Bike shock absorbers: power and energy consumption?

[Christophe]

I ask myself the question of the energy "absorbed" by the shock absorbers on a light vehicle of the bicycle type ...

To my knowledge, no racing bike (even at the Tour de France, though not all roads are nickel) has ever been depreciated (other than through tire pressure) so it's good that the damping consumes energy (or power) ...

My question is how much? In order of magnitude?

Obviously it will depend on the mass moved, the road and the average speed (but also the acceleration and braking but we will neglect that) but an order of magnitude would be interesting.

Hypotheses:
- 25 km / h average
- 100 kg moved
- Road in "average" condition let's say a bump of 10 cm / km

How much energy will have been "lost" in the damping after 100 km under these conditions?

To our neurons!

[Ahmed]

To my knowledge, no racing bike (even at the Tour de France, though not all roads are nickel) has ever been depreciated (other than through tire pressure), so it's good that damping consumes energy (or power) ...

This is a reasoning that seems incorrect to me, because in the case of a racing bike (lightened to the maximum) it is the cyclist's mass which is by far the most important and it is necessarily his body that will cushion the irregularities in the road: this therefore does not change the energy dissipation. However, it is clearly detrimental to comfort not to resort to damping on the fork and on the saddle (the latter is rarer in factory installations, but on a fairly "urban" bike, this is where the saddle rests. almost the entire mass of the cyclist, so not to be neglected: your vertebrae will thank you!

[sen-no-sen]

There are nevertheless road bikes with shock absorbers, Cannondale produced one with shock absorbers at the base of the stem, it was used by runners on Paris Roubaix.
Specialized makes one too,the Roubaix with very discreet front and rear damping devices (20mm of travel).

[dede2002]

...

How much energy will have been "lost" in the damping after 100 km under these conditions?

To our neurons!

The same energy as that which will have been "lost" in the vertical movements of the vehicle "without shock absorbers"?

More that induced by the additional mass moving ...

[Christophe]

This is a reasoning that seems to me incorrect, because in the case of a race bike (lightened to the maximum) it is the mass of the cyclist who is by far the most important and it is necessarily his body which will amortize the irregularities of the road: this does not change anything to the dissipation of energy.

There are dampers at only 200 grams currently.

If we do not preserve the bodies of champions who spend 6 8h a day on their bike with it is that there is a reason!

No racing bike is damped (other than on the saddle)

However, it is clearly detrimental to comfort not to resort to damping on the fork and on the saddle (the latter is rarer in factory installations, but on a fairly "urban" bike, this is where the saddle rests. almost the entire mass of the cyclist, so not to be neglected: your vertebrae will thank you!

Are the saddles of the Tour de France amortized?

[Christophe]

There are nevertheless road bikes with shock absorbers, Cannondale produced one with shock absorbers at the base of the stem, it was used by runners on Paris Roubaix.
Specialized makes one too,the Roubaix with very discreet front and rear damping devices (20mm of travel).

Oh ok but they are very rare and little used ... why?

[Christophe]

The same energy as that which will have been "lost" in the vertical movements of the vehicle "without shock absorbers"?

More that induced by the additional mass moving ...

The pumping effect consumes energy ... no?

[dede2002]

Because of the extra mass?

...

How much energy will have been "lost" in the damping after 100 km under these conditions?

To our neurons!

The same energy as that which will have been "lost" in the vertical movements of the vehicle "without shock absorbers"?

More that induced by the additional mass moving ...

In fact, there is theoretically no energy lost in the vertical displacements, the rising energy being returned to the descent, if there are no deformations of matter. The damper absorbs the energy of the vertical displacements and dissipates it in heat ...

[sen-no-sen]

There are nevertheless road bikes with shock absorbers, Cannondale produced one with shock absorbers at the base of the stem, it was used by runners on Paris Roubaix.
Specialized makes one too,the Roubaix with very discreet front and rear damping devices (20mm of travel).

Oh ok but they are very rare and little used ... why?

The reason is simple, a racing bike requires maximum responsiveness, it is for this reason that materials such as carbon are used, it allows to have a nervous frame that responds to the solicitations instantly.
You only have to test an all-carbon and all-steel bike to understand how "soft" it is.
Depreciation is generally of little interest except in races like Paris Roubaix (we understand why!) Or for cyclists seeking a little more comfort, the condition of the roads does not require this kind devices weighing and energy-consuming (power loss by pumping).

The pumping effect consumes energy ... no?

Oh yes! Because it creates a moment up which dissipates the energy produced by the cyclist, this loss comes to parasitize the channeling of the effort towards the wheels.
There is only to experience: take a suspended suspension shocked MTB and launch you in a climb to 10% ... does the same thing with the amortized blocked, it changes everything.

[Ahmed]

Dede2002, you write:

In fact, there is theoretically no energy lost in the vertical displacements, the rising energy being returned to the descent, if there are no deformations of matter. The damper absorbs the energy of the vertical displacements and dissipates it in heat ...

This is true, but in practice there is deformation of matter, whether it is that of the frame of the bike or the body of the cyclist.
As noted Sen-no-sen, the mechanical damping limits the responsiveness of pedaling by absorbing part of the effort, but this phenomenon has no negative consequences in a "cushy" use of the bike while the comfort provided by these devices has very positive ones ...