100 Mountain Bike Helmet - Grey



Made for protecting the cyclist's head on a road bike, MTB or even during urban outings.
This essential helmet (available in two sizes), offers excellent ventilation.
Sizes guide


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Ventilation15 vents openings.
Lightweight240 g in size M.
Ease of useAdjustable chin strap with sliders.
Waranty2 Years
SizesM (54-58 cm) L (58-62 cm)

ColourAnthracite grey and black

Weight240 g in size M
Information / Concept / Technologie
Foam : 100.0% Expanded Polystyrene (EPS) Shell : 100.0% Polycarbonate (PC) Buckles : 100.0% Polyoxymethylene (POM) Webbing : 100.0% Polypropylene (PP)

Stockage tips
Do not expose to high temperatures (60°C max.) and store in a dry place away from UV light.Clean with a soft sponge and neutral soap.

Maintenance tips
Clean with a soft sponge and neutral soap.


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Helmet purchase
Used for 2 to 8 weeks
Good value. Simple design.
Good value for money
Used for 2 to 8 weeks
Just the right size. Nice design and value for money.
Very well priced
Used for 1 week or less
I found this to be a great price and fitted my boy perfect. As a whole I found the staff very helpful, I intend to be using them again very soon.
Misleading, Ugly, Doesn't Fit
Used for 1 week or less
The videos attached to the product page show a helmet that can be adjusted, which this helmet cannot. Therefore it wobbles and does not feel like a safe fit. Because of the price it's not even worth returning because you have to pay the postage, so it's a waste of money.
Response of the brand
I'm sorry to read that the helmet does not fit you well enough.
This model is not adjustable and the purpose of the films is to demonstrate how to adjust a helmet. It is a generic film and in this instance I can see how it could be misleading and I will aim to remove it to avoid further confusion.
Peter Lazarus UK Cycling Market Manager DECATHLON
Not Practical
Used for 1 week or less
You can't adjust the fit, every helmet I've bought it comes with an adjuster so you can fit it to your head size.
Response of the brand
I can appreciate that you can't adjust the head size on this model. We sell another version for £12.99 which has a great adjuster: https://www.decathlon.co.uk/100-cycling-helmet-blue-id_8381882.html
Peter Lazarus UK Cycling Market Manager DECATHLON
Jamie found this answer helpful
Fair Price
Used for 1 week or less
I recommend this product fair price rated
good ehelmet in nice price
Used for 1 week or less
helmet is not black only - it is black-grey-black..
Good quality
Used for 2 to 8 weeks
It is a good quality helmet
Fits my big head like a glove
Used for 1 week or less
I went through a couple helmets before I finally found a helmet that actually fit my above average head, and that helmet was this one.

Initially wanted the 320 bullet helmet by the same brand but unfortunatly those weren't meant for people like me, luckily I found this and to a bargain of a price though.
Perfect fit (for me) price and quality seem good
Nothing really
Great helmet
Used for 2 to 8 weeks
Great helmet for a great price. It's the first helmet that I've purchased as I normally hate them!
I bought the helmet with a few cycling accessories/clothing from Decathlon Bolton and am very pleased to have spent so little on a lot of cycling kit.
The helmet is fully adjustable and looks great. I have worn it a number of times and can honestly forget that I'm wearing it as it's so comfortable. No reason not to buy for such a competitive price! Would highly recommend.
Comfortable, great colouring and adjustable.
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