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What size bike do I need? That’s the first question most riders face, and the answer depends on your height, inseam, and riding style. This hub brings together all of our bike sizing guides and charts so you can quickly find the right fit.

Whether you need a mountain bike size chart, a road bike sizing guide, or details on hybrid, kids’, electric, or BMX bike sizing, each category has its own dedicated page. You’ll also find step-by-step inseam tips and an Ape Index calculator to check your reach if you’re between sizes.

Use this page as your starting point, then jump to the discipline-specific guides for full charts and geometry recommendations.

Quick Answer

Most adult riders fall into a bike size chart range based on height and inseam. The rule of thumb:

  • Road & Hybrid bikes: Use frame size (in cm) matched to your height.
  • Mountain bikes: Use frame size (in inches or S–XL) plus stand-over clearance.
  • Kids’ bikes: Choose wheel size (12″–24″) by child’s height and age.
  • BMX bikes: Standard 20″ wheels for most riders, with toptube length by height.
  • Electric bikes: Follow road/MTB sizing depending on style and geometry.

To dial it in: measure your inseam for stand-over fit, and use the Ape Index calculator to check reach if you’re between sizes.

How to Measure Your Inseam

Check Your Reach (Ape Index)

Ape Index Calculator

Fit Tips

  • Stand-over: Aim for ~2 cm (0.8 in) clearance for confident stops.
  • Between sizes: Longer reach → size up; shorter reach → size down.
  • Brand charts: Geometry varies—confirm with the manufacturer’s guide.