It doesn’t seem all that long ago that Yeti Cycles celebrated their 25th Anniversary of creating progressive mountain bikes, but here they are again, announcing special 30th birthday editions of their SB6c enduro sled and the brand new SB4.5c.

Sydney’s MTB headquarters, Summit Cycles, have had a pre-production SB4.5c for a few months now, kept under wraps from the press until its official debut at Eurobike 2015, last weekend in Berlin. Well, now the covers are off.

It used to be that both cross country and downhill events could be won on the same day on the same bike but, as mountain biking evolved, specific machines were needed for each discipline. Even then, the technology was progressing so fast that those bikes were obsolete from one season to the next.

Today, bikes are getting smarter, and we’re again returning to a place where one bike can tackle a variety of terrains and gradients. The SB4.5c is billed as a short travel 29er and is filling a grey area in the market for riders who want to ride everything from their local trails to enduro events.

The 4.5 in SB4.5c stands for the four-and-a-half inches of travel offered in the rear, which equates to 115mm. That’s married to a Fox Factory 34 fork with a Kashima Coat that sports 140mm of travel, which seems at odds with itself, but from all accounts, works exceptionally well.

There’s a lot of anticipation surrounding this new addition to the Yeti range. The company has always been focussed on constant improvement and the aforementioned progressive nature of their bikes has produced the crux of their SB dual suspension bike range: Switch Infinity — a ‘translating main pivot’.

Tucked away in a carbon fibre cave, directly above the bottom bracket, is a little ‘hooha’ which consists of a twin mini stanchion device that was developed in association with Fox Racing Shox. Basically, it’s the culmination of Yeti’s thirty years off-road racing development.

Just over four years ago, Yeti announced their revolutionary Switch Technology rear suspension design, an eccentric pivot that re-established their status as a leader in MTB innovation. Within three years, however, they released Switch Infinity, which seemed to fix something that wasn’t even broken.

The eccentric nature of Switch Technology tended to ‘hang up’ through the arc of the suspension travel as it reverted back to its resting place, a feature that was eliminated by the Switch Infinity design, which allows the pivot point to flow smoothly up and down through the travel stroke.

This means that the SB range of Yeti Cycles both climbs brilliantly and descends smoothly. The incredibly stiff rear triangle soaks up micro-vibrations and larger hits in rock gardens and drop-offs are absorbed with a seemingly bottomless suspension.

The pre-production models were spec’d with XT brakes, but when released to the public, will come with SRAM Guide RSC units instead, and will run a SRAM X01 drivetrain. The 605mm top tube is designed for a short stem and wide bars, piloting a trackable 67.4° head tube angle.

Yeti claims the frame weight to be a featherlight 2.45kg, with a complete build weighing in at around 11.76kg — an impressive weight for such a substantial trail killer. They’re due to hit dealers in mid-September, so get your order in. Big thanks to Adam Macbeth and the guys at Summit Cycles.

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