£1,500 vs £4,500 trail bike: do you really need to spend the extra money on your next MTB?

Calibre Bossnut

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The previous Bossnut’s heritage of offering amazing bang-for-buck is well and truly alive in this latest model.

Updated with modern geometry and a frame adorned with functional yet cost-effective kit, even the non-members £1,700 asking price is appealing.

It’s got an X-Fusion Manic dropper post, 1x Shimano drivetrain and Maxxis tyres. On paper, this 29in-wheel trail bike is the bargain of the century.

Calibre Bossnut specifications

• Weight: 16.71kg (36.86lb), large size without pedals
• Sizes: XS, S, M, L*, XL
• Frame: 6061 aluminium, 135mm (5.3in) travel
• Fork: RockShox Recon Silver RL, 140mm (5.5in) travel
• Shock: RockShox Deluxe Select R
• Cranks: Shimano CUES 32T
• Cassette: Shimano CS-LG300, 10 speed, 11-48T
• Rear Mech: Shimano RD-U600 CUES
• Shifter: Shimano SL-U6000-10R CUES
• Wheelset: 30mm alloy rims on Shimano TC-500 Boost hubs
• Tyres: Maxxis Minion DHF 29x2.5in (f) and Maxxis Forekaster 29x2.4in (r)
• Brakes: Shimano BL-MT401 and MT410, 180/180mm rotors
• Bar: Unbranded alloy, 780mm
• Stem: Unbranded, 45mm
• Seatpost: X-Fusion Manic 170mm dropper
• Saddle: Calibre Trail
• Price: £1,700 (£1,499 with Go Outdoors members card)

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YT Izzo Core 3

Recently updated, YT’s 130mm-travel Izzo runs on 29in wheels with a 140mm Öhlins RFX36 m.3. fork and a high-spec Öhlins TTX1 Air rear shock.

Elsewhere, it features more performance-focused parts, including Maxxis tyres, a Shimano SLX drivetrain with the all-important XT shifter and SLX brakes, plus finishing kit from Renthal. These parts are hung on an Ultra-Modulus carbon fibre frame, giving the Izzo a super-premium feel without a prohibitive price tag.

Even at full retail, it’s a bargain, but reduce the price by £700 (as it currently is) and it’s a steal. The five-size range boasts a 66-degree head angle and 77-degree seat tube angle, along with generous reach figures, cementing its status as a lightweight trail bike.

YT Izzo Core 3 specifications

• Weight: 14.19kg (31.28lb), large size without pedals
• Sizes: S, M, L*, XL, XXL
• Frame: Ultra-modulus carbon, 130mm (5.1in) travel
• Fork: Öhlins RXF36 m.3, 140mm (5.5in) travel
• Shock: Öhlins TTX1 Air
• Cranks: Shimano SLX
• Cassette: Shimano SLX M7100
• Rear Mech: Shimano SLX M7100
• Shifter: Shimano XT
• Wheelset: DT Swiss XM1700
• Tyres: Maxxis Minion DHR 29x2.4in (f) and Maxxis Minion DHR 29x2.4in (r) tyres
• Brakes: Shimano SLX M7100, 203/180mm rotors
• Bar: Renthal Fatbar 35 Alloy, 780mm
• Stem: Renthal Apex, 50mm
• Grips: ODI Elite Motion V2.1
• Seatpost: YT Postman V2 150mm dropper
• Saddle: SDG Be Air Overland 3.0
• Price: £4,499 (reduced to £3,799)

Details deep dive

Starting with the frames, there’s already a cavernous divide. While the Bossnut’s alloy front and rear triangles are far from clunky and ugly, they’re still less sleek and more industrial-looking than the Izzo’s high-tech carbon tubing.

But the devil is in the details; while the Bossnut’s general outline isn’t miles apart from other alloy mountain bikes, money has clearly been saved once you look a bit closer.

Forgoing internal cable routing, the bike’s brake lines, and shifter and dropper cables are routed along the top of the down tube and stays using bosses.

Mechanics and tinkerers will rejoice at how easy these will be to replace, while those focused on aesthetics are likely to be scornful of its looks.

Equally, the lack of chain-slap protection is another good example of how a brand can shave off precious pennies without negatively impacting performance, even if it means the bike’s noisier riding downhill.

Reminding you the Bossnut’s been built to a tight price, the under-top-tube accessory mount and water bottle bosses extrude from their tubes’ surfaces rather than sitting flush within them.

