Keis B601 Ultraflex heated bodywarmer review

Date reviewed: January 2026 | Tested by: John Milbank | Price: £180 + battery (RRP) | keisapparel.com

Make no mistake, heated kit really is a winter essential. If you commute throughout the year, or even just take the bike out on chillier days, investing in electrically-heated motorcycle clothing like the Keis B601 heated bodywarmer on review here really can transform your rides.

I’ve been wearing a Keis V501 heated vest for a few years now (you can read Steve’s review of his here), which is a lower-power garment that doesn’t include the heated neck of the B601. After using the new bodywarmer for several months on my 2019 BMW R1250GS, 2001 Honda VFR800 and a 2025 Triumph Scrambler 400XC, I have my favourite, but which is right for you will depend on several factors…

I’d love to know what you think is the best choice after reading this unbiased review, so please let me know by tagging me in on our exciting new free BikeClub motorcycle forum.

Pros & Cons

Construction

With a nylon / spandex outer and polyester / spandex liner, the B601 bodywarmer is very stretchy throughout, hugging the body well to deliver the best heat possible through its ‘micro carbon fibre’ heating elements. There are four heating panels – one on each side of the chest, one on the back and another around the collar.

Compared to my V501 vest – which lacks the collar – this ‘Ultraflex’ design is much stretchier. Not that the older vest is uncomfortable, but the difference is noticeable.

The B601’s fabric is a lot more breathable that that of the V501, which can potentially make it more comfortable but also means it’s even more important that your outer kit is as windproof as possible, to limit how much air coming in can cool the heating elements. I don’t want this to sound like a criticism as both garments have kept me very warm in testing.

The B601 comes with a controller, making it work out at just £2 less than the lower-powered V501 when one’s added to the purchase price. And that doesn’t have any collar heating.

A connector in each armpit can supply power to Keis gloves (if you have another brand you’ll need to find an adaptor), and there are two good-sized zipped pockets on the outside. Inside is a pocket for the optional battery pack.

Keis is so confident in its tech that it offers a lifetime warranty on the heating element. The clothing itself and accessories have a two-year warranty, and the portable battery packs have 180 days.

Fit

Fit is of course very subjective, but the B601 is true to its size for me, a Large being my usual choice at 5’10” and 14 stone. The stretch construction makes it very easy to wear, but it’s important to point out that the heated collar, while not thick or bulky by any measure, and great under a lot of my bike kit, does make the Rukka Hybrid-R, for instance, very restrictive.

Now this of course isn’t Keis’ fault (or Rukka’s), but with the B601 undeneath I really struggle to move my head. 

The pockets are particularly handy when you’re off the bike

Temperature

It’s hard to accurately measure the temperature achieved by a heated garment as positioning the probe can be a bit hit-and-miss, and it doesn’t take into account windchill and body temperature. Subjective experience is the best guide, and riding at 5°C for nearly two hours I was very comfortable with the B601 on the medium setting. On another ride in late November I only needed low to keep me snug.

In my experience, it’s easy to grow accustomed to a heated vest, bodywarmer or jacket, and end up not thinking it’s that ‘hot’ after a while on the bike, but as long as you have windproof riding kit on (anything with a waterproof membrane should be perfect), you’ll likely find that you start with the vest in the high mode, then soon knock it down to medium or low. It’s only when you turn the heating off (or the battery runs out) that you realise just how much of a difference it’s been making.

As a comparative measure of the temperatures inside the Keis B601 and V501, I ran both while not wearing them for 10 minutes using the optional battery in low, then 10 in medium, and 10 in high, with the room temperature at 19°C:

I used the same new controller with both the B601 and V501 in this test, and had the probe wrapped in cotton wool pads to reduce any variation based on how close the sensor was to a heating element. While this doesn’t represent the heat your body would be at when riding, it gives us some comparison between the modes.

I’m surprised that the V501 showed higher temperatures in my testing than the B601 – perhaps the more breathable nature of the bodywarmer allowed more heat to escape. It’s important though to remember that on a motorcycle you’ll have your other kit over the top, which will trap air. Also, this is indicative testing – the reality on the bike is that you’re warm in either.

Power

As standard, the Keis B601 bodywarmer comes with the wiring loom to pull power from your bike – a capped connection cable is fitted directly to the battery (or via a power distribution module like the Hex ezCan), and stowed near the seat to make it easy to plug in. If your bike already has an SAE connector, for instance for an Optimate, you can connect via that with this £17 SAE to Keis adaptor.

2, 3, 5 and 7.5A fuses are supplied – if you’re only powering the bodywarmer, the 5A fuse will be ideal, but if you’re using the vest as a hub for other kit too – like heated gloves, trousers or socks – you’ll need to use the 7.5A. The supplied printed instructions explain fully if you’re not sure.

