what does seatpost offset mean

Full Answer

When is a seatpost with offset necessary?

A seatpost with offset is necessary when the seat tube angle of the frame is too steep to give the desired saddle setback (the horizontal distance between a plumb line hung from the nose of the saddle and the bottom bracket spindle).

What is the difference between a zero offset and layback seatpost?

A zero offset seatpost will place the saddle directly above the clamp – though of course you can adjust it forward and back on the rails. A layback seatpost slopes slightly backwards, placing the saddle further back, something you’d want to do if you can’t get your knee in the right position over the ball of your foot with a zero offset version.

What is a seatpost on a bike?

Your seatpost slips into the seat tube and attaches your saddle to your bike. Though there are exceptions, most of them look pretty unassuming. So what should you look out for in a seatpost upgrade?

Why do some people ride with zero-offset seat posts?

One reason. Some riders (especially those with short femurs) shove their saddle all the way forward to achieve what they believe to be a proper position over the bottom bracket. For these riders, a zero-offset seat post makes sense.

Does seatpost offset matter?

The zero offset helps to put those folks over the pedal easier. Zero offset posts also work well if the top tube (real or virtual) is longer then ideal. Moving the seat forward reduces the distance between the stem and the saddle.May 9, 2017

How do I know if I need an offset seatpost?

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.May 24, 2019

How is seatpost offset measured?

It's measured from the seatpost centerline to the center of the clamp....Most manufacturers do this:trace an imaginary line (or tie a string) along the center of the seatpost entry into the bike a few inches down the seat tube.extend that straight line past height of the seat rail clamps on the post.More items...•Nov 17, 2009

What is a zero offset seatpost?

Seatposts can be zero offset, or come with layback. A zero offset seatpost will place the saddle directly above the clamp - though of course you can adjust it forward and back on the rails.Mar 30, 2022

What is saddle offset?

Bike saddle offset is similar to saddle setback, although offset or “layback” comes from the seat post rather than adjustment of the saddle. Bike saddle offset can range from 0 mm to 45 mm and is often used when riders with longer femur's need to get further behind the bottom bracket.Aug 19, 2021

How much is a saddle setback?

The more traditional method, know as 'Knee Over Pedal Spindle' (KOPS), proposes that optimal saddle setback occurs when the tibial tuberosity is directly over the pedal spindle when the crank arm is at 90 degrees in the downward stroke.

How do you measure a setback saddle?

Your setback is measured as the distance between the vertical planes of the center of your bottom bracket and the nose of your saddle.Apr 5, 2018

What length seatpost do I need?

The CPSC rule in the US is that the seatpost must be inserted two diameters of the seatpost into the frame. If it's a 27.2 mm seatpost, it must extend 54.4 mm into the frame, which is 2 1/8".Oct 5, 2010

Do I need carbon paste for seatpost?

It is absolutely necessary on some bikes, in some places. Particularly the seatpost. I've had a couple that absolutely would slip with proper torque applied if I didn't use carbon friction paste. In most cases, it probably just falls into the 'It's always a good idea' category.Jul 31, 2018

Are titanium seatposts any good?

The USE titanium shaft has both qualities in spades. Fit it in place of your alloy seatpost and you'll feel the difference. It's not suspension or a magic cure for the bump allergic, but it does allow you to relax in the saddle, to commit your weight to the seat when riding over intermediate level trail chatter.Jan 30, 2012

Suspension Post for rocky rides

A suspension post helps by allowing a rider to sit more on long rocky rides. The best is the Thudbuster. It's worth it if you ride very rocky and can't afford full suspension.

Seatposts of a Bicycle

The seatpost size is dependent on the seat tube of the bicycle. They come in a variety of lengths and diameters. The centerline of the seatpost tube is offset.

The seatpost of a superleggero-crossover bike

Cyclists love to upgrade their bikes, and saddles, handlebars and wheels are all items that impact ride quality, comfort and speed. The seatpost is an important component that gets overlooked. The Bontrager Comp post is simple and affordable.

The Ergon CF3 seatposts

The amount of suck is king for dirt road use. The seatposts are straight carbon and have the highest degree of vertical flex on big bumps. Excellent damping abilities and lots of deflection are what suspension seatposts are known for.

Seat Posts with Zero Offset

A zero offset seat post is better for shortening reach and for placing your knee in line with the crank. It can help those with a bad knee. A zero offset seat post is a better option than moving your saddle too far forward and losing the flexibility of the rails to dampen bumps.

Measurement of the Space Needed for a Dropper Post

The dropper post is a style of seatpost used for mountain biking. The seatposts use internal cable to allow a cyclist to drop their seat when they approach technical terrain without having to get off the bike and operate a quick-release mechanism. Seatpost lengths can be as short as 75mm to as long as 400mm.

Bicycles Stack Exchange

People who build, repair, or commute on bicycles are encouraged to visit the Bicycles Stack Exchange. It takes a minute to sign up.

When is an offset seatpost needed?

