German brand Ion was originally known for making windsurfing and watersport focused kit but has since branched out into the world of dirt.

With a focus on details, its kit has been developed with specific criteria in mind and the Transom 16 pack is no exception, designed for day-long mountain bike trail rides.

Ion Transom 16 backpack specifications

Ion Transom 16 mountain bike backpack — There are loads of internal organisers, which is good, but these are all located in one single pocket, which isn't so good. Simon Bromley

Even though the Transom’s only got one main zipped pocket, it is crammed full of features.

Inside this pocket, there’s space for your bladder behind the separate tool organiser with five compartments, two of which have zip closures.

The tool organiser is attached to the bag’s body with Velcro and is removable. Inside the main pocket are two additional elastic compartments and a further fleece-lined zipped pocket.

The outside of the bag has two elastic side pockets, a zipped pocket on the right-hand hip strap and a smaller zip pocket on the bag’s body and, finally, helmet and kneepad securing points.

Ion Transom 16 mountain bike backpack — Air Conditioning activated. Simon Bromley

Although the amount of storage is impressive, the bag’s party piece is its Air Conditioning system that relies on a slider that can be set to move the bag away from your back, creating an air gap to help reduce heat and a sweaty back.

The bag’s got multiple levels of adjustment to fine-tune the fit of the shoulder straps, as well as the Air Conditioning system and a padded waist strap.

There’s also an adjustable chest strap and it has built-in bladder hose clips. Included with the bag is a detachable rain cover.

Ion Transom 16 backpack performance

Ion Transom 16 mountain bike backpack — The bag's got a lot of adjustments on it. Simon Bromley

Because of the high levels of adjustability, I found the bag particularly tricky to set up correctly and make comfortable on my back, even when following the instructions to the letter.

During the setup process, I managed to pull the plastic chest strap clean off its fabric runner. It was possible to reattach the strap, but I had to damage the material of the runner slightly to force it back on.

It's likely this was an isolated incident, and plenty of bags use the same system as Ion to allow vertical adjustment of the securing straps.

Ion Transom 16 mountain bike backpack — The first time I used the bag the chest strap broke away from its mounting point. Simon Bromley

The sheer number of internal pockets in the bag was welcome, but if you’re not selective with where you put bulky items, the risk of them damaging more valuable possessions is high.

This is because there’s only one compartment to store all of your things.

Ion Transom 16 mountain bike backpack — More space for more items. Simon Bromley

The dedicated bladder section works well and the elasticated retaining straps kept it in place as it emptied.

However, the bladder sits quite deep in the bag, so finding one with a long hose is essential if you don’t want to contort your neck to drink from it.

The bag was comfortable once I got it set up and hid its weight well even when fully loaded with a 3-litre bladder and a day’s worth of supplies.

The bag’s weight is mostly concentrated through the large, padded hip strap, but the size and location of this strap prevents access to jacket pockets and compressed any items I had in there into my body.

Ion Transom 16 mountain bike backpack — There's plenty of space for helmets. Simon Bromley

When loaded up, it did bounce up and down over bumps but never from side-to-side. Considering the lengthy setup process and number of adjustments I was disappointed at how much it moved.

The Air Conditioning system did reduce sweat build up on my back and there’s a marked difference between it being on or off.

In theory – and to some extent in practice – it’s a clever system, but it’s difficult to operate, especially when you’re on the move.

Ion Transom 16 mountain bike backpack — The Air Conditioning system is hard to use and adds weight but is good at keeping your back less sweaty. Simon Bromley

The clips are quite stiff to open and the bag is hard to slide along the rails in the correct plane when opening or closing the system on the move. I found that stopping and adjusting the bag was the only way the system was guaranteed to work.

The extra bulk and complication it adds to the bag’s design certainly aren’t outweighed by the benefits it brings, particularly because it’s hard to use.

Rainstorms were brushed off with impunity and the bag’s smooth surface was very easy to clean once it got covered in muck. For torrential downpours, there is a rain cover, but I never opted to use it.

Ion Transom 16 mountain bike backpack — There's plenty of space for helmets. Simon Bromley

The helmet carrier is storied in its own zipped pocket on the outside of the bag and is attached to four loops on each corner. It’s easy to set up and is big enough to take both full-face and open face helmets.

Helmet storage is secure and I wasn’t worried that my lid was going to bounce out even over very rough terrain. The helmet carrier doesn’t interfere with the knee pad carrying straps and it’s possible to attach both to the bag simultaneously.

Ion Transom 16 mountain bike backpack — There's a microfibre-lined pocket for delicate items. Simon Bromley

Removable chin bars can be safely stored in the lid carrier, too.

Ion Transom 16 backpack bottom line

Ion Transom 16 mountain bike backpack — Each strap can be adjusted to fit your shape. Simon Bromley

Despite having some very natty features the bag’s execution is less refined. In fact, it weighs almost double the majority of other bags I’ve tested with similar carrying capacities.

Combine the hard-to-use features with its sheer bulk and I just can’t rate the Transom 16 over more simple designs.

Product

Brand	ion
Price	134.95 GBP
Weight	1600.0000, GRAM (L/XL) - L/XL size
br_whatWeTested	Ion Transom 16 L/XL

Features

br_bagCapacity	16.0000
br_bagCapacity	LITER