5 reasons why YT’s Jeffsy is the coolest 29er to own in 2016

Big wheels and a do-it-all attitude, packed into a machine with serious promise

YT’s Jeffsy 29er trail bike has piqued interest for a while with the #ihatejeffsy social campaign. Today it was officially unveiled, and after spending time with it in Madeira, we reckon we like it – a lot.


We’ll be honest; when the first ‘#ihatejeffsy’ pictures started cropping up on social media we were as confused as anyone. Then came the video. It’s an elaborate tale of two lovers who’ve each got a different take on the impact ‘Jeffsy’ has made to their relationship, one positive, one negative. 

OK, I think we all knew it was a bike, but what exactly was Jeffsy? A 140mm travel 29in wheeled trail bike, that’s what. But how will the Jeffsy compare to the likes of the highly praised Specialized Stumpjumper 29 and Evil’s The Following? We trotted off to Madeira to find out more…

1. It’s perfectly packaged

The jeffsy cf pro in all its shiny glory:

While the wheel size may divide opinion and continue to be shrouded in negativity – we’ve all heard the naysayers grumble, “29ers aren’t as much fun” and “You can’t corner a 29er as well as a 650b wheeled bike” – it still has its believers and for good reason. Get those big wheels packaged in the right frame with decent geometry and 29ers can be seriously impressive performers. 

But why have a gravity-orientated brand like YT – remember, these guys sponsor the current downhill World Cup winner, Aaron Gwin and former Redbull Rampage winner, Andreu Lacondeguy – adopted the wheelsize?

“It was by chance. We decided to go for trail or all mountain bikes and we started riding and trying to figure out what could be the best way, and which kind of way would fit with YT, keeping the YT genes in the bike. We tested a lot of stuff, made our own ideas and we found out that the 29er was perfect,” says Stefan Willared, head of development at YT. 

“We had a clear idea of what we wanted. We wanted it to feel like home. The load distribution was pretty clear because we know how our bikes should feel. We considered the cockpit from the beginning and it was clear for us that we needed to have a riser bar. It was the position of the riser bar and the adjustability (of the stem on the steerer) with spacers that were considered from the first sketch.”

That short head tube means yt could use a riser bar, helping the jeffsy to look more aggressive without sending the bar height sky high:

Take a look at the Jeffsy and it’s clear that it shares its roots with the likes of its smaller wheeled counterpart, the Capra. The stumpy head tube, riser bar and low slung top tube certainly give a nod towards the more aggressive style of riding YT’s bikes are well known for. 

Looks aside though, it’s the numbers here where much of the promise lies. A flip chip at the rearmost shock mount gives the option of slackening the 67.6 degree head angle to a more aggressive 66.8 degrees which in turn drops the bottom bracket by 8mm. The low setting also means an effective seat tube angle of 74.7 degrees. 

Chainstay length was also another big focus for YT, and interestingly, the Jeffsy’s increases as you move from the medium size bike to the large. So, while the small and medium bikes use a 435mm chainstay, both the large and extra-large models get a 440mm. Stefan elaborates, “It’s not the shortest back end, but it’s for the balance and the load distribution.”

While the back end of the bike is still relatively compact, YT claims that the extra bit of length will help riders find the ‘sweet spot’ when cornering, even when fatigued. As for the differing chainstay measurements, Stefan says: “We also found that because of the change in reach length, we had to modify the rear end length.”

2. Trail manners that goad you to ride hard

The jeffsy cf pro is no slouch and feels just at home being launched and popped through tricky sections of trail:
Rob Weaver puts the YT Jeffsy through its paces

“Firstly, we wanted the suspension feel to have a lot of pop so you could ride the bike fast, aggressive but still it should be sensitive enough when you’re sitting and pedalling through trails”, says Willared. “That sensitivity, we want to have it but it was not our main goal. The sensitivity should be there but the overall feeling, especially the mid-stroke and the smooth end stroke which allows you to load the bike through berms, so you could ride hard, that was the main thing”.

Getting the suspension feel right is critical and has, in the past, held some seriously promising 29ers back. YT did everything they could to make sure the suspension was more than capable of unlocking the Jeffsy’s potential. 

“The feeling of the bike was pretty clear,” says Stefan. “We’ve got a lot of feedback from good riders, from normal consumers so we have a clear vision of what to do. While pedalling, you should have some suspension which lets you relax a little bit, but when it becomes faster with berms and root sections, the bike should give you confidence, and that works only if you have a good supported mid-stroke and a good match with the front end.”

