Newmen study on 32-inch wheels: Clear recommendations from the wheel experts

32 inches is rolling in - and with vigour. Behind the scenes in the bike industry, intensive development, customisation and testing is already underway to make the next wheel size ready for the market. The advantages of larger wheels are well known: better rollover behaviour, smoother running and a noticeable increase in speed.

However, the step up to 32 inches not only brings progress, but also new challenges - and not just for wheel manufacturers. With a 64 millimetre larger diameter compared to 29-inch wheels, there are other special design features that need to be taken into account.

In order to take a closer look at the next generation of wheels, the manufacturer Newmen built over 60 different wheel variants and tested them in the laboratory. In addition, around 20 setups were ridden in practice on the trails to compare theory and reality. Newmen has now published the results of the study.

Do not repeat mistakes

With its research, wheel manufacturer Newmen wants to play its part in making sensible use of the lengthy development processes of past years in order to bring mature bikes with 32-inch wheels to the trails right from the start.

The special requirements of larger wheels should be taken into account right from the start - instead of launching immature solutions on the market and going through the learning curve at the expense of users. Looking at the history of wheel sizes, especially in the mountain bike sector, the makers of the study say: "Let's do it better this time!"

What is currently happening with the new 32-inch wheel size is very reminiscent of the upheaval around 20 years ago, when the change from 26 to 29 inches was imminent. Back then, everything began with experiments - including some misguided developments - before sensible standards gradually became established.

Today, the larger flange spacing of 29-inch hubs is a matter of course. Solutions such as Boost and in some cases even Superboost have been introduced to compensate for the lower stiffness compared to 26-inch hubs. A look at the standardised ETRTO measurement shows how close the dimensions are: Back then, the diameter of the wheels grew by 63 millimetres, now it is 64 millimetres.

However, more size not only means more speed, but also brings disadvantages - higher weight and lower stiffness. Under identical lateral loads, the large wheels deform around 31 per cent more.

Stiffness and durability

At the same time, Newmen poses the question of whether modern 29-inch wheels are not already too stiff. In the enduro and downhill sector in particular, work is being carried out to reduce stiffness in order to improve handling behaviour.

This may work for light riders with an optimal setup. In practice, however, things often look different: Not everyone weighs under 80 kilos or has a team that is constantly providing new material. E-MTBs in particular, with system weights of up to 150 kilograms, place significantly higher demands on the stability of the wheels. 32-inch wheels must also be designed for these areas of use - and not just for lightweight riders in the cross-country or gravel segment.

The right balance is crucial here: the tests of the Newmen study show that the lateral stiffness must not fall below a certain minimum threshold in order to ensure a precise and controllable ride. On the test bench, this limit can be quantified as a maximum deflection of 8.5 millimetres with a lateral load of 300 newtons.

It is not only the ride feel that is significantly influenced by wheel stiffness, durability also plays a decisive role. If a wheel is too soft, the spokes are more often completely unloaded during riding. This increases the susceptibility to loosening nipples and, in theory, leads to reduced spoke tension in the long term - with correspondingly higher maintenance costs.

Wheels with slightly higher stiffness and less deflection than 8.5 millimetres have advantages here and require significantly less maintenance. Simply increasing the diameter of a wheel and waiting to see how it behaves is not enough.

If neither handling precision nor durability are to suffer, the move to 32 inches requires customised designs. Factors such as the number of spokes, spoke type and the installation width of the hub and the resulting flange spacing must be specifically selected and, if necessary, rethought - both in the gravel and MTB sectors.

Variables in 32" impeller construction

In the course of the 32-inch study, Newmen defined four variables that can influence the construction and riding characteristics of wheels. All variables and their influence on the performance of a wheelset were measured under laboratory conditions.

1. impeller diameter

With an identical construction, a 32-inch wheel is on average 31.36 per cent softer under lateral load than its 29-inch counterpart. This difference varies slightly depending on the type of spokes used: with Sapim Laser spokes it is 33.7 per cent, with Sapim D-Light spokes 29.01 per cent.

