# Spin bike flywheel weight explained

Source: https://rowandspin.co.uk/blog/spin-bike-flywheel-weight
Published: 2026-10-12
Publisher: Row and Spin

**In short:** A heavier flywheel stores more momentum, so the pedals keep turning smoothly through the dead spots of each stroke. Weight alone is not the whole story, though: where the weight sits on the wheel and the gearing between pedals and flywheel also shape the feel. Many home spin bikes list flywheels from around 6 kg to over 20 kg.

Flywheel weight is one of the most quoted numbers on spin bike listings, often in large type. The idea is simple: a heavier flywheel feels smoother. The reality is a little more complicated, because two bikes with the same flywheel weight can feel quite different. This explainer covers what the flywheel does, why weight matters, how rim weighting and gearing change the feel, how magnetic and friction resistance work with the flywheel, and what to check on a listing.

## What the flywheel does

The flywheel is the heavy disc the pedals drive through a belt or chain. Once it is spinning, its momentum carries the pedals through the parts of each stroke where your legs push least, at the top and bottom. That makes the pedal stroke feel continuous, like riding a bike on the road.

Without enough momentum, the pedals can feel jerky, especially at low cadence or high resistance. You notice it most when standing on the pedals, where an uneven stroke feels unstable.

## Why weight matters, and why it is not everything

More weight means more momentum at the same speed, so a heavier flywheel usually feels smoother. That is why studio bikes often have heavy flywheels.

But the feel depends on **inertia**, which depends on how the weight is spread and how fast the flywheel spins. Weight near the rim adds more inertia than the same weight near the centre. And gearing matters: a lighter flywheel that spins much faster than the pedals can feel as smooth as a heavier, slower one. Some makers use this to keep bikes lighter without losing smoothness.

| Factor | Effect on feel |
| --- | --- |
| Heavier flywheel | More momentum, smoother stroke |
| Weight at the rim | More inertia for the same weight |
| Higher gearing | Flywheel spins faster, feels smoother |
| Fixed flywheel | Pedals keep turning with the flywheel |
| Freewheel | Pedals can stop while the flywheel spins |

General principles

## Flywheel weights on bikes in our guides

Listings state flywheel weight inconsistently, and some do not state it at all. Where they do, the range is wide. For example, the VirtuFit Stage 2.0i lists a 22 kg flywheel, while the Sunny SF-B220030 upright lists 2.5 kg and the YOSUDA folding bike lists 3 kg. The upright and folding bikes are designed for seated riding, where a lighter flywheel is normal.

Compare like with like. A spin bike designed for standing efforts generally benefits from a heavier or higher-inertia flywheel, while an upright for seated riding does not need one. Our [spin bike vs exercise bike](https://rowandspin.co.uk/blog/spin-bike-vs-exercise-bike) comparison explains the difference in purpose.

## Magnetic versus friction resistance

Resistance is applied to the flywheel. On **friction** bikes, a felt or leather pad presses on the flywheel when you turn the knob. It is simple and gives fine control, but the pad wears and can be noisy, and the flywheel rim can mark.

On **magnetic** bikes, magnets move closer to the flywheel without touching it. The resistance comes from eddy currents in the metal wheel. It is near silent and has no pads to wear. Most new home spin bikes use magnetic resistance, often with numbered levels. Our guide to [exercise bike resistance not working](https://rowandspin.co.uk/blog/exercise-bike-resistance-not-working) covers faults on both types.

Note: On fixed-flywheel spin bikes, the pedals keep turning while the flywheel spins. Slow down gradually or use the emergency brake as your manual describes.

## Front or rear flywheel?

Most spin bikes have the flywheel at the front, where it is visible and the weight sits under the handlebars. Some have a rear flywheel, which can make the bike feel more like a road bike and keeps sweat off the flywheel. Neither is better in itself; the feel depends more on weight, gearing and the resistance system.

Rear flywheels are usually covered, which also protects fingers and keeps the bike tidy.

## What to check on a listing

Our guides to the [best spin bikes](https://rowandspin.co.uk/best/best-spin-bike-uk) and [best spin bikes under 500](https://rowandspin.co.uk/best/best-spin-bike-under-500) list resistance type and flywheel details where the listing gives them.

- **Flywheel weight**, if stated, and whether the bike is designed for standing efforts.
- **Resistance type**: magnetic for quiet and low upkeep, friction for simplicity.
- **Drive**: belt for quiet, chain for a classic feel; see [chain drive vs belt drive](https://rowandspin.co.uk/blog/spin-bike-chain-vs-belt-drive).
- **Fixed or freewheel**: fixed suits class-style riding; freewheel suits casual use.
- **Max user weight and frame**: see [max user weight explained](https://rowandspin.co.uk/blog/exercise-bike-max-user-weight).

[See our best spin bikes](https://rowandspin.co.uk/best/best-spin-bike-uk)

## Frequently asked questions

**What is a good flywheel weight for a spin bike?** Many home spin bikes list 6 kg to over 20 kg. Heavier usually feels smoother, but gearing and rim weighting matter too.

**Is a heavier flywheel always better?** Not always. A well-geared, rim-weighted lighter flywheel can feel as smooth, and a heavy one makes the bike harder to move.

**Why do some listings not state flywheel weight?** Some makers focus on resistance or inertia instead. Check the manual or ask the seller.

**Is magnetic resistance better than friction?** Magnetic is quieter and needs no pads. Friction is simple and gives fine control, but the pads wear.

## Buying guides on this topic

- https://rowandspin.co.uk/best/best-spin-bike-uk
- https://rowandspin.co.uk/best/best-spin-bike-under-500
- https://rowandspin.co.uk/best/best-exercise-bike-uk