Compared to the Capra, YT claims the mid-stroke is similar in feel, if not even more supportive, but the end of the stroke is less progressive and smoother.

3. Attention to detail all the way through

Thanks to the flip chip located at the rearmost shock mount, you can easily and quickly adjust the jeffsy’s head and seat angle, as well as alter its bottom bracket height:
Note the flip chip at the rearmost shock mount

We’ve already covered off the small flip chip located at the rearmost shock mount which lets you easily switch your geometry up, but look a little further and you’ll soon spot some tidy little touches elsewhere. 

Down on the chainstay, YT have not only included some frame protection to help hush up any irritating chain slap, they’ve also integrated a metal plate just behind the chainring and another just in front of the driveside dropout. This is to help protect the carbon chainstay should the chain stray from where it ought to be.

Other neat features include the cable routing which is, for the most part at least, external and therefore a big plus when it comes to maintenance. We also like the fact that there’s room for a bottle cage (though admittedly only YT’s specifically designed one), the stiff 12x148mm Boost rear axle and we particularly like the way YT have tucked the chainstay brace in just below the pivot which should prevent it becoming a mud shelf when the weather does take a turn for the worse.

4. Big choice of build options

Only the top tier jeffsy cf pro is equipped with fox dampers. the fox dps shock is a seriously capable unit and offers a good mix of comfort and support:
The top-tier Jeffsy CF Pro gets Fox suspension front and rear

While most attention will fall on the pricier options, it’s worth noting that YT are offering six build options – three carbon frames, three aluminium frames – and four different sizes – so in theory, there should be something for everyone. YT are also offering one carbon and two aluminium models with a front mech. 

Pricing starts at €2199 (not including shipping) for the Jeffsy AL which includes the RockShox Pike RCT3 fork and Monarch RC3 rear shock, along with a full complement of Shimano SLX gearing and brakes. 

At the other end of the pricing sits the Jeffsy CF Pro. This is the only Jeffsy to get Fox suspension front and rear, using a Float 34 Factory fork and DPS rear shock, DT Swiss XCM 1200 Spline carbon wheels and SRAM’s X01 gearing and their Guide Ultimate brakes, all of which will set you back €4499 (not including shipping). 

YT has wisely chosen to spec all models with a RockShox Reverb Stealth post too, so even if you rinse your bank account on the cheaper model, at least it’s safe knowing you’ll not need to save up for a dropper post as soon as the bike arrives. 

Another interesting point here is that the Jeffsy uses 46mm fork offset, as according to Stefan, “We go for the short offset as it leaves the bike feeling a bit quicker”.

5. The ride: flickable, balanced and eager

It took no time to get used to the natural, balanced feel of the jeffsy which played a big part in hitting lines with confidence:

From the outset it’s clear that Stefan got what he was after in terms of suspension feel. The flickable, easy-to-manoeuvre nature of the Jeffsy lets you throw it about the trail with relative ease, and thanks to the well balanced suspension, you can do so with an element of recklessness, knowing the bike is happy to deal with harder riding. 

That willingness to be popped and hopped is definitely helped by the low 12.66kg/27.9lb (size medium with pedals) of the Jeffsy CF Pro, and also means it’s eager enough to get up any climbs put in front of it with very little fuss.

Get into trickier terrain and the Jeffsy feels balanced and confident, and at no point did we feel hindered by the bigger wheels, even when linking tight, high-load fast turns together.

The jeffsy felt happy being slung from turn to turn at speed, and tracked the terrain impressively well

In high-speed, rough, blown-out sections of trail where root and rock are keen to disrupt any real flow, things remain balanced and controlled, and the Jeffsy will cover ground at a serious pace. 

When clouting into really rough sections, you’re reminded that this lightweight trail machine prefers to be finessed rather than pummelled in order to maintain your speed, but that’s not to say it won’t take a beating and at no point did we ever feel like the rear end was at all lacking in progressivity. 

So who’s this all mountain, do-it-all machine for then? “It’s a mountain biker,” says Willared, simple as that. 


We’re eager to put some miles in on the Jeffsy on our local trails as soon as it lands with us and let you know just how it fares.

YT Jeffsy CF first ride