How do I know my seat tube size?

You can easily measure the size of the post using a digital caliper and the metric calipers to check the diameter of the existing seat post. First, if you have an old saddle-post that attaches firmly, then you can measure its outer diameter for an accurate estimate of what you need to buy.

What size is a trek seatpost?

Lower end Trek Aluminum frames are 29.2mm seatposts. My wife’s 2003 4300 is that. This is an odd size so you are going to be pretty limited. If your looking to upgrade, I would recommend a 27.2mm post with a 2mm shim.

What size seatpost clamp do I need?

Note: The seat clamp diameter needs to match the diameter of your seat tube rather than your seatpost, which is a little smaller. For example, a 27.2mm seatpost (a size commonly found on road bikes) fits inside a 28.6mm diameter seat tube, so it’s a 28.6mm clamp you need.

How do you measure a seat clamp?

Seat post clamp size refers to the inside diameter size of the clamp. This should correspond to the outside diameter of bike frame where the clamp is used. Just measure the outside diameter of the frame where the clamp will be used.

How do you measure a diameter?

Measure just the radius of the circle if it is very large. The radius is the distance from the center to any point on the circle. Multiply the radius by two to produce a measurement for the diameter.

Are all seat posts the same size?

Seatpost diameters generally range from 22 mm to 35 mm in 0.2 mm increments. The most common size is 27.2 mm (1.07 in) for most bikes, especially for the higher-quality models. BMX bikes commonly use 25.4 seatposts. In some modern bikes with thicker alloy or carbon tubing, larger diameters such as 30.9 mm are used.

How do you measure a quick release seat clamp?

What tool do you use to measure diameter?

Calipers. They are usually of two types- inside and outside calliper. They are used to measure internal and external size (e.g. diameter) of an object.