Late last year, Yeti launched some rather large updates to three of its bikes, the SB120, SB140 and SB160. Since the brand has shown no signs of slowing down recently, it introduced another bike to the line-up, the SB135 LR. While at first, the name is just a recognisable collection of digits, it means one thing; there’s a 650b-wheeled full-suspension in the range. We paid a visit to FlyUp 417 to see if little wheels still belong in mountain biking.

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We test a lot of bikes here at off.road.cc and, in recent years, it’s become rare to see a 650b bike roll through the office doors which definitely puts an air around the place the 650b wheels are sadly fizzling out. Especially with 29ers and mullet bikes dominating all corners of mountain bike racing at the elite levels, and even on the gravel racing circuits.

But, refreshingly, despite a bit of confusion, Yeti has persisted with the little wheel and has launched the Yeti SB135. With 29-inch or mullet wheel set-ups setting the standard, Yeti’s release of a full 650b (27.5in) wheeled bike certainly raises questions. Though we’re told that the previous generation SB140 27.5 was still selling rather well, so reluctant to bin little wheels, Yeti has brought all of the updates we saw on the 29ers, to a little wheeled format. 

Those updates come in the form of a tweaked Switch Infinity link in a bid to boost durability, stiffness and performance. This little Kashima-coated gadget found just rearward of the bottom bracket increases bottom-out resistance in the last third of the shock’s stroke for a bottomless suspension feel across Yeti’s bike range. Though this time around, the brand has re-engineered the pivot races, linking them radially and axially, pairing those with a Floating Collet axle that tightens against the bearings, reducing play and misalignment, says the brand. It also gets a new bushing assembly, corrosion-resistant bearings and machined bearing covers.

While we’re already talking about the SB135 LR’s suspension goodness, the wishbone shock extender has been shrunk considerably, which has allowed the standover height to lower while maintaining Yeti’s desired suspension kinematic. It also gets 14% progressivity in its leverage curve.

As we saw on the 29-inch bikes, this one gets 25mm more downtube clearance, which angles the flatter portion of the downtube before it reaches the BB more upwards to fend off rock strikes more effectively.

The bike’s geometry is very similar to the SB140 LR but there have been a couple of tweaks here and there. Namely, the bottom bracket is two millimetres lower and its axle-to-crown length is 20mm shorter at 558mm, which is understandable given the smaller front wheel. The chainstay is also a tad shorter, measuring 435mm on this large frame. Again, that’s another worthy byproduct of the smaller wheel.

The geometry continues the theme of little tweaks as the SB135 LR gets a 475mm reach, a 76.5-degree effective seat tube angle, and a 65-degree head tube angle. While subtle compared to its bigger wheeled sibling, these figures look to really lean into the inherent agility of 650b hoops. There’s then a 1,229mm wheelbase.

Though not available on the heavier-hitting Lunch Ride (LR) builds that get longer travel forks, the little wheels have allowed Yeti to offer an XS, so there’s now a Yeti mountain bike for most sizes of humans. What’s cool is that the XS frame isn’t just a shrunk version of the SB125 but it’s a whole new frame that’s designed especially for smaller riders. Though it must be noted that there isn’t room for a piggyback shock of that size.

Yeti SB135 LR T3 - Componentry

I was fortunate enough to have a go on the SB135’s Launch Ride build in the T3 spec. As a T3 bike, it benefits from Yeti’s mega fancy Turq series carbon frame. Carrying on with this bike’s fanciness is a Fox Factory 36 GRIP2 fork with 160mm of travel which is paired with a Fox Factory Float X rustling up 135mm of damping.

And it goes on as this bike rocks SRAM’s latest XO Eagle AXS Transmission drivetrain that’s complete with SRAM Code RSC brakes. There’s then a set of DT Swiss Custom EX1700 wheels with 200mm brake rotors bolted on. Those are then wrapped with a 2.5in Maxxis Assegai at the front and a 2.4in Maxxis Minion DHR II at the rear. Both of those come with EXO+ casings.

