YT leaked photos of a prototype Tues downhill bike with an idler, but this was simply a test mule, not a pre-production bike. So, much to our surprise, the new Tues MK4 bucks the trend for high-pivot idler DH bikes, and looks remarkably similar to the MK3 YT Tues bike that we reveiewed alongside the Canyon Sender and Propain Range in our Best Direct-Sales Downhill Bike test.

But before we get into what’s new on the eagerly awaited Tues MK4 being raced for the first time in anger at this weekend’s Fort William World Cup DH, let’s take a closer look at what’s stayed the same. Well, the Tues MK4 still has a full carbon frame and 200mm of rear wheel travel from its V4L suspension linkage, but other than that everything else is new. So let’s dive in.

New race season and a new bike for the YT mob. YT Tues MK4

One frame, two wheel sizes

Up until now you could get the YT Tues with either 29in wheels or 27.5in wheels, but not a mix of both. So the headline on the new Tues MK4 is that it is finally MX and 29in wheel compatible.

Flip the suspension link for 29in or MX wheels on the same frame. Neat.

To achieve this with the same full carbon frame, YT employed an asymmetric shock link, dubbed the Flip LInk – where flipping the entire linkage corrects the geometry for either a full 29in setup or an MX setup with a 27.5in rear wheel. And yes, that means YT is saying goodbye to the full 27.5in Tues, at least for now.

Cosmetically, the new Tues looks unchanged from the old bike.

Five sizes instead of three

Along with the old 27.5in or 29in split, there was a confusing split in sizes on the YT Tues. The 27.5in Tues ran from S to XXL, while the 29er was Regular, Long or XL. With the merging of 29in and MX wheel sizes on a single frame, the Tues MK4 falls in line with YT’s five-size approach. So regardless of your preferred wheel size, there are now five frame sizes to choose from with 20mm jumps in reach measurements. Reach on the size S is 430mm and grows to 510mm on the XXL. Also, with addition of the EC49/ZS56 head tube standard, the Tues is now compatible with reach-adjust headsets to further fine-tune fit.

Adjustable chainstay lengths, but only by 5mm

Adjustable chainstay lengths

Another new feature on the Tues MK4 is the introduction of adjustable chainstay lengths. Flip chips in the rear dropouts offer 5mm of adjustment. Which isn’t a lot, but the plus side is that you probably won’t need to adjust the length of your chain when flipping between settings.

All of the numbers on the YT Tues MK4 Core 4

Size specific chainstay lengths

Technically this isn’t a new feature on the Tues, as the old 27.5in model had them, and technically the chainstay lengths on the new bike are not size specific. And that’s because the size S, M and L all share the same chainstay assembly with 438/443mm sizing, while the XL and XXL both share the same 448/453mm rear end. It’s a positive move though as you can now tweak the weight distribution of the bike to a greater degree. Oh and those are the chainstay lengths with the Flip Link in the MX position, as switching to the 29in setup will  increase all of those measurements by 2mm.

SRAM UDH and regular 148mm Boost hub spacing

Standard 148x12mm rear hub spacing

Interestingly, the new Tues frame now uses standard 148x12mm Boost rear hub spacing. Not only does this make for a more slender chainstay assembly and improved heel clearance, it will make it really easy to swap wheels between say, your enduro bike and your downhill bike. The addition of SRAM’s Universal Derailleur Hanger (UDH) also makes life a little less complicated.

Look closely at the lower shock mount and you’ll see the geometry flip chip

High/Low shock flip chip

In addition to the Flip LInk, YT has also added a flip chip in the lower shock mount for adjusting the geometry. In the low setting the head angle sits as a slack 63.2º and the BB height is 346mm. Flipping the chip into the high position raises the BB height by 5mm and steepens the head angle to the DH industry standard 63.5º.

Meet the YT Tues MK4 Range

The privateer’s choice – YT Tues MK4 Core 2 MX

YT Tues MK4 Core 2 £3,999/$3,999/€3,999

The entry point to the new YT Tues line is the Core 2. You get the same full carbon frame as the top-end Core 4, but instead of Fox Factory suspension the Core 4 comes with a RockShox Boxxer Base fork and Super Deluxe Select shock. Other highlights include the SRAM GX DH drivetrain, Maxxis tyres, SRAM DB8 brakes and a Race Face cockpit.

Race ready straight out of the box – YT Tues MK4 Core 4 29

YT Tues MK4 Core 4 £5,999/$5,999/€5,999

Want a race ready WC calibre DH bike, then the Core 4 should be top of your list. With Fox Factory suspension, TRP brakes, Crankbrothers Synetheis wheels and a Renthal cockpit, nothing is left wanting. Factor in the new level of adjustability and one of the best DH race bikes just got a whole lot better.