The first bicycle frames were made mostly from steel, with steel tubes of a standard (outer) diameter. The British and Italian standard diameter for seat tubes was 1 1/8″ (28.6 mm). Older French bicycles used 28 mm tubing. Old US bicycles (mostly BMX and older bikes that used one-piece cranks) was 1″ (25.4 mm). The in-house brand of the huge Accell group (who distribute Raleigh, Lapierre, Haibike), XLC gets close to value-leaders Brand-X on price. With a maximum drop of 150mm, the SP-T13B isn’t the best for taller riders, but is internally adjustable in 5mm increments for perfect extension up to that height. 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. It’s great to see the 27.2 option if you are running a skinnier posted bike. Andy McCandlish / Immediate Media

The post comes with a shifter-style under-bar remote and internal cable routing, unlike the regular Ascend (also included in this guide), which has external routing. Our main criticism of the LEV is how the cable is mounted – it’s clamped at the post end instead of the lever. This means accurate cable tension and length is needed to get it working well and it takes longer to set up than posts where the cable is clamped at the remote end. But measuring the circumference means you only have to distinguish a 0.6 mm difference (because everything is multiplied by 3.14…), which is doable.Dropper post internals vary from very complex to relatively simple. The XC-focused DT-Swiss D-232 is one of the less complex options on the market. DT Swiss A narrower post will typically be lighter and can offer improved comfort, because it’s able to flex more easily than a stiffer, oversized post. 30.9mm seatpost Since measuring often can’t be done to a 1/100 of a millimeter in accuracy, the next section gives a list of the most commonly used standard seatpost diameters. If a measured diameter differs, it can be assumed that the correct diameter is the standard one that most closely matches the measured diameter.

Overall, the Bontrager Line Elite is hard to fault, performing without issue in testing and proving easy to install.

The Loam dropper comes with some nifty features including customisable speed return and easy on-bike travel adjustment. SRAM’s Matchmaker and Shimano’s I-Spec standards allow you to combine a dropper and brake lever on one mount to keep the handlebar tidy. If you find any other mistakes, feel free to note them. I try to keep this as correct, and up-to-date as possible. ideal for longer days in the saddle – the Specialized S-Works SL Pave is a prime example. What is the most cost-efficient type of seatpost? PNW offers good value for money across its range of products and its Loam dropper post is no exception.