2. spoke type

The slightly heavier Sapim D-Light spoke (with 56 spokes in 32 inches, this results in an additional weight of 41 grams) increases lateral stiffness by 7.54 per cent with an otherwise identical construction.

3. hub width & flange distance

32 inch on a gravel bike

If you compare the flange spacing of non-boost and boost gravel wheels, there are clear differences for 32-inch wheels. The front wheel clearly shows the influence of a larger flange distance: Widening by 10 millimetres (from 12 x 100 mm to 15 x 110 mm) increases the lateral stiffness of a 32-inch wheel by 15.5 per cent.

A larger mounting width also has a positive effect on the rear wheel. The associated increase in flange spacing noticeably improves stiffness - with a comparatively low additional weight of around ten grams per hub. Specifically, the increase from 12 x 142 to 12 x 148 leads to a stiffness increase of 11.5 per cent on a 32-inch wheel.

32 inch on a mountain bike

In the MTB sector, an installation width of 110 millimetres is currently the limit for the front wheel. A further logical step would therefore be a Superboost standard on the front wheel, for example in the form of 15 x 120 millimetres. Although 32-inch front wheels with a deflection of 7.55 millimetres still achieve just sufficient stiffness even with lightweight Sapim Laser spokes, a larger flange distance offers additional potential.

Stiffness could be further increased with a wider hub - or alternatively optimised with fewer or lighter spokes. A 15x120 Superboost hub on the front wheel could achieve the same stiffness as a 29-inch wheel - with the same number of spokes and without the use of heavier spokes.

The effect can also be clearly seen on the rear wheel: the step from 12 x 148 (Boost) to 12 x 157 millimetres (Superboost) increases the stiffness of a 32-inch wheel by 16.4 percent with the same number of spokes and identical spoke type. The greater flange spacing made possible by the Superboost standard also allows the stiffness level of a 29-inch rear wheel to be achieved - without additional spokes or increased weight.

4. number of spokes

A higher number of spokes also increases the stiffness of a wheel. If a 32-inch rear wheel is fitted with 32 spokes instead of 28, the lateral stiffness increases by 10.87 per cent according to Newmen. However, the four additional spokes result in an additional weight of 49 grams per wheelset (with Sapim D-Light).

The results of the study

The results of Newmen's study on 32-inch wheels can be summarised in five findings:

1. 32" wheels are 31 % softer than 29" wheels under lateral load with identical construction.
2. To increase the stiffness of 32" wheels, heavier spokes can be used, which increases the stiffness by 7.5 % with a weight increase of 41 g (28 hole, 32 inch) per wheelset.
3. The increase in the number of spokes from 28 to 32 results in a 10.9 % higher stiffness for 32-inch wheels, with an additional weight of 49 g per wheelset.
4. An increase in the mounting width and thus an increase in the flange distance by a maximum possible 9 mm (from Boost to Superboost) on the rear wheel can increase the lateral stiffness of the 32-inch wheel by 16.4 %. A 32" Superboost rear wheel would therefore be almost as stiff as a 29er rear wheel with Boost mounting dimensions. On gravel bikes, widening the rear hub from 142 to 148 mm increases stiffness by 11.5 %. With only a minimal increase in weight on the hub (+10 g each), the mounting width and thus the flange distance can also be increased to increase lateral stiffness.
5. On the 32-inch gravel front wheel, increasing the flange distance by 10 mm has an effect of 15.5 %.

Further 32-inch components

The increase in wheel size from 29 to 32 inches also affects other components on the gravel or mountain bike. The Newmen study can also provide important insights into brakes, forks, frames, stems and steerer tubes.

