YT Izzo Core 4 Review

Should I Buy This Bike?

The Izzo is the shortest travel bike in YT's lineup, and they market it as being “sharp like a katana sword, agile and just plain fast.” It's also the only bike in their range that they bill as a trail bike, and it is most certainly that, but we found this lightweight 130mm travel bike leans a bit to the XC side of the trail riding spectrum. Make no mistake, this is no beefed-up XC (or "downcountry") bike, this is a proper trail bike that just happens to be pretty darn lightweight, super quick, and very responsive. “Tight” is a word that often came to mind when coming up with adjectives to describe the way this bike feels on the trail. The stiff carbon frame and high-end Core 4 build we tested lends itself to a feeling of precision and sharpness, not unlike a…katana sword? The bike's crisp and nimble handling is undoubtedly also a result of the Izzo's modern, but somewhat conservative geometry. While many other brands are stretching and slackening their short travel trail bikes out at the expense of agility, YT chose a different approach. A comfortably long reach and low bottom bracket combine with a moderate head tube angle, wheelbase, and short chainstays to make the Izzo super maneuverable, quick, and playful. We found the pedaling platform to be relatively calm and efficient, and this 27.5 lb bike flies up the climbs and through rolling terrain. It rips on the descents too, but this bike is far from a plow machine. Instead, it is super engaging and it is an absolute blast to slice and dice the trail to pieces. The Izzo was made to go fast and eat up the miles, and it does that very, very well.

The Revel Rascal is an interesting comparison to the Izzo. This 29er also has 130mm of rear-wheel travel but is paired with a 140mm fork. It has a modern but somewhat moderate geometry and is a fun do it all trail bike. The Rascal feels a bit more confident in steep, rough terrain than the Izzo, but it can't quite match its nimbleness or speed on the climbs or in rolling terrain. One of the primary reasons is that the Rascal GX build we tested weighs a full three pounds more than the Izzo Core 4. That said, we would steer riders who want a super-versatile mid-travel bike that can truly do it all towards the Rascal. Riders who frequent less aggressive terrain and prioritize weight, rolling speed, and agility should go for the Izzo. There's also the price difference to consider. The Rascal GX costs roughly the same as the Izzo Core 4 with a much less impressive build.

Frame Design

The YT Izzo is built around a full carbon fiber frame with an aluminum rocker link. The bike has wide but thinned-out top and down tubes with clean lines that we found to be very pleasing to the eye. It has 130mm of rear-wheel travel paired with a 130mm reduced offset fork. The suspension design is a departure from the typical V4L (Virtual 4 Link) system found on the other models in YT's line. The Izzo employs a 4-bar or Horst-Link system that drives a vertically mounted shock and opens up space within the front triangle for a larger water bottle. The main pivot is just above the bottom bracket, with pivots on the chainstays just in front of the rear axle, and a rocker link attached on the seat tube just below the junction with the top tube. The junction of the downtube and seat tube is heavily reinforced presumably to add stiffness to the frame, but also to create a mount point for the rear shock. The downtube has a recessed bottle mount designed specifically to fit a Fidlock Thirstmaster bottle (a regular bottle cage can be mounted as well), and there are bosses under the top tube for an accessory mount. The chain and seat stays have molded rubber protection, and YT installs protective tape on the bottom of the downtube, cable contact, and potential heel rub areas.

Our size large Izzo Core 4 tipped the scales at a svelte 27.5 lbs without tubes or pedals. We measured our bike in the low geometry setting and found it had a 616mm effective top tube and a 472mm reach. It has a moderate 66-degree head tube angle and a 77-degree effective seat tube angle, although the actual seat tube angle is a fair amount slacker than that. It also has relatively short 432mm chainstays (sizes S-L) and a 1209mm wheelbase, along with a 334mm bottom bracket height (40mm BB drop). Flipping the chips in the upper shock mount to the high setting steepens the head and seat tube angles by 0.5-degrees and raises the bottom bracket by 5mm. The Izzo comes in 5 frame sizes, S-XXL.

