Back before the 2019 World Cup season began, the UCI updated the rule book to allow the use of mixed wheel sizes in mountain bike competition. We'd already had an abundance of 29" downhill bikes, starting in 2017, but some racers chose to stick with 27.5" as the bigger wheels were buzzing their arses or they simply preferred the feel of a 27.5 inch wheel in the rear of the bike.
With the change of the rules, we began to see riders racing the mixed wheel, or mullet, setups to noticeable victories - none more so than Loïc Bruni and his domination of the 2019 season with the World Cup overall and World Championship victories. This was all while Specialized only had a full 29" setup available, leaving fans and avid racers wondering if their mixed wheel Demo would ever see the light of production.
The Demo has been openly developed and tested on the World Cup circuit with immense success in the 2019 season under Loic Bruni.
Today Specialized answer that with the official release of the latest iteration of the Demo platform, allowing not only a mixed wheel size setup but adjustability in the geometry to open the Demo up to even more riding styles and preferences.
The layout remains the same as the Demo 29 that was released back last year with its six-link suspension layout bringing a drastic change in suspension characteristics for the brand. The Demo uses a four-bar system to define the acceleration and braking responses of the bikes, with an additional two links then driving the shock which is mounted low and central in the frame. This layout change, compared to the previous Demo generation, upped the amount of anti-squat and anti-rise considerably. Leverage ratio progression was upped too and all curves are now much straighter lines, promoting predictability in the bike.
<Deleted photo>Geometry, Sizing & Adjustability
Three sizes are still on offer with Specialized's own naming, S2, S3 and S4, which represent reach numbers of 426mm, 446mm and 466mm respectively in the mixed wheel size setup.
Now the Demo has adjustability via a chip at the Horst pivot. There are three modes, Short, Middle and Long, which Specialized correspond to a certain wheel size setup. Short is dedicated to 27.5" rear wheel and promotes manoeuvrability, Long is dedicated to a 29" rear wheel setup and promotes stability at speed and Middle can accommodate both rear wheel sizes and offers a slightly more stable 27.5" setup or a slightly nimbler 29" setup. The Demo comes as standard with a 29" front wheel and 27.5" rear wheel, following the success that their race team found on this combo, but it's definitely nice to have the options for any combo you want.
Added to this adjustability, Specialized also give geometry numbers for the bike as it comes from the factory with the mixed wheels, a full 29" setup and a full 27.5" setup. All those comparisons are given in the middle setting, apart from the chainstay lengths which show the differences the Horst pivot chip can make.
It might seem like a lot of numbers in the table to get you confused, but it actually opens up a lot of ability for the rider to play around with the bike to make it fit their riding style and terrain. It takes a little time to experiment with all the settings, but nothing ever worth learning came quickly. This can also be a useful tool for the keen racer to adapt their bike to the track and conditions in hand when they're trying to go as fast as possible.
Currently, we've got no information on specs, pricing or availability. But we do have a new Demo on the way to Champéry ready to start testing. We'll report back with more information on the bike and ride impressions soon.