1. brakes on 32 inch bikes

With the larger 32-inch wheel, the spoke angles change: they are steeper and move closer to the brake calliper, which can cause space problems. At the same time, the leverage forces between the wheel and brake disc shift, which reduces braking power by around ten per cent. In order to achieve the same braking power as with 29-inch wheels, larger discs would be required (e.g. 220 mm instead of 200 mm or 180 mm instead of 160 mm), which would also alleviate the space problem caused by the steeper spokes.

2. fork and frame of 32 inch bikes

In order for 32-inch wheels to fit in the fork and rear triangle, both the fork insertion length and the chainstays have to be longer. The resulting longer levers increase the load on the frame, especially in the head tube area. On 32-inch bikes, which already have a low front end and therefore short head tubes, this load is further increased - both for the fork and the frame.

3. stem and steerer tube of 32 inch bikes

The same applies here: build as flat as possible to compensate for the longer installation length. However, the low clamping height on the stem increases the load on the steerer tube. A thicker steerer tube or a thicker diameter may therefore be advisable. Negative stems are often necessary, especially for smaller frame heights of 32-inch bikes, which increases the choice of stems. In addition to the length, they also differ significantly in their angle.

Conclusions for the bike industry

Insights for wheel manufacturers

Based on the Newmen study, wheel manufacturers must realise that increasing the hub width brings the greatest stiffness benefit per gram of additional weight and at the same time does not cost the wheel manufacturer more.

More spokes increase the stiffness values more than thicker spokes, but the additional weight and production costs for spokes and nipples are also higher. More spokes also mean more centring work and therefore higher centring costs.

Insights for bike manufacturers

Lightweight and sufficiently stiff 32-inch wheels cannot be realised with conventional, narrow Boost widths. Increasing the number of steel spokes from 28 to 32 incurs additional costs of 1.50 to 3 euros per wheel - including the additional work involved in inserting, nippling and centring.

With an annual production of 100,000 bikes, this adds up to an additional 300,000 to 600,000 euros, as well as 5600 kilograms more spoke material. A jump to 36 spokes to further increase stiffness would even double these figures.

In the case of wheels with carbon spokes, higher numbers are reflected even more strongly in the price: an increase from 24 to 28 spokes already makes the wheel 10 to 20 euros more expensive, including construction costs. In addition, more spokes have a negative visual impact, the wheels often look less elegant and the aerodynamics also demonstrably suffer from the additional number.

With a jump to Boost hub width (148 instead of 142 mm), lightweight designs with a low number of spokes and light spokes can still be realised even with 32-inch gravel bike wheels. At the same time, it is still possible to build sufficiently stable wheels for bikepacking or heavy riders - without having to resort to unnecessarily heavy or excessive spokes.

Changing from Boost to Superboost on the rear wheel of a mountain bike is highly recommended - there are virtually no additional costs involved. Thanks to the longer chainstays, not even the Q-factor needs to be adjusted.

As with the grey wheel, the change to the next higher hub width for 32-inch wheels on MTBs also enables lightweight designs with a low number of spokes and light spokes. With the Superboost width of 157 instead of 148 mm, stable wheels can be built for more extreme applications or heavy riders without having to resort to unnecessarily many or heavy spokes.

If the hub width were increased in proportion to the jump from 29 to 32 inches, a completely new rear wheel size of 163 millimetres with 75 millimetre flange spacing would be required. A slightly wider front wheel would also make sense - a simple step from 15 x 110 to 15 x 120 would suffice here. In addition, the brake disc mounts on the fork and frame of both the MTB and the gravel bike should each be increased by one disc size.

Conclusion

With its in-house 32-inch study, Newmen provides interesting data on the stiffness and construction options of 32-inch wheels in the MTB and gravel sector. The most impressive appeal is in the direction of the Superboost hub standard. New standards are not exactly popular in the scene, but the new wheel size requires new frames and components anyway. It remains exciting to see in which direction the industry will develop. - Jan Timmermann, BIKE editor

>> Our reporter built his own 32-inch bike in frame construction. Click here for the report.

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