Castelli Regular Shorts

Fabric Tech and Chamois Performance

Start with the chamois, because that's where Castelli earns its reputation. The KISS Air2 seat pad is the workhorse of the range - a well-profiled, breathable pad that suits regular training rides and sportive efforts up to around three hours comfortably. It's not trying to be everything; it's a solid, honest chamois that performs consistently without drama.

The Progetto X2 Air seamless seat pad is a different proposition. Dual-density foam targets sit-bone pressure directly, and the seamless construction removes any stitch line from the skin-contact surface - the thing that causes chafing on longer efforts. If your rides regularly push past three hours, or you're building toward an audax or multi-day trip through the Cairngorms, the Progetto X2 Air is the chamois to look for. The difference between the two isn't just marketing hierarchy; you'll feel it on hour four.

The Forza fabric - carrying 38% Lycra - gives genuine muscle support along the quad and hamstring without the stiff, unyielding feel of cheaper compression fabrics. It moves with you. On a muggy August ride through the Chilterns, where humidity sits heavy and every layer feels like too much, Forza's breathability keeps things manageable. Flat Giro4 leg grippers keep the hems locked down without creating that uncomfortable band of pressure mid-thigh - the so-called sausage-leg effect that cheaper raw-cut grippers often cause. Anatomic waistbands are cut to follow the body's natural curve, so they don't roll down or dig in during efforts out of the saddle.

Getting the Fit Right Across the Range

Castelli sizing runs small. That's not a rumour - it's consistent across the range, and it's rooted in traditional Italian pattern-making designed around lean road cyclists. If you're between sizes or carry any muscle in the thigh, size up. This applies whether you're buying an Entrata or a more race-oriented cut. A too-small Castelli short will compress the quad uncomfortably and the waistband will dig in; going one size larger gives you the intended fit - supportive and close without being restrictive.

The range itself works across clear use cases. The Entrata sits at the accessible end: a straightforward Castelli non-bib cycling short that suits commuting, leisure riding, and indoor sessions without demanding a big outlay. Mid-range options step up the fabric quality and chamois specification for regular training. The Free Aero sits toward the top - a race-level cut with aggressive compression and aero-focused panelling that's genuinely designed for riders who want to go fast and stay there.

Looking for upper-body support on longer days? Take a look at our Castelli Bib Shorts. Heading off-road? Our Castelli MTB Baggy Shorts are the better fit for trail riding. Need something slim to wear under casual trousers on the commute? Check our Castelli Liner Shorts for a low-profile option.

When Waist Shorts Make Sense for UK Riding

Bib shorts are brilliant. But they're not always the right tool. Indoor turbo training is the clearest case for waist shorts - bib straps trap heat against your core in a way that's genuinely uncomfortable when you're stuck in a garage pushing through a Zwift race. No straps means better airflow across the upper body, and you'll notice the difference by the end of a hard interval session.

Commuting is the other obvious one. Stopping mid-ride - whether that's a café, a meeting, or a public loo - is significantly less complicated in waist shorts. No need to strip your jersey and base layer to deal with bib straps. That convenience adds up across a week of commuting, and it's the kind of practical consideration that doesn't get enough credit in spec sheets.

For spring and autumn riding, Castelli endurance shorts in a waist format pair cleanly with Castelli knee warmers on those mornings when it's 8°C at the start but likely 16°C by the time you're back. You can strip the warmers off and stuff them in a pocket without having to faff with an entire kit change. That adaptability matters on UK roads, where the weather tends to do what it likes regardless of the forecast.

Pair the shorts with a suitable Castelli jersey and you've got a full kit that works across a wide range of conditions - from a muggy summer commute to a brisk Saturday club ride. The waistband construction keeps things tidy under a jersey without bunching, which matters more than it sounds when you're riding in a close-cut road cut.