Marginal Gain Orient: Two Chainrings Without a Front Shifter

By MTBSA contributor

The Marginal Gain Orient revisits the two-chainring drivetrain with an unusual idea: let the chainline choose the front ring. Instead of a conventional front derailleur, a diagonal transition section guides the chain between two parallel rings as the rear derailleur moves across the cassette.

A passive shift at the front

With a typical 12-speed cassette, the transition is intended to happen around the middle of the range. The aim is to reduce the extreme chain angles encountered by a single chainring at either end of a wide cassette.

The development focus is primarily gravel and road riding, where small gear steps and efficiency are important. Mountain-bike compatibility is being explored, but it is not the sole design priority.

Frame clearance remains part of the equation

The demonstrated 25 mm-offset version uses a Blackwater Bicycles frame with elevated chainstays to create clearance. An 18 mm-offset version is also in development, intended to fit more conventional mountain-bike arrangements.

Current ring combinations are identical or close in tooth count, such as 30/32 teeth. This is therefore not simply a replacement for a conventional double with a large difference between ring sizes. Bigger steps would require additional shifting hardware and change the concept.

Interesting, but still a development story

The team also has plans for a forward-mounted rear derailleur to improve clearance and chain wrap. Those plans should be distinguished from the chainring prototype already demonstrated.

For South African riders, the relevant questions are frame clearance, actual gearing, chain retention and replacement-part support. The supplied article does not establish local availability, pricing or independent efficiency gains. Treat Orient as a drivetrain idea worth following rather than a proven upgrade for any existing bike.

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