Design Highlights

• Carbon frame

• 29-inch wheels only

• 130mm of rear-wheel travel

• Designed around a 130mm fork (Blaze build comes with 140mm fork)

• Flip-chip adjustable geometry

• Single-sided hardware for easy maintenance

• Internal cable routing

• Molded chainstay and seat stay protection

• Offered in 3 Core builds ranging in price from $3,399 to $5,599 (tested)

• Blaze build comes with a 140mm fork

Downhill Performance

On the descents, the Izzo is a lively and energetic bike that handles with precision and likes to go fast. It really thrives in pedal-y, rolling terrain where its efficiency and ability to carry speed are especially noteworthy. We also found it to be a blast in moderately technical situations whether carving around or popping over obstacles due to its maneuverability and quick, playful demeanor. In super rough or steep terrain, we found the Izzo does have limits, but we could ride just about anything by dialing back the speed and picking good lines.

Unlike many of the new breed of modern short travel trail bikes, the geometry of the Izzo doesn't pretend to make it a mini-enduro bike. Instead, its somewhat moderate numbers help to define its zesty ride quality and super responsive handling. Sure, it has a modern reach measurement and relatively low bottom bracket, but the moderate length wheelbase, short chainstays, and moderately slack 66-degree head tube angle (low setting) give it a liveliness and agility that most other trail bikes lack. This bike feels very precise, and its 27.5 lb weight also contributes to its energy and the ability to move the bike around very easily. It is highly maneuverable, making it easy to pick your way through tight technical sections and around tight corners. At the same time, the low bottom bracket helps to maintain stability through high-speed berms or long straightaways. At truly warp speeds, it doesn't feel quite as stable as longer and slacker bikes, but it never felt particularly sketchy either. The flip-chip in the upper shock mount allows you to steepen the head and seat tube angles by 0.5-degrees and raise the bottom bracket by 5mm, which may appeal to riders in mellower terrain.

The Izzo has a progressive suspension feel that isn't necessarily the most forgiving but contributes to the bike's lively feel. We settled on 25% sag which we felt provided excellent mid-stroke support for pushing, pumping, and popping off and over obstacles in the trail (YT has a suspension setup guide on their website to help with initial setup). It also never felt like it was wallowing or bogging down when we got on the gas out a corner. Small bump compliance was good, but it didn't feel quite as supple off the top as some other bikes. Ample progression at the end of the stroke meant that we rarely found the end of the 130mm of travel except for a few super flat landings. Of course, with just 130mm of travel to work with, we found it best to pop over chattery sections when possible and chose to pick our way through super rough sections rather than just plow. Similarly, at the front of the bike, the 130mm of travel is adequate for most situations that the rider choosing an Izzo will encounter most frequently. If you're looking for a bike to smash through rowdy terrain, there are better options. If you're looking for a fast, fun, and lightweight bike for XC style or light trail riding, the Izzo has you covered.

We found it hard not to be impressed by the Core 4 build we tested. This bike is very smartly specced by YT to match their intentions for the Izzo, and the price to build ratio is sky-high. First, the Fox Factory suspension components are top-notch. The Fox Float 34 fork has the Grip2 damper and features plenty of adjustments to dial it exactly how you like. This fork is also lightweight and stiff enough to handle the type of riding this bike encourages. The Fox DPS rear shock handles the rear suspension duties well with external rebound adjustment and a 3-position compression damping switch. Our only complaint is that the valve is somewhat tricky to access with certain shock pumps. The SRAM G2 RSC brakes work well, with numerous adjustments, good modulation, and a 200mm rotor in the front to provide plenty of stopping power. The 780mm Race Face Next R carbon handlebar provides excellent steering leverage, although we'd probably swap the stock 60mm stem for something a little shorter. Our large test bike came with a 150mm YT Postman dropper which we found to be plenty reliable, although our long-legged tester could have easily fit a longer travel post. The DT Swiss XMC 1501 Carbon wheels are light, stiff, precise, and they feel quite durable. If DT Swiss is listening though, we feel they should have faster engagement than 10-degrees come standard on their high-end wheels. The Maxxis ForeKaster tires are an interesting choice that speaks directly to the Izzo's light and fast intentions. These tires are light and fast-rolling, and we were actually pleasantly surprised by their cornering traction. That said, riders who frequent rockier terrain will likely want to swap them out for something burlier, a relatively inexpensive upgrade.

