YT Jeffsy Blaze review – BikeRadar

Freda Walters

YT’s Blaze editions give the Izzo, Jeffsy and Capra ranges a new step on the ladder with even more aggressive builds and tuneable componentry for a little extra Grrr.

This 29in-wheeled Jeffsy Blaze is a bike for riders looking for the burliest of trail-bike builds and gets a 150mm RockShox Lyrik Ultimate, a SuperDeluxe Ultimate shock, grippy Maxxis Minion tyres on DT Swiss hoops, and highly adjustable SRAM G2 RSC brakes.

YT Jeffsy Blaze frame

YT’s limited-edition Jeffsy Blaze impressed us during testing.
Russell Burton / Immediate Media

While YT offers a 160mm version of the Jeffsy with 650b wheels, I’ve got the 150mm 29er here.

The frame is constructed with carbon and comes with a number of smart touches that should make living with the bike fairly easy in the UK.

Full internal cable routing is guided neatly through the frame, with only one bolted clamp needed to secure it in place; the bearings get additional sealing washers to keep dirt and water out; and, should you wish to strip the pivots down, they’re all accessible from the non-driveside of the frame to make life easier (except the driveside rear pivot, for obvious reasons).

Rear view of the YT Jeffsy Blaze full suspension mountain bike

I loved the simple colour scheme and smooth lines of the Jeffsy.
Russell Burton / Immediate Media

The chainstays get both chainslap and chain-suck protection, while the down tube has a bolted protector to save its belly from rock strikes.

Those prone to scuffing chainstays will likely do the same on the relatively wide rear-end here, though.

Suspension travel is doled out via a four-bar linkage, with a swing link sitting mid-way down the heavily kinked seat tube and the shock bolting into its yoke on the down tube. There’s still room for a bottle in there, just.

While no brand is going to make negative claims about its suspension kinematic, YT says that the Jeffsy has plenty of pop for boosting off lips along with plenty of progression at the end of its stroke.

YT Jeffsy Blaze kit

The Jeffsy gets one of the stoutest forks around, with RockShox providing its distinctive red Lyrik up front. Given it’s the Ultimate level of suspension, it’s packed with plenty of slippery travel and enough adjustability to get it feeling just right.

While I prefer the latest offerings from Fox (thanks to the updated air spring), the Lyrik is still one of the best forks on the market for the more aggressive rider.

At the back it’s matched with a SuperDeluxe Ultimate shock, again providing plenty of adjustability and a great feel.

For further adjustability, the frame is able to accept ZS49/ZS56 reach-adjust headsets, should you want to alter the front-end length of the bike.

Continuing the SRAM theme are the drivetrain and brakes. The GX Eagle groupset has the big 52t sprocket at the back of the cassette, while you get all the adjustments the G2 RSC brakes offer.

A pair of Minion tyres (some of my favourite all-rounders) sit on DT Swiss M1900 wheels, while YT supplies its own Postman dropper and Renthal the cockpit.

YT Jeffsy Blaze full suspension mountain bike is equipped with a DT Swiss M1900 wheelset

DT Swiss’s M1900 wheels are relatively budget, but roll smoothly and give a decent volume to the Maxxis tyres.
Russell Burton / Immediate Media

YT Jeffsy Blaze ride impressions

The YT Jeffsy has been a stalwart of our Trail Bike of the Year test for a few years now – a previous winner and frequent visitor to the podium – and this year’s limited-edition Jeffsy Blaze continues to perform near the top of the pile.

The Blaze moniker was added to a number of YT’models earlier in the year with a limited number available. While they come with the top-spec, beefed-up RockShox suspension, they still use the same frame as the regular models.

Unfortunately, the Jeffsy Blaze is already sold out, but for the same price you can get an identical parts list on the Jeffsy Core 3 but with Fox Performance Elite suspension, in the guise of a 36 fork and DPX2 shock, which seems fairly comparable in terms of performance in this context.

If you’ve got a little less to spend, the Jeffsy Core 2 gets Performance level suspension and an NX Eagle drivetrain for around £1,000 cheaper.

Male cyclist in red top riding the YT Jeffsy Blaze full suspension mountain bike over rocky ground

The Jeffsy has a super poppy feel that’s great fun to get on the trail with.
Russell Burton / Immediate Media

Every time I’ve ridden the Jeffsy it’s been an absolute hoot. The bike almost defines ‘playful’, seeking out every lipped undulation in the trail, waiting for you to lift up and tweak the bar, and encouraging you to square off every corner and manual through whoops.

The early part of the suspension is really supple, which makes short work of trail chatter and helps the bike quickly pick up speed on gentle descents without getting rattled. Though, it does steal a touch of zip when putting short dabs of effort through the pedals.

Cyclist in red top riding the YT Jeffsy Blaze full suspension mountain bike downhill over rocky ground

Though its geometry isn’t as radical as some, I still found it a perfect partner on singletrack.
Russell Burton / Immediate Media

The Jeffsy is also fairly happy entering into the middle of its travel and manages to ramp up, giving support, before it has a chance to feel wallowy and vague.

This gives the bike oodles of snap and an insatiable appetite for getting up into the air or accelerating through turns. As you might imagine, the deeper into the travel you get, the more you have to have pushed the bike – bang it off a drop with little finesse, and the rear suspension calmly provides you with its 150mm of rear wheel travel.

Braking traction is not the best out there but it’s more than capable of bringing you to a halt and keeping you out of trouble when hauling on the anchors over matted roots and through harsh compressions.

YT Jeffsy Blaze full suspension mountain bike has a chip to adjust the frame's geometry

As many frames have these days, there’s a small chip to adjust the frame’s geometry.
Russell Burton / Immediate Media

The Jeffsy’s geometry isn’t so radical that you have to re-adjust your attitude to bike handling, though, with the 470mm reach in a large, paired with a 66-degree head angle, short 435mm stays and a 350mm bottom bracket height making it a very natural bike to jump on and ride.

But when you do want to tackle tight and twisty tracks, you won’t be left behind.

There’s a geometry chip too, should you want the bike to be a touch taller and steeper – though I never did!

While the Jeffsy is capable on the steeps, perhaps a slacker head angle would improve things, and I’d like to see a longer dropper post provided on the Large too, because I reckon I could get away with more drop than the 150mm available.

Thanks to…

A massive thank-you to BikePark Wales for granting us access to its trails despite the bike park being closed to the public.

Cheers also to Fox clothing for sorting the kit for the photo and video shoots and Garmin for sorting us out with bike computers to log the many miles of testing.

And not forgetting Muc-Off, for its help keeping the bikes washed and lubed throughout testing.

Bike of the Year 2021 contenders

A decent trail bike should also be fast and capable on the descents, but with less weight and travel (130–150mm) than enduro bikes, they’re nimbler on flatter trails, less of a drag on longer rides and better on the climbs.

The following bikes were shortlisted for our Trail Bike of the Year award, with a price range of £2,999.99 to £4,695.

  • Bird Aether 9 (winner)
  • Canyon Spectral 29 CF 7
  • Intense Primer 29 Expert
  • Lapierre Zesty AM CF 6.9
  • Privateer 141 SLX/XT
  • Propain Hugene
  • Saracen Ariel 30 Pro
  • YT Jeffsy Blaze 29
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