Canyon. After back-to-back rides between it and the YT, I was far more impressed with the Spectral in both climbing and descending.
  • 15 2
 Why would anyone buy any of the other bikes in this test?
  • 27 3
 Cuz they want a hardtail?
  • 4 4
 Its hard to argue with but if you are a beginning biker (which lots of folks looking at the budget options are) the support and comfort of a shop is compelling.
  • 12 2
 The San Quentin is a compelling alternative. Costs $1000 less, weighs 4 pounds less, still shreds, and some folks prefer a hardtail. I would rather have it than a 36 pound FS bike, regardless of price.
  • 6 1
 because they're available? I've already mentioned this on the YT channel, but only XL in yellow and XXL in black are currently available from the Canadian site...
  • 6 0
 @mtmc99: I own a shop, this isnt a problem anyone who ever has bought a bike online has ever complained about.
  • 7 3
 I appreciate that YT connects the rear shock directly to the seat stays instead of using a clevis/yoke which is incredibly hard on shocks. I don't understand why more companies don't do what YT does (I'm looking at you Specialized and Ibis).
  • 4 0
 Yeah good point. Never thought of that. I will say however I have had no issues with my Commencal Meta TR which does also use the yoke and a coil shock.
  • 3 0
 I'm guessing Ibis does it to maintain the max seatpost insertion. They essentially design their bikes around that feature which is pretty nice. Not sure wtf Spesh is thinking though
  • 4 0
 @KUBBY: The Meta TR uses a pretty short clevis, so it minimizes the negative effects.
  • 4 1
 @Bad-Mechanic: I managed to crack an air shock damper shaft on mine
  • 4 1
 If those Swing links come loose, you will destroy a shock instantly - same with canyon bikes.

Also connecting directly to the seat stays means the rear triangle has to be stiff AND ALIGNED or every drive of the shock will be a twisting motion aswell.. its effectively a short clevis design but uses normal shock bushings to wear instead of the shock shaft.

I had a few failures on canyon's spectral, Bolt loosend and snapped a super deluxe AIR(alloy bike)
on my cf8 the alignment was messed up and it used to destroy rear shock bushings every 2nd ride - Canyon did however replace chainstays and then the whole frame.
  • 1 0
 dw link fully rigid rear triangle that wont work. I prefer link driven suspension as the frame doesnt flex as must side to side compared to Horst link
  • 1 0
 @SwiftFixBike: There are plenty of ways to drive the shock with a DW Link or VPP without resorting to a clevis.
  • 6 0
 Would happily cope with the extra few lb's in weight and have a bike capable of being ridden how it was intended.

Is there a better bike its class for just over $2k?
  • 9 1
 Ibis please take note of the routing around the bb for you aluminum bikes.
  • 3 0
 Preach. The cable routing on my Ripley AF is turrible.
  • 2 2
 @grnmachine02: So is your spelling ;-)
  • 8 1
 Same weight as my downhill bike! Probably not as good going down though….
  • 15 1
 Every bike now has to be fat proof,stupid proof/ fat and stupid proof.
We all pay the price. In pounds.
  • 5 2
 Probably MUCH better going up though because a few lbs either way makes very little difference if you're not racing to pay the bills.
  • 7 0
 can you tell me which 2500-3000 Euro downhill bike on 29 or MX wheels weighs 16kg? I will wait.
  • 4 0
 I bet it'll out climb this bike too...what size dropper is on your DH bike?
  • 4 4
 @WheelNut: it’s sweet. Set up downduro-retro. Full 27.5…. No dropper post. But bigger gears & rear vivid air shock. It gets lots of looks n kisses when it’s in Finale, in a sea of e bikes and mullet enduro bikes
  • 5 0
 @notphaedrus: so not really a comparison. You have a bike that has lighter front wheel because of the size, no dropper. significantly worse seated pedaling position and I doubt a TR500 bike could be built up @ $2500 with MSRP priced parts.

So your comment is like going "omg this Mazda MX5 is slower in a drag strip than my drag prepped LS swapped 700hp Mustang". Lol. No shit.
  • 1 0
 @nozes: for reals. I started MTB when budget trail bikes were 30 lbs. I haven’t demoed the newer bikes in a while. Does the geometry make up for the extra weight? Is everyone slower on climbs and faster on downhills?
  • 3 0
 @wutamclan: are we really back to 1995 myths? There are 2 things that affect climbing speed the most:
1. Tires - Pressure, Compound, Thread, Thickness/weight
2. Position. If you have a better position you won't struggle for traction on the uphills and you won't feel like you're killing your body.

I've rode a dh bike to reach bikepark trails and it was always a pain. I've had a very lightweight DH bike. Now I have an enduro bike that weighs exactly the same as my old dh bike and I can cruise on the flats at 2x the speed with 20% of the fatigue. I can also legitimately do 500m of elevation and that would be near impossible on a dh bike unless I wanted a really shit day.

