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Bontrager's MIK Commuter Boot Bag is a really well made and superbly stable rear rack bag with surprisingly decent carrying capacity, excellent waterproofing and impressive practicality both on and off the bike. It's a little heavy and a fair price, but you won't be disappointed.
I don't know the absolute data but I suspect trunk bags probably finish in third place behind panniers and rucksacks when it comes to most people's preferred way to carry stuff while cycling. On the basis of Bontrager's MIK Commuter Boot Bag, that's a shame because if you only need to carry things of relatively limited size, it does the job exceptionally well.
The bag's main USP is the MIK system functionality. Essentially, it uses a large plastic MIK bracket on the bag's bottom to clip into a compatible hole in a MIK rear rack to offer enhanced stability and security. It's a bit like a KlickFix mount for handlebar bags, albeit positioned horizontally rather than vertically. If you really don't like it or you don't have a MIK rack, the bag's bracket can be unscrewed and removed, though.
I talked at more length about the MIK mounting system in the review of Bontrager's MIK Commuter Double Pannier. I wasn't bowled over by the system in the case of the double pannier because I felt one of MIK's main selling points – enhanced security – is a moot point. Bontrager says you need to use the included key to 'unlock' the mounting system from a compatible MIK rack, but really you can just push the retaining tab back with your fingers to remove any MIK bag – not exactly thief proof by any stretch.
I also felt that such a secure mounting system was a little bit over the top for panniers. During the decades that they have been with us, I'm not certain that attaching or securing non-MIK panniers has ever been a major technical issue. However, in the case of the trunk bag, I have to say the MIK mount does come into its own.
Primarily that's because you can pack a fair bit into its 7 litres – it would certainly make a hell of a lunch box. You can't squeeze an A4 pad flat in there, but it's not far off; if you're happy to roll and dog-ear a magazine slightly, that would fit, though. So, if you're used to carting a trunk bag laden with heavy goods, the extra stability supplied by the rock-solid MIK system is actually very welcome. This thing simply will not move on your rack.
The MIK Commuter Boot Bag also addresses some of the other criticisms I had with the Bontrager Commuter Double Pannier. For example, there are a couple of very handy zipped external pockets on each side where you can quickly store and access valuables, tools, and so on. There's also a bungee cord on top to offer further carrying potential, and an open elasticated pocket at the far end.
Build quality, as is customary with Bontrager kit, is superb. Everything feels fantastically well put together. The outer material is cordura-style material, and feels very durable. Access to the main compartment is easy with a three-quarter-length zipped and reinforced lid, which flops wide open to reveal an internal roll-and-clipped waterproof inner to keep contents safe from moisture. There's also a semi-hidden internal side zip to allow you to secrete things beneath this waterproof liner.
Finally, topping off practicality, there are reflective highlights on the sides, and a poppered strap conveniently joins the carrying handles for off-the-bike hand luggage duties, or you can attach the included shoulder strap to the D-rings for hands-free carrying. What more could you want?
At £69.99, the MIK Commuter Boot Bag looks like fair value, although if budget concerns are high, the BTR Waterproof Bike Bag at £39.99 is a steal. However, despite its fab waterproofing, the BTR is a rugged rather than refined option and not particularly commuter friendly. Far closer competition comes in the form of Topeak's MTX TrunkBag DX, which has all the functionality of the Bontrager but offers a lot more carrying-potential 12.3 litres for the same money.
Looking at spec and price sheets, then, the Topeak seems to steal a march on Bonty's best. But I wouldn't dismiss it on that basis alone because there's still that MIK stability to enjoy. As long as it is able to carry enough for your needs, I think the combination of MIK technology with sturdy build quality and classy design means Bontrager's MIK Commuter Boot Bag should be near the top of the list if you're looking for a rear rack bag.
Top-quality rear rack bag that does everything you ask of it while being particularly stable on the bike
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road.cc test report
Make and model: Bontrager MIK Commuter Boot Bag
Size tested: 7 Litres
Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
This is a rear rack-mounted boot bag, probably mostly aimed at commuters. Bontrager says: "A versatile trunk bag designed to fit a wide range of cargo that quickly and securely mounts to compatible MIK racks. The MIK Commuter Boot Bag offers versatile and secure on-bike storage that's easy to install and remove without the need for tools. It has multiple pockets to keep you organised, and a durable design to keep your gear secure. A sturdy handle makes off-the-bike handling a breeze."
Tell us some more about the technical aspects of the product?
MIK rack mounting system
Main pocket, two external zipped pocket, elasticated rear pouch
Handles or shoulder strap
Light loop for easy rear light mounting
Dimensions: 32cm x 19cm x 21cm
Really very nicely made bag that feels close to being a premium product.
Excellent on-the-bike stability and decent carrying potential. Easy off-the-bike carrying as well.
Has stood up to use so far and still looks good.
The addition of the MIK mounting bracket pushes weight to more than 1kg, which is on the heavy side.
Feels great in the hand and on the shoulder. Not really 'comfort' per se, but super stable on the bike.
About right for the quality of the product in this market. The BTR Waterproof Bike Bag costs less at £39.99 but isn't such a premium-feeling product. More similar is the Topeak's MTX TrunkBag DX, which costs the same as the Bonty but is far more capacious at 12.3l.
Tell us how the product performed overall when used for its designed purpose
Really well. On the bike you wouldn't know it was there – it causes absolutely no issues while riding. In terms of carrying potential, despite its relatively limited capacity, the nice square shape and semi-rigid construction mean you can cram a fair bit in.
Tell us what you particularly liked about the product
Build quality, waterproofing and the good balance between carrying options but overall simplicity.
Tell us what you particularly disliked about the product
The MIK's bracket is super-effective for secure attachment to the rack, but it does makes the bag a bit heavy and clunky off the bike.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
The BTR Waterproof Bike Bag is a steal at £39.99. However, despite its fab waterproofing, it is a rugged rather than refined option and not particularly commuter friendly. Topeak's MTX TrunkBag DX has all the functionality and is nearer the 'feel' of the Bontrager but offers a lot more carrying potential at 12.3 litres for the same money.
Did you enjoy using the product? Yes
Would you consider buying the product? Yes
Would you recommend the product to a friend? Yes
Use this box to explain your overall score
If you're in the market for a decent rear rack bag, I genuinely don't think you could find a much more practical or classy option than Bontrager's MIK Commuter Boot Bag. It's very well made, waterproof, and offers decent carrying capacity with sensible additional practical features. It's also secure and stable on the bike, and conveniently transportable when off of it. I took a mark away for it being a bit heavy and a bit pricey, but if you can cope with those minor issues, you should be very happy. It's excellent.
About the tester
I usually ride: Islabikes Beinn 29 My best bike is: 25-year-old Dawes Galaxy
I've been riding for: Over 20 years I ride: Most days I would class myself as: Experienced
I regularly do the following types of riding: commuting, touring, sportives, general fitness riding, mtb, Leisure