HOW TO GET YOUR  RIGHT BICYCLE SIZE

 

How to measure for an inseam when buying a bicycle

Properly measuring for a bike is incredibly important and being comfortable matters to both professional and casual cyclists alike.

Firstly Mountain bikes come in standard sizes (S, M, L) that generally correspond to your height. Many bike manufacturers include size charts that list a height range for each bike size. (If you’re in-between sizes, so it’s best to bit on the smaller side as more sizing accommodations can be made with a smaller frame than with one that’s too large.)

Secondly having a basic understanding of bike geometry can also be helpful when comparing one bike to another or dealing with a specific fit issue. A few of the key indicators are:

  • Effective top tube length
  • Reach
  • inside height
  • Seat height
SIZING GWHAWK

Mountain Bike Effective Top Tube and Reach

Effective top tube (ETT).

Describes the horizontal distance between the head tube and the seat tube, so regardless of whether you have a straight top tube or one that slopes down. ETT is a common measurement to look at when sizing your bike and is a good indicator of how long a bike will feel while you’re seated.

Reach:

Reach is the distance from the center of the bottom bracket to the center of the head tube in a horizontal line. Reach has become a more popular way to measure length on mountain bikes because it identifies how long a bike will feel while you’re out of the saddle, a common position to be in when descending or climbing steep singletrack.

Mountain Bike Inside Leg Height

 

Although it is no longer used as often as it once was for sizing bikes, inside leg height can still be an indicator of whether or not a bike fits you.

First, make sure you can straddle the bike with your feet flat on the ground. Whenever you lift a mountain bike, you want at least 2 inches (5 cm) of clearance between the tires and the ground. This will allow you to be comfortable getting out of the saddle to dismount quickly on the trail. It’s not uncommon for aggressive riders to look for 3″ to 5″ of clearance. Ensure you wear your cycling shoes when assessing crotch height, as they can affect the overall length of your legs.

Note that the amount of clearance is greatly affected by the slope of the top tube toward the rear wheel. For example, if the slope is very steep, you are likely to have ample clearance regardless of frame size. Therefore, you can’t rely solely on interior legroom to determine if a bike is suitable.

GW BIKES INSIDE LEG

Online Shopping Tips:

GW and most bike brand websites include sizing charts for bikes featured online. Look for listed Inside leg heights and compare that number to your inseam. The difference between your inseam and the Inside leg height should fall within the target ranges. (For example, if you have a 30” inseam, you’ll want a mountain bike with about a 28” Inside leg height.)

To measure your inseam: 

Gather a large hardcover book or notebook, tape measure, and pencil. Then:

  • Stand against a wall (with bike shoes on).
  • Straddle the book, spine up, as if you were sitting on a saddle.
  • Use the pencil to mark where the spine of the book meets the wall.
  • Measure from the mark to the floor. This is your inseam.
  • Repeat the measurement another time or two to make sure it’s accurate.

 

Mountain Bike Seat Height

 

When deciding if a bike fits you properly it’s important to have the seat height correctly adjusted so you can get an accurate feel for the bike. To check your seat position, ask a sales associate or friend to hold the bike upright while you step on the saddle:

The Proper position for ascending hills and riding flat ground:

With your foot at the bottom of the pedal stroke, you should see a slight bend in the leg, reaching about 80-90 percent of full leg extension. This helps you pedal efficiently and powerfully using your major leg muscles.

The proper position for descents:

Lowering your seat lowers your center of gravity, which gives you better control and more confidence through steep descents. You’ll need to experiment with different seat heights to find what feels best but start by lowering your seat about 3 in. from the height you set it at for climbing hills and riding flat terrain.

Adjusting the seat height:

Release the quick-release lever on the seat post (or use a wrench if there’s a binder bolt) and raise or lower the post as needed. Be cautious not to raise the post outside the “minimum insertion mark” etched into its side. (If you need to change the seat height that dramatically, you might need a different frame size.)

Retighten the quick-release lever or binder bolt before riding. (Be cautious not to overtighten the binder bolt. Use a torque wrench to tighten the bolt to the manufacturer’s requirement. Be especially careful with a carbon-fiber frame and/or seat post.)

If you expect to progress quickly on your mountain bike, you may want to look for bikes with dropper seat posts or consider adding one. These seat posts let you raise or lower the seat by pushing a button, helping you adjust instantly to varying terrain.

