Free online bike size charts so riders can find the right frame size by height and inseam. Covers road, MTB, gravel, kids, and more.
• Bike size charts for road, mountain, gravel, and kids bikes
• Frame sizing guidance using rider height and inseam
• Simple, free reference guides for choosing a bike size
• Compare sizing before buying a new bike
• Find a suitable frame size for road, MTB, gravel, or kids bikes
• Use height and inseam measurements to narrow down options

Ran it with 173 cm height and 79 cm inseam, road, Giant Defy Advanced. It returned S with M as the alternative, and the explanation was clear: I'm right at the top of S (163–173 cm, 74–79 cm inseam) and inside M's 171–180 cm. The brand comparison was the most useful part for me. The same numbers land on Scott XS (52) but Hiland M (53), which shows exactly why labels mislead. One suggestion: the result tells me to compare handlebar reach between the two sizes, but the Frame details box shows a single front-end height (577 mm) and reach (384 mm) without saying which size they belong to. Showing S and M side by side there would make the tie-breaker usable without opening the geometry chart.

Using inseam alongside height is the right input — height alone misses a lot, especially for riders who fall between sizes. The kids' charts are a particularly useful inclusion, since children outgrow frames fast and parents often end up guessing. Question: do the charts try to account for reach and stack differences across brands, or are they meant as a starting point before checking a specific manufacturer's geometry?
The comments below already nail the key insight — height alone is a weak predictor, since two riders at the same height can have very different inseams. What makes this useful as a reference is that it covers the categories where sizing confusion is worst: kids bikes, where parents are usually guessing, and gravel/MTB, where geometry varies a lot between brands. Genuine question: do the charts account for differences in reach and stack across brands, or are they primarily height-plus-inseam lookup tables?
It's an useful resource for anyone trying to choose the right bike size, especially since sizing can vary quite a bit between road, MTB, and gravel bikes. There is no time to relax once the ball starts gaining speed and the track begins twisting,https://slope3.com .

Ran it with 173 cm height and 79 cm inseam, road, Giant Defy Advanced. It returned S with M as the alternative, and the explanation was clear: I'm right at the top of S (163–173 cm, 74–79 cm inseam) and inside M's 171–180 cm. The brand comparison was the most useful part for me. The same numbers land on Scott XS (52) but Hiland M (53), which shows exactly why labels mislead. One suggestion: the result tells me to compare handlebar reach between the two sizes, but the Frame details box shows a single front-end height (577 mm) and reach (384 mm) without saying which size they belong to. Showing S and M side by side there would make the tie-breaker usable without opening the geometry chart.

Using inseam alongside height is the right input — height alone misses a lot, especially for riders who fall between sizes. The kids' charts are a particularly useful inclusion, since children outgrow frames fast and parents often end up guessing. Question: do the charts try to account for reach and stack differences across brands, or are they meant as a starting point before checking a specific manufacturer's geometry?
The comments below already nail the key insight — height alone is a weak predictor, since two riders at the same height can have very different inseams. What makes this useful as a reference is that it covers the categories where sizing confusion is worst: kids bikes, where parents are usually guessing, and gravel/MTB, where geometry varies a lot between brands. Genuine question: do the charts account for differences in reach and stack across brands, or are they primarily height-plus-inseam lookup tables?
It's an useful resource for anyone trying to choose the right bike size, especially since sizing can vary quite a bit between road, MTB, and gravel bikes. There is no time to relax once the ball starts gaining speed and the track begins twisting,https://slope3.com .
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