Not entirely: a little chain growth is needed to generate anti-squat (the chain tension holds up the suspension under pedaling). The problem is the excess, which produces annoying pedal kickback and can slow the suspension's movement in the rough.

Suspension Cluster · Kinematics

Chain growth and pedal kickback: why your pedal kicks back

Q: What is pedal kickback?

It's when the suspension, compressing over a bump, stretches the chain and the chain pulls the cranks backward, giving you a small tug on your feet. It's caused by chain growth, and it's most noticeable on big hits with your feet planted on the pedals without pedaling.

Quick answer

When the suspension compresses, the rear axle moves away from the bottom bracket and the chain has to stretch: that's chain growth. Since the chain is fixed to the cog, that stretch pulls the cranks backward and gives you a tug on your feet: pedal kickback. A little is necessary (it generates anti-squat); too much is annoying. Bikes with a strongly rearward axle path use an idler pulley to neutralize it.

Ever felt a little "tug" at the pedals when riding through a hard bump without pedaling? You're not crazy and your bike isn't broken. It has a name and a cause.

Imagine a rope tied to two posts. If you move the posts apart, the rope tightens and pulls on both. Your chain does the same when the wheel moves away from the bottom bracket.

As the suspension compresses, the cog moves away from the chainring, the chain stretches (chain growth) and pulls the cranks backward (pedal kickback) — The wheel moves away → the chain stretches → your pedal kicks back.

How it chains together (literally)

1. Chain growth: as the suspension compresses, the distance between the chainring and the cog grows. The chain needs more length than it has. 2. The chain pulls: since it's meshed on the cassette, that stretch is transmitted to the chainring. 3. Pedal kickback: the chainring rotates a touch backward and, with it, your cranks and your feet. On an isolated bump it's a tap; in a very rough section with your feet planted, it's annoying and can even slow the suspension down.

Why it's not entirely bad

Without some chain growth there'd be no anti-squat: it's precisely that chain tension that holds up the suspension under pedaling and prevents the "hobby horse" (pedal bob). Good design seeks the balance: enough chain growth to pedal firm, not so much that kickback ruins the descent.

The high-pivot solution: the idler

Bikes with a strongly rearward axle path (high-pivot) swallow hits incredibly, but they generate a ton of chain growth. So your feet don't get hammered, they fit an idler pulley near the pivot: it reroutes the chain so the stretch doesn't reach the pedals. It's the price (friction + weight + noise) of being able to float over the rough stuff.

Common mistake: confusing pedal kickback with "play" or a mechanical problem, and taking the bike to the shop hunting for a fault that doesn't exist. If the little tug only shows up on hard hits and the bike runs fine otherwise, it's almost certainly design kickback, not a failure.

Frequently asked questions

What is pedal kickback?

The backward tug of the cranks when the suspension stretches the chain over a bump. It's caused by chain growth.

Is chain growth bad?

In the right amount, no: it generates the anti-squat that makes you pedal firm. The problem is the excess, which produces annoying kickback.

Feeling odd tugs at the pedals?

Tell us when they show up and on which bike; we'll tell you whether it's design kickback or something to check. Message us on WhatsApp

How suspension works → Axle path → Anti-squat → High-pivot + idler →

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BikeLab-pedia · Suspension Cluster / Suspension kinematics explained / Carlos Eduardo Ravello Joo · BikeLab Studio · Trujillo, Peru