Why does my bike rock when I pedal hard?

Lack of anti-squat. If your bike's anti-squat is low in the sag zone, weight transfer sinks the suspension with each pedal stroke and the bike 'bobs' (pedal bob). Raising anti-squat reduces it, but it's done through the frame design, not with the shock.

What does 100% anti-squat mean?

That the chain forces exactly cancel the suspension's tendency to sink under pedaling: it stays neutral. It doesn't mean it pedals 'perfectly', only that at that point in the travel and in that gear it neither sinks nor extends.

Is high anti-squat always better?

No. High anti-squat = less bob and more efficiency climbing, but its price is more pedal kickback (the chain tugs at the pedals over bumps) and sometimes less traction. It's a balance, not a value to maximize.

Suspension Cluster · Kinematics

What is anti-squat (why your bike bobs when you pedal)

Quick answer

Anti-squat measures how much the design resists the suspension sinking under pedaling. When you pedal, your weight pushes the rear down; chain tension holds it up. If weight wins (low anti-squat), the bike rocks: that's pedal bob. At 100% it's a tie: it doesn't move. But raising it has a price — pedal kickback. It's part of suspension kinematics.

If your bike rocks like a hobby horse when you pedal hard while seated, it's not the shock: it's the geometry. And it has a name.

Have you noticed some bikes rock up and down when you pedal hard while others stay firm as a rock? That difference isn't set by the shock. It's set by anti-squat.

When you pedal, two things happen at once: your weight transfers rearward (tending to sink the suspension) and the chain pulls on the swingarm (tending to hold it up). Anti-squat is, quite simply, who wins that tug-of-war.

Anti-squat: pedaling weight tends to sink the suspension and chain tension resists it; 100% is the tie — Anti-squat = the tug-of-war between the weight that sinks and the chain that holds up.

What the numbers mean

100% = a tie: the suspension doesn't move under pedaling. Below 100% = weight wins, the bike sinks and "bobs" (pedal bob). Above 100% = the chain wins, the suspension even extends under pedaling.

That's why a bike with good anti-squat in the sag zone climbs firm without you having to use the lockout all the time. It's "free" efficiency, straight from the factory.

The price nobody tells you about

Raising anti-squat sounds ideal — but it has a downside. To generate anti-squat, the chain has to pull hard on the swingarm, and that causes pedal kickback: over big hits, the chain stretches and kicks your pedals backward. Lots of anti-squat = a very efficient climbing bike, but with more kickback and sometimes less traction in the technical stuff. It's not a number to maximize: it's a balance that the engineer tunes according to what the bike is for.

An important detail

Anti-squat isn't a single number: it depends on the sag you measure it at, the gear you're in (the chainring and cog change the chain angle) and how compressed the suspension is. That's why when a brand says "110% anti-squat", you always have to ask: at what sag and in what gear? Without that, the number is incomplete.

Common mistake: blaming the shock for pedal bob and spending on an expensive shock. If the bob comes from a frame's low anti-squat, no shock fully fixes it — it only masks it with the lockout. Design bob is corrected through kinematics, not through the oil.

Frequently asked questions

Why does it rock when pedaling?

Low anti-squat in the sag zone: weight sinks the suspension with each pedal stroke (pedal bob).

What is 100%?

A tie: the chain cancels the weight transfer and the suspension stays neutral. It doesn't mean "perfect", only "neither sinks nor extends" at that point.

Is more anti-squat always better?

No: it brings more pedal kickback and sometimes less traction. It's a balance, not something to maximize.

Does your bike rock when you pedal?

Tell us the model and how it feels; we'll tell you whether it's the frame (anti-squat) or the setup, and what to do. Message us on WhatsApp

How suspension works → Chain growth and pedal kickback → Leverage ratio → What is SAG →

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