The Return of 36H Wheels – A Choice for EMTB and Other Heavy-duty Applications

The latest trend in wheels has been to lower the spoke count, usually in the name of reducing weight and aerodynamic drag, although on a trivial scale at best. Even though, modern wheels work well or even exceptionally well with the current 28-32H spoke count, a case can be made for a higher spoke count.

Read further to learn why that is!

What Makes a Wheel

First, credit should be given where it’s due. This article is largely based on the realizations that took place after reading this excellent article at – Eine besonders seltene Konstruktion

Once credit has been given, let’s start with the basics. A spoked bicycle wheel is a pre-tensioned structure with a very high strength-to-weight ratio. Thanks to the threaded connection between the spokes and nipples, the rim and the hub are connected by accurately applied tension that’s distributed evenly across the whole wheel. 

The properties inherent to a pre-tensioned structure of a bicycle wheel are the factors that make the increased spoke count a beneficial proposition in certain applications. More about that in a moment, though! 

When a wheel is stressed, whether by the forces caused by pedalling, braking, cornering or radial loads caused by a landing, the tension within the wheel changes momentarily; some spokes lose their tension partially whereas others encounter a higher tension compared to a static state.

Ideally, the magnitude of tension variations is as small as possible, so that not a single spoke or a group of spokes lose their tension entirely and goes slack. If this happens, the nipples can unwind, and worse, the wheel loses its stability for a moment. 

Strong & Durable

In certain applications, like EMTB, enduro, dirt jump, pump track riding or downhill racing, utmost strength and durability is asked from the wheels. Often times these two qualities are thought as of synonyms. While they both go hand-in-hand usually, we are talking about two different qualities. 

Strength (or ultimate strength) = The greatest force that the structure – a wheel in this case – can withstand while preserving its original shape and structure. In practical words, how big of a case or misjudged landing or an all-out berm roast the wheel can withstand and remain true, or at least in rideable condition.

Durability = The structure’s ability to withstand forces and stresses below its ultimate strength over a certain time period, ideally as long as possible. A durable wheel functions as intended for a long time even under heavy loading while requiring minimal or moderate service measures at best.

The classical theory in wheel building has been that a strong wheel is achieved by choosing a strong, and wide rim. In other words, to strengthen a wheel, the rim should have increased mass by adding material to the rim in the form of increasing its cross-sectional area and wall thicknesses. A durable wheel, on the other hand, that functions over a long period of time and keeps coming back for more, is achieved by increasing the spoke count. 

The rationale presented is of the “classical type”. Currently, we cyclists are living in the best time ever since most of the high-quality modern wheels are strong and durable by default, thanks to the development that has taken place in material sciences, manufacturing, and improved quality control processes. 

To sum up this section, a quote from Roger Musson is warranted. His book, the Professional Guide to Wheel Building 7th Edition is a highly recommended read.

A well-built wheel is seen as strong because it doesn’t go out of true and can take a few knocks. If you want to make a stronger wheel, then use a heavier and wider rim. A durable wheel is one that continues to perform over a long period of time and if you want a more durable wheel use more spokes. That’s the theory, but today’s modern rims are so well designed they are all very strong, even the lightweight ones. Spoke material is now very good at withstanding stress, so we tend to build strong durable wheels by default and those wheels that are problematic when used are usually caused by poor wheel building. Obviously, the super light rims are more susceptible to dents and flat spotting and you should always pay more attention to the maintenance of them by checking for rim damage and adjusting spoke tension where necessary, and if you are a long-distance touring cyclist then keep away from lightweight components and low spoke counts. 

More Tension

At this point, we are familiar with the pre-tensioned structure of a wheel. Increasing spoke count – to 36H for example – is directly linked to this very fact. Taking a single spoke under scrutiny tells why that is.

All of the components used in a wheel have a rating for maximum tension. For Onyx Racing Products hubs, the maximum allowed spoke tension is 1200N or 120kgf in classical terms. The spokes themselves can withstand considerably more, up to three times the tension listed! However, building a wheel to a higher tension than specified will lead to failure in some parts of the wheel, whether it happens on the hub, rim or nipples. 

The 1200N tension is roughly equivalent to 120kg of mass in the Earth’s gravity field. In a professionally built wheel, each spoke on the high-tension side is tensioned to this very figure. When we’re talking about modern mountain bikes with disc brakes, that means the non-drive side in the front, and the drive side in the rear. The fact that 120kg weight is hanging on every spoke on the high-tension side, figuratively speaking, is a thing worth appreciating if not considered before. 

The space needed for the disc rotor and the rear cassette necessitates dishing the wheel during the build process. This means, that the rim isn’t placed symmetrically between the hub flanges. The desired dish is achieved by tensioning the spokes in a certain ratio that is dependent on hub flange distance, flange spacing, flange diameter, and rim diameter, among other things. Typically, the tension ratio is in the range of 60-700/100. If using the 1200N tension stated earlier, it means that the low-tension side is tensioned to 720-840N.

