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Castelli Alpha RoS jersey review

13 Feb 2018

The Castelli Alpha RoS jersey is versatile enough to make weather-driven kit choice a non-issue

Cyclist Rating: 
Breathability, level of weatherproofing, insulation, fit
The performance is going to cost you

Buy the Castelli Alpha RoS jersey from Wiggle here

I’ve never been one for layering. I can’t deal with the faff, nor have I the bike handling skills, to take off or put on gilets/midlayers/accessories when I’m out on a ride. The garb I put on tends to stay on, so versatility is always high on my list of priorities when it comes to picking out kit.

If Castelli’s marketing claims for its new Alpha RoS jersey are to be believed then it should suit those who, like me, prefer a garment to cope with a range of conditions.

The Alpha RoS builds on Castelli’s well-established Alpha jerseys and jackets, which are known for their good insulation and breathability but low bulk thanks to the liberal use of DWR-treated Gore Windstopper panels but little voluminous thermal fleecing.

‘The big thing for us was to try and design a garment that the rider would choose to wear based purely on temperature, no matter if it was raining, sunny or windy,’ says Rich Mardle, Castelli’s brand director at it’s UK distributor, Saddleback.

Diving into the jersey’s technical features, the dual-layered front panels, where there is the outer zippered layer but also a zippered vest inside the jersey, are carried over from the previous generation of Alpha apparel.

‘This allows the rider to open the zippers to manage their temperature based on their speed and level of exertion to remain dry and warm,’ says Mardle. ‘Climbing, you could open the Windstopper top layer to allow more ventilation, while descending that front layer can be done back up to prevent windchill.’

Castelli says that the second inner layer also acts as a wicking/diffusing layer, taking vapour away from the skin in an attempt to prevent excess heat build up but also preventing a baselayer from becoming saturated with sweat and chilling the rider.

The front of the Alpha RoS jersey is distinctly different to its back. Here Castelli introduces its proprietary Nanoflex Xtra Dry fabric. It is stitch-woven but also treated with a DWR treatment, so it should be flexible and breathable yet shrug off rain pretty well.

Particularly exposed seams (most notably at the shoulders) are taped in an attractive contrast-colour to further aid weatherproofing.

The amount of research and development Castelli has pumped into the Alpha RoS has meant it is prohibitively expensive but its purported level of performance is borne out on the road.

The dual layers helped me regulate my temperature at the front easily (I can manage to undo a zip), while the lighter rear panels act as a great exhaust to prevent overheating.

Considering how low-mass the Alpha RoS jersey is you would expect it to not be suitable when the weather gets really cold, but the Gore Windstopper and DWR act as a very effective barrier to the elements that would lower your body temperature, namely wind and rain.

Without that weather penetrating the jersey, once you start generating heat the Alpha RoS retains it, so with a decent base layer underneath I was happy in it from ten degrees down to around zero, although it is worth noting I do tend to run hot.

It could make me question the necessity of the Alpha RoS jacket - basically a heavier duty Alpha RoS jersey - certainly in this country, because the jersey copes so well throughout the British winter.

The Alpha RoS comes in Castelli’s standard racy fit, so I would recommend sizing up, but the flexible rear panel means it is svelte and comfortable, plus it has a couple of neat refinements that add a bit of bit class.

The outer zip subtly lists to the left towards the bottom of the jersey, meaning the jersey sat pleasantly flush over my stomach, while the rose petal-like cuffs easily slide underneath gloves and the reticulated collar cosseted the back of my neck when I was in the drops.

The cost of the Castelli Alpha RoS jersey is shocking initially and certainly not a garment for those on a budget.

That said, its performance is proficient enough to justify its price tag when you consider that you would probably have to buy two garments from another brand to cope with the range of weather conditions and temperature that Alpha RoS takes in its stride.

Buy the Castelli Alpha RoS jersey


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