Specialized Fuse 27.5 (2021) review

The Specialized Fuse 27.5 is the Big S’s cheapest hardcore hardtail mountain bike.

Chunky plus-size tyres, a dropper post and a 1×11 drivetrain are matched to relatively up-to-date geometry on a sleek alloy frame.

It looks the part, but how does it ride?

Specialized Fuse 27.5 frame and geometry

While the two pricier Fuse models come with 29in wheels, the 27.5 has big 2.8in tyres on wide 650b rims.

The frame is compatible with 29er hoops, too, but has a 10mm longer head tube than the Fuse 29 and a bottom bracket (BB) height optimised for the smaller wheels.

Features include a Boost rear axle, threaded BB and two bottle mounts. Cables are routed internally from the head tube to BB. The former is compatible with a tapered-steerer fork, adding more upgradability.

Unlike the S-Sizing of Specialized’s more expensive ranges, where your riding style dictates the size of bike you should ride, the Fuse 27.5 is offered in a more conventional extra-small through to extra-large.

At 178cm, I opted for the large, which has an adequate 460mm reach. Anyone wondering about upsizing to a longer frame should note that, while the seat tube on the large is a reasonable length, at 455mm, the leap to 505mm on the extra-large will rule this out for most.

The head tube sits at 66 degrees, while the seat-tube angle is 74 degrees.

Specialized Fuse 27.5 kit

The biggest talking point here is the plus-size tyres – a Specialized Butcher and Slaughter combo, with the brand’s GRID TRAIL casing and GRIPTON compound.

They’re wrapped around Stout rims – Spesh’s in-house brand – with a super-wide 38mm internal width.

A TranzX dropper post with 120mm of travel helps justify the extra cost over similar bikes like the Vitus Sentier 27. However, the cable is clamped at the actuator end, which means setting cable tension can be tricky, and if you ever replace the post you may need to buy a new cable-clamping remote.

Up front is a RockShox Judy Silver TK fork with an adjustable air spring, rebound damping and lockout.

You get Shimano Deore M5100 gearing with a wide-range 11-51t cassette and 30t chainring. This should provide ample gearing for even steep climbs, matching most 12-speed set-ups.

The cranks use a square-taper BB, which will complicate things if you ever want to upgrade them.

Finishing the bike off are Shimano MT200 brakes and a host of Specialized’s own kit, including its Bridge saddle, Trail grips, and Stout 780mm bar and 45mm stem.

Specialized Fuse 27.5 ride impressions

Despite installing all of the Fuse 27.5’s headset spacers underneath the stem to raise the bar height, I couldn’t get it high enough for my preferences.

The bike has a shorter stack height than the others I had on test, so the front end feels lower. While the slightly more aggressive, over-the-front position this encourages is beneficial on steeper inclines, it isn’t ideal when descending (more on this below).

I feel the stack height on the Fuse 27.5 (615mm) could do with being taller, as on the Fuse 29 models (639mm), to help raise the bar.

Fitting 29in wheels would help, but the fork is 650b-only, so an additional upgrade would be required. This would also raise the BB height.

The seated climbing position is comfy thanks to the fairly generous effective top tube length (637mm), which never left me feeling stretched out or cramped, and ensures that weight shifts fore or aft aren’t met with twitchy changes in grip.

This is helped by the generous volume of the tyres, which, when run at lower pressures, provide enormous amounts of comfort and low-speed climbing traction, even over boggy terrain, where the fairly aggressive tread pattern of the Slaughter rear tyre bites into the ground.

Stood-up climbing is a little more cramped, despite the reasonable reach. This is mostly down to the low front end, which makes your knees feel higher and closer to the bar than on a bike with a taller stack height.

Nonetheless, it’s possible to scale steep ascents without too much ado, with the 30t chainring and 51t largest sprocket giving a more than adequate lowest gear.

When in the big cog, the chain is extremely close to the rear tyre – due to the tyre’s width and the cranks’ chainline – so it quickly gets covered in mud and, on particularly boggy days, can clog up.

Specialized’s Bridge saddle is one of the comfiest perches I’ve used and its Trail grips are another favourite, with a widely-liked diameter and soft feel.

The RockShox Judy fork is also nice and supple, ironing out trail chatter even after I increased the air-spring pressure to reduce sag and increase the height of the bike’s front end. Add the high-volume tyres at lower pressures, and general comfort is good.

I was impressed by the dropper post, too, which is light to actuate and quick to extend. In fact, Specialized’s finishing kit feels considerably more premium than the bike’s price tag would suggest.

On flatter, trail-centre-style descents, the low front end didn’t slow me down a great deal, especially once I’d increased fork pressure. In fact, at cruisy speeds on your average red run, the Fuse 27.5 feels particularly calm and composed, proving to be a fun bike to ride.

It certainly isn’t bad on steeper tracks, but I reached its limits more quickly, with the limited stack pitching my weight forward and making it harder to stay in a balanced position between the wheels.

The plus-size tyres mean there’s more steering friction – where the bike feels like it’s riding in glue and tends to hang onto its current trajectory – than with thinner rubber, which does take some getting used to.

Specialized’s GRID TRAIL carcass, specced at both ends, also tends to flex and squirm when pushed hard. Higher pressures help mitigate this, but decrease comfort and grip, reinforcing my opinion that the Fuse 27.5 is better for cruising-speed runs than flat-out schralping.

The Specialized’s rear end doesn’t kick as hard on steeper descents, thanks to its shorter seat tube, which lets you drop the saddle further out of the way – although the dropper’s limited travel (120mm) meant I had to drop the post manually when tackling anything particularly vertiginous.

Like on the other bikes on test, the brake pads were noisy in the calipers, and the internally-routed cables also tended to rattle. There wasn’t much chain slap, although some was audible. Again, these are curable issues.

Specialized Fuse 27.5 bottom line

Ultimately, the 650b Fuse is held back by its stack height. If you can stretch to the 29er version, it should feel better on faster and steeper trails because the front end is jacked up by the big wheels, giving more control. There’s also the added benefit of smoother rolling.

But that’s not to say the Fuse 27.5 is a bad bike. It’s comparatively capable on steep descents and is great fun to hustle around trail centre loops, its parts working well together to give the feel of a premium package without the price tag.

If you’re going to be riding the steepest trails around you may prefer something like the Merida Big.Trail 500, but the wide-tyred Fuse has its comfortable, fun-to-ride-at-cruising-speed place. I loved swinging a leg over it.