Also this is a burly trail bike. You can take it to a bike park. The old trailbikes you are thinking about were like a 26'' Specialized Pitch. I rode one and it was half as capable as modern trailbikes, the chain dropped if you rode it too hard, the suspension was much worse, it was not as stiff and it had no dropper. Modern trailbikes, even cheap ones are much better. Buy a modern, relatively cheap trailbike, upgrade the susp and breaks, get good tires and you're golden.
  • 5 0
 Since I know YT is here in the comments: Why no TRUE Uncaged version yet? The Uncaged 13 wasn't really the ~12 kg top spec monster that is missing in the lineup...
  • 1 0
 You could dangerholm it if you really wanted one...
  • 2 0
 A truly 'Uncaged' version would be a frame that you could build up to your own spec, just like The Mob riders do.

I'd love to get an Izzo or a Jeffsy frame, and built it up with a Manitou Mara and Mattoc and all the other components of my choice.

Does anyone other than Canfield offer a frame only, no shock?
  • 1 0
 Wasn't there the Uncaged 12 version that was really mint?
  • 3 1
 They cheaped out with an SX rear cassette but otherwise it's solid. I'd prefer Shimano Deore with a Microspline rear freehub body but I'd upgrade the wheels anyway so I'd also upgrade to an SLX cassette, Deore derailleur and XT shifter. Love the yellow colour too!
  • 4 0
 The next spec level up has DT Swiss wheels and GX, plus Fox Performance suspension, for $700 more. Might want to just go for that rather than piecemealing it together. And then another 800 will get you that nicer spec, but with a much lighter carbon frame; that's the Core 3, currently on sale at 3,799. To me, that's the min/max sweet spot - the _only_ thing I'd want to upgrade on that one would be the Code R brakes, but that's a personal preference thing (hate working with DOT fluid).
  • 2 0
 @g-42: Sadly there's no Shimano option on their website, so buying a cheaper model and upgrading might be the only option.

Personally, if I bought a Jeffsy then I'd probably swap the brakes to Shimano before its first ride too (I'd be faffing with the brakes anyway as I'm from the UK)
  • 1 0
 The Jeffsy is a crazy level of bang-for-buck, especially given there are often YT coupon codes to be found. I'm not riding one any more but I had the 2020 cheap-spec version and put about 1,500 miles into it, only selling it because I fell in love with something else. Over that time it held up remarkably well (other than the SX derailleur it came with that I replaced immediately because those are trash), had basically zero issues with it and it was pretty fun on almost any kind of trail.

I would wholeheartedly recommend one to any newbie, and if I ever had to sell my bikes and replace them with just one bike that was cheap, the one bike would be a Jeffsy.
  • 3 0
 I just bought the exact same bike 2 weeks ago. I'm in love with it. A little heavy but great performance and the price is unbelievable
  • 5 0
  • 12 3
 ...my brother uttered as we stood before the familiar yet altered visage of the old house, an eerie silence enveloping us. We moved through the once lively hallway, its stillness foreign, to the kitchen where the scent of Mother's breakfast buns had long since faded. A sense of oddity hung in the air. Turning to my brother, I found him rooted in place, eyes wide, staring out the window. The impossible view that met our gaze spoke a silent truth; a vista of stars, galaxies, and nebulae unfurled beyond the glass. With startling clarity, it became evident—we were not home, but aboard a space ship!
  • 6 0
 @Wabit: wow morning mushroom dosing FTW!
  • 4 0
 @BermJunky: just chatGPT Wink
  • 1 0
 @Wabit: Is your last name Lovecraft by any chance?
  • 3 0

Fourth paragraph.
Says: “dhr/dhr II”
Should say: “dhF/dhr II”
  • 12 0
 They should prob shut the website down
  • 1 0
 2020 capra came full slx/ codes lyrik maxis rubber super deluxe dt 1900 and weighed 33lbs with pedals. what the hell is going on around here?
  • 2 0
 2020 capra also cracked as hell and had smaller tires.
  • 1 0
 Wow, GREAT looking bike, lockout, nice suspension, maybe replace the NX down the road with Deore 10/11spd or LinkGlide, but that's a pretty small proposition.
  • 3 0
 Hey this is appropriately priced! Alright!!
  • 1 0
 Would you call it “intermediate entry level bike” because of the performance, or components?
  • 2 0
 Components and (mainly) price
  • 2 0
 Maybe just what an entry level bike should be?
  • 1 0
 The enthusiasm is killing me…. Can we have SOME voice reflection Please!
  • 1 0
  • 3 0
 @opetruzel: *infection
  • 1 1
 You get what you pay for with bikes, Canyon and YT are no exception. Buy a bike from a shop.

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