Best MTB of the Year: Calibre Bossnut

The first thing I want to make clear about our MTB of the Year for 2024 choice is: this is not just because it’s cheap. It’s not even because it’s cheap and decent. The Calibre Bossnut is our MTB of the Year because it is brilliant.

• Brand: Calibre
• Product: Bossnut
• Price: £1,700
• From: Calibre Bicycles
• Tested by: Benji for 5 months

Pros

• Great geometry
• Good suspension
• Still unbeatable value

Cons

• Not UDH
• No chainstay protection (yet)
• Price fluctuation

A word from Jonny, the designer:

Calibre Bossnut review

The first thing I want to make clear about our MTB of the Year for 2024 choice is: this is not just because it’s cheap. It’s not even because it’s cheap and decent. The Calibre Bossnut is our MTB of the Year because it is brilliant. And cheap.

Even with it being considerably more expensive than the original £1,000 Bossnut (which is getting on for ten years ago now), not to mention more expensive than the £1,500 price tag it launched with last autumn, at the current SRP of £1,700 it is still far and away the best ‘budget’ bike out there right now.

Enough talk of value. Everyone can see what spec you get for the money. You don’t need me to break it down for you. I’m here to tell you what you don’t know; how it rides.

How does it ride?

My overriding thought is that the new Bossnut is way better than any of the previous 27.5 Bossnuts. Yep, the new Bossnut is a full 29er. Which is totally the correct move for a trail bike. That said, the very smallest (kid jibber friendly) XS size is a 27.5in bike. There will also be an aftermarket clevis link available to make the S-XL sizes into mullet machines.

In terms of amount of travel, the new Bossnut has gone up 5mm at the rear (to 135mm travel) and increased 10mm up front (to 140mm travel fork).

In actual fact I think the new 135/140mm travel Bossnut is better approached as a slammed version of the 150/160mm travel Calibre Sentry. Not only does it aesthetically much more closely resemble the Sentry, but the whole attitude and handling of the Bossnut is way more capable than old Bossnuts.

The very first ride on the Bossnut pretty much told me everything I needed to know. The bike needs a bigger front disc rotor (it comes with 180mm rotors front and rear). Because this bike can smash the heck out of anything you sling it at. Nothing – apart from the front brake power – really feels like it’s holding you back from riding just as full-on as you do on top-end mountain bikes. A 203mm rotor would be the first thing on my upgrade list. More about the potential upgrade path later.

Tellingly, I was surprised to see how much it weighed (16.6kg for this XL). Surprised yet not surprised; overall bike weight is so not the whole story. The Bossnut has a super efficient geometry and a super punchy and responsive suspension feel. It also has Shimano TC500 hubs which seem to roll for days. Not to mention a great choice of rear tyre (Maxxis Forekaster).

You’re well-balanced, in a good position, with ‘rally car’ suspension, on sweet spinning wheels and zippy rear rubber. There are much lighter but much more inefficient bikes out there, that’s for sure.

The suspension stuff

The rear suspension, in my opinion, is exceptionally well executed. The bike is super stable and solid at its dynamic ride/sag height. It’s hard to describe how it feels but I’ll give it a go… It’s quick and silky below the sag point but supportive and reassuring above it (in the sag-to-bottom-out zone). It was still possible to achieve full travel when needed, it doesn’t ramp up crazily progressive. It reminded me of how new generation Saracen Ariels behave, which is no bad thing.

As mentioned, it very much has a rally car feel. It’s not a cushy old Citroen or Rolls Royce. It’s a bike that digs in for traction as opposed to soaks up. Which can make it a bit of handful on roots and wet rock but that can be offset by running softer compound tyres and/or letting some psi out of the tyres.

The front suspension – 140mm RockShox Recon Silver RL fork – may look as cheap as it is, and the dials are pretty rough feeling in actuation, but the actual on-trail performance was impressive. There was no notchiness or spiking or unpredictable rebound ker-twanging. And it was plenty stiff enough for my weight (73kg).

Although it’s tempting to say that a new fork would be another item high up the upgrade wishlist, the fact of the matter is that significantly better forks cost a heck of a lot of money these days. I’d be looking at upgrading the internals of the existing Recon to something better (this is exactly what I’m researching at the moment in fact).

Geometry is its trump card

The Bossnut has a set of geometry numbers that are pretty much bang on. Whilst personally, I’d probably tweak a couple of things a few mm here and there, ultimately the set of geo numbers sported by the new Bossnut is some of the best you’ll find at any price point.

The head angle chart may say 64.5° but by my measuring it’s much closer to 64° (and dynamically rides slacker). The long reach and actually steep seat angle (77° ish by my reckoning) put you in a lovely position for seated riding/climbing with plenty of force being directed into both wheels. It’s great not having to be constantly fluctuating between front tyre or rear tyre with where you need to put your traction at any given moment. Again, it’s just way more efficient and energy saving.

The chainstays may not be on-trend lengthy ones (for taller riders) but at 445mm they’re in a manageable window and the low-slung bottom bracket height does help with keeping things grounded and preventing front wheel lift on truly steep uphill pitches.

The low BB is one of the things to be aware of. If your terrain or riding style is prone to pedal strikes, the Bossnut may not be for you. It’s not something you can cure by running less sag in the rear shock; the rear shock sag needs to be around 30% to get the best overall performance out if it. As it is, I did consciously opt to run the slimmest pedals I could find when riding the Bossnut. Despite not being very glam, or indeed cheap, shorter cranks would probably be very high up my upgrade list.