Armed with this information, a new variable can be introduced – the total tension that the structure of the wheel contains. Let’s call it preload for the lack of a better term, and in order to keep things simple. Let’s take 28H and 32H wheels under some closer examination with an assumed 65/100 tension ratio. This leads us to the following calculations in which Fmax is the highest specified tension of 1200N.

High-tension side = Fmax x Spoke Count

Low-tension side = Fmax x 0.65 x Spoke Count

Preload on a 32H wheel = 1200N x 16) + (1200N x 0.65 x x16) = 19200N + 12480N = 31680N

Preload on a 28H wheel = 1200N x 14) + (1200N x 0.65 x x14) = 16800N + 10920N = 27720N

These simple calculations grant us numbers of 31680N and 27720N, meaning that a 32H wheel has roughly 14% higher preload. When a 36H wheel is welcomed to the party, it has a preload as follows:

Preload on a 28H wheel = (1200 N x 18) + (1200 N x 0,65 x 18) = 21600 N + 14040 N = 35640 N

Now, the following table can be produced, establishing a 32H wheel as a baseline to which other variants are compared.

Spoke Count Preload Tension Ratio
36H 35640N 112.5%
32H 31680N 100
28H 27720N 87.5%

More Spokes, Fewer Worries 

Increasing the spoke count makes a stronger and more durable wheel by increasing the preload of the wheel, and by making service procedures easier. With a higher spoke count, the forces subjected to a wheel are absorbed by a greater number of spokes, meaning lower momentary tension loss per spoke. A higher preload value granted by the increased spoke number also means that the wheel can withstand higher forces without failure, like buckling for example.

Servicing properties are also enhanced with a greater spoke count. As said earlier, truing the wheel can be done by adjusting the tension of a greater number of spokes lightly as opposed to adjusting the tension greatly in a smaller number of spokes. 

In addition to this, if a spoke failure happens, a very rare occurrence in a well-built wheel, but still possible, the wheel will not be subjected to as large of a change in its tension state and remains in a true state better than a wheel with a low number of spokes. An argument can be made that all of the remaining components are subjected to less stress before a repair can be performed in the form of replacing the broken spoke.

Low spoke counts have been marketed with claims related to weight savings and aerodynamic benefits. In mountain bike applications, the scale of these factors is trivial at best. If on the other hand, one is racing for the rainbow jersey on the road, things might be slightly different, and options should be considered accordingly. You should know if this applies to you or not. 

Component Selection 

Now the somewhat large elephant in the room – what about parts? If one is convinced of the benefits of running a higher spoke count, a question of the most practical nature arises, where can I find rims and hubs with almost non-existent 36H spoke count? 

Interestingly enough, DT Swiss has introduced an eBike-specific component lineup and hasn’t made much noise about the fact that it’s offered in 36H variants. In eBike, and especially EMTB applications, strength and durability are the overriding criteria. The HX 531 rim is of particular interest here since it sports much of the same features and dimensions as its “organic cousins”, the EX511 and FR541.

Some of the main numbers to give out are 30mm inner width, 29″ or 27.5″ diameter, and a weight of roughly 600g in the former diameter. The HX 531 retails for around 100€. 

The Onyx Racing Products Classic hub has been available in 36H configuration since its introduction! The Classic hub has earned nearly legendary status with its performance, and carefree nature, thanks to the patented sprag clutch mechanism, 2nd-to-none quality, and hybrid ceramic bearings. Last, but not least, the Classic rear hubs are available in all common axle standards, such as:

  • 135×10 mm Bolt-on axle
  • 142×12 mm Thru-axle
  • 148×12 mm Boost Thru-axle
  • 150×12 mm Thru-axle
  • 157×12 mm Super Boost Thru-axle
  • 177-197x12mm Thru-axle (fat bike sizing)
  • All of the listed axle sizes are available in all commonly used freehub drivers and in ISO 6-Bolt or Centerlock disc mounting.

The Front hub selection consists of the following axle sizes:

  • 100×15 mm Thru-axle
  • 110×15 mm Boost Thru-axle
  • 110×15 mm Boost Torque Cap Thru-axle
  • 110×20 mm Thru- Axle
  • 110×20 mm Boost Thru-axle
  • Rock Shox RS-1
  • Lefty
  • All of the listed options are available in ISO 6-Bolt or Centerlock disc mounting.

All hub models are available in 24 different shell colours, paired with 10 end cap colour options. 

Who Should be Interested?

If you’re looking for strength and durability and want wheels that provide as service-free performance as possible, wheels with a 36H spoke count built around Onyx Racing Products hubs should deserve a spot on your list of options. Typical applications include but are not limited to eMTB, bike packing, enduro and downhill riding & racing, and heavy-duty trail riding.

The patented sprag clutch mechanism found in all Onyx Racing Products hubs makes the Classic model a prime candidate for these use cases. The sprag clutch mechanism in the Classic model is dimensioned in a such way that it can easily handle the combined torque produced by the drive system and the rider.

Onyx Classic Hubs for an E-MTB – goes electric!

Last, but not least. Onyx Racing Products / HX 531 29″ 36H wheels are available now! 

If interested in a custom wheelset, send an inquiry to info[at]