• Free UK DeliveryMainland ex H'lands (over £25)
  • Free Returns*Mainland UK over £25
  • Finance Available0% on orders over £300
  • 15+ Years OnlineTried, tested, trusted
  • 365 Day ReturnsRefund or exchange
  • 200+ Top BrandsUK's largest range

Free UK Delivery

It's really simple, if you spend over £25 with us, delivery is free of charge to any mainland UK address (excluding Islands & Highlands).

Free Returns*

We now offer free returns on any UK Mainland order (excluding Highlands) over £25. Most importantly, returning an item to us is super simple. Just click here or on the 'create a return' link located at the bottom of every page, and create your return in under 1 minute. You can choose from any UPS Access point close to you where you can drop off your return at a time convenient for you.

Finance Available

Why wait? We now provide some of the best finance packages around to help spread the cost and get you on the road. We now offer finance on most orders from as little as £280 with 0% packages starting at only £300. The online application process is super simple too and takes around only 5 minutes to complete! The best part is, there's no paperwork to print and in most cases you'll have a decision in under 10 minutes. Just select finance as a payment method and take it from there!

15+ Years Online

We've been serving the motorcycle community for more than 15 years now and in that time we've grown to be the largest online retailer of motorcycle clothing & accessories in the UK.

365 Day Returns

We simply don't believe in making the sale and moving on, we want to make sure our customers are happy with their purchase. That's why we now offer a full 365 day returns period. Simply relax, take your time and make sure it's right! All we ask is that you try the items within your own home and return with the tags intact.

200+ Top Brands

There simply isn't a better selection of biking brands anywhere in the UK and we're constantly updating every range to ensure you have the best choice available.

Alpinestars Nucleon KR-2I Back Insert - Black

Best Seller
in Body Armour

CE approved Level 2 back insert for Alpinestars jackets and suits

View full details

Our price


Online Availability

Please select option above

Add to wishlist
Free Delivery & Returns
Seen it cheaper?
Get a price match
Quick find: 213640

Customer Reviews for Alpinestars Nucleon KR-2I Back Insert - Black

Alpinestars Nucleon KR-2I Back Insert - Black
June 11, 2019

Comfortable and Sturdy

Fitted it into an Alpinestars T-Missile Drystar jacket. Comfortable and feels very secure. Great bit of kit. Highly recommend.

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
June 11, 2019

Upgrade your gear!

I hope it doesn't get tested, it feels good and fits perfectly on my Alpinestars Gunner jacket.

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
June 10, 2019

Essential item

Bought the back protector to go in my Alpinestars 3L jacket as the one supplied is little more than a thin piece of foam. The back protector fits the jacket perfectly (2xl jacket with the L protector). It makes you the jacket stiffer when you pick it up but once you put the jacket on you would never know it was on. Reassuring to have level 2 protection. Hope to never need to test it out.

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
May 16, 2019

Great Quality

Fitted this to a Leonis Drystar jacket. It is very pliable, moulds easily to your back and is comfortable to wear. Purchased a size Large, which fits my XL jacket perfectly. Recommended.

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
May 11, 2019


My view is you can't skimp on safety features great quality and fit and feel, hope this helps

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
May 7, 2019

Worth the money

Fits my alpinestars sektor tech jacket perfectly, with luck I'll never have to find out whether or not it provides the level of protection required however it's always better to have and not need than need and not have and at £35 it's priced far cheaper than I'd be willing to pay to avoid a spinal injury. Just buy it .

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
April 18, 2019

Solid piece of mind.

Light, well ventilated with the ability to mould to your back. Easy to install in my Alpinestars atem jacket. An essential purchase. Medium size for medium jacket. Cheapest price I found. Excellent delivery and communication.

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
March 27, 2019

Lightweight flexible but sturdy

Bought this with an Alpinestar Leonis Drystar jacket. Very pleased, it's very light, comfy and flexible but reassuringly thick so I think it will offer good protection. You don't notice it when wearing jacket.

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
March 19, 2019

Cracking value for money

Surprisingly good quality for the money. Fits perfectly into my Motegi jacket.

Read more
Alpinestars Nucleon KR-2I Back Insert - Black
February 13, 2019

Almost can't feel it

Although this is a rigid back projecter, you almost can't feel it once in the jacket. Looks like it will give a lot of protection to the back. All in all, a nice bit of kit

Read more

Alpinestars Nucleon KR-2I Back Insert - Black

OptionMaximum heightMaximum width

The latest in back protection inserts from Alpinestars is the Nucleon KR-2i soft back protector insert. Suitable for all Alpinestars jackets or suits that feature a back protector pocket. It's design conforms to the latest back protector standards with it's Level 2 CE-certification (EN1621-:2014). The 'Nucleon' back protector's design has been ergonomically profiled for an optimised fit, whilst the lightweight design and flexibility with incorporated airflow system helps to keep the wearer both cool and comfortable. This highly protective back protector is quick and convenient to insert and offers the perfect fit for the ultimate in safety performance.

Back protector compatibility chart

  • Level 2 CE approved
  • Lightweight, Flexible Design
  • PU Injected Impact Foam
  • Ergonomically Designed Profile
  • Perforated For Breathability & Comfort
  • Channel Ventilation System For Optimised Airflow


Alpinestars, a truly world class brand of motorcycle apparel. Founded in the early 1960s by Sante Mazzarolo, Alpinestars has grown to be a world leading manufacturer of professional racing products such as leather jackets, jeans, boots and 1 piece suits. Whilst their leathers are worn by some of the biggest names in bike racing, they also specialise in high performance textile jackets, jeans and gloves. From F1 to Karting, the World Rally Championship to NASCAR, Alpinestars work with the very best drivers and riders to bring design innovations to all aspects of professional motor-sport.

See all Alpinestars products
Questions and Answers

Questions and Answers

  • I have just received an Alpinestar Ares goretex jacket 2xl what back proctor will fit this jacket? Many thanks.

    December 13, 2018

    A 2XL jacket requires the large Nucleon back protector.

  • Hi I have purchased an Alpinestar Jaws Leather Jacket off yourselves recently- size 42 chest. I'm 6ft 3" and slim. Jacket is snug but good fit. Which size would you recommend re. the back protector?

    September 6, 2018

    We would recommend the medium back protector.

  • Hi, looking at purchasing the Alpinestar GP plus R v2 size 46 U.K. Q1 is this the best back protector? Q2 what size for the 46?

    April 25, 2018

    This is the Level 2 CE approved back insert that Alpinestars recommend. If you were to purchase an Alpinestars Jacket in a UK size 46, you require the Large insert.

  • I have an Alpinestars Motegi Leather Jacket size EU56. Which size do I need as the compatibility chart isnt clear if they are using the Euro or product size?

    August 14, 2017

    You will need a size large for your jacket

  • I have an Atem one Piece suit 3 years old.It has no pocket for a back protector just the press stud fixings. How is the Nucleon held in place as there are no reciprocal stud fittings shown on the photos of the protector ?

    January 26, 2017

    This product is only suitable for all Alpinestars jackets or suits that feature a back protector pocket.

View similar products

Browse all Alpinestars Body Armour, Browse all Motorcycle Body Armour
Your Recently Viewed items
What people say about us