A seatpost with offset is necessary when the seat tube angle of the frame is too steep to give the desired saddle setback (the horizontal distance between a plumb line hung from the nose of the saddle and the bottom bracket spindle). Conversely, an "in line" post may be required if the seat tube angle is too slack.

What is offset on bicycle seatpost?

They come in various diameters, lengths and offsets. Offset is the distance between the centerline of the seatpost tube, and the centerline of the clamp area. Shims are often available to adapt a too-small seatpost to a too-large seat tube.

How do dropper seatposts work on mountain bikes?

Dropper seatposts on mountain bikes can be remotely adjusted while riding using a lever or switch on the handlebar. This can be used to quickly lower the saddle and position it out of the way to allow for better body positioning and maneuverability on technical sections. The same lever or switch can then be used to return the saddle to its normal position for better pedaling efficiency. Most dropper seatposts use a hydraulically damped air or coil spring with cable, hydraulic, or electronic actuation.

How to prevent seatposts from seizing?

Seatposts should be periodically removed from the frame, cleaned, greased and refitted to prevent the seatpost seizing in the frame. This is particularly important with bikes which do not have mudguards (fenders) that are regularly ridden in wet conditions. Care should be taken not to overtighten the bolt or quick-release lever which clamps the post in the frame, especially where this acts on two brazed lugs rather than a separate clamp-on collar. Overtightening can bend or break the frame lugs or strip the threads in a separate collar. Metal seatposts should be very well greased, with the slot in the bicycle's seat tube also filled with a smear of grease. This helps to prevent water from running down the seat tube.

What is the diameter of a bike seatpost?

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. Tapering seatposts often have a diameter of 22.2 mm (⅞ in) at the top.

How to attach a seat post to a bicycle?

To attach it to the bicycle's main frame, the seatpost is inserted into the seat tube, which must be of a very slightly larger diameter (or a cylindrical shim can be used). The seatpost is held in place by squeezing the top of the seat tube with a tightening ring (temporarily reducing its diameter; a vertical slit cut into the tube allows this to happen without crumpling) until the tube firmly hugs the post where it leaves the frame. A hole for a pinch bolt (also known as a "binder bolt") may be built into the frame for this purpose, or a "seat post clamp" may be purchased separately (but must be sized to closely fit the diameter of the seat tube). Whether integrated or separate, the seat post bolt can have a simple nut, can be an Allen bolt, or can include a quick-release mechanism, with a handle that releases the clamp without tools. A quick-release allows easy height adjustment of the seat, though increases the risk of seat theft unless it is also used to detach the seat when parking.

What is a plain seatpost?

A "plain" seatpost (silver) connects the saddle to the frame (red).

Why are seatposts important?

Very few people think about the ride quality of a seatpost, which is precisely why I think they’re the most overlooked bike component. They’re arguably even more important for bike travel as touring and bikepacking bikes are usually set up with higher handlebars, resulting in a larger proportion of our body weight on our saddles (normally 80%+). Couple that with our penchant for seeking rough roads, and seatposts really are the key to unlocking all-day comfort on your bike.

What is a good seatpost?

A good seatpost is the key to achieving a comfortable ride. That’s because along with your tyres, seatposts actually make up the bulk of your bike’s comfort – in fact, according to the data available, a well-designed carbon seatpost flexes at a rate 100x greater than a steel frame. The Ergon CF3 carbon seatpost requires 69N ...

How much does a suspension seatpost weigh?

The main downside to choosing a suspension seatpost is the weight. Most of them tip the scales between 450-550 grams (1.0-1.2lb) which is more than twice the weight of most carbon seatposts available. That said, there is one truly lightweight suspension seatpost…

How much force does a carbon seatpost need?

The Ergon CF3 carbon seatpost requires 69N of force to flex one vertical millimetre (0.04″). In comparison, a typical bike frame may require more than 7000N of force to flex one vertical millimetre, demonstrating how much a seatpost (and how little a frame) plays in the comfort equation.

What is a damping seatpost?

Image: BikeRadar. Damping is the speed at which a seatpost will move over repeated bumps, and it’s the most important characteristic for cycling on smoother surfaces . A seatpost that dampens vibrations effectively will insulate a rider from much of the road buzz coming up through their bike.

What are seatposts made of?

Seatposts are manufactured using three different construction materials. The majority are made from aluminium which is lightweight, reliable and very cheap to manufacture. Titanium seatposts are much less common and are typically paired with titanium frames for a nice aesthetic.

Why do bikes have flex seatposts?

This is because a larger proportion of the overall shock and impacts will need to be taken up by the seatpost. Bikes with wider tyres still have a lot to gain too, as flex posts help to take the edge off bigger impacts.

Do setback posts help?

Setback posts often flex more than inline versions, so it does help take some of the edge off. How much you'll notice it is anyone's guess, especially if you have large tires at low pressures.#N#Moving the saddle rearwards does take weight off your hands, which may help if you currently have too much weight on your hands.

Do setback seatposts flex?

