Why is size important?

Riding a bike is one of the most rewarding things you can do; great for your physical and mental health with benefits for the whole community. But riding a bike that doesn’t fit can ruin the whole experience.

Cycling should be a fun activity and if you aren’t comfortable on your bike, you are more likely to conclude that cycling isn’t for you.

If the bike is too small for you, you will be riding in a cramped, awkward position. If it is too big, it may be difficult to handle. In either case, you will not be able to deliver your full range of movement or power efficiently and you risk injuring yourself.

There are a variety of different types of bike out there, and riding position/sizing will be a little different depending on what style of bike you go for and the kind of riding you are doing, but there are a few general principles that you can follow to ensure you are getting the most out of your new bike.

If the bike is the right size for you, you should be able to:

  • Stand over the top tube with around two inches of clearance
  • Pedal with a slight bend in your knee at the bottom of the stroke
  • Reach the handlebars and brake levers comfortably

This page is a guide only and we would always recommend visiting the shop or speaking to our friendly staff.

Choosing the right size

Different manufacturers measure bikes in slightly different ways, so things can seem a little confusing at first. Road bikes and Hybrids are generally measured in metric (cm) and Mountain bikes usually measure in Imperial (inches).

Sometimes the manufacturer will simply mark the frame as Small, Medium or Large! In this case, you may need to reach for the measuring tape…

Generally, a measurement on the bike refers to the seat-tube size. This is the tube where the seatpost/saddle attach to, but the effective top-tube length is also important when thinking about your reach. More on that below.


Inside leg measurement will determine your stand-over height. This is the clearance between the top-tube and your crotch when you are standing off the saddle with the bike between your legs. We would suggest no less than two inches of clearance so that you can hop on and off confidently and safely.


Your upper body dimensions will play a role in how stretched out you are along the top-tube of the bike. If you are in between bike sizes, the top-tube length / reach could be the determining factor for you. If you have long arms, go a size up and if you have short arms; size down.

Kids Bikes

Kid’s bikes are slightly different and are usually categorised by age ranges and wheel sizes.

Use these catagories as guidance only. If your child is tall for their age, go with the bike that they are more comfortable with and size up if necessary. It’s always worth trying out a couple of sizes and going with what fits instead of what the guidance says.

Use height and inside leg measurement just like you would when fitting an adult and don’t be too tempted to buy a larger size for your child to grow into. While a little growth room is good, a bike that is too big might be more difficult to control and could affect their confidence when riding.

Sizing Charts

Below are some sizing charts you can use for reference.

Mountain Bike sizing (Hardtail)

HeightInside LegFrame Size
4’10” – 5’0”26” – 28”13”
5’0” – 5’3”27” – 29”14”, 15”
5’4” – 5’7”28” – 30”16”, 17”
5’8” – 5’9”29” – 31”18”, 19”
5’10 – 5’11”30” – 32”20”
6’0 – 6’2”32” – 34”21”
6’2” – 6’4”33” – 35”22”

Hybrid sizing

HeightInside LegFrame Size
4’10” +26” – 28”13”, 14”
5’0” +27” – 29”15”
5’2” +27” – 29”16”
5’4” +28” – 30”17”
5’6” +28” – 30”18”
5’8” +29” – 31”19”
6’0” +30” – 32”21”
6’2” +32” – 34”22”

Road Bike sizing

HeightInside LegFrame Size
5’1” – 5’3”27” – 29”48cm
5’3” – 5’5”28” – 30”50cm
5’5” – 5’7”29” – 31”52cm
5’7” – 5’9”30” – 32”54cm
5’9” – 5’11”31” – 33”56cm
5’11 – 6’2”32” – 34”58cm
6’1” – 6’3”33” – 35”60cm
6’3” – 6’5”34” – 36”62cm

Kids Bike sizing

AgeInside LegWheel Size
2-4 30cm12” or balance bike
11 +66cm26”

We hope this guide helps give you an idea of the size of bike you may require. We would be more than happy to discuss measurements with you and advise and it is always a good idea to come and see us to get a feel for a bike before you buy.

If you have any further questions or queries, just get in touch!