In my testing at 13.8V, the B601 draws very little power. It’s more than the V501, but still shouldn’t be any problem for most motorcycles, even those with quite weak alternators:

The other option is to use Keis’ 5,000mAh battery, which costs an additional £90. Weighing 266g and with an LED remaining charge display (which is always on when the bodywarmer is running) it has rounded corners and edges to reduce the chances of it causing any injury in a crash.  It can also be used as a power-bank if you want.

Brilliantly, the Keis battery doesn’t need any special charger or cable – it’s got a USB-C input and output port, and also a micro-USB input port, so you’ll have no problems topping it up easily with charging kit you likely have already at home, or that you take on your travels. Note that you can’t charge the battery while it’s in use.

A USB-C charging cable is supplied, with a USB-A adaptor tethered to one end, but you’ll need to use your own charger. If you don’t have one with a decent power output, Keis offers its own 30W USB-C charger for £20, which comes with UK, EU and US pins.

While the additional current drawn of the B601 over the V501 is negligible when powered by the bike, when using the optional 5,000mAh battery it can make a big difference to runtimes:

The Keis B601 certainly heats a larger area of your body, but when run from the battery pack it’s at the expense of runtime. As I swap around bikes a lot I often use the battery for power (and really appreciate it when I’m out walking or even sitting at my desk working), so while on the face of it not as good value as the B601, it’s the V501 that I tend to use most.

Control

Keis supplies a triangular controller with the B601, which has a simple one-button control. Press and hold to turn it on, then press once to cycle through the modes.

It’s fairly easy to locate the button thanks to the shape of the controller, but you really need to be able to see it to check the power output. If you set a level before setting off it’s not a problem, but it can take some stretching of your neck to see the it on the bike as it has a limited length of cable from the garment. It’s enough to poke out under your main jacket, and you get used to positioning it for easier reading, but if you’re really struggling Keis offers a Bluetooth controller for £60, which allows you to use an app on your phone or navigation tablet, as well as the button that’s still moulded in.

Three alternatives to the Keis B601 bodywarmer

There’s a wide range of heated kit on the market at various prices, but before you snap up an apparent bargain on places like Amazon, AliExpress and Temu (not to mention Facebook) from unknown brands, keep in mind that you’re putting an electric heating element very close to your skin. This review of some heated kit saw our reviewer suffer minor burns on her legs. Here are some others you might consider…

• Keis V501, £178 with controller | It’ll be no surprise to anyone who’s read this review to see the V501 as an alternative recommendation here. It’s not as powerful as the B601, and it doesn’t heat the neck, but it does offer significantly better battery runtime. Read Steve Rose’s review of the Keis V501 here.

• Gerbing Heated Vest Liner, £259.98 with controller | It’s a long time since we’ve reviewed any Gerbing kit so can’t comment on its quality now, but it is a relatively expensive option. Strangely, the Gerbing website claims that you can only buy it direct from the Netherlands, but major retailers like Sportsbikeshop and The Visor Shop do carry stock. We haven’t reviewed the Gerbing Heated Vest Liner, but you can find out more here.

• Warm & Safe Heated Jacket Liner, £349.98 with controller | We haven’t tested any Warm & Safe kit, but a user on the BikeClub forum sung its praises. It’s extremely expensive compared to the other options available, though the US price at the current conversion rate – rather than the price from the single UK importer, MotoLegends – is a more reasonable £260.13. That’s quite a margin if you consider the 40% discount that the company says it offers dealers, though shipping, taxes and tariffs do need to be considered. You can find out more about Warm & Safe heated kit here.

These are just three of many alternatives – you can find all the heated kit we’ve tested here  and be sure to regularly check for the discounts available through Bikesocial membership.

Keis B601 bodywarmer review: Verdict

“Avoid clichés like the plague.” Sound advice, but heated kit is one of those rare cases were calling it a ‘game-changer’ is more than just a trope: rides in everything from cooler spring evenings to the depths of winter are far more enjoyable with heated kit. You’re more comfortable, you’re better able to concentrate on the ride and you’re safer.

As it comes with a controller, and it heats more of the body, the B601 on review here is clearly better value at just £2 more than the V501 when you’ve added its controller. If you’re buying purely on price, the B601 is the best bet.

Equally, if neck heating is important then the B601 again is the best choice – especially if you’re powering it from the bike.

But if you have a jacket with a high collar do check how it fits with the B601, and if you intend to power it via the optional battery pack, be aware that runtimes are significantly reduced.

The Keis B601 is a superb piece of kit, but personally I prefer the long battery life and ease of fitting under more of my kit that the V501 provides. Both keep me lovely and warm in the coldest conditions here in the UK, so I’d suggest you think carefully about which is right for you. Fortunately, both are brilliant and come highly recommended.

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