Genesis Tarn 20 review£1,900.00

Plush frame and sorted kit amplify plus-sized playfulness

BikeRadar score4.5/5

It’s easy to assume the big, fat tyres of plus bikes dominate their ride character to the point where they all feel the same. But the more we ride the more it’s clear you can end up with very different bikes even with the same balloons wrapping the wheels.

Related: Trail Tech: Exploring 27.5+

It’s also clear that not all manufacturers have got their handling or clearances sorted to make the best of the bigger volume rubber. The good news is the Tarn is the one of the best plus hardtails we’ve ridden, and it has a great parts package for the price too.

Classy chassis

That second bit is particularly impressive, given the tapered head tube, super-sloped top tube, Boost 148x12mm rear axle frame, built from Genesis’s own double-butted Mjolnir steel tubing blend. The wide-spread rear stays provide a smoothly supple ride that really syncs well with the kind of experience you’re likely to want from a plus bike. Rather than feeling dead under power like some steel frames it’s got a really lively spring as you press on the Race Face cranks.

148x12mm 'boost' rear axle spacing on the genesis tarn
148x12mm 'boost' rear axle spacing on the genesis tarn

'Boost' 148x12mm rear axle spacing features out back

Despite being much heavier, the Maxxis Chronicle tyres roll really fast and, remarkably, the complete bike is lighter than both the other steel bikes we were riding alongside the Genesis (namely the Onza Jackpot and Ragley Piglet).

We rarely ran out of braking and driving grip even on the sketchiest scree sections of the surrounding wild bridleways either. Add the root- and rock-ignorant, momentum-maintaining tyre volume and the Tarn repeatedly dropped the Ragley and Onza on the rougher singletrack sections.

Properly dialled

This has actually become more significant the more we’ve ridden other plus bikes too. That’s because several of those have proved to either under- or over-steer frustratingly or just have an awkward overall balance that’s left us dabbing and cursing.

The genesis tarn, out on the trails in the english lake district
The genesis tarn, out on the trails in the english lake district

The Tarn's personality is lively and playful – what you want from a plus bike

In contrast, the Tarn’s combination of super long stretch and 68-degree head angle made the fat front tyre feel confident yet easily responsive at all speeds. It even feels okay on the sloppy, slippery conditions that are a nightmare on most plus bikes.

The 110mm wide Boost axle of the Reba fork is further stiffened with oversized hub contact caps for rich front end feedback and the under-seat dropper lever means it’s definitely not scared of the steeps.

It’s always the sign of a good bike when we’re scratching around for something to offset all the positives with. However, the only things we didn’t like on the Tarn were the racer-style foam grips, which neither feel good nor last long. That makes them the polar opposite of the rest of this surprisingly playful, well-sorted plus-sized package.

This article was originally published in What Mountain Bike magazine.

Guy Kesteven

Freelance Writer, UK
Guy started filling his brain with cycle stats and steaming up bike shop windows back in 1980. He worked the other side of those windows from '89 while getting a degree in “describing broken things covered in mud" (archaeology). Dug historical holes in the ground through the early '90s, then became a pro bike tester in '97. Guy has ridden thousands of bikes and even more components the world over since then and can remember them all in vivid, haunting detail. Can't remember where the car keys are, though.
  • Age: 45
  • Height: 180cm / 5' 11"
  • Weight: 68kg / 150lb
  • Waist: 76cm / 30in
  • Chest: 91cm / 36in
  • Discipline: Strict sadomasochist
  • Preferred Terrain: Technical off-piste singletrack and twisted back roads. Up, down, along — so long as it's faster than the last time he did it he's happy.
  • Current Bikes: An ever changing herd of test machines from Tri bikes to fat bikes and everything in between.
  • Dream Bike: His Nicolai Helius AM custom tandem
  • Beer of Choice: Theakston's Old Peculier (not Peculiar)
  • Location: Yorkshire, UK

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