A setback seatpost will typically flex a little more than a straight version, ti and carbon seatposts will flex more than aluminum, etc. but they have their limits. If you get onto more rocky, rough terrain, they are still going to feel largely like a rigid seatpost. At that point, you're probably going to be better off with a sus post.

Why do riders use zero offset seat posts?

One reason. Some riders (especially those with short femurs) shove their saddle all the way forward to achieve what they believe to be a proper position over the bottom bracket. For these riders, a zero-offset seat post makes sense. With the saddle at the same position over the bottom bracket, the zero-offset post would clamp their saddle ...

What is a zero offset saddle post?

With the saddle at the same position over the bottom bracket, the zero-offset post would clamp their saddle around the middle of the rails instead of at the very ends of them.

How far does a saddle move forward?

Also, if you have the saddle height set 3cm lower than someone else of your height, that alone moves the saddle forward about 1cm.

What is the bolt on a seatpost?

The bolts are meant to be parallel (evenly spaced apart from the seatpost tube). The only support the rails see are the cup shaped peice that rotates/rests against the seatpost's tube.

Why do saddles bend?

With a flexy saddle shell, the rails tend to bend if the rider is heavy enough, bend caused by the ends of the rails being pulled towards each other.

Can you bend a seatpost?

If you have a seatpost similar in design to what I have, (KCNC Ti-Pro Lite) where the rails are poorly supported, and you have the saddle biased to one end (in my case as far back as the top tube length is short on the Kona), you can bend the rails.

Is femur length important for pedal position?

Fewer people all the time take any stock in the idea that femur length and the resulting knee over pedal measurements are relevant to producing the proper rider position. It's better to have the rider properly balanced over the saddle and ignore KOP

What is seatpost on bike?

Your seatpost slips into the seat tube and attaches your saddle to your bike. Though there are exceptions, most of them look pretty unassuming. So what should you look out for in a seatpost upgrade?

How to stop seatpost from slipping?

If you use a carbon seatpost, make sure to fit it using a thin layer of carbon paste as this stops it slipping. Pay attention to the quoted torque at which you should tighten the bolt - overdoing it can cause it to snap.

What is clamping on a saddle?

Clamps and saddle adjustment. All seatposts clamp to the saddle in their own unique way, and have different methods of allowing the saddle to point slightly down, slightly up or remain flat. Some clamps are delightfully easy to use. Others are temperamental at best and will only cause you vexation.

What is a floating seat clamp?

A floating seat clamp means that saddle tilt is not affected by the comfort providing flexion. These are only available in a 27.2mm diameter and the carbon construction weighs in at 220g. There is a layback version, the S15.

What is the length of a system ex seatpost?

The System Ex seatpost does that. Forged from 6061-T6 aluminium, it's 400m in length and comes in several widths including the 27.2mm and 31.6mm most commonly found on road bikes.

How much does a carbon seat post weigh?

The Vision TriMax carbon seat post is from FSA's performance brand and under the £100 threshold - but weighs in at 221 grams and is available in a 25.4mm, 27.2mm and 31.6mm diameter. It's got 20mm offset and uses a one bolt attachment system that's compatible with round and oval saddle rails.

Can you cut a seatpost that's too long?

However, whilst you can always cut a seatpost that's too long, you can't add to the length if it's too short.

What is offset on a wheel?

What is Wheel Offset? In short, offset is the distance from the center line of your wheel to the mounting pad. If the mounting pad is closer to the face of the wheel from the center line the wheel is a positive offset, if the mounting pad of the wheel is at the dead center of the center line the wheel is a zero offset and if the mounting pad ...

How does offset affect fitment?

The easiest way to understand how the offset affects your fitment is, the higher the offset the closer the wheel is to your chassis and the lower the offset the further the wheel is from your chassis.

What Offset Does My Vehicle Require?

No vehicle has a set number that they require , every vehicle has a minimum and maximum offset tolerance they can use. It is very important that the wheels you choose are within that minimum and maximum offset range to prevent fitment issues.

How to measure backspacing on a wheel?

Measure your backspacing. With the wheel laying flat on its face measure the distance between the mounting pad of the wheel and the outer edge of the wheel barrel.

What is the difference between backspacing and offset?

If you skipped that section, the backspace of a wheel is the distance from the outer edge of the wheel to the mounting pad. While the offset of the wheel is the distance from the centerline of the wheel to the mounting pad.

When did the Corvette require high offset wheels?

In 1984 Chevrolet introduced the C4 Corvette which was possibly one of the first american vehicles to require high offset wheels.

Is offset wheel a measurement?

However for the cast wheel industry and a greater portion of the factory and aftermarket wheels being produced offset is going to be the measurement primarily referenced.

Overview

Sizes

The size of the seatpost is dependent upon the internal dimensions of the seat tube of the bicycle frame. They come in various diameters, lengths and offsets. Offset is the distance between the centerline of the seatpost tube, and the centerline of the clamp area. Shims are often available to adapt a too-small seatpost to a too-large seat tube.
Seatpost diameters generally range from 22 mm to 35 mm in 0.2 mm increments. The most co…

Attachment points

Types

Maintenance

External links