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Stem Cell XLaccessory bag

Lightweight and spacious stem-mounted padded accessory and bottle bag for keeping your stuff protected and accessible; UK-made to last.

Stem Cell XL stem mounted bag grey

Stem Cell XL accessory bag

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No matter how hard you try to pack ultralight, sometimes you just need a bit more stuff to hand; enter Stem Cell XL – a tardis in bike luggage form.

Stem Cell XL provides spacious, easy-to-access, protective storage space for the stuff that you’ll need frequently during your ride.

Constructed from waterproof, bombproof, and lightweight VX21 with a minimalist design in our UK factory, Stem Cell XL is made to endure the demands of life on the road without compromising on weight.

A bar-tacked webbing ladder offers endless attachment points around the flight deck; simply cut the VELCRO® strap provided to size.

Stem Cell XL is spacious enough to carry a BruKit, camera, a light extra layer, or your lunch; drawcord closure maximises capacity.

Key features
  • 25 Year Alpine Bond
  • Easy-to-access, extra spacious storage
  • Made to last in the UK
  • Bombproof, waterproof, and ultralight VX21
  • Minimalist design for lightweight storage
  • Elasticated drawcord closure
  • Padded walls protect your stuff
  • Bar-tacked webbing ladder for endless attachment points
  • Attaches to either side of stem
  • VELCRO® strap provided
More images
Vital stats

Outer: VX21
Stitched seams
Elasticated drawcord closure
VELCRO® straps


Weight: 88 g
Width: 11 cm
Height (min - max): 16 - 23 cm

Origin: United Kingdom

Dimension Polyant fabric is extremely weatherproof but we do not guarantee these bags are waterproof as the seams are not sealed and it has a big hole at the top. On a long ride water may eventually seep through, keeping anything that absolutely must stay dry in a lightweight drybag such as an Airlok is good practice. Custom options: if you would like a bespoke made Stem Cell to match your bike’s colour scheme or you wish to add features not offered on the standard model please give us a call or drop us an email and if we can, we’ll make it for you. We love the challenge!


UK Made Adventure - Stem Cell

An insight into the creation of a bike packing set up here at Alpkit HQ UK factory. The Stem Cell.


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Free UK Shipping on all orders

Free 2 day delivery to UK addresses is included in all orders so the price you see is the price you pay. Upgrade to next day at the checkout.

Free No hassle 123 Day Returns

Buy with confidence and if you are not happy, change your mind or want a swap for any reason then return it for free and we will exchange or refund no question. The price you see is the price you pay. Just return the kit as you receive it - in its original condition, unused, unworn, with original packaging and fit for resale.


We offer a range of finance options from 0% to 9.9% starting on orders over £500. Please give us a call on 01773 417007 to apply for finance. Our customer support heros will take your order and talk you through the quick and easy application process.

Alpine Bond

If one of our products does not meet your expectations upon delivery or, if it does not live up to the demands placed upon it, please return it within 3 years of purchase for repair, replacement or refund. If the problem is our fault then we will do this to your satisfaction if it’s your fault then we will help out the best we can.


2 Reviews


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Stem cell xl

Extremely well made, durable, tardis like bag. The velcro straps make it rock solid. I was initially concerned it would get in the way when climbing uphill, but it doesn't as it sits so snugly to the stem. I've used the stem cell to take a shirt, lunch, keys, and phone to work. I use it every day and love it, do yourself a favour and get one.

Really good but better with straps

Just to say I took two of these across the Great Divide in USA/Canada. They are tough and made to last. Some of my stuff got holes in but these look like new after a spin in the washing machine. My only observation really would be that I found them better when you use some sort of buckle strap to lash them to frame from beneath. I used two straps and fed them through the tops of the forks. This means that they don't flap up and down. Other than that they are great.