Of course, the Izzo’s also been built to a price. The frame’s construction will need to sit within certain parameters, but you only need to take one look at it to see things are slicker.

Cables are routed internally via ports and there’s a healthy amount of chain-slap protection. Likewise, the bottle and accessory bosses are recessed into the carbon tubes.

And those tubes are smooth, slender and beautifully shaped. Unlike the Bossnut, the Izzo has SRAM’s Universal Derailleur Hanger, the patent and design files for which are open source.

Adding it is virtually cost-free and it future-proofs the frame for any upcoming drivetrain innovations.

As a bonus, it means hanger replacement is easier than a bespoke design. It’s a shame Calibre couldn’t get the UDH to work on the Bossnut.

Geometry

Calibre Bossnut

The Bossnut is living proof that decent geometry is free. Up-front, it’s got a 64.5-degree head angle, ideal for the trail riding it’s designed for. Likewise, there’s an effective (claimed) 78-degree seat tube angle, which is as steep as it needs to be.

Reach figures are bang on for each of its five sizes, spanning 420mm for the XS up to 500mm for the XL.

Then there’s the chainstay length, which apart from the XS bike’s 425mm is 445mm across the range. The XS runs 27.5in hoops, while the rest of the size range is on 29ers. Once again, this is spot-on. Calibre’s gone all-in with the bike’s geo figures and proven unequivocally that doing so costs no extra money.

YT Izzo Core 3

The Izzo’s geometry is also a representative example of what a lightweight trail bike should be. But the extra cost on its asking price affords you geometry adjustment, where it can be switched between high and low settings.

This changes the head and seat tube angles by 0.5 degrees and the bottom bracket height by 5mm. The adjustments are hardly monumental, but it’s a neat feature that helps justify the extra cost.

Key figures include (in the low position) a 66-degree head angle, 77-degree seat tube angle (claimed), 334mm bottom bracket height and different chainstay lengths depending on size. XL and XXL frames in the five-size range get 437mm stays compared to the S through to L’s 432mm figure. Reach numbers are spot-on, with my size large measuring 472mm.

On paper, the Izzo looks like the more conservative bike, but there’s more to it than that. Some of the secret ingredients – where a bike’s performance is a culmination of all its parts – will be at play to expand its feel beyond just numbers and specs.

Suspension showdown

It’s not always the amount of travel that matters, but rather how it’s damped and the design’s kinematics.

In the case of our two contenders, the Izzo has 130mm of rear-wheel Horst-link squish and the Bossnut has 135mm of single-pivot linkage-driven travel.

The five-millimetre difference is virtually negligible, but the Horst-link and single-pivot designs are functionally quite different because the rear wheel axle is connected to the seatstay rather than chainstay.

This means anti-rise – which is how the suspension is affected when applying the rear brake – is easier to tune and can be tuned independently of anti-squat – which is how pedalling interacts with the suspension (think pedal bob).

On paper, the Horst-link design is better, but many manufacturers have proven the linkage-actuated single pivot can still be a top performer.

Component comparison

The price difference is highlighted most starkly in each bike’s specs. The Izzo has Öhlins’ newest RXF36 m.3 fork with three different damper adjustments and two ways to tune the air spring, with the potential for a wide range of internal re-tunes.

This makes RockShox’s Recon on the Bossnut look rather stone age by comparison, with a simple air spring, external rebound adjustment and a compression threshold lever.

It’s the same at the rear end of both bikes; the Calibre’s RockShox Deluxe Select damper only has spring and rebound adjustment, while the Öhlins unit on the Izzo has four ways to fettle it, along with a host of possible internal tweaks.

Elsewhere, the story continues; YT’s 12-speed Shimano SLX drivetrain – with crisp XT shifter – goes up against the CUES 10-speed system of the Bossnut.

While a smaller number of gear ratios isn’t an issue if the spread of gears remains the same, you also lose the 51t lowest sprocket of the SLX system for a 48t maximum on CUES.

The DT Swiss XM 1700 wheels complement the rest of the Izzo’s high-quality parts, including a Renthal bar and stem, SDG saddle and SLX brakes.

In the Bossnut camp, own-brand rims are laced to basic Shimano TC500 hubs, and it’s got an unbranded bar and stem, an own-brand saddle and Shimano’s non-series MT410 brakes.

