A bicycle wheel can only be as good as its parts. A wheel is made of three main parts; hubs, rims and spokes. If any of these is poor then it will lead to a poor wheel. Even a stout rim will go out of true rapidly the wheel is built badly; a good build requires good spokes. Spokes literally hold the whole item together. The spokes enable wheels to have remarkable strength with surprisingly little weight.

I use (almost exclusively) Sapim spokes. Sapim offer a range of high end products, at least as good as DT at more competitive prices. I do have some old DT stock purchased prior to their recent price increases. There is nothing wrong with DT; only that they are the same quality yet more expensive than Sapim.


Different spoke types

The most basic spoke is known as the plain gauge spoke. Sapim’s Leader spokes is an example of this. There is a big variety in plain gauge spokes, although you may be unable to tell this by eye. Sapim’s leader spokes receive the same strengthening treatments as their butted spokes, which means they have a lot more strength than most competing versions. Their main disadvantages over other Sapim spokes are weight and flexibility. However, it is important to note that Leader spokes are the exception, most plain gauge spokes are weak and should be avoided.

A spoke is subject to two key kinds of force. One is constant, because of the tension it is held under. The other is inconstant and more violent; when an impact is made upon the wheel. It is when a wheel receives these sudden forces that butted spokes become important. The dimensions of a butted differ from plain gauge because they are not a continuous thickness throughout. The most common is the double butted spoke which is thicker at the elbow and threaded end. Butted spokes can flex and absorb impacts better than plain gauge because their central butting allows them to stretch. The extra material around the elbow and nipple allow strength to be retained in the areas that commonly fail.

Sapim’s most common double butted spokes are called Race spokes. This is equivalent to DT’s Competition spokes. They are 2.0mm thick both ends and 1.8mm thick in the central section. Sapim also offer a higher quality but lighter duty version known as the Laser which are butted in a 2.0mm-1.5mm-2.0mm design. These are slightly more expensive than Race spokes and are better suited to light weight road wheels. Sapim have recently released a triple butted spoke known as the Force, although this is not available in the UK. This is butted in a 2.2mm-1.8mm-2.0mm design. Spokes most commonly break at the elbow, furthermore hub manufacturers have increasingly moved towards 2.5mm hub drilling, which means that a 2.0mm elbow can sit quite loosely. The Force takes advantage of the butted spokes flexibility and reinforces the spoke at its weakest point. Being 2.2mm at the elbow the Force will still fit in 2.3mm hub holes. The Force is one of Sapim’s most expensive spokes, although it is also one of their best. One other butted spoke that is relevant is Sapim’s Strong spoke. This is single butted in a 2.3mm-2.0mm design. Single butted spokes possess less flexibility than double butted. However it is more economical and more available than the Force and it is strong option when flexibility is less important.


One final spoke in Sapim’s range is the CX-Ray. This is an aero spoke and is their most expensive. It is 2.0mm at the elbow, the centre section is oval and is 2.3mm deep but only 0.9mm wide. This not only improves aero-dynamics but also makes for an exceptionally strong spoke – Sapim’s strongest. It is also their lightest. It also has the longest fatigue life. However it is nearly eight times the price of Sapim’s Race spokes. One disadvantage of previous ‘bladed’ spokes is that they often required hub filing. This was not only tedious but also weakened the hub. Some hubs came pre-filed but this limited choices for builds, now bladed spokes have now fallen out of fashion in favour of aero spokes. These are less aero-dynamic but they are stronger and more stable. Sapim’s CX-ray spokes really are the best money can buy, they are the strongest, lightest, hardest wearing spokes out there and they are aero-dynamic. They can be used in both downhill wheels and high end race wheels. However their price makes their application less common.

Here is a chart with a technical comparison of Sapim spokes:

Front wheels and lacing patterns

When selecting spokes for a wheelset it is important to understand each wheel differently. The front wheel carries less stress than the rear. Therefore it does not need as strong spokes and fewer spokes are required. Sapim Race spokes are appropriate for most front wheels, although Sapim Lasers could be used if weight saving was important or better still CX-Rays. A front wheel can normally be both radially or tangentially laced. This means the spokes can either come directly out of the hub to the rim, or they can come out at tangents to the hub. Tangential spokes normally cross three other spokes before they reach the rim. This has given rise to the term 3X, which is the most common lacing pattern. Many hub manufacturers refuse to warranty products built into radial wheels. There have been instances where the spoke has been pulled straight through the hub flange.

Many wheel builders refuse to build wheels with radial lacing patterns because of the risk of the spoke being pulled through the flange of the hub. However many major wheel manufacturers have moved towards radial front wheels because of aesthetic benefits as well as some weight saving advantages. I have built many wheels with radially laced spokes and none have ever failed at the hub. However, I always point out before building that with the majority of manufacturers, radial lacing invalidates the warranty. I would also discourage the use of radial lacing because it distorts the hubs making for a weaker wheel and it makes for a slightly rougher ride.


Dishing and rear wheels

A rear wheel is quite different to a front. It is normally ‘dished’, it also carries a higher proportion of the bike’s load. It cannot be completely radially laced because a rear wheel has turning forces exerted upon it from the hub, these would stress and break the hub flange as the spokes are pulled out. Most commonly rear wheels are 3X, although wheels with large numbers of spokes can require 4X or even 5X, others which require particularly short spokes such as Brompton or Rohloff wheels require 2x.

Dishing occurs on rear wheels which uneven centre to flange measurements, normally there to incorporate external gears. The right hand flange is moved towards the centre line of the hub in order to fit in the cassette or freewheel. This means that the right hand or ‘drive side’ spokes need to be under greater tension than the left hand or ‘non-drive side’ spokes. The tensions on a drive side are more than double that as on the non-drive side and wheelbuilders and manufactuers have been creative in their solutions to this problem.

Sometimes people opt for twice as many spokes on the drive side, however quality rims normally have an allocated direction so this can be an inelegant solution with spokes facing the wrong way in the rim. Another solution which I sometimes use is to have different spokes on the drive side to the non-drive side. The non-drive side will commonly use the same spokes as used on the front wheel. The drive side will have heavier duty spokes an importantly spokes with less flex. This means that the spokes flex more evenly on both drive side and non-drive side. A light duty build could use Sapim Laser spokes for the front and non-drive side and Sapim Race for the drive side. Heavier duty could be Sapim Race for front and non-drive side and Sapim Strong for the drive side. Many wheelbuilders neglect such detail, although it is important for a well balanced wheel. Moreover it does not need to add considerably to the cost of the build. An important factor to consider before doing this is that sometimes a larger spoke elbow will sit badly in a hub. Considering the quality of the spoke I use as standard, most wheelsets can be laced with the same spokes throughout.

There is a lot more information available about choosing wheelsets, building wheels and selecting component parts as well as information on repairing wheels in Bicycle Wheelbuilding: The Manual an ebook which is available to purchase exclusively here:

http://www.dcrwheels.co.uk/products-page/product-category/bicycle-wheelbuilding-the-manual/