The Future of Crank Length – SRM’s New Adjustable Cranks
Crank length has always been one of those things most riders never think about. You buy a bike, it comes with 172.5 mm cranks, and that’s what you ride. But for years, people have argued that shorter or longer crank arms can change your comfort, power, and pedalling efficiency. Until now, testing those differences meant swapping entire cranksets — not exactly practical.
SRM just changed that
SRM Origin Adjustable Cranks
The new SRM Origin system introduces bolt-on crank tips that let you change the crank length in small increments, typically between 160 mm and 175 mm, without replacing the whole crank arm.
You simply remove a small end piece, swap in a different one, and you’ve effectively changed your crank length. The design uses precision-machined tips that bolt securely to the main crank body, keeping stiffness and power transfer identical across all lengths.
It’s a smart idea for riders who want to fine-tune their setup or experiment with different positions — especially as bike geometry and rider flexibility evolve.
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Why It Matters
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Adaptability: One crankset, multiple lengths. Perfect for riders experimenting with different setups, or for families sharing bikes.
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Performance: Shorter cranks can improve cadence and hip clearance; longer ones may give more leverage on climbs.
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Comfort: Riders dealing with knee or hip issues can now try shorter options without investing in new cranks.
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Aesthetics: SRM even offers the tips in multiple colours, so you can add a subtle custom touch.
What’s the Catch?
The main downside is price — this is SRM, after all. The full setup (arms, spider, power meter) can push well past $3,000 NZD, depending on configuration. It’s a high-end system designed for riders who want adjustability and data in one package.
Still, the concept is solid and could trickle down to more affordable options in the future.
The Takeaway
The idea of an adjustable crank isn’t new, but SRM has made it practical, sleek, and ride-ready. Whether you’re fine-tuning your position, experimenting with shorter lengths, or just like the idea of tech that adapts with you, this could be one of the most interesting upgrades of the year.
Why this is big for riders:
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Instead of buying separate cranksets in multiple lengths (and bottom brackets/spindles), you adjust within one system.
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It enables real-world testing of crank length: set the fit bike/trainer with one length, switch to another, compare knee/hub/back position.
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Because adjustability is in smaller increments (2.5 mm), it offers a finer fit dial than standard 5 mm jumps typical of many crank length options.
Things to watch / caveats:
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Price: The full setup (crank arms + power meter spider + chainrings etc) is expensive. One article quotes approx €3,561 for one configuration. BikeRadar
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Installation & compatibility: Bottom-bracket/spindle standards must match. Some older bikes may not be compatible.
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Changing crank length affects other fit dimensions (seat height, fore-aft, hip angle) — you’ll still need to re-check those.
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For many riders, the difference between lengths may be subtle; incremental gains might matter most for high-performing riders or those with specific comfort issues.
