Lal Bikes Supre Drive – A Better Derailleur Solution?

Is this the week when all the stupid annoying bits of mountain bike tech are finally going to be fixed? We’ve already seen two takes on improving the infinitely annoying Presta valve, and now we have a new take on the rear derailleur. Will the Lal Bikes Supre Drive eliminate rock bashing woe? Will our derailleurs no longer dangle, tangle and bend? Let us see…

The inventor of the Supre Drive is Cedric Eveleigh, a mechanical engineer and mountain biker, operating from his parent’s basement in Quebec, Canada. His company, Lal Bikes, is named after Pierre Lallement, who is considered by some to have invented the bicycle. Eveleigh first built his prototype in 2019, and today he’s releasing the idea on the world. (Thanks to Tom Howard for the eagle eyed tip off!)

Lal Bikes will manufacture the derailleur, chain tensioner, and idler pulley in Canada (and maybe also in Europe later on). These parts will be sold to bike companies that spec the Supre Drive, and also directly to mountain bikers, etc. Lal Bikes collaborates with mountain bike companies in the development of frames equipped with the Supre Drive.

Cedric Eveleigh – Lal Bikes

During its development, he’s been posting on Instagram, indicating that that a bike company was interested in his design, but that it needs frames designed specifically for the Supre Drive:

The Supre Drive is different enough that it requires frames to be designed around it. This past summer, I was put in touch with a major mountain bike company. After seeing my second prototype bike on a video call, they covered my flight so that they could test ride it. The test rides were fun and they were stoked. I’m now collaborating with them while they develop a prototype frame of their own that’ll use the Supre Drive. This is a photo from when my dad dropped me off at the airport for this trip in August. No, the bike company isn’t Norco. I just like that t-shirt. It’s from when I used to wrench in a bike shop that sold Norcos. This collaboration with a bike company is exciting, and I plan to collaborate with many others while I focus on the drivetrain parts.

Cedric Eveleigh

Who might he be collaborating with, then? Knolly, or Banshee? Forbidden already plays in the idler world, and Guerilla Gravity is into doing things differently. It will certainly be interesting to see – and to see whether the Supre Drive idea takes off or joins the ranks of inventions that never quite made it.

This all hints at a drivetrain built into the frame. Another earlier Instagram post said ‘A cassette and no derailleur to be seen, but I can assure you that this bike has a functioning drivetrain’. Combined with his reference to the chain tensioner and idler pully, it sounds rather like what Chris Porter says he would do if he had a pile of money to sink into a project – except Chris talks of gearboxes:

If I found a couple of hundred grand down the back of the sofa tomorrow, I’d make a linkage fork gearbox bike with a transferable drive where the drive is moveable – you can move the drive point in relation to the pivot, up and down, so that you could make it squat or not – with a seat post on a four bar linkage, and I’d do all of that with recycled steel tubes. That would be amazing, to be able to use old bicycle tubes to make the most technologically advanced bicycle but without actually having a single patentable or technologically advanced process, just brazed steel tubes. That would be amazing.

Chris Porter

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A further clue lay in the name: Supre, which means ‘above’ in Esperanto. Given Eveleigh says he’s trying to solve the problem of bent and broken mechs, it seemed likely that he was somehow turning the whole thing upside down, with a derailleur above the cassette – and perhaps idler pulley to make the elevated chainline work?

Apparently we won’t have long to wait – he’s going to reveal it at some point today. But feel free to speculate wildly until we have some hard facts. We’ll update this story when all is revealed!

And Here It Is…

Eveleigh has now released details of his new design:

Lal Bikes Supre Drive: How does it work?

The derailleur has no cage, clutch, or torsion spring. The equivalent of these parts is transferred to a chain tensioner at the middle of the bike. The tensioner arm pivots around the bottom bracket axis.

The blue line represents the chain in the lowest gear, and the red line represents the chain in the highest gear. Shifting to lower gears makes the tensioner arm pivot backward, and shifting to higher gears makes the tensioner arm pivot forward.

There’s no derailleur hanger and no B screw, but it has high and low limit screws. The derailleur is rigidly mounted to the frame at two points, making it well-braced and capable of withstanding impacts. However, impacts are unlikely because of the ground clearance.

The Supre Drive moves the task of tensioning the chain to the middle of the bike and lets
the derailleur focus solely on shifting. The tensioner arm is connected by a cable to a cartridge that contains a spring and a damper. This cartridge is inside the down tube. Whereas conventional derailleurs produce increasing chain tension in the low gears, the tensioner system of the Supre Drive produces approximately constant chain tension across all gears. This is achieved by decreasing the leverage of the cable on the tensioner arm as the tensioner arm rotates back during shifts to lower gears. This decrease in leverage compensates for the increase in force from the spring. The approximately constant chain tension improves the efficiency of the Supre Drive. Additionally, the large size of the pulleys also improves the efficiency of the Supre Drive. The damper is hydraulic. It’s speed-sensitive, meaning that there’s a lot of force when the tensioner arm rotates fast (which occurs while riding over rough stuff) and there’s less force when the tensioner arm rotates slowly (which occurs while shifting).

Supre Drive Specifications

• Compared to other high pivot bikes with an XT derailleur, the Supre Drive has around 130g less unsprung weight but 100–200g more total weight. This extra weight is sprung weight at the middle of the bike. In other words, the Supre Drive increases the sprung to unsprung weight ratio.
• Compatible with off-the-shelf hubs, bottom brackets, cranks, chains, shifters, and cassettes. Two specific requirements are a 52mm chainline and a T47 bottom bracket.
• The frame must be designed around the Supre Drive.
• The latest version works with a 10-51t Shimano cassette (although the prototype bike shown here has a 10-45t cassette).
• Adjustment is the same process as conventional derailleurs except easier because there’s no B-limit, setting the chain length is simpler, and there’s no derailleur hanger alignment.

I designed and built two prototype bikes with the Supre Drive. In this announcement, I’m showing the second prototype bike. It has a steel frame and high pivot suspension. I designed and built all of the unique parts, including the derailleur, chain tensioner, idler pulley, and frame. I machined the pulleys and several other parts, I 3D printed many of the derailleur and tensioner parts, and I welded the frame.

Cedric Eveleigh

Now you can see more, what do you think? Will this make Cedric’s fortune and it’s the drivetrain of the future? Or will the laws of unintended consequences kick in and we’ll find some other problem that renders this another interesting historical curiosity in the history of drivetrain innovation?

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