Vehicle Dynamics

chassis and steering

To corner well and tipping properties are an essential factor for safe rides.

With the M9 development proved Daniel Fenn his focus on safety, he decided to go for an additional 20% fronal-area and took the impact on aerodynamics. [also positive impact on turning radius, Daniel claims to win back the areodynamic loss somewhere else] (link to source)

rollover protection

most velomobiles increased their safety focus in case of potential rollovers throughout the last decade. Latest developments seem to even have slightly higher towers behind the head to further improve the cyclist’s protection.

strong gusts of crosswind

Wim Schremer states that sidewinds with Bft 6 or more might cause velomobiles to tilt over. (Link to source)
Thus Wim developed the so called “Stormstrips” to make velomobiles more stable despite strong crosswinds.

Daniel Fenn critized the vision groove or knee dome as one of his biggest mistakes, which he made in the past. (Link to source)

The vision groove results in an aerodynamik pressure to the side. (eg. old DF design). The latest flat front of the M9 and other models create an upwards suction, similar to the EVO-R velomobiles.

considerations for potential impacts

Velomobile engineers review various potential accicent scenarios and impacts on the velombile during the design process.

rear impact

of all crash scenarios is a rear impact on a velomobile one of the more easy to resolve topics. However there are some key points to consider:

• the cyclists needs to be one object with the velomobile head rest to avoid a breaking of the neck. Thus the mounting of the seat becomes an essential factor.
  (each bottom mounting of the M9 has to withstand about 300 kg / 660 lbs on each side – Link to explanation)

interior design

the interior design is a key point to reduce potential injuries for the velomobile cyclist.

All edges with an angle <=90° (90 degrees and smaller) are to be avoided as those are a potential threat to the cyclist.

One typical challenge is the shoulder and manhole areas, as there are typical edges in the design.
The Evo-K got nice round shoulders, also the M9 comes with round shoulder areas. Other velomobiles fill up the shoulder area and add an additional PVC protection strip at the shoulders.
Compare this to a car – you’ll not find any sharp edges in any designs (too many velomobiles are not on this level yet).

cornering

Most velomobiles don’t offer a ‘leaning into corners’ in difference to upright bikes. (Velotilt concept is an exception).

3-wheel velomobiles have the tipping axis is very close to the center of gravity, which leads to a threat of tipping over.

• The higher the speed,
• the tighter the corner,
• the higher the tipping threat

energy absorbant materials

Velomobile designers are taking energy absorbant materials into account.
The picture on the left shows a Katanga WAW, which uses aramide or carbon-aramide.
The latest M9 development has glasfibrein in front of the driver, as this absorbs 10-20 times more energy than pure carbon, which makes the velomobile safer.

We’ve reviewed the Katanga WAW with the safety consultant Trevor Ashline, who used to be Vice President of Engineering and Product Development at Simpson (Formula 1 and NASCAR safety system provider). He is kind of a guru for safety and was in charge of several saftey systems studies. He contributed to the “lay-down style IRL car” study and the study on “Nitro Fuel Funny cars”, which have certain similarites – though for sure with different speed levels and weights. 

The number 1 priority for velomobiles (specifically the WAW) is a slowing down of the vehicle in case of an impact.

Trevor Ashley

While there might be various technical solutions to achieve this, the most effective and lightweight way to achieve a slowing down of the vehicle seems to be a unidirectional impact attenuator. A specific product would be the ‘IMPAXX™ 700 Energy Absorbing Foam’.