There are two key advances that Giro have incorporated into the new Ionos helmet; one is the improved fit and the other is the amount of ventilation. Obviously on longer rides, these two aspects are quite critical. This helmet takes over top spot from the Atmos.
The fit has been adjusted to have the helmet ride lower on the head, giving a more enclosed position and a more comfortable fit. However,
this has not compromised the ventilation and the Giro Ionos has 21 large air tunnel vents, together with optimised internal exhaust channels to aid the removal of heat from around your head.
This has created the challenge for Giro of compensating for less safety material by using their technological research to install key composites into various parts of the Ionos helmet.
The sub frame is of carbon and composite with a composite weave of carbon and glass fibre reinforcing the large vents to increase the tensile strength. These composites in the sub-frame provide excellent structural support, impact dispersion and resistance to penetration. This is inside the bulk EPS which then has a hard exoskeleton, which has been extended somewhat under the front and back of the helmet to help prevent damage to the EPS.
The Giro Ionos also has a new feature in its X-Static fabric pads which intended to kill 100 percent of bacteria therefore reducing the risk of odour development or fungi forming within 4 hours after a ride!.
Finally there is Giro's own Roc Loc 4 system which is often regarded as the best for easy adjustment while providing excellent hold without discomfort.
There are plenty of comments that the helmet has a great deal of ventilation improvement, even to the extent of perhaps having to wear a cap inside it on colder days ! In terms of performance for competitive cyclists in warm conditions this is obviously a great benefit.
The lower and snugger fit is also liked by many and because of the air flow, it has not made the helmet hotter, just more comfortable.
There are some comments that the Giro Ionos is quite expensive, but as always that depends on how you value the features. A price tag over 120 pounds doesn't seem that much to pay for improved cooling of the part of your body that suffers in heat, if you're serious in competition. Feeling better while exerting yourself may be less tangible than saving 100g on a wheel weight, but it may well have just as big an effect.