Both rigs run Maxxis tyres, but the YT’s are triple-compound MaxxTerra variants and the Bossnut’s are the hardest-wearing dual-compound versions. Again, it’s clear to see how spending more improves the bike’s kit.

With this luxurious spec comes a significant weight advantage. The large Izzo is 14.19kg without pedals, edging closer to downcountry bike figures rather than all-mountain bruiser territory. On the other hand, at over 2.5kg more, the 16.71kg Bossnut (size large) is as weighty as some enduro bikes.

Top of the mountain

What does all this mean where it matters out on the trails? Pointing uphill, the Izzo’s got loads of pep in its step thanks to that impressive headline weight.

This feels rewarding when you’re fighting gravity’s cruel laws on the steepest inclines; fewer of your legs' precious watts are lost to a weighty bike, and you’ll scale climbs quicker and more easily compared to the heavier Bossnut. But it’s not as clear-cut as 'the lighter it is, the better it is'.

The Izzo’s seat tube angle – while steep on paper – feels slack in reality, especially with your seat at full mast.

At my preferred seat height, I measured it at a relatively slack 74.5 degrees. Here, your hips are behind the bottom bracket rather than directly over it, which influences pedalling efficiency and comfort.

The seat tube angle isn’t the slackest-feeling on the market and, if you’ve only ridden the Izzo, you’ll struggle to notice it.

Once you’ve adjusted your seat nose down and pushed it as far forward on its rails as you can, it’s less of an issue.

But it’s when you jump on another bike with a steeper figure that the differences are highlighted. The Bossnut is only one degree steeper on paper, but it's two degrees more upright in reality.

Measuring 76.5 degrees at my preferred saddle height, out on the trails the difference is palpable.

Putting your hips more over the BB, the Calibre has a comfier, more upright riding position, where your back is straighter and more perpendicular to the floor.

It’s vastly more efficient to pedal with your feet beneath your body than out in front of it, as you do with a slacker seat tube angle.

For high-paced vision-blurring efforts, it’s not as aggressive as the more stretched-out Izzo, but whenever you’re not absolutely burying yourself, it’s more comfortable and relaxing to ride.

There’s still more at play. The Bossnut’s chainstay figure – longer by 13mm on my large bike – helps centralise your weight between the front and rear wheel axles.

Significantly steepen trail gradient and technicality, and you’ll be grateful to be sitting closer to the middle of the bike; accidental rearward weight shifts don’t rare up the front, reducing steering control.

Equally, weight shifts too far forward don’t cause the rear wheel to instantly spin; instances of skidding as if you’ve run over a banana peel in Mario Kart are fewer and further between.

On the Izzo, smaller intuitive weight shifts are continually exchanged between you and the bike to keep both wheels in check.

The shorter rear end means you need to be sharper and more concise with any of your inputs if you want to make the same level of subdued, controlled progress as you would on a longer rig such as the Bossnut.

Increasing complexity

However, the complications don’t stop there; if anything, the level of complexity doubles down once you start thinking about each bike’s suspension design and components.

The Izzo’s Horst-link design is taut and rigid on the gas, barely flinching as you pedal with intent on short sprints or long burns. Speed is one of the Izzo’s biggest draws.

While the Horst-link is generally renowned for being balanced and well-rounded, how it’s executed on the Izzo pushes the bike further into the realms of efficiency over comfort.

Factors such as leverage ratio and shock tune combine to create this, but there’s no denying the result is lacking in plushness.

The Bossnut’s also not as smooth as it could be, which is caused most likely by the rudimentary damper.

While its heft and general feel give the impression it’s a bigger, burlier bike, the rear end doesn’t live up to those expectations. It’s far from harsh, but neither is it as plush and trail-smoothing as it could be.

On both the Izzo and Bossnut, damper re-tunes or upgrades could help boost performance in line with plusher bikes if you’re looking for a more cushioned rather than faster ride.

Then we focus on the components. The Bossnut’s hard dual-compound Maxxis tyres – while adorned with a big name and clad with the best tread patterns – feel pingy and harsh.

Super-technical ascents, littered with rocks and roots, are challenging – especially if they’re wet. The tyres deflect off rather than stick to the ground.

The Izzo’s much calmer here, with the triple-compound and thicker-casing rubber doing a better job of adhering to the trail’s surface and muting any teeth-rattling vibrations.

Like the tyres, both bikes’ drivetrains share Shimano branding. However, the Izzo’s 12-speed setup is better than the 10-speed CUES on the Bossnut.

