Which rim height is optimal?
The rim height has an effect on the aerodynamics, weight, stiffness, side wind susceptibility, sound and appearance .
|
rim height |
aerodynamics |
mass |
rigidity |
Crosswind tolerance |
| up to 30mm |
- |
++ |
- |
++ |
| 38mm |
- |
+ |
- |
++ |
| 45 / 50mm |
+ |
+ |
+ |
+ |
| 55 / 60mm |
++ |
- |
++ |
- |
| 70/80 / 90mm |
+++ |
- |
+++ |
- |
| Scheibenrad |
++++ |
--- |
++++ |
only rear wheel |
The advantages of 'real' aero-rims mentioned below (where the resistance decreases with increasing angle of attack instead of rising) are only possible from wheel heights (rim plus tires) with 2.5 times the tire width (example: tire width 25mm -> wheel height (Rim + tires) = 63mm).
Everyone has to make their own decisions about optics and sound. 38mm hardly noticeable, whereas from 55mm the rims optically dominate the road bike.
The high rims amplify driving noise of all kinds with their powerful resonance chamber. They rumble, rumble and siren, that it is a pleasure. The sounds can really motivate, because this is how tempo can be experienced acoustically . The harder you kick, the louder it hisses from behind. The sound from 50mm carbon rims can be 'addictive' and definitely boosts the motivation at high speed .
Note on stiffness:
The higher the rim height, the wider the rim, the more the spokes are angled, the thicker the spokes and, to a lesser extent, the tighter they are, the higher the lateral rigidity of an impeller. But also the spoke elasticity (mm / N) and especially the number of spokes contribute to this.
Here, in particular, the rear wheel at a disadvantage, because the spoke angle on the sprocket side is low (only 4 °). That's why front wheels are usually stiffer.
A high general stiffness is especially noticeable in the sprint and saddle on the mountain (from 500 watts).
Drivers who are strong (> 1200 watts) weigh more than 75kg should pay attention to a high stiffness of the rear wheel .
Particularly important for a lossless power transmission to the rear wheel is the torsional stiffness , so that your muscle power for propulsion does not disappear in the deformation of the impeller.
A stiff front wheel is important, as the weight of the body weighs mainly on the front wheel. The lateral stiffness of the front wheel is also responsible for accuracy, directness and steering precision.
Conclusion:
If you weigh 75kg and more and can walk more than 1200 watts, you should pay attention to high rigidity in order to be prepared for all driving situations.
For a high stiffness, we recommend at least 45mm for the front wheel and 55mm or more for the rear wheel.
The 2: 1 spoking of the rear wheel with the 16 spokes on the sprocket side causes a very high torsional stiffness for a lossless propulsion.
Note on aerodynamics:
From 15-20 km / h, aerodynamics is the more important factor for speed. This is also important for a hobby cyclist. Who classifies the low air resistance as its priority should select as high as 60mm rims. Unfortunately, however, then the crosswind tolerance on the front wheel is an important factor. More below ...
The rear wheel is not susceptible to side wind. Therefore, the maximum rim height should be chosen here for maximum aerodynamics. But due to the higher weight and the dominant appearance, a difference in height of at least 10mm between the front and rear wheels is recommended (example 45/55 or 55/80 or 60/90).
The recommended rim height for the front wheel depends on the purpose. At the front there is always a compromise between good aerodynamics and low side wind susceptibility .
For the front wheel you can choose from 38mm, 45mm, 50mm, 55mm or 60mm. As a pure competition wheel for time trial 80mm or 90mm.
38mm and 45mm on the front wheel is always trouble-free with a view to crosswind susceptibility .
But 38mm are undersized for a carbon rim, has few advantages and does not speak for the desired 'appreciation'.
Depending on the wind force / frequency, 60mm and 70mm are often too windy and do not make fun on long training runs in windy conditions. This is something for races, fast rides and areas with low to medium winds. The 60 / 70mm rim height is good to ride in cycling or time trial, but for long training runs, the steering in spite of toroidal profile could annoy you.
80mm and 90mm are only recommended for competitions (time trial) and time trial training.
50mm and 55mm on the front wheel has already good aerodynamics compared to the flat rims, is visually appealing, is only slightly susceptible to side wind and is the all-rounder. In the wind during the race and training completely mobile and compatible. The 50 / 55mm are never a danger or scary.
The steering pressures in gusts with crosswind are adjusted at 50 / 55mm to 90% in the subconscious mind. At 60 / 70mm it is only about 70%. So you often feel the rim height and wishes for a longer training sessions one size smaller.
Conclusion:
No impeller can do everything optimally.
In order to be able to combine good aerodynamics, low weight, low side wind susceptibility and high rigidity at best, a combination with different rim heights is recommended.
A good compromise in terms of low weight and low crosswind are 50/50 or 55/55 combinations or 50/60 or 55/80 for better aerodynamics.
The high rims amplify driving noise of all kinds with their powerful resonance chamber. They rumble, rumble and siren, that it is a pleasure. The sounds can really motivate, because this is how tempo can be experienced acoustically . The harder you kick, the louder it hisses from behind. The sound from 50mm carbon rims can be 'addictive' and definitely boosts the motivation at high speed .
