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Commencal Supreme DH 650B

Oct 15, 2013

ROC D'AZUR, FRANCE

Commencal
Supreme DH 650B

Commencal have been one of the most open companies with their approach to the Great Mountain Bike Wheelsize Conundrum. Nearly every bike company out there has tested on all three wheelsizes, but Commencal are one of the few we can think of who offer all three sizes to the public in the all-mountain line up. Their first experience with mid-sized wheels was with the new Meta AM and, after they had rode that bike for a while and found its strengths, they began looking at their downhill bike, the Supreme DH, and thinking "What if?" There was also interest from the Commencal Riding Addiction team, as rider and team manager, Thibaut Ruffin, explains, "It's something we asked for at the beginning of the season because we were looking at all the discussions on that new wheelsize. Every team and constuctor is going for it so we were just curious to see how it goes." At the Roc D'Azur festival this past weekend they unveiled the bike to the public.

With the Meta AM 650B we instantly felt faster with than with the 26" wheels. We felt more confident, the bike was faster in rough sections, and geometry-wise we really like the lower BB drop. So why not try a DH bike with 650B wheels? World Cup tracks are fast, incredibly rough... It was worth a try. - Nico Menard, Engineer

Small Changes

If you are familiar with the current Supreme DH, then the first thing that will strike you about this bike is how similar it looks to the current bike. There's good reason for that: it is the same, the only change they have made to the bike is the rocker link that drives the suspension. Because the two wheelsizes are so closely matched, the larger wheels fitted into the existing swingarm. If you look closely, you can see that the clearance on the rear tyre is quite limited. It does limit the chainstay options, the bike they had on display was set with 445mm chainstays and it is clear they couldn't have gone any shorter than this. For production this would be an issue, but as the World Cup riders who are using this bike tend to keep the wheelbase stretched out for the high speeds, this isn't a worry for them.

(Clockwise from top left) The 650B (yellow) vs. the 26" (pink)... Looking at the two linkages side-by-side, you can see how visually different the new link is on the 650B bike

Visually the new rocker link looks far more streamlined than the previous incarnation, but Commencal are clear that in terms of construction, the differences are largely aesthetic and there is very little weight saving there. However, the changes from the link, while subtle are incredibly important. First and foremost it changes the bottom bracket drop of the frame - the height of the bottom bracket below the imaginary line between the two wheel axles. On the 26" bike the BB sits 8mm above the axles, with the 650B wheels it sits 7mm below that line, a 15mm change to compensate for the way the bigger wheels raise the BB height. To keep the trail constant the head angle was steepened from 63 degrees to 63.8 degrees on the new bike. If you're not familiar with the concept of rake and trail, check out our To The Point interview with Cannondale's Murray Washburn where he breaks down the topic for us. In short, while the head angle may be steeper, because of the bigger wheels, the steering should feel the same on the trail.

(Clockwise from the top left) The mud clearance comparison is clear (650B is yellow, 26" pink) and we're sure the bike will not go into production with this swingarm. The chainstay is set out to 445mm and on this test bike they are using 2.4" High Roller IIs - the Riding Addiction team is supported by Kenda, who have not yet released a 27.5" DH tyre.

The Bos Connection: The final piece to this puzzle is the suspension, for which Commencal are working closely with Olivier Bossard and his company, Bos Suspension. The last time Max Commencal [The owner of Commencal] and Olivier worked together was on the Sunn race team of the 90s, when Nico Vouilloz and Anne-Caroline Chausson dominated the gravity disciplines for them... On their advice the rear wheel travel has been reduced from 200mm to 190mm, they have also re-tuned the shock to the changes in the linkage, although being Bos, they were giving few details about that away.

Nico Menard says catergorically that, "This is the first batch of samples, we are still on testing process, there is still a possibility to modify the design." After his first few days on the bike, Thibaut is impressed though, "I built my 650B last in Verbier three days ago and I was pretty curious to see how it was. I just tried my enduro 650B two weeks ago, I'd never tried a 650B bike before, and yeah, it was good. It wasn't really different to a 26, to be honest, just riding the same. In the end, nothing changed with riding. It goes better when it is straight and rough, and I found it was a bit harder to get into the turns... but once you are in the turns there is more grip and more confidence. Remi [Thirion] has to try as well, I can't take a decision for the rest of the team. For me, with the way the tracks are going for next season, with South Africa, Leogang, Norway, even Mont St Anne, I think those tracks are better with 650B. In Verbier the track wasn't that steep, really fast with lots of berms and rough sections, but it was good. I will try it this weekend at home on a really steep track..."

At the Andorra World Cup Max Commencal committed to doing something "special" in partnership with Bos Suspension and, if history is any guide, their approach will involve looking at the bike as a whole package, so we'd expect to see further evolution for the World Cup racers next year. For the public, if testing goes well, this bike, or at least a version of it, should be available April 2014.

www.commencal.com