Men’s Bike sizing chart

Height
Inside leg
Men’s road bike size
Men’s mountain bike size
Men’s hybrid bike size
147cm-152cm / 4’10”-5’0″ 66cm / 26″ 47, 48cm (XX Small) 13” (X Small) 13”, 14″ (X Small)
152cm-160cm / 5’0″-5’3″ 69cm / 27″ 49, 50cm (X Small) 13”, 14” (X Small) 14”, 15” (X Small, Small)
160cm-170cm / 5’3″-5’7″ 71cm / 28″ 51, 52, 53cm (Small) 15”, 16″ (Small) 15”, 16″ (Small)
170cm-175cm / 5’7″-5’9″ 76cm / 30″ 54, 55cm (Medium) 17″, 18” (Medium) 17″, 18” (Medium)
175cm-180cm / 5’9″-5’11” 79cm / 31″ 56, 57, 58cm (Large) 18”, 19″ (Medium, Large) 19”, 20″ (Large)
180cm-188cm / 5’11”-6’2″ 81cm / 32″ 58, 59, 60cm (X Large) 19″, 20” (Large) 20″, 21” (Large, X Large)
188cm-196cm / 6’2″-6’5″ 86cm / 34″ 60, 61, 62cm (X Large, XX Large) 20″, 21”, 22” (Large, X Large) 21”, 22” (Large, X Large)
196cm+ / 6′ 5″+ 91cm / 36″ 62, 63cm (XX Large) 23″, 24” (XX Large) 23″, 24” (XX Large)

 

Fitting Women’s Mountain Bikes

Women tend to have slimmer shoulders and longer legs than men, and female-specific bikes are designed to meet these needs. Ladies’ bikes often have narrower handlebars and shorter or more compact frames. Some women find that men’s bikes fit well and are comfortable, but ladies specific bikes may offer a more exact fit for some.

Women’s Bike sizing chart

Height
Inside leg
Women’s road bike size
Women’s mountain bike size
Women’s hybrid bike size
147cm-155cm / 4’10”-5’1″ 66cm / 26″ 44, 45, 46cm (XX Small) 13”, 14″ (X Small) 13”, 14″ (X Small)
155cm-160cm / 5’1″-5’3″ 69cm / 27″ 47, 48, 49cm (X Small) 13”, 14” (X Small) 14”, 15” (X Small, Small)
160cm-165cm / 5’3″-5’5″ 71cm / 28″ 50, 51, 52cm (Small) 15”, 16″ (Small) 15”, 16″ (Small)
165cm-172cm / 5’5″-5’8″ 76cm / 30″ 53, 54, 55cm (Medium) 17″, 18” (Medium) 17″, 18” (Medium)
172cm+ / 5’8″+ 79cm / 31″ 56, 57cm (Large) 19″ (Large) 19″ (Large)

 

Fitting Kids’ Mountain Bikes

If you’re buying a bicycle for a young rider, it’s easy to want one that he or she will “grow into,” but it’s especially important to buy a bike that fits well so he or she can ride comfortably and confidently while learning.

Inside leg height:

As with adult bicycles, check the inside leg height. Whatever the style of the top tube, look for clearance of about 2″-4″.

Seat height:

Most kids’ bikes are designed so they ride in a more upright position. They should be able to sit comfortably, see around them easily and grip the handlebars with a slight bend in their elbows. Their legs should be slightly bent at the bottom of the pedal stroke.

Online Shopping Tips:

GW and most bike brand websites include sizing charts for bikes featured online. Look for listed Inside leg heights and compare that number to your inseam. The difference between your inseam and the Inside leg height should fall within the target ranges. (For example, if you have a 30” inseam, you’ll want a mountain bike with about a 28” Inside leg height.)

To measure your inseam: 

Gather a large hardcover book or notebook, tape measure, and pencil. Then:

  • Stand against a wall (with bike shoes on).
  • Straddle the book, spine up, as if you were sitting on a saddle.
  • Use the pencil to mark where the spine of the book meets the wall.
  • Measure from the mark to the floor. This is your inseam.
  • Repeat the measurement another time or two to make sure it’s accurate.

 

Mountain Bike Seat Height

 

When it comes to deciding if a bike is right for you, it’s important that the saddle height is correctly adjusted so you can get an accurate feel for the bike. To check the saddle positioning, ask a dealer or a friend to hold the bike upright while you climb into the saddle:

The correct position for climbing hills and riding on flat terrain: With your foot at the bottom of the pedal stroke, you should see a slight bend in your leg, reaching about 80-90 percent of full leg extension. This helps you pedal efficiently and powerfully using the major leg muscles.

The proper position for descents: Lowering your seat lowers your center of gravity, which gives you better control and more confidence through steep descents. You’ll need to experiment with different seat heights to find what feels best but start by lowering your seat about 3 in. from the height you set it at for climbing hills and riding flat terrain.

Adjusting the seat height: 

Release the quick-release lever on the seat post (or use a wrench if there’s a binder bolt) and raise or lower the post as needed. Be cautious not to raise the post outside the “minimum insertion mark” etched into its side. (If you need to change the seat height that dramatically, you might need a different frame size.)

Retighten the quick-release lever or binder bolt before riding. (Be cautious not to overtighten the binder bolt. Use a torque wrench to tighten the bolt to the manufacturer’s requirement. Be especially careful with a carbon-fiber frame and/or seat post.)

If you expect to progress quickly on your mountain bike, you may want to look for bikes with dropper seat posts or consider adding one. These seat posts let you raise or lower the seat by pushing a button, helping you adjust instantly to varying terrain.