Cool is comfy. And fast.
The “summer” cycling jersey conceit seems weird at first. Kind of like the equal and opposite of “winter” fleece cycling shorts. Both seem extravagant. Until you wear them in the right conditions.
Castelli calls this summer jersey the Climber’s 2.0 Jersey FZ on the idea that the jersey is light and well ventilated, both of which make it great for going uphill. The truth is that the jersey works great not only on hot days, but on moderately warm days as well. And no, not only for climbing, just any time you expect that your effort will leave you profusely sweating. Your performance will thank you.
When Castelli first debuted the jersey, they pitched it as summer gear, but the team they were sponsoring at the time, an iteration of the various Garmin/Slipstream outfits, used the jersey most of the season.
We had a consumer version of that first-generation jersey. It was incredibly light and cool for a cycling jersey. Great on 90-degree Fahrenheit days, but also good for 65-degree days with a light baselayer when riding tempo. Which is probably why the pros took to it. If they were racing all day, with the temps starting in the 50s and rising to the mid-60s, they could wear it with a vest and arm-warmers at the start and strip down as the day went on.
The 2.0 version updates both the paneling and the material of that original jersey. It resembles their Aero Race 5.1 jersey in terms of how the fabric is cut and where the seams lie, but it’s lighter than both the first Climbers Jersey, and more breathable than the 5.1. The sample Climbers Jersey 2.0 we have is a size small and weighs in on our scale at 100g. Advertised weight is 83g. The original weighs 150g, also in a small. According to Castelli, this jersey is only two watts slower in the wind tunnel than the 5.1; trading some aero for greater cooling might be a beneficial trade-off much of the year.
As with the earlier Climber’s Jersey, this top is minimal everywhere to save weight. The zipper is chosen for weight, isn’t covered by overlapping textiles to keep a seamless look to the jersey and doesn’t possess a fabric tab on the zipper pull. There’s no gripper material at the waist hem. The gripper bands on the arms are meshy, feature a raw edge, and have no silicon or rubbery material in the fabric. The pockets don’t have gussets at the bottom for expansion. The reflective tabs are adhesive. The material is super thin. Strada Pro 3D fabric, used on the back, the pockets, part of the arms, and the front of the waist is so thin they warn has a sun protection factor (SPF) of 16. If you burn easily or are going out for a long time, you might need sunscreen. The Flusso 3D fabric used for the torso and part of the arms might be even thinner than the back fabric.
Another place Castelli saved weight was at the collar. The collar they’ve designed for this jersey is so small as to be non-existent. It’s fine when unzipped. If you’re used to having a collar that seals to your neck and keeps wind from going down your jersey, it takes some getting used to.
With a cool spring this year, we were a bit slow to test out this jersey. Our concerns were validated on the first ride, when we went out in 64-degree weather for, with a base layer underneath, and the ride was a bit on the chilly side for the moderate efforts we were doing. Can’t imagine wearing this jersey below 60-degrees Fahrenheit, unless racing. Even then, it might be too cool for the setting.
What is a liability in one place is can be a benefit in others. We brought out the jersey for a planned long ride at the highest tempo we could manage. It was only 66-degrees Fahrenheit when we went out, but forecast to go to the low 70s. We skipped the base layer. The first half-hour, mostly a roll out, was a bit too cool. But once we moved to the big ring and turned the tempo gas on, it was great. The comfort was a striking contrast—our head was warm and sweaty, while our torso felt cool, barely breaking a sweat. That’s a great thing, and a good sign for the upcoming swelter of summer.
And like most of Castelli’s top-end jerseys, the aero design is both form-fitting and comfy, though it looks loose in back when standing up. At 150lbs, we’re concerned that the small size is actually a bit big—any smaller and we’d be concerned about flapping, though as the material stretches, it might be a bit thinner than it already is when shielding from the sun.
We do have some concerns about the Climbers Jersey 2.0 in terms of durability. While we are comfortable with the expectation that it will be destroyed quickly by any crash, we do wonder how long it will handle machine washing. So far, so good, but we’ve been washing it for a few months, not a few years.
We still feel a bit funny about the idea of a summer jersey. But as summer is getting warmer thanks to global warming, this jersey could see regular use from mid-April into mid-October. Aero plus cool equals faster, which makes us happy to have this as a jersey option going into the hottest part of the year.