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Bicycles

Binary Gear doubles an MTB's gear ratios, without a front derailleur

By Ben Coxworth
June 08, 2023
Binary Gear doubles an MTB's gear ratios, without a front derailleur
Designed primarily with mountain bikes and gravel bikes in mind, the Binary Gear is compatible with third-party chainrings and pedals
Designed primarily with mountain bikes and gravel bikes in mind, the Binary Gear is compatible with third-party chainrings and pedals
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Designed primarily with mountain bikes and gravel bikes in mind, the Binary Gear is compatible with third-party chainrings and pedals
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Designed primarily with mountain bikes and gravel bikes in mind, the Binary Gear is compatible with third-party chainrings and pedals
The Binary Gear is cable-controlled
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The Binary Gear is cable-controlled

Even though almost all new mountain bikes now have just one chainring and no front derailleur, it would still be nice to have all those other gear ratios again. The Binary Gear is designed to bring them back, without reintroducing a front derailleur.

Currently the subject of a Kickstarter campaign, the Binary Gear is manufactured by Italian bicycle tech company MagneticDays.

The device – which comes with a system-specific set of adjustable-length cranks included – replaces a bike's existing bottom bracket. Of course, it could also simply be built into new bikes. For now, it's only compatible with bicycles that have a PF46 or T47-type bottom bracket.

Instead of simply incorporating a single axle that runs through the bottom bracket between the cranks, the Binary Gear features a 2-speed mechanical gearbox. At one speed, crank revolutions are translated into chainring revolutions at a 1:1 ratio (just like they normally would be). At the other speed, however, that ratio climbs to 1:1.25 – so in other words, the chainring revolves 25% faster than the cranks.

Riders switch between the two speeds via a cable-linked handlebar-mounted lever.

The Binary Gear is cable-controlled
The Binary Gear is cable-controlled

We're told that the whole system is about 500 g (18 oz) heavier than a conventional bottom bracket. That said, buyers will be able to reduce their bike's total weight by being able to switch to a smaller chainring, smaller cassette cogs and thus a shorter chain.

Assuming the Binary Gear reaches production, a pledge of €267 (about US$288) will get you a setup – the planned retail price is €890 ($960). There's more information in the video below.

Prospective backers might also want to check out Classified Cycling's Powershift system, which incorporates a 2-speed rear wheel hub.

BINARY Gear - The innovative drivetrain by MagneticDays

Sources: Kickstarter, MagneticDays

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BicyclesCyclingMountain BikesgearboxKickstarter
5 comments
Ben Coxworth
Ben Coxworth
Based out of Edmonton, Canada, Ben Coxworth has been writing for New Atlas since 2009 and is presently Managing Editor for North America. An experienced freelance writer, he previously obtained an English BA from the University of Saskatchewan, then spent over 20 years working in various markets as a television reporter, producer and news videographer. Ben is particularly interested in scientific innovation, human-powered transportation, and the marine environment.

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5 comments
George Fleming
The Binary Gear has four advantages over the Classified two-speed Powershift hub:

1. There is no additional weight at the rear wheel
2. No need to modify the rear wheel
3. No complication in removing or installing the rear wheel
4. There is one, but I forgot it.

Both devices will have the same chain line, better than 1x but still not perfect. That is, straight and constant.

The Classified two-speed Powershift hub has one important advantage over the Binary Gear. It uses the gears for low speed and direct drive for high. That puts the inefficiency of the gears where it does the least harm. The Binary Gear uses direct drive for low speed and the gears for high, where the inefficiency of the gears does the most harm.

A major disadvantage of the Binary Gear is that it won't fit on bikes with threaded bottom brackets. That is, most bikes.

A major disadvantage of both gearboxes is that they use gears. Aside from the inefficiency of gears, they are expensive and require accurate alignment and rigid mounting. That is why all geared drives cost so much and weigh more than chain drives. And gearboxes require sealed gear cases. Seals waste power.

I wonder how many of us think it is a worthwhile advantage to eliminate the front derailleur. I am not one of them. Mine works fine. But I am not some wild and crazy mountain biker who doesn't mind spending part of the year in the hospital and the rest of the year earning the money to fix the bike.
akarp
LOL, $960MSRP is pretty silly when a near-top-of-the-line front derailer is $45...

I still use a 2x10 setup. I like being able to drop several gear ratios with only 1 tap.
WONKY KLERKY
Revolutionary?
Yup - It goes round.
Historical:
These things have been out since Edwardian times.
Post WWII:
There was a Swiss gentleman who used to knock them out in his home workshop.
Much acclaimed and much expensive they were the 'Mountain Drive' gearboxes.
It appears that that they are now manufactured in Germany under the title of the 'Shlumpf Mountain Drive'.
Trylon
So they can sell Kickstarter units at $288 presumably without losing money but production units will cost $960. That's a hell of a markup. And I don't get what's so revolutionary about this. There have been several planetary bottom brackets for bikes over the years, the best known being the Schlumpf Speed and Mountain Drives that were introduced in the 1980s and are still sold today.
geemy
for MTB eddi own y is more important for climbing.
I don't see why it would improve the chain line compared to a traditional 1x
speaking about MTB again, I like the simplicity of a single shifter, range is sufficient, and every gear is useful. I guess for XC having closer gear, could help a bit but you're eon a trail and constantly changing gear, it helps to never have to think more than upshift or downshift