The limited range and 48t lowest sprocket make the Bossnut harder to pedal uphill than the Izzo – you need to be stronger and fitter.

Combine this with its added weight and, if climbing at pace is your bag, you’ll be grateful to be on the Izzo.

Downhill domination

Like the climbs, both bikes have distinct personalities on the downhills. For the most part, this comes from their vastly different front and rear dampers; the Bossnut’s RockShox Recon is free-moving on slower, smoother hits, but it struggles to insulate you from harsher square-edged ones.

Increase your speed – and therefore the ferocity with which you’re hitting bumps – and it can’t compress quickly enough on successive impacts without spiking.

Even one-off compressions, such as a chunky rocks or roots, reverberate through the handlebar, requiring a fair amount of skill and forward planning to help you keep tracking your chosen line.

This performance feels at odds with the skills of riders who are most likely to be enticed by its entry-level price tag; beginners are going to need all the help they can get.

Adding insult to injury, the choked high speed is matched with a lack of low-speed compression damping.

Undulations and weight shifts cause the fork to oscillate in and out of its travel, upsetting its balance and necessitating constant corrective movements. Like the tyres, this potentially puts speed and control out of your grasp.

The YT’s high-tech fork, unsurprisingly, is way more supple and supportive than the basic Recon. The newest RXF36 m.3 feels excellent whether you’re cruising or smashing your way down the trail.

Its performance bandwidth far exceeds what the Izzo’s frame is capable of, making it a worthy partner for even the rowdiest trails.

The damper has loads of low-down grunt, providing resistance against weight shifts, while it’s still free to flutter in and out of its travel at the start of its stroke.

Switch your focus to the rear of the bike and, unless you’re absolutely nailing it, it’s the Bossnut that feels better. While the Calibre’s 5mm of extra travel is unlikely to make any difference, the shock’s tune – which is much lighter on the Bossnut – has a big effect.

The Izzo’s damper isn’t especially plush nor forgiving, unless you’re riding at the bike’s limits. Just cruising about, it’s got a numb, dead and harsh feel to it; impacts aren’t absorbed freely, and smoothness always seems to be a few extra but non-existent damper adjustments away from your reach (I had the shock’s adjusters fully open).

Increase your riding intensity to heavy-handed and it gets better.

The harder you work the shock, the more it moves in and out of its travel, but no matter how much fettling I did with its settings, I couldn’t get it to feel plush.

The Bossnut – despite its less-tuneable single-pivot suspension – felt much freer to move in and out of its travel, providing comfort and control at lower speeds. While the Calibre’s performance is good, it’s far from the cure-all panacea for riding with reckless abandon some riders may be looking for.

Both bikes, in my opinion, would massively benefit from re-tuned or upgraded dampers – there’s performance potential, but it evades you unless you’re riding in a very specific way.

Hard rubber

But what the Izzo loses in smoothness, grip and control from its damper, it more than makes up for with its tyres.

The MaxxTerra-compound DHR II combination sticks convincingly to treacherous terrain, especially when compared to the dual-compound models fitted to the Bossnut.

On the Calibre, you’ll be fighting your way through slick rocks and roots, where I often chose to deviate from my line to avoid losing control.

A tyre upgrade – unless you’re riding sedate fireroads or green trail-centre runs – will be essential for most riders on the more affordable bike.

Line choice

Switching to the bikes’ geometry and the Bossnut proves two things. Firstly, that top-performing figures are totally free, and secondly, a bike’s overall performance is the sum of its parts.

Here, the slacker head tube angle and long chainstays play significantly in the Calibre’s favour, providing a calm platform from which you can explore and get creative with lines down the trail.

There’s an inherent stability that makes riding easier, unlocking skill progression and confidence that bikes with less generous figures can’t.

But no matter how good a bike’s geometry is, if it doesn’t have the components to back up that performance, it’s wasted; the Bossnut’s parts are great for the cash, but they still put a glass ceiling on its performance.

The YT’s figures give it a different character on the downs; handling is responsive and quick rather than inert and lazy. The gnarlier the trail, the more you need to have your wits about you, but this can be fun and engaging – especially once you reach top speed and have the skills to hold on.

Sensations of high-paced intensity are reached sooner compared to calmer-feeling bikes; this means you don’t need to go as fast to get the same sort of rush.

While the Bossnut’s longer, slacker figures offer up more performance potential than the Izzo, its spec limits overall speed and composure, tipping the balance in the YT’s favour.