All-round trail bike

But yeah, generally the geometry – in tandem with the supportive suspension – makes for a bike with excellent handling that can handle everything you choose to through it at. Uphill or downhill or technical traverses. It can do it all with a panache that totally belies its price tag.

The frame is decently put together and offers a neutral-to-lively chassis feel. It doesn’t feel like a dead stick, nor does it yaw undesirably under G-out turns or anything. There really is not a whole lot wrong with boring old aluminium tubing when it’s done well.

The Bossnut is no longer just interested in gravity assisted bombing. The Bossnut is a true trail bike that can turn its hand to anything and everything pretty much.

The new Bossnut is not a My First MTB that you’ll ditch and move on to a ‘proper brand’ offering. It outclasses the big brands where it counts. Essentially it’s a bike you will not want to give up. You’ll keep it and upgrade it, personalise it, into the perfect trail bike for your needs.

Which, by the way, is what we’re going to do with it throughout 2025. We’re keeping hold of the Bossnut to act as our testbed trail bike.

Build kit

Whilst it’s not technically ‘build kit’, I’m a massive fan of external cable routing as that found on the Bossnut. Not only does it make maintenance and parts swapping/upgrading miles easier, it’s also quieter than the sort of internal routing you encounter on so-called budget bikes.

The silence afforded by the external cabling does mean however that you soon notice the chain slap. The Bossnut does not currently come with a chainstay protector. There is one promised and it will be available aftermarket but for the time being it’s a case of providing your own (we had an inner tube wrapped around our driveside chainstay).

The other slightly rough edge you notice is the drivetrain. In the extreme top and bottom gears, there’s a distinct grumble to felt in your feet as you pedal. This roughness did ease off a bit during the test period as the parts wore into each other but it never entirely disappeared. This is just a fact of life with lower end drivetrains. The 10-speed CUES drivetrain shifted just fine and it’s not something I’d be in a rush to upgrade until something actually completely wore out.

As mentioned earlier, the brakes weren’t bad but they weren’t up to the capability of the rest of the bike. After a few rides I did up the rotor to 203mm and this really did unleash the bike’s potential. The brake levers may look a bit budget but the lever feel was really good and totally consistent. Honestly, with larger rotors and high quality brake pads, I’d be fine to keep these brakes on for the foreseeable.

The no-name stem and handlebar did the job and most folks will be fine with this set-up. As usual with almost all XL bikes I encounter, I think the supplied 780x20mm bar is too low a rise. With a 40-50mm riser bar on there this XL Bossnut was a better beast.

The own-brand lock-on grips were lovely. Quite possibly the best lock-on grip I’ve encountered in fact. A complete polar opposite experience of most chainstore or direct-sales bike grips. These delightful cushy mushroomy grips have a very slight taper to them, and are single collar. If Calibre sell these as an aftermarket item, I’m going to stock up on them!

The own-brand saddle was nothing to write home about but it was fine and has stayed in place atop the X-Fusion Manic dropper post. With 170mm travel it may offer a bit less drop than my privileged posterior is used to but it’s noticeably more useful than the 125-150mm travel droppers you get on entry-level full-sussers.

The wheels and tyres were something of a surprise and a highlight. The wheels rolled sweetly and are tubeless ready (I converted them to tubeless after a month or so of testing with no trouble). The Maxxis tyres are a very well chosen pairing for all-round trail duties. The Minion DHF up front is still a great tyre. The Forekaster out back is fast-rolling which may lack a bit in braking traction but does just fine when cornering or climbing.

Anything else? There’s room for a bottle and there are two sets of accessory bolts under the top tube. Which is nice.

Overall

The Calibre Bossnut has what it takes to start mountain biking. It has way more than that. The new Bossnut can go toe to toe with any other trail bike out there. It will actually cope better than most of them too. This bike has dialled geometry, excellent suspension and a decent build kit that can tackle every and any sort of terrain. You don’t really have to change anything on this bike from the get-go but that said, the Bossnut is just going to get even better as you ride it, upgrade it and live it with it over the ensuing years of mountain biking joy.

Calibre Bossnut specification

• Frame // 6061 alloy, 135mm
• Shock // RockShox Deluxe Select R, 210×55
• Fork // RockShox Recon Silver RL, 140mm
• Wheels // 30mm ID Tubeless Ready rims on Shimano TC500 hubs
• Front Tyre // Maxxis Minion DHF EXO 29×2.5in
• Rear Tyre // Maxxis Forekaster EXO 29×2.4in
• Chainset // Shimano CUES, 170mm, 32T
• Drivetrain // Shimano CUES, 10-speed, 11-48T
• Brakes // Shimano MT401, 180/180mm
• Stem // Alloy 31.8mm, 45mm
• Handlebars // Alloy 31.8, 780x20mm, 3° up x 6° back
• Grips // Calibre Ribbed Lock-on
• Seat Post // X-Fusion Manic 170mm
• Saddle // Calibre Trail
• Weight // 16.6kg

Geometry of our XL size

• Head angle // 64.5°
• Effective seat angle // 78°
• Seat tube length // 460mm
• Head tube length // 125mm
• Chainstay // 445mm
• Wheelbase // 1,277mm
• Effective top tube // 636mm
• BB height // 38mm BB drop
• Reach // 500mm

Review Info