A very lightweight set of arm warmers, ideal for those who want extra protection when it's chilly, without too much pocket bulk once warmed up. The fabric provides warmth without causing overheating - but it is delicate, and the lack of silicone gripper means these slip down on uneven terrain.
Insulating but breathable
Gripper won't take rough terrain
Arm warmers are a staple of any cyclist's wardrobe, allowing riders to head out in a short sleeved jersey despite the temperature being just too nippy for bare arms. Difficulties can arise when you become warm and want to stash the warmers but don't want to put up with too much bulk in your pockets. Enter: these Pro Seamless arm warmers from Castelli.
Castelli worked with Team Ineos to research and create these seamless tubes of material. The brand opted for a polyester/nylon/Lycra blend over a traditional nylon/Lycra construction - with the additional polyester chosen for its quick drying attributes.
When I first unwrapped these warmers, I thought they might be some sort of strange 'half warmer', or a very odd pair of socks. Because of the high stretch of the fabric, until you put them on, they're very short. I measured one arm warmer, flat, at 34cm. However, pulling the warmers on to my arms I was surprised to find they covered the full length from bicep to wrist - that's 44cm with my arm outstretched.
These warmers are a bit shorter than other versions I have tested, most models continue over my wrist and towards my hands. This is a positive for me, but might be annoying for anyone with longer arms.
Testing these warmers on chilly evenings, I found they kept me warm without overheating on the climbs. They dried quickly when I got sweaty and I found the seamless fabric very comfortable against my skin. There are clever weave pattern changes at key areas such as the elbows, presumably offering more stretch here, as well as white logos heralding the brand on the forearm.
Unlike Castelli's more robust NanoFlex warmers, with their water resistant treatment, these don't have silicone grippers to hold them up. Instead, the brand has opted for a simple high stretch band. This worked well on road rides and kept the warmers up. However, on off-road gravel rides I did find they began to fall down, leaving a slither of exposed skin. This shortcoming is something to be aware of if you like to venture off the beaten track.
The material is also very delicate. Unfortunately after just two outings, I noticed a 'pull' in the fabric, which is a bit unfortunate. This didn't impact performance and showed no signs of unraveling, but I'd expect an item from Castelli to have more resilience.
The real plus side to these is the weight and ease of folding. At 34g for a size small/medium, I could roll them into a ball and stuff them in my pockets alongside a full complement of essentials (pump, snacks, phone, inner tube, allen keys, tyre levers) with no uncomfortable cramming.
Michelle Arthurs-Brennan is Cycling Weekly's Tech Editor, and is responsible for managing the tech news and reviews both on the website and in Cycling Weekly magazine.
A traditional journalist by trade, Arthurs-Brennan began her career working for a local newspaper, before spending a few years at Evans Cycles, then combining writing and her love of bicycles first at Total Women's Cycling and then Cycling Weekly.
When not typing up reviews, news, and interviews Arthurs-Brennan is a road racer who also enjoys track riding and the occasional time trial, though dabbles in off-road riding too (either on a mountain bike, or a 'gravel bike'). She is passionate about supporting grassroots women's racing and founded the women's road race team 190rt.
She rides bikes of all kinds, but favourites include a custom carbon Werking road bike as well as the Specialized Tarmac SL6.
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