SourceBMX is a 100% rider-owned and run store - we live and breathe BMX! That's why we know BMX frame geometry can look daunting, especially if it's the first frame you're buying. This handy guide has been created to give you all the tools you need to scratch up on your BMX frame knowledge and help you find the right frame to mee your needs.

We hope you find this guide useful and remember we’re always here to help - chat to us on our 24/7 live chat service, pick up the phone or get in touch through our Contact Us page

BMX frame geometry

Frame Geometry can take a bit of understanding - but at SourceBMX, we are here to help! Keep reading on to understand how the angles change how your frame will feel and check out our sizing chart below!

headtube angle

Head tube angle determines the angle of your forks. A steeper HT (i.e 75°and higher) will make the bike turn quicker than a mellower angle (i.e 74.5 and lower°). The more responsive the frame, the more twitchy it will feel, especially at high speed!

chain stay length

The chain stay is essentially the length of the rear end of the bike. A shorter CS length will make the bike more responsive and a longer one more stable. As a rough guide, a 13.5" long chain stay is about average.

seat tube length

Seat tube angles don’t vary too much (around 71°) and affect the centre of gravity. The steeper the angle the shorter your bike will feel. Some frames have a mellower seat tube angle (example 69˚) which makes for a longer frame without actually being longer and reduces how fast your frame turns.

stand over height

Standover height is essentially how high your frame is. A frame with a low standover height is more responsive and easier to ‘throw around’ whilst a high SO height is more stable; particularly useful when going fast.

BMX frame size chart

BMX frame sizing is very much a personal preference, some riders like them longer, others shorter. Our guide is a great starting place if you're not sure and if you have any questions remember we are here to help!

Rider Height (Feet and Inches) Rider Height (CM) Top Tube (Inches)

2'0" - 3'0"

60cm - 90cm

11.5" - 13"

2'8" - 3'4"

80cm - 100cm

12.8" - 15"

3'0" - 3'8"

90cm - 110cm

14.5" - 17"

3'6" - 4'6"

105cm - 135cm

17" - 18.5"

4'0" - 5'4"

120cm - 160cm

18" - 20.25"

5'0" - 5'8"

150cm - 170cm

20" - 20.5"

5'6" - 6'0"

165cm - 185cm

20.25" - 21"

6'0" +

180cm +

20.75" - 21.5"

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