THE INSIDE LINE
No more bent mechs, as Canadian engineer Cedric Eveleigh has invented a rear derailleur hidden inside the rear triangle
Aman in a shed has just invented a way of hiding the derailleur inside a bike’s rear triangle, thereby ending the age-old problem of smacking your mech off on a rock. Called the Supre Drive, the derailleur is protected by the rear stays and projects forwards not downwards, keeping it well clear of the ground.
Mech, check mate.
In the spirit of all great inventors, Cedric Eveleigh developed the system in his shed. He’s Canadian, so it’s probably bigger than most UK houses of course, but a shed none the less. As such it’s not available on a production bike or aftermarket… yet. The Supre Drive works with a conventional chain, BB, crankset and 11-speed cassette (12-speed is coming), but you need a purpose-built frame to house the new design. So you’ll be wasting your time trying to squeeze it inside your enduro frame, even if you are rocking Super Boost Plus.
“Ever since I was a youngster I was aware that derailleurs sucked,” Cedric explained to us. “I’d had some bad experiences, as most mountain bikers have, so I wanted to make mountain bikes better, and have an adventure for myself too.”
And voilà, Supre Drive was born. Cedric built two prototype bikes for his fledgling brand, Lal Bikes, teaching himself TIG welding in his spare time by watching Youtube. The mech he created uses a cable-operated shift mechanism, just like most derailleurs, to guide the chain up and down the cassette. The clever part is that the mech doesn’t tension the chain, as it does on most drivetrains, instead there’s a separate chain tensioner arm that pivots around the bottom bracket. It’s this eureka idea that makes the mech small enough to fit inside the rear triangle.
PARADIGM SHIFT
If you thought that was ingenious, the next part is inspired. The tensioner itself has its own spring and hydraulic damper, just like your shock does, and it’s hidden inside a cartridge in the down tube and connected via a cable. Cedric says it’s far more effective than any clutch mech because it’s speedsensitive, applying more force to the chain when the bike and tensioner arm is moving fast, and less when it’s moving slowly under shifting. What’s more, the chain tension is the same across all gears, unlike a conventional mech that applies more tension in the lower gears.
In theory this means it’ll be better at damping the chain when you’re pinballing down something fast, and also less restrictive and therefore better at shifting than a conventional mech.
If all that sounds like a weighty old set-up, you’d be right, the Supre Drive adds around 100-200g. That’s not the full picture, though, because the unsprung mass of the bike is actually reduced by some 130g compared to Shimano XT because the derailleur is lighter and there’s less chain around it, Cedric says. This is a pretty decent advantage and should mean better suspension, with less weight for the shock to control. There’s also no hanger and no B-tensioner, instead the mech is fixed to the frame at two points, and this makes it easier to set up too.
The eagle-eyed among you will have spotted the Supre Drive system requires a high-pivot idler suspension design,
making it very much on trend for 2022. Cedric didn’t set out to design a zeitgeist bike though, the high-pivot idler is more the byproduct of his drivetrain set-up than the goal.
“The idler pulley is a key element of the drivetrain,” he explains. “If you don’t have the idler pulley to redirect the chainline then you can’t have the full range of motion on the tensioner where it comes all the way forward. That range of motion is what makes a wide-range cassette possible.”
It’s a happy coincidence that the bike industry has decided once again that the high-pivot idler idea is a good one then, but it didn’t start this way for Cedric. “When I started working on Supre Drive the only significant bike with a highpivot idler was the Forbidden Druid,” he says. “It was uncertain about the range of adoption, there was a history with downhill bikes with idlers but no trail bikes. I’d also never ridden any high-pivot bike when I came up with the invention, I studied reviews on the Forbidden Druid and tried to make a call on whether idler bikes would be good enough.”
Is it good enough? One big (unnamed) brand certainly thinks so, and is now building a prototype frame based around Cedric’s derailleur. “I showed up there with my second prototype bike, we swapped bikes and they rode my bike,” he says. “They were stoked, they liked the way it worked and they got to see all the advantages, and that the bike performed really well too… they said it’d be silly not to develop a prototype bike.”
Is this really the end of the derailleur as we know it then? The interest is certainly there, and Cedric hopes to meet the demand by building the Supre Drive drivetrain and parts in Canada, before selling them to a range of manufacturers and customers, rather than being locked into one brand. There are other barriers to entry of course, chiefly the need to have a specific frame, and a high-pivot idler design at that. But if we never suffer another bent derailleur again, it could well be worth the trouble.
THE MECH DOESN’T TENSION THE CHAIN... A TENSIONER ARM PIVOTS AROUND THE BB