Uphill Performance

Starting a climb from the trailhead on the first test ride, it was immediately apparent that the Izzo was a zippy climber. Not only is this bike pretty darn lightweight at 27.5 lbs (size large), but we found the suspension to feel relatively calm and the stiff frame and high-end components came together for an overall feeling of efficiency. This is the kind of bike that almost begs you to push the pace and stay on the gas.

The geometry of the Izzo is generally quite comfortable and contributes to its responsive handling and maneuverability. The 77-degree effective seat tube angle is in line with modern standards, although the actual seat tube angle is a bit slacker than that. Tall riders, like our lead tester, may find themselves a bit further back than they're used to, though we were able to compensate for it by slamming the saddle forward as far as it would go. Once the seat position was adjusted, we found a comfortable position right above the cranks. The relatively short 432mm chainstays, moderate length 1,209mm wheelbase, and 66-degree head tube angle (low position) make this bike feel very responsive and easy to control, and picking your way through technical sections and negotiating tight switchbacks is a breeze. The 472mm reach length is plenty spacious, and the 60mm stem stretches it out a bit more than that. Compared to some trail bikes, the front end of the Izzo feels a little lower, but we feel it works well for its almost race-inspired feel. The 334mm bottom bracket height (low setting) means that your cranks are pretty close to the ground once the suspension sags, and we definitely had a few pedal strikes as we were figuring it out.

The Horst Link suspension platform provides a relatively calm pedal platform. It remains active enough to provide excellent traction in the shock's open position but barely moves at all under smooth, seated pedaling. Out of the saddle efforts result in a fair amount of suspension movement, but we never found it to be a crippling issue. The rear shock has a 3-position compression damping/climbing switch, and we occasionally used the middle/trail position when gunning for uphill KOMs and PRs, but otherwise just left the shock open. The stiff frame and tightness of the whole Core 4 package also just makes it feel like all of your effort is going into forward momentum.

On the climbs, the components of the Core 4 build are impressive. The drivetrain consists of a full SRAM XO1 kit including the derailleur, shifter, cassette, chain, and carbon crankset. This setup provides crisp shifting and plenty of gear range to tackle just about any steepness of climb. The Maxxis ForeKaster tires are lightweight, fast-rolling, and they provide great traction in the right conditions. The tires are mounted to a set of DT Swiss XMC 1501 carbon wheels. These wheels are lightweight and stiff, and along with the ForeKaster tires they help to give this bike its zippy feel with low rotational weight. We do have one gripe with the wheels, however, and we lodge this complaint with DT Swiss. The 240 hubs are nice and all, but they have 10-degree freehub engagement which we feel is sub-par for a high-end carbon wheelset. Sure, it works, but a bike like the Izzo deserves faster engagement than that. On a more positive note, the SDG Bel-Air 3.0 saddle is super comfortable and is quickly becoming one of our favorites.

Photo Tour

Value

YT's direct sales model brings a lot of value to the consumer. This carbon-framed bike comes with a component specification that would cost significantly more from a mainstream brand. While the retail price of this bike is no small potatoes, it is definitely an excellent value. That said, the Izzo Core 4 will be the best value to the rider seeking a lightweight trail bike that's more about speed and covering distance than it is about getting rowdy. It also comes in two other less expensive builds as well as the Blaze edition with a longer travel fork.

Conclusion

The Izzo Core 4 is a shorter travel trail bike that truly shines for its light weight, razor-sharp handling, and all-around quickness. This bike is fast both up and down the hill and it operates with agility and precision that few other models we've tested can match. It's not the best choice for super aggressive riders or terrain, but that isn't what it was designed for either. If you prioritize weight, quick handling, and your style or terrain leans a bit more towards the XC side of things, we feel the Izzo is an excellent option to consider and a great value too.

Build Options

The Izzo is currently offered in three Core build options including the Core 4 we tested which sits at the top of the line. It also comes in a Blaze build that comes with a 140mm travel fork.

The Core 3 is the mid-range model that costs $1,300 less than the Core 4. It comes with Fox Performance Elite level suspension, a SRAM GX Eagle drivetrain, SRAM G2 R brakes, and DT Swiss M 1900 Spline wheels.

The Core 2 is the least expensive build. It has a carbon front triangle paired with an aluminum rear. It comes with Fox Performance level suspension, a SRAM NX Eagle drivetrain, SRAM G2 R brakes, and DT Swiss M 1900 Spline wheels.