Non-Lunch Ride builds get inline shocks, 150mm of fork travel, 180mm brake rotors, and lighter-weight tyre casings.

Costing £9,800, Yeti says this T3 LR  build weighs around 14.5kg.

Yeti SB135 LR T3 - Ride impressions

It’s been a long time since I swung a leg over a bike that runs anything other than mullet, or 29-inch wheels so there was definitely quite an adjustment period when riding the SB135 LR. Thankfully, that’s period was surprisingly brief as this bike feels very much like a Yeti, and having ridden a handful now, it was simply the small wheels I had to get my head around. But one thing was glaringly clear, this bike felt very small, and very low, however, as you may have guessed, that’s compared to 29-inch-wheeled rigs.

Though what’s really excellent about this ‘Yeti’ feel, is that the brand has taken the essence of what makes a Yeti bike so… Yeti, and made it work seamlessly with the 650b format. So the bike takes all of the performance, and goodness expected from the brand’s bikes but it simply rolls smaller hoops.

That comes with a lot of help from the characterising Switch Infinity linkage which works impressively on this particular bike. As it’s designed, it aids climbing by holding the shock around its sag point without blowing too far past it when pedalling. Combine this with small wheels and it results in a bike that accelerates with a good helping of pep, which both encouraged brief blasts up steep sections but it also rewarded cheeky post-corner efforts with a shed load of easily attainable speed.

Though uphill, the bike is very well-behaved and it pedals efficiently, making the lengthy shlep up to FlyUp 417’s trailhead as pleasant as it could possibly be. It’s comfortable while ascending too, and despite the short chainstays and taller head tube, it remained planted and more than controllable, even during steeper sections.

On the descents is where a lot of acclimatization was needed with the change in wheel size but one thing’s absolutely certain, and that’s that the SB135 LR is super maneuverable. It takes quick changes of direction well within its stride which helped to no end in keeping momentum flowing whilst whipping throw steep, tight consecutive berms.

As for capability, the SB135 LR doesn’t hold back as I’ve been able to throw myself and the bike into rock gardens with absolute conviction. Even though the bike hangs up a little more through chunk, hanging onto momentum is a doddle as the rear suspension, once pushed past sag, opens up to absorb all of the lumps. This adds a welcome hint of composure to the bike, which is much needed considering the more exhilarating ride that’s achieved thanks to the 650b wheels.

Not only is the little wheel more eager to shift into a lean but when slammed into the bowl of a berm, its short chainstay helps the bike whip around the corner, while the supportive midstroke of the suspension kinematic keeps the rear end high in its travel, allowing the rider to ping out of corners whilst hanging onto as much momentum as possible. 

Yeti’s work to stiffen the linkage comes into play here too as there’s little flex in the frame, which ups the confidence further.

The suspension's performance under heavy braking deserves an honourable mention, too. Heavy braking down steep and rocky sections before heading in to catch berms is very much like dropping an anchor. Importantly, the rear suspension stays super active under heavy braking, which is a tough feat to achieve. This boosts the rear wheel's grip, resulting in a tonne of power when slowing down. Then, of course, better braking performance makes for an all-round faster bike. 

Clearly, the bike can get mighty rowdy whether you’re hauling it through said rock gardens, or simply jibbing around the place but that’s the whole point. I'll admit, at first, I was questioning Yeti's decision to persist with 650b bikes but in practice, the SB135 LR wrings out every inch of fun almost any trail has to offer. 

In a world where 29 is taking over in many forms, I’m very happy that Yeti is sticking to its guns and offering a 650b wheel option and doing it whilst clinging onto that defining Yeti charm. It’s a bike for small riders but also those who want the ultimate in manoeuvrability without sacrificing confidence when throwing themselves down something more technical.

• yeticycles.com

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