BMW Tank Bags
Three ways to attach a bag to a tank
A tank bag can be fixed to a bike in three different ways, and they are not interchangeable. The one behind most of what is on this shelf is a ring-mount system. A bike-specific ring is fitted to the tank or filler surround, and the bag clicks onto it. SW-Motech makes this ring in three families, PRO, EVO and Ion. A bag built for one will not click onto a ring from another. That rules out mixing and matching between them.
| System | How it attaches | What it needs |
|---|---|---|
| Ring-mount (PRO, EVO, Ion) | A bike-fitted ring clicks the bag on with a spring-loaded release | The ring model built for your bike |
| Magnetic (Legend Gear) | Magnets hold the bag to the tank directly, no ring involved | A steel fuel tank |
| Strap-on (Legend Gear, PRO Enduro) | Webbing straps buckle round the tank or frame | Any tank, steel or not |
The PRO ring adds a magnetic guide that helps the bag line up before it clicks in. That is all the magnet does. It is not what holds the bag on; the mechanical lock does that. Most of what is stocked here is the PRO ring on its own, with Ion some way behind, and no EVO ring currently listed.
The second system does away with the ring altogether. SW-Motech's Legend Gear magnetic bag holds itself to the tank with magnets alone, and the manufacturer says this works on almost all steel fuel tanks. The third is a strap-on bag, buckled round the tank or frame. It does not rely on a ring or on the tank's surface at all. It is the fallback for a tank the other two cannot use.
Check what your tank is actually made of
Magnetic mounting only works on steel. Not every tank is steel all the way through. Some bikes fit a plastic cover over the real tank, and a magnetic bag will not hold to that at all, however solid it looks. One rider raised this back in 2012. The post is old, but the mechanism it describes has not changed. Ring-mount avoids the problem entirely, because it fixes to the bike's own frame or filler surround, not to the tank itself. That is also why it turns up on plastic-tanked adventure bikes as often as steel ones.
One recent UK reviewer already ran a ring-mounted bag on one motorcycle and chose the magnetic version for a second bike, because that tank is metal and the first one was not set up for a ring at all. If you are not sure what sits under your own tank's paint, that is worth checking before you order the magnetic version instead of a ring-mount or strap-on one.
What it is like living with one
Fine scratches in the tank's finish are a known trade-off, not a fault. SW-Motech pads the underside of its Legend Gear magnetic bag specifically to protect the paint, which is the manufacturer's own admission that some protection is needed. A UK forum thread from 2011 has several riders describing the same thing after years of use: light marks where the bag sits, most living with it, one applying a clear film underneath as a workaround. It is cosmetic wear from a solid object resting on paint. That has not changed with newer bags.
Filling up is easier than it sounds. Recent UK reviews of both the ring-mount and strap-on systems describe fuel stops as quick once you know the routine: release the ring's catch, or undo the side buckles, and the bag lifts or slides clear of the cap. One reviewer on a ring-mounted bag said it followed the curve of their KTM's tank well and stayed put doing so.
Size is the thing to watch. One current review warns that a bigger bag can start to get in the way of the rider's controls. An older account describes an expanding bag growing tall enough to block the instrument cluster. Both point the same way. Buy for the smallest bag that does the job, not the largest.
One downside came up in a review from earlier this year: a rain cover that let wind get underneath it, adding height and becoming a distraction at speed. That is a single account, on one accessory in the range, not a pattern found elsewhere in what we read.
Capacity, and what they are made from
Sizes on this shelf run from around 3 to 5 litres at the small end, up to 12 to 17 litres for the largest PRO bag. The smallest is SW-Motech's Legend Gear magnetic bag, which expands by zip from 3.5 to 5.5 litres and weighs about 0.4kg empty.
Materials vary by line. SW-Motech is specific about why. EVA foam shapes the lids and sidewalls on many PRO bags, giving the bag proper structure instead of leaving it as soft luggage. The Ion line uses lighter 600D polyester and drops the front GPS holder. SW-Motech is upfront that this is how it keeps Ion priced as the budget option. The WP bags, SW-Motech's weather-protected line, use welded TPU instead of stitching, because a weld leaves no needle holes for water to find.
The quick-release trade-off
The same catch that makes a ring-mount bag quick to take off is not a lock. Two UK forum threads on this exact system, two years apart, show the same split in opinion. One owner rigged a bolt through the release to stop it opening while the bag was left on an unattended bike. Another replied that this missed the point: a quick-release exists so you take the bag with you, not so it stays locked to the bike while you are away. A separate thread makes the same observation independently: unlike a locking hard case, a tank bag is not built to be left on the bike. Neither view is wrong. It is a genuine choice between convenience and security, and the quick-release is built for the first one. SW-Motech do sell an anti-theft part for the PRO and EVO bags, and it is on this shelf (TRT.00.640.20001). It makes the bag harder to walk off with. It does not turn it into a locking case.
Tank bags and tank rings on this page are for sale with 10% off RRP and free UK delivery available. If you need to carry more than a tank bag holds, our pannier and side case options and the luggage racks that carry them sit alongside this shelf.