Smith Optics Mainline Mips Full Face MTB Cycling Helmet
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Give credit where credit's due. Thank your mom, your legs, and your gear for giving you the opportunity to land that rocky gap. Made for going big, going fast, or both, the Smith Mainline is our pinnacle, downhill certified enduro bike helmet. Safety innovations like Koroyd™ and MIPS® provide energy-absorbing impact protection so you have the confidence to get aggressive on the trail. It doesn't matter if you're slaying the EWS in Whistler or suffering through the last stage of your local enduro race, you need a breathable, lightweight helmet that pairs well with goggles and fits like a glove. The Mainline integrates with your bike goggles for efficient venting and fog-free vision. Multiple pad sets including liners and neck-rolls let you customize the fit.
- 21 fixed vents for consistent airflow
- Adjustable visor
- Hybrid X-STATIC® / XT2® anti-bacterial performance lining for odor resistance
- Weight: (Size M, MIPS®): 27 oz / 77 g
- Sizes: S - 51-55cm, M - 55-59cm, L - 59-62cm
- Aerocore™ construction featuring complete Koroyd® coverage for lightweight, energy-absorbing and ventilated impact protection
- MIPS® Brain Protection System reduces rotational forces caused by angled impacts to the head
- CPSC CE EN 178 and ASTM F1952 downhill certified
Fit / Integration
- Designed for ultimate integration with Smith performance goggles for maximum comfort, venting and storage convenience
- AirEvac™ ventilation system integrates with Smith goggles for fog-free lenses
- Three washable cheek pad kits, two crown liners and two neck rolls let you fine tune the fit
- D-ring chin strap fastener for a snug fit
Occasionally, without notice, manufacturers change product design and/or specifications.
Smith Helmet Sizing
Smith Helmet Size Guide
Use the below chart and guide to find the correct size Smith helmet for you.
Head circumference (cm)
51 - 55
55 - 59
59 - 63
63 - 67
How to measure
To find the circumference of your head, place a tape measure in the centre of your forehead, wrap it around above your ears and around the back of your head. If there's a slight difference between two different sizes, always go for the tighter size.
Once you know