Let me start with a caveat - I’m no expert.
I’ve owned several helmets from several brands and covering a wide range of price points. Currently I sport a Catlike Mixino and I often borrow Steph’s Kask Mojito. Now I’ve put a Giro Synthe into the mix. I’m a bigger guy and I get very warm when I ride, so I’m usually looking for three things: fit, ventilation and appearance. I don’t like looking like a mushroom head.
The Synthe (in size S for me) is snug. I tried on small and medium and found the medium still left a lot of “play” around the sides of my head, while the small was snug. Initially I was a little wary as I could feel two parts of the structure clearly pressing on my head. The good news is that after getting on the bike my head and posture move enough to eliminate that feeling and give the impression I’m barely wearing a helmet at all. The Giro mechanism for tightening the helmet is solid and it clamps down well without being uncomfortable. Only the Mixino has been close. During riding the helmet barely moves and is hardly noticeable at all.
Having owned a Bell Sweep, Giro Atmos and Catlike Mixino - as well as using a Kask Mojito - the ventilation on the Synthe is outstanding. I was genuinely surprised at how well air passed through the helmet and around my head. The Mixino possibly does a better job at lower speeds (20km or less) but around the 30km mark the Synthe and the Mixino are inseparable. During a lunch ride where I was pushing pretty hard I could feel my head warming up, however, I could also feel the Synthe funnelling air around my head to cool it down. There is a point though at which airflow can be disrupted. Looking down at a Garmin or doing a Chris Froome (staring at your stem) will put the flat blades of the helmet into the wind and limit the air. Looking at the road works best.
I can’t really comment about the aero efficiency of this lid. I’ve felt quick wearing it but that could be any number of things, from having fresh legs on a still day to the choice of wheels on my bike. It could be anything. I’d need to get out in an air attack and the Mixino in a more controlled environment to compare. Also, I’ve yet to go climbing in this helmet and I have no idea how I’ll go in the hot months with it. Time will tell.
Let’s get the “premium” feel of Kask’s leather strap panelling out of the way. The Kask has it, pretty much no other helmets do. It’s a selling feature for them and I only ever notice it when I do the helmet up or take it off. I’m never riding along thinking about how great that little bit of leather is.
The Mojito can look a bit weird on my head, the Mixino works well for me but the POC Octal (regardless of size) looks awful on me. The Synthe, I think, looks pretty good. I’ve got one in white & silver to be versatile across my bikes and also to be a little bit more visible in failing/poor light. The design strikes a nice balance between old and new, looking both modern and sleek as well as harking back to the days of simpler helmet design.
The mushroom effect isn’t as pronounced as many helmets I’ve tried and the simplicity of the design means it should age well and be versatile. The glasses cages are great as well. They’re a bit loose for my Oakley Racing Jackets, however my POC Do-Blades are locked away firmly and don’t budge at all. This is a gripe I have with the Kask (not with the Mixino or Octal). When I’m wearing the Oakleys these are a little more comfortable, not quite resting on the rear retention mechanism of the helmet. The slightly longer arms of the Do-Blades do sit on the rear caging but do so firmly and without issue.
For me this is an expensive helmet ($400 in store at Saint Cloud). My Mixino wasn’t this expensive, nor was Steph’s POC Octal. Even an Air Attack is cheaper. The construction of the helmet feels good though, the design is simple and uncomplicated and there are supposed aerodynamic benefits from this helmet. It ventilated extremely well, comes in four colours (locally at least) and feels absolutely excellent to wear. By far the biggest surprise for me was how well it ventilated. It really does feel very good. I’ve done around 100km in the Synthe so far, including an hour on the track today, so I’ll post an update in another couple of hundred kilometres (or if I go climbing in it). I would rate this helmet a 9/10 for me and what I need it for (apart from keeping my brain inside). It ticks all the boxes I need, I would just say it is expensive.