Here is a sound sample of my 60mm aluminum carbon rims CLICK
Note on stiffness:
The higher the rim height, the wider the rim, the more the spokes are angled, the thicker the spokes and, to a lesser extent, the tighter they are, the higher the lateral rigidity of an impeller. But also the spoke elasticity (mm / N) and especially the number of spokes contribute to this.
Here, in particular, the rear wheel at a disadvantage, because the spoke angle on the sprocket side is low (only 4 °). That's why front wheels are usually stiffer.
A high general stiffness is especially noticeable in the sprint and saddle on the mountain (from 500 watts).
Drivers who are strong (> 1200 watts) weigh more than 75kg should pay attention to a high stiffness of the rear wheel .
Particularly important for a lossless power transmission to the rear wheel is the torsional stiffness , so that your muscle power for propulsion does not disappear in the deformation of the impeller.
A stiff front wheel is important, as the weight of the body weighs mainly on the front wheel. The lateral stiffness of the front wheel is also responsible for accuracy, directness and steering precision. The magazine TOUR writes that a front wheel rubbing on the brake during a kicking step mainly results from a too soft fork. More is here .
Conclusion:
If you weigh 75kg and more and can walk more than 1200 watts, you should pay attention to high rigidity in order to be prepared for all driving situations.
For a high stiffness, we recommend at least 45mm for the front wheel and 55mm or more for the rear wheel.
The 2: 1 spoking of the rear wheel with the 16 spokes on the sprocket side causes a very high torsional stiffness for a lossless propulsion.
Note on aerodynamics:
From 15-20 km / h, aerodynamics is the more important factor for speed. This is also important for a hobby cyclist. Who classifies the low air resistance as its priority should select as high as 60mm rims. Unfortunately, however, then the crosswind tolerance on the front wheel is an important factor. More below ...
The rear wheel is not susceptible to side wind. Therefore, the maximum rim height should be chosen here for maximum aerodynamics. But due to the higher weight and the dominant appearance, a difference in height of at least 10mm between the front and rear wheels is recommended (example 45/55 or 55/80 or 60/90).
The recommended rim height for the front wheel depends on the purpose. At the front there is always a compromise between good aerodynamics and low side wind susceptibility .
For the front wheel you can choose from 38mm, 45mm, 50mm, 55mm or 60mm. As a pure competition wheel for time trial 80mm or 90mm.
38mm and 45mm on the front wheel is always trouble-free with a view to crosswind susceptibility .
But 38mm are undersized for a carbon rim, has few advantages and does not speak for the desired 'appreciation'.
Depending on the wind force / frequency, 60mm and 70mm are often too windy and do not make fun on long training runs in windy conditions. This is something for races, fast rides and areas with low to medium winds. The 60 / 70mm rim height is good to ride in cycling or time trial, but for long training runs, the steering in spite of toroidal profile could annoy you.
80mm and 90mm are only recommended for competitions (time trial) and time trial training.
50mm and 55mm on the front wheel has already good aerodynamics compared to the flat rims, is visually appealing, is only slightly susceptible to side wind and is the all-rounder. In the wind during the race and training completely mobile and compatible. The 50 / 55mm are never a danger or scary.
The steering pressures in gusts with crosswind are adjusted at 50 / 55mm to 90% in the subconscious mind. At 60 / 70mm it is only about 70%. So you often feel the rim height and wishes for a longer training sessions one size smaller.
Conclusion:
No impeller can do everything optimally.
In order to be able to combine good aerodynamics, low weight, low side wind susceptibility and high rigidity at best, a combination with different rim heights is recommended.
A good compromise in terms of low weight and low crosswind are 50/50 or 55/55 combinations or 50/60 or 55/80 for better aerodynamics.
Following is a table depending on where your priority is:
For hobby riders or as training wheelset :.
The red marked sizes characterize the 2017 COMPETITION rim heights
| aerodynamics | 50/60 or 55/55 |
|
Weight / acceleration |
38/50 or 45/55 |
|
Crosswind tolerance |
38/50 or 45/55 or 45/80 |
|
rigidity |
50/60 or 55/80 |
For cyclists:
| aerodynamics | 55/55 or 70/80 |
|
Weight / acceleration |
50/60 or 55/55 |
|
Crosswind tolerance |
45/55 or 55/55 |
|
rigidity |
55/80 |
For triathletes and time cyclists:
| aerodynamics |
70/80 or 80/80 or 90/90 or |
|
Weight / acceleration |
Not relevant |
|
Crosswind tolerance |
60/90 or 55/80 or |
If you want the same rim heights front and back, I recommend the 50/50, 55/55 or 60/60 wheels. Also many professionals drive different high rims.
Some customers also buy the 38 / 45mm front wheel for training and for races 60mm or higher.
Those looking for stress-free, fast wheels for all days will be happy with our bestselling 50/60 and 45/55 clincher wheels .
The aerodynamics of the wheels are very good, the side wind / gustibility is suitable for everyday use and the rear wheel is very stiff.