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2020 Calibre Bossnut review

Refined version of a budget classic

Our rating 
4.5 out of 5 star rating 4.5
GBP £1,100.00 RRP
With Go Outdoors discount card
Best mountain bikes under £1,000

Our review

Impeccable trail performance for the money and an excellent-value spec too
Pros: Good shape; great kit for the money; amazing trail manners
Cons: Non-Boost axles limit your wheel upgrade options; SRAM Level T brakes lack power with stock 160/180mm rotors
Skip to view product specifications

At this price there’s not much trail-ready competition for the Bossnut, but that hasn’t stopped Calibre improving the bike.


The latest version has a decent shape, adjustable suspension front and rear, and a 12-speed SRAM Eagle groupset – all for the same cost as the fork on some bikes.

Calibre Bossnut frame

The alloy frame delivers 130mm of travel via a single-pivot swingarm and linkage-driven shock. A (non-Boost) thru-axle helps stiffen up the rear end.

The top tube drops a touch on its way towards the seat tube to boost standover height. There’s a pair of bottle cage bosses under the down tube. External cable routing keeps maintenance simple, and there’s provision for a future dropper post upgrade.

Calibre Bossnut
The Calibre Bossnut is an easy-riding trail bike.
Laurence Crossman-Emms

While not revolutionary, the geometry is on the money for an easy-riding trail bike.

On the large, that means a reach of 460mm, a 66-degree head angle and 74.5-degree seat angle.

The seat tube is fairly long, at 480mm, while the chainstays are relatively short, at 436mm, and the bottom bracket sits 24mm below the axles.

Calibre Bossnut kit

SRAM features heavily on the Bossnut, taking care of both the drivetrain and the suspension.

Up front there’s a 130mm-travel RockShox Recon RL fork, with adjustable low-speed compression and rebound damping. This is paired with a Monarch R shock.

SRAM’s new SX Eagle drivetrain provides the drive, with its 11-50t cassette, while its Level T brakes bring it to a halt.

WTB i29 rims provide a wide base for the Vigilante and Trail Boss tyres from the same stable – a highlight being the High Grip compound used on the heavily-treaded front tyre.

The finishing kit is Calibre’s own.

Calibre Bossnut ride impressions

It’s no surprise the Bossnut is so popular because it provides the best all-round trail performance of any bike at this price.

On climbs, it’s fairly stable, unless you’re really hauling on the pedals. There’s no low-speed compression lever on the shock, which would help temper any bob, but when sitting and spinning it’s fairly efficient. This is helped by the faster-rolling Trail Boss rear tyre, which doesn’t suck too much speed.

On flatter, pedalling-heavy trails, there’s a fair bit of zing to the ride. The Bossnut is eager to accelerate and, with its neutral shape, is easy to control around corners and pop off rollers and roots.

That grippy front tyre, which has a good shape on the 29mm (internal) rim, gives you confidence to hit corners with decent speed, knowing that it’ll likely keep on gripping through to the exit.

The Trail Boss at the rear is predictable in looser conditions, although if you’re going to ride the muddiest of tracks, you’ll want more traction.

The Bossnut continues to impress on descents too. Its rear suspension isn’t the most refined out there, with a hint of kick on the biggest impacts, but for the most part it’s well-controlled and predictable, once you’ve dialled in the rebound.

On chattery trails, the harder-compound rear tyre skips around a bit, but the shape of the bike means you can keep it in check and generally ride it out until you hit the next smooth section of trail.

There’s enough support to allow you to push the bike through rollers and berms, generating extra speed, without it feeling too wallowy.

Calibre Bossnut
The Bossnut is eager to accelerate and easy to control around corners and pop off rollers and roots.
Laurence Crossman-Emms

Although the fork has enough adjustability built in to allow it to tame most tracks, the relatively skinny legs do flex through the biggest compressions and impacts, and the fairly basic Motion Control damping can get choked up.

While I’m being critical, the Level T brakes are one of the first things I’d upgrade because extra power would be welcome on longer descents. Fortunately, there’s no need to replace the brakes themselves because just fitting bigger rotors should improve things for not too much cash.

The addition of a dropper post would set you back a bit more – although you can now get reliable models for under £150 – but would further enhance an already excellent bike.

Riding the Bossnut, it’s easy to forget just how little it costs compared to most full-sussers because its performance rivals that of trail bikes that would set you back hundreds of pounds more.


For the money, I’m left scratching my head trying to think of another bike that competes. It’s not quite perfect – I’d love to see Boost-width axles front and rear, for example, simply because the frame is such a great base to upgrade from and that would open up many more wheel options – but it’s as close as you’ll get for this kind of money.

Product Specifications


Price GBP £1100.00
Weight 15.3kg (L) – Without pedals
Brand Calibre


Available sizes S, M, L, XL
Brakes SRAM Level T, 180/160mm rotors
Cassette SRAM SX Eagle
Cranks SRAM SX Eagle
Fork RockShox Recon RL, 130mm (5.1in) travel
Frame Hydroformed 6061 aluminium alloy, 130mm (5.1in) travel
Handlebar Calibre, 780mm
Rear derailleur SRAM SX Eagle
Rear shock RockShox Monarch R
Saddle Calibre Trail
Seatpost Calibre rigid
Shifter SRAM SX Eagle
Stem Calibre, 45mm
Tyres WTB Vigilante High Grip Comp (f) and WTB Trail Boss Comp (r) 27.5x2.3in
Wheels WTB i29 rims on Formula hubs