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The Adventure Top Tube Bag from LifeLine is a small, neat bag offering 0.7 litres of storage within a single zipped compartment. It may be basic but it's a slim, stable and effective way of keeping snacks and phones to hand.

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While it's designed primarily to fit up against your steerer, it's just as happy against your seat post, and proves surprisingly handy. The 0.7 litre size may sound small, but it's enough to keep plenty of food for a full day's riding.

The bag is made from 300D ripstop fabric, which is waterproof and pretty tough, and sealed with a waterproof zip and seams. Throughout testing it stayed dry inside.

The bag is secured with two hypalon (it's a kind of synthetic rubber) and Velcro straps. The front strap goes under your stem, so it won't fit well on tall front ends with slammed bars.

That said, there's no reason why you can't fix it to the seatpost end of the top tube, as the straps are long enough to fit most posts – even deep aero designs. It's not as easily reached there, obviously, but stays out of the way.

The main strap is bigger than on most similar bags, and provides a reassuring amount of support. Even when full there's no movement from the bag, either sideways to interfere with pedalling or back and forth.

The zip makes for easy access and, with a small zip garage for when it's closed, the zip puller stays in place.

There is a small cable port for running external light batteries or charging your phone on the go, which is handy, and when closed it still proves good at keeping rain out.

At just 4.5cm wide, the Adventure is slim enough to not bulge out on almost any bike, and I never found it interfered with pedalling.

The LifeLine Adventure Top Tube Bag is small, simple and reliable, and at just £15 it's really well-priced. The Mack Workshop Top Tube Bag is £28 and not waterproof, for instance, while the Apidura Expedition is waterproof but costs £47.

Buy the LifeLine Adventure instead and that's a lot left over for cake to stuff inside...

• www.hotlines-uk.com

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