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Questions and answers about sports

Anyone make a 31 or 31.1 mm seatpost?

6 min read

Asked by: Takeshi Ballard

What is the most common seatpost diameter?

27.2mm

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’).

What size do seatposts come in?

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.

What diameter seatpost do I need?

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).

How do you measure for a new seatpost?

Quote from video: And you're going to want to measure like a couple different angles preferably about 90 degrees apart. And you're going to play with a little bit trying to find the largest. Numbers between there.

How long should your seatpost be?

a) Seatpost should end at least 25 millimeters below the lower part of the horizontal tube weld to the seat tube. b) Total inserted length should be at least 90 mm from the top end of the seat tube.

How do I choose a seatpost?

Quote from video: There's a very simple method which is to go ahead and loosen up your seat clamp bolt here slide your saddle. And your seat post out. Look at the seat post and see if there's a number printed on there.

Can I get a longer seat post on my bike?

Pretty much all you can do though is put a longer stem, possibly raise and lower it, use wider handlebars and adjust the saddle angle+ position a bit further back (which may be easier with a different seat post). The biggest things you have to do are get the effective top tube right.

What is the size of giant seatpost?

Most giants use a 27.2mm post in a 30.8/9 shim. 30.8 and 30.9 doesn’t sound like much, but it’s the difference between a post that slips and one that doesn’t. Older giants used a 30.8,which was a stupid giant only size. recently they switched to 30.9 which is a pretty common size.

How do you extend a bike seat post?

Quote from video: Extender is offered in three frame sizes with round tubes for 22.2 frame 25.4. And a 27.2 seat post size. On those you will need a secondary c-clamp to go with it which you need the 25.4.

Will a 31.6 seatpost fit a 30.9 frame?

You can fit a narrower post into a wider frame using a shim (a thin sleeve of aluminium or plastic), for example a 30.9 mm dropper post into a 31.6 mm frame. However, there is no way to fit a wider post in a narrower frame, for example a 31.6 mm post into a 30.9 mm frame.

What size seat clamp do I need for a 27.2 seatpost?

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 I choose a seatpost setback?

Straight and Setback Seatposts



The amount of setback or offset is best determined through a basic bike fit at a participating bike shop. They will look at the relationship between your knee and pedal axle, as well as your hip angle/mobility and will determine how far you should sit behind your crankset.

How Short Can I cut my seat post?

If you want to cut your Seatpost shorter, it’s recommended that you cut it at a maximum of 1-inch per side. For example, if your bike has a 27.2mm Seatpost diameter and you want to shorten it by two inches, you can cut the post down to 25.2mm in diameter.

Can I cut my seatpost down?

Cutting your seat post is one of the most effective ways of tearing your seat tube to pieces. Also, if you cut off the bottom, you will have to adjust the max height line by the same amount…that is, you need a certain amount of length in the tube to have the seat post be safe.

Why do my thighs hurt when cycling?

A common reason for encountering cycling leg pain is because of a build-up of lactic acid. Whilst you are cycling the body utilises oxygen to break down glucose for energy. If the exercise intensity is too much you might run out of oxygen for this process.

What size seat clamp do I need for a 27.2 seatpost?

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.

What is the size of giant seatpost?

Most giants use a 27.2mm post in a 30.8/9 shim. 30.8 and 30.9 doesn’t sound like much, but it’s the difference between a post that slips and one that doesn’t. Older giants used a 30.8,which was a stupid giant only size. recently they switched to 30.9 which is a pretty common size.

What size seat clamp do I need for a 34.9 seatpost?

Clamp diameter: 34.9mm. Seat Post Fit: 31.6mm. Weight: 25g.

What size is a Schwinn seat post?

Schwinn Scripted Chrome Seat Post 20.57mm x 5/8″ Top 14″ Long – New.

How do you extend a bike seat post?

Quote from video: Extender is offered in three frame sizes with round tubes for 22.2 frame 25.4. And a 27.2 seat post size. On those you will need a secondary c-clamp to go with it which you need the 25.4.

What is a seatpost offset?

Quote from video: We can see this post here is a straight post I lined it on that line of the yoga mat. So you can see it goes kind of straight up and down there. And you got the midline and slant right in line with