What is a bike seat tube?

Asked by: Steve Gettman

A bicycle seatpost, seatpin, saddlepole, saddle pillar, or saddle pin is a tube that extends upwards from the bicycle frame to the saddle. The amount that it extends out of the frame can usually be adjusted, and there is usually a mark that indicates the minimum insertion (or maximum extension).

What’s a seat tube?

A bike’s seat tube angle – often called ‘seat angle’ – is simply the angle between the horizontal and a line that starts at the bottom bracket and goes up through the seat tube. Like stack and reach, seat tube angle refers solely to the frame.

Is bike size top tube or seat tube?

Anatomy of the bicycle frame

Seat tube length is often used to denote size, but top tube length is the more important number for establishing the right fit.

Is seat tube the same as frame size?

Bike frames are commonly measured in centimetres or inches representing the length of the seat tube. For example, a manufacturer may measure the seat tube length of a bike as 51cm, and then describe it is a small frame.

What is a seatpost on a bike?

The seatpost is a tube that connects the frame of the bicycle to the saddle, where the rider sits. Seatposts are useful because they allow for adjustability. In this way, the same frame can accommodate riders of different sizes or can be adjusted for different riding styles or terrain types.

Why are seat tubes steep?

A steeper seat angle puts you in a more centered position for climbing, and it’s easier to shift your weight forward and backward as needed, compared to feeling like you’re going to loop out any time you start climbing.

What is a slack seat tube?

– Given an equal distance from the seat to the bottom bracket, a slacker seat tube places your seat lower vertically. This makes it easier to rip with your seat at full pedaling extension. – Most of us have a tendency to keep our butts near our seats.

How do I choose a bike seat post?

Length. Make sure you have the correct length of seatpost for your needs. Seatposts are available in several lengths from 280mm to 400mm so measure the amount of post you have showing (plus the minimum amount of insertion that needs to be in the seat tube) before purchase. If in doubt, measure your old post.

Are bike seat posts universal?

While there are any number of post diameters out there, most modern road and MTB bike frames accept a seatpost of either 27.2mm in diameter (‘standard’), 30.9 or 31.6mm (‘oversize’).

How do I know my seatpost size?

To find out the diameter of your seatpost, you must remove the seatpost from the bicycle frame and look for the size, which is stamped just below the “Minimum Insert” line toward the bottom. The number will be a three-digit number (such as 26.8 or 27.2 or 31.6).

What seat tube length do I need?

Touring Bike

Where is the seat tube on a bike?

ST: Seat Tube: Measured from the center of the bottom bracket along the center to a point near the seat post binder. The exact location of this point may vary between manufacturers depending on the frame design.

How do you measure a seat tube?

Seat tube length is the straight line distance between the centre of the bottom bracket and the top of the seat tube.

Does seat tube size matter?

These days, seat tube length is still important in some cases: To understand the lowest position of a saddle, especially important when sizing up to a larger frame or considering a bike with a classic, level top tube. To determine the amount a saddle may be lowered when using a dropper seatpost.

How do you measure a bike seat tube?

First, find the centre of the crank where it joins the bottom bracket. Next, measure a line following the seat tube upwards to where the collar sits. This is the ‘actual’ length of the seat tube.

How do you measure a bike tube seat?

The first measurement is from the center of the bottom bracket to the center of where the seat tube and top tube connect. This measurement is called Seat tube length (c-c). The second measurement is from the center of the bottom bracket to the top of the seat tube. This measurement is called Seat tube length (c-t).

What does a 26 inch bike mean?

And what does it mean when they say “26 inches”? A 26 inch mountain bike means that the wheels have an internal diameter of 26 inches. This measurement is commonly used in reference to mountain bike. For example, a man who stands 5’8″ would be best suited for a 26-inch frame.

What is a seat stay?

Seat Stays

The seat stay connects the seat tube to the rear dropout. Most bike frames use two parallel tubes that connect above the rear wheel. This is also the spot on the frame where the rear brake caliper is attached.

What is seat tube CC and CT?

Seat Tube Length

“Centre to Top” or C-T is the length from bottom bracket centre to top of seat tube. Useful because you can measure it and helps you work out how much seatpost you need. “Centre to Centre” or C-C is the length from bottom bracket centre to the middle of where the top tube meets the seat tube.

What does CT stand for in bikes?

The CT designation has been used for the Trail Cub series of bikes since 1964.

How does seat tube angle affect ride?

Seat tube angles range from about 70-75 degrees. A steeper angle moves the saddle forward while a shallower angle moves it back. Steep is fine for racers. It allows them to ride hard in an aero crouch, as the more open hip angle doesn’t constrain breathing or power transfer.

What is ct size of a bike?

Center to Top (C-T) – This is the length of the seat tube, measured from the center of bottom bracket to top of the seat tube. Metric (cm) – Road bikes are measured in centimeters.