As an example, a traditional 1-1/8in external threadless headset with a straight steerer would be defined as follows: Older loose bearings rolled directly on the hardened steel race. Benedict Pfender / Immediate Media The bearings just drop in to preformed seats, and are held in place by the preload Benedict Pfender / Immediate Media Tapered steerer tubes are the most common arrangement on modern bikes. This attempts to provide the best of both worlds, with a wide crown that provides improved steering stiffness, with a tapered top section that saves a little weight. This is found on both mountain bikes and road bikes. As above, the bearings sit in cups, but these, in turn, sit inside, rather than proud of, the head tube, with only a small lip protruding to locate the cup and prevent it being pressed all the way inside the head tube.

The stem – known as a quill stem – attaches separately, sliding inside the steerer tube. It is secured by tightening the top bolt, which engages an expanding wedge at its base to clamp the stem in place. What is it? A technologically advanced and fully waterproof helmet designed for various activities like cycling. Incidentally, the interface between bearing and fork is called the race (crown race and top race) because it originally acted as the raceway, with the bearing balls in the headset rolling directly on it. Loose ball-bearing sizes are determined by the diameter of the ball bearing itself. This is usually expressed as a fraction of an inch: 3/16in (4.7625 mm).The dimension of the headset is further defined by codes identifying the diameter of the fork steerer at the top and bottom of the head tube. Subsequently, they sacrifice a small amount of performance because forces within these moving parts usually have a non-radial vector associated. As a result, they have to compensate with decreased tolerances. The top bearing interfaces with a slotted conical compression ring. As preload is applied, the compression ring effectively gets wedged between the top bearing and the steerer tube, tightening around the steerer as preload is applied and the slot closes.

What is it? A handy strap made of leather that you can attach to your bicycle’s frame. It serves as a handle to help you carry your bike more easily and comfortably. Needle bearings, which are also known as roller bearings, are relatively uncommon in the cycling world. What is it? It’s like a spa day for your two-wheeled friend, containing all the essential products to keep it looking pristine and performing at its best.Defining the SHIS code will tell you what kind of headset will fit the bike, but there are also some additional choices you can make. The number following the headset type denotes the head tube bore diameter (or bearing/cup outer diameter). The number is given in whole millimetres, but does not always correspond exactly to the dimensions of the bore. Instead, the head tube is bored with conical seats. When preload is applied, these angled seats result in the bearings self-aligning, as well as securing them in place, creating a rigid assembly. What is it? It’s a 3-in-1 holder for your bike that can carry your water bottle, phone, and keys all at once.