Castelli's Undersaddle Mini is a sleek saddle bag that's big enough to hold the essentials. The water-resistant material is strong and shuts out water very effectively. I found it to be secure and easy to access when needed.
The Undersaddle Mini has proven to be perfect for my riding needs. It lives on my road bike and on the rare occasion that I need something from inside, I can get at it easily, making roadside repairs that bit quicker.
I don't tend to carry much on the bike – a couple of tubes, a CO2 canister, tyre boot, quick link and multi-tool with chain tool will get me out of most mechanicals. Anything worse than that and I'll be seeking refuge in the nearest cafe and ringing for a lift! The Undersaddle Mini is easy to pack with these items and I even had space for a rag to wipe oily hands. If you wrap the inner tubes tightly you can also get a tyre lever in there, though this isn't required for my clincher tyres.
The inside is a simple single space with a small mesh pocket for your multi-tool. This is the only thing I'd change about the design. The Allen keys snag on the mesh material, making it fiddly to get out. A minor gripe which I solved by putting the mini-tool in a small plastic bag.
Outside, the bag is 'water resistant' though I've soaked it with the hosepipe during washing and there's no sign of any water getting through. The zip has also been made water resistant. This doesn't affect its smoothness. It's still really easy to open up and get at your stuff, though you do have to remove it from the bike. Personally, I don't see that as an issue.
When on the bike, I really like the way that this looks. There are no straps flapping around and it's held securely to the saddle rails with no movement. The subtle branding and small silhouette mean it's barely noticeable. Add to this good stitching and I can't see this needing to be replaced for many years.
Thigh rub is something that can cause a lot of pain but, try as I might, I couldn't make contact with the Undersaddle Mini. The strap is easy to trim if you need to take a bit of length off. This should keep it from catching your shorts if you've got wider thighs. The zip sits in its own 'cave' to keep it out of harm's way.
One feature that I wish had been carried over from the XL version is the external pump sleeve. Putting my pump in a jersey pocket isn't the worst, but it's harder to forget if it remains strapped to the bike.
In terms of value, you're paying quite a bit more for this than the very good Fabric Contain Small saddle bag at £21.99, but nowhere near the eye-wateringly expensive Silca Seat Roll Premio at £48. I reckon it's a price worth paying: you're getting a very well made, stylish and compact saddle bag that sits very securely on the rails and holds a lot for its small silhouette. I'd call that very good value. That said, for a fiver extra you can have the XL version with the pump holder.
Overall, this is a fabulous saddle bag that sits quietly under the saddle without movement and allows easy access to spares when needed. It's well made, looks great and I can see it lasting a fair few years between my summer and winter bikes.
Small, neat and well made – a great saddle bag
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road.cc test report
Make and model: Castelli Undersaddle Mini
Size tested: Mini
Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
Castelli says, "Part of the Castelli Race bags range, the Undersaddle Mini is the perfect bag for sticking on your road bike to carry some summer essentials.
"Super compact this fit and forget under saddle, seat-pack can be crammed with a couple of (road) inner tubes 18-25mm a multi-tool, a spare link and a few £10s. In short most of the things you might require on a ride. It fits with a single strap (through the rails no need for a seatpost stabiliser), this strap uses a magic moulded hook and loop fastener that can be trimmed at home and that won't fur your shorts. The Mini bag is also weather resistant as is the zip. It's not totally waterproof but its better than most. The zip pull sits in a little cave so it stays silent and doesn't open mid-ride. The rear wordmark is reflective and the lining is in a pimp corporate red. Could you ask for more?
"Possibly the greatest accolade for the Castelli Undersaddle Mini is you forget its there."
Tell us some more about the technical aspects of the product?
Water and stain resistant materials
Water resistant construction
Adjustable hook and loop attachment strap
Internal storage pocket
External dimensions 5 x 5 x 13cm (enough room for a Lezyne V-Tool with chain-breaker or similar 2 road bike inner tubes a spare link and some folding cash).
Tell us how the product performed overall when used for its designed purpose
Very well. The spares are stored securely and then they're pretty easy to get to when needed.
Tell us what you particularly liked about the product
The compact size. Let's face it, I'll rarely use this, so being secure on the bike and being small and forgettable is really important. I can't stand things rattling in a saddle bag.
Tell us what you particularly disliked about the product
Nothing really. I'd like to see the pump sleeve included in the future.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
It's at the higher end, but nowhere near the Silca Seat Roll Premio (£48).
Did you enjoy using the product? Yes
Would you consider buying the product? Yes
Would you recommend the product to a friend? Yes
Use this box to explain your overall score
This carries all the spares that I need while being very compact, secure and looking great, though it's a shame it doesn't have a pump strap like the XL version.
About the tester
I usually ride: Cannondale Supersix Di2 My best bike is:
I've been riding for: 5-10 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, club rides, general fitness riding, I specialise in the Cafe Ride!
Son of a Marathon runner, Nephew of a National 24hr Champion, the racing genetics have completely passed him by. After joining the road.cc staff in 2016 as a reviewer, Liam quickly started writing feature articles and news pieces. After a little time living in Canada, where he spent most of his time eating poutine, Liam returned with the launch of DealClincher, taking over the Editor role at the start of 2018. At the weekend, Liam can be found racing on the road both in the UK and abroad, though he prefers the muddy fields of cyclocross. To date, his biggest race win is to the front of the cafe queue.