Castelli Undersaddle XL – review

Castelli may be best known for their clothing but they've also just launched a new range of luggage that includes two rolling travel bags, a duffel bag, a backpack, a rain bag and two ‘undersaddle bags’ – or as you probably know them, saddlepacks (or saddlebags).

The whole range takes the same black on black colour scheme, giving it all rather understated cool and, practically, makes them easy to keep clean.

There are only a few factors that matter in a seat pack: capacity and security of fastening. Water resistance/waterproofing is a bonus – especially if you want to use it during the winter – although it really depends on what you’re going to be carrying in there as inner tubes and inflators don’t really have too many issues with a little water, whereas a soggy fiver isn’t doing anyone any favours.

Anyway, on to mounting, and securing the bag on your bike is extremely simple. There are two velcro straps, one designed to loop around the seatpost and the other to loop through the saddle rails, around the bag and fasten on the other side. The good thing about the main strap also looping around the bag before fastening is that it means you end up with a long contact area between the two sides of the velcro, making for a very secure fit. The secondary seatpost strap means that there’s no side-to-side swaying as you ride, which is another factor that can end up with the velcro coming loose.

And the fastening system does an excellent job in practice, too. On multiple rides – including some terrain that would make Paris-Roubaix look like an airport runway – it didn’t come loose once, even when fully loaded.

What should you put in your saddlebag?

Capacity-wise it’s pretty good. ‘XL’ might be overstating things somewhat, but it’s only XL in relation to the smaller ‘Mini’, rather than XL in a larger, more existential sense. If you want to put numbers on it, the external dimensions are 6 x 6 x 15cm. I’ve been able to fit an inner tube, two tyre levers, an inflator, two CO2 canisters, a multi-tool, some patches, glue and a small piece of sandpaper. In fact, if I was feeling like really pushing the proverbial boat out, I could have probably fitted a few more patches in there. In all seriousness, though, it’s not bad at all and doesn’t take into account the fact that there’s also an external pocket for holding a mini pump.

As far as waterproofing goes, it’s water resistant rather than fully waterproof. The zipper is sealed, much like you find on wet bags, and the seams on the bottom are taped although those on the top aren’t. In fact, the only gripe I have about the bag at all is that the contents still managed to get wet when riding in what can hardly even be called rain. Like I said before, it’s not all that important as nothing in there could be damaged but it still suggests that the water resistance isn’t quite as good as Castelli may have hoped.

A final nice little touch is the logo on the end of the bag, which is hyper-reflective and shines brightly when hit by headlights.


Irrespective of whether you’re a firm disciple of ‘The Rules’, a saddlepack is a really useful way to free up your jersey pockets and make things a little more comfortable. And Castelli’s first shot at making one has gone rather well. Even though it’s called ‘XL’, it falls well within the parameters of being large enough to carry what you need without being too bulky and it’s understated look is not only in keeping with the rest of the Castelli luggage range, it’s pretty cool in itself.


– Strikes a good balance between capacity and bulk
– Reflective logo is a good high-vis touch
– Fastens very solidly to the bike and won’t fall off mid-ride


 – Water resistance doesn’t withstand more than very
light rain

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