Alpkit Stem Cell bikepacking bag

The Alpkit Stem Cell is designed to either behind or in front of your bar. Offering 1.8 litres of space and made from ripstop nylon, it's light and durable. It offers a useful amount of space and provides easy, one-handed access to essentials, although some riders might find it interferes with pedalling – and the way it closes is vulnerable to rain.

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The VX21 fabric – a four-layer waterproof nylon coated with DWR – means this bag is pretty tough but very light at just 68g including all straps. This Regular version (there's a three litre XL for £2 more) is 15cm wide at the top and tapers to 7cm.

The whole thing's 21cm tall, not including the 7cm black 'extension tube' on top, though obviously you can't quite use all of that as length.

Fitting is very simple – one bit of velcro wraps either the stem or the handlebar, and one (optional) strap goes to the fork. The top strap has several attachment points on a webbing ladder, allowing you to tweak the fit.

The closure is a simple elasticated drawstring, and easy to use even one-handed on the go, but it inevitably leaves a hole that water can drain through. The drawstring is quite long, too, meaning the excess needs to be tucked away, though that's easy (if fiddly) to do.

This bag could especially suit bikepackers: the rounded shape suits things like mugs and gas canisters, which can often be tricky to fit neatly elsewhere on the bike.

With the Stem Cell mounted behind the bars, I found I had to slightly adjust the timing of pedal and frame swing to avoid my knee knocking the bag each time, but it very soon became fairly natural. The pack can also squash against the top tube and stop you turning the bars – it takes quite a severe angle thanks to the taper, so it's perfectly safe, but it can still irritate.

In general drop bar bikes are more affected, and pedalling out of the saddle on climbs makes knee contact worse. If you've got space behind your cables, mounting this bag ahead of the bars works better.

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At £32.99 the Alpkit Stem Cell is priced fairly high, with the likes of PRO's Discover Food Pouch being £30, and the basic yet very similar BBB Bar Buddy costing considerably less at £18.95.

Alternatively, front-mounted bags such as the Topeak Compact handlebar bag at £36.99 or the Lotus SH-6406 Commuter Handlebar Bag at £25.99 are usefully larger for similar money.

Overall

If that spot on your bike is already taken, though, the Stem Cell is neatly made from rugged fabrics, is a good shape for some traditionally awkward items, and is handy for keeping phones, snacks or tools close to hand. It's pretty stable too, but the closure wastes the waterproofing and needs a rethink, while the potential for knee-strikes is a little high on compact frames.

Verdict

Handy extra storage for often-used items, but can clash with knees – and not waterproof