off-road.cc

The Frame-Pack Toptube offers four litres of space and the high quality, fully waterproof design you expect from Ortlieb. It has lots of adjustment for fitting and makes a good option for riders looking to keep their bottle cages accessible.

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Ortlieb is renowned for waterproof bags, and this one is seriously waterproof. It meets the IP67 standard, which means it gets the highest possible dustproof rating and waterproofing that totally resists 30 minutes in one metre of water.

Bear in mind anything meeting the IPX5 standard is also 'waterproof,' but that only involves three minutes of hosing. In other words, IP67 is impressive, especially for something with a zip.

The adjustment options mean it will fit most bikes, although on my 54cm Ritchey Outback the frame was only just long enough for it to fit. There's only one size, too (50x13x6cm), so it's worth checking if you run small frames – handily, Ortlieb offers a printable template for download on its website.

Three straps secure this to the top tube, and the front and rear ones have two fitting points each. The straps are long enough for even the chunkiest carbon frame, if a little long on slim steel tubes. I found the rear one could occasionally catch my leg while pedalling,  and ended up running it loose to avoid this – and had no issues.

The down tube and seat tube straps can be moved to suit the frame too, and there are even attachment points on the bottom of the bag should you need them. All the Velcro straps feel very durable and well made.

The zip is a big, tough thing from TIZIP, a company specialising in waterproof and airtight zips. It's unlike any other zip I've used, feels extremely durable and has a T-shaped puller I'm very grateful for as it takes some force to close – the final section to full seal, in particular, is stiff. It's not a bag to use one-handed or while riding.

That isn't a complaint, though, as it's simply the price of that incredibly impressive waterproofing. The small zip holder is a neat touch too, as it's an effective zip garage and stops all these chunky components from rattling.

Obviously there's no way to include a cable port given the waterproofing, so if you are looking to charge stuff or run remote batteries, look elsewhere.

The fabric is light but strong and at 170g complete, the Frame-Pack Toptube compares well even to smaller and less protective bags.

At £110 it's not cheap, especially when you can get good bags such as the Lifeline Adventure for just £20. But the Ortlieb is exceptional in its design and materials, and if you're looking for totally waterproof bag that's built to last, this is it.

I have not seen or used anything that beats it – if you're planning for the biggest, toughest and wettest adventures, this is the bag to have.

• www.ortlieb.com

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