Castelli is not the first company to integrate a hydration bladder into a jersey or top but it is one of a few new options on the market aiming at gravel riders where aerodynamics and the ability to stay fuelled over long distances is vital. But with a premium price, no bladder and fewer features than a standard hydration vest, does the Castelli Unlimited Pro Jersey provide any real benefits?
- Apidura Racing Hydration Vest review
- Camelbak Chase bike vest review
- Buyer’s guide to hydration packs for mountain biking
Camelbak was the first company to try a cycling-specific hydration pack integrated into a garment of clothing with the Racebak. It was never a big hit and have only seen one worn while riding and racing but it was ahead of its time in many ways. It was not perfect, though. The Racebak was difficult to refill and caused mild overheating but if it had been released now, I think more racers would find it beneficial.

Castelli Unlimited Pro Jersey Jacket – Technical details and fit
The Castelli Unlimited Pro is made from lightweight, breathable Air_O Stretch fabric. The sleeves feature a dimpled construction, giving a nod to the aerodynamic performance that has become an important factor for gravel racing.
Three standard-size pockets are on the rear of the jersey and a fourth zipped pocket is on the right-hand edge of the pockets.

What sets the jersey apart from a typical one is how a hydration bladder, up to 1.5 litres in capacity, can be fitted into a pocket area on the back. There is a reasonable-sized opening at the top to insert the bladder with small loops on the shoulder and right torso area to hold the hydration hose in place while riding.
Castelli does not include a bladder. No specific bladder is required but, after testing, I have found that a 1.5-litre Camelbak bladder and an underfilled Apidura bladder were both suitable. (Bladders with a more rectangular shape are slightly easier to place and remove). You can fit more than 1.5-litres into the space provided but weight becomes the problem.
The jersey has a slim fit, which is to be expected for a garment designed for races, and the size guide is correct to size.
Castelli Unlimited Pro Jersey – Performance
When used purely as a jersey, the quality of the fabrics and the cut hug the body contours. However, with such light material, it never feels too tight or obstructive.
Castelli recommends use in 18-30 degrees Celcius conditions and the material is very thin – it’s a jersey for warm rides only.
With the bladder fitted the jersey has a very different feel and the weight is immediately noticeable as it pulls downwards through the lightweight mesh material. With a full 1.5-litre bladder, the extra 1.5kg feels like it is pulling down through two sections of thin material – almost as if you are carrying the weight of the bladder on two pieces of string. Put simply it’s not comfortable.

The jersey has limited ability to hold the bladder in place and on rougher sections. It moves around a bit and is most frustrating on steeper descents, where it all moves close to your neck. When in a more typical riding position it sits over the rear pockets, making the central rear pocket a little harder to access.
Refilling isn’t easy if you need more than one full bladder per ride. You may need to take the jersey off to access the bladder, which might not always be practical. One small benefit of having the bladder so close to your body is that it is easy to reach back and feel how much is left. Should you be riding without a bladder, the mesh pocket can be used to store other items including a lightweight jacket/gilet but you will need to be quite flexible to reach back and fish them out.
Castelli Unlimited Pro Jersey – Verdict
The Castelli Unlimited Pro costs £135, which makes it one of the more expensive summer jerseys Castelli produces, at the same price point as the race-focused Aero 7.0 jersey, but with a feel and fabric weight more like the £120 Climbers 4.0 jersey. On the one hand, you could consider the extra £15 an investment over a more standard Castelli jersey but you will need to factor in the price of the bladder as well.

Hydration packs are spread across a wide price range with budget options including the Rockrider XC Light backpack for just £40 (including a bladder). While it might not be the most stable compared to other hydration packs, it is better than the Castelli Unlimited Pro with a full bladder fitted. The Apidura Racing Hydration Vest is another minimal design with good stability, plenty of pockets and adjustment. At £143, it’s a few pounds more than another new option from Restrap – Race Hydration Vest.
The benefits of a hydration jersey compared to a bulkier mountain bike hydration pack are certain but the comfort and practicality of such systems need refinement.
You might also like:
- Five things that weren’t cool – until gravel happened
- What is the spirit of gravel biking?
- Buyer’s guide to hydration packs for mountain biking
Product purpose:
Available in plain colours or a vivid pattern, the Castelli Unlimited Pro Jersey will help you keep going with few stops during your endurance race.
The jersey features aqua pack compatibility, with a sturdy mesh pocket and two anchor points for the hose, one on the right shoulder and one near the right pocket, making hydration breaks a thing of the past.
The soft, raw-cut sleeves are made from aerodynamic dimpled fabric, while the body is crafted from Castelli’s own breathable, unrestrictive material that is also form-fitting and fast.
Equipped with a trilogy of strong drop-pockets and a fourth valuables pocket, to hold all your trail necessities, this speedy yet practical, durable jersey will help you complete your route faster.
Build extra:
• A durable, pro-level jersey designed to boost your speed
• Perfect for multi-surface racing or adventuring
• Mesh pocket will hold a filled 1.5L bladder
• With two fabric loops to stabilise your hose and keep it accessible
• Features dimpled, raw cut aero sleeves
• 3 drop pockets and a zippered valuables pocket will guard your ride necessities
• With a silicone strip to anchor hem
• Weighs 130g (M)
• Made for a temperature range of 18-35°C
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