Both of these bikes cost less than £1,000 and more importantly were met with huge critical acclaim, performing as well as other bikes many times the price. New for 2018 is the Bossnut Evo, an evolution of the Bossnut, and one that bring select upgrades that should make for an even better bike at no extra cost.
Calibre Bossnut Evo highlights
- Modern, up-to-date geometry on a budget bike
- 130mm travel front and rear
- Air sprung suspension with adjustable damping
- 1x11 SRAM NX drivetrain
- Wider tubeless-ready rims
- Short 45mm stem and wide 780mm bars
- £999 (with £5 discount card) with international shipping available
Frame: the same sorted chassis is now ready for an internal dropper post
The Bossnut Evo is still based on the same 6061 hydroformed aluminium alloy frame, though it now features internal routing for a dropper post. Understandably, Calibre hasn't managed to squeeze a dropper onto this bike but if you do decide to then the 30.9mm seatpost should give you lots of options to consider.
The biggest change on the Bossnut Evo is the move to a 1x11 SRAM NX drivetrain to drop a bit of weight, but more importantly to reduce chain drops. Calibre has really taken heed of what a lot of its customers have been doing anyway. It's also nice to see a proper SRAM cassette specced, which should ensure good shifting.
That doesn’t extend to the chainset, which is from Samox and is a component that we've seen used by Marin for a little while now. Crucially, it also arrives with a narrow-wide 32t chainring, which should help with chain retention and mud clearing.
Geometry remains the same and provides a decent reach of 429mm for a size medium. Couple that with a 66.8-degree head angle, 73.5-degree seat angle and 436mm chainstays and you’ve got a bike that uses modern and up to date geometry (long and slack) comparable to many big-brand competitors, and a long way away from many of the short, steep and twitchy budget frames found at a similar price.
Suspension: uprated fork for 2018
The suspension is a linkage-driven single-pivot design that provides you with 130mm of travel controlled by a RockShox Monarch R shock. Like on the V2, the pivot is a single forged piece that is claimed to improve rear-end stiffness and give better tyre clearances over the first generation bike.
At the front, the fork has been upgraded to a 130mm travel RockShox Recon RL with a 15mm bolted thru-axle. Calibre claims these offer improved stiffness and should in turn provide more accurate steering.
With both the fork and shock being air-sprung, and damping on both easily adjusted, you’ll be able to tune the suspension to your exact requirements. That’s almost unheard of at this price.
Wheels & tyres: wider tubeless-ready rim and more aggressive rear tyre
The chassis rolls on 27.5in wheels, which are now built up with wider WTB ST i29 32 hole rims like those found on the company's Line 10 hardtail. These are laced to a Formula hub at the front, and a QR Shimano hub at the rear. The budget clearly didn't extend to a thru-axle at the rear.
However, it’s definitely nice to see the wide 29mm internal rim width that will help shape tyres nicely, improving stability and cornering performance.
Speaking of tyres, Calibre has stuck with the all-round 2.3in WTB Vigilante front tyre, but chosen a more aggressive (and more suited to wet UK conditions) 2.25in WTB Trail Boss at the back. This should help improve traction and mud-clearing capabilities compared to the tightly packed tread of the previously fitted rear tyre.
While the WTB rims are tubeless compatible, unfortunately the tyres are stuck with the Comp casing. That’s not surprising, but does mean that if you are looking to run a tubeless setup you will have to invest in new tyres. That said, upgrading tyres to something suited to the riding you do is something we would recommend anyway, so it’s not too much of a loss.
The i29 rims are not light by any means, but should provide a robust and sturdy platform for all manner of riding. The claimed weight for the Bossnut Evo stands at a reasonable 32lbs / 14.5kg.
Kit: upgraded brakes and a fresh cockpit
As before, it’s nice to see the simplicity of a standard threaded bottom-bracket and external cable-routing for transmission and brakes.
The Shimano BR-MT500 is essentially a non-series version of the venerable Shimano Deore brakes. These stalwart stoppers with 180mm rotors front and 160mm at the back should provide more than enough power. We’ve always been impressed by how well the budget Shimano brakes perform.
Other changes now see a 45mm stem for all sizes and 780mm wide Kore bars — more than enough width to have the leverage to navigate through twisting, technical, terrain and a departure from the unusually shaped Ritchey items fitted to the first generation bike.
Calibre has very much stuck to the philosophy of “if it ain’t broke don’t fix it.” As the name suggests this is an evolution rather than a revolution, building on the success of the previous frame, with thoughtful component changes to improve performance and reliability.
Calibre Bossnut Evo pricing and availability
Take the official RRP of £1,300 with a pinch of salt, this is because you can simply buy a £5 GO Outdoors discount card to get the bike for £999. Shipping in the UK is free, and international shipping is only £9.95 (though you may be liable for local import duties).
The Bossnut is available in four sizes from S/M (15.5in) to XL (21.5in) and a ladies specific version will be following in about two months.
We’re not quite sure how Calibre has managed to eke out even more from the Bossnut at this price point, but the Bossnut Evo looks to be one of the most capable budget full-sussers out there. We've just taken delivery of ours and will be heading out on it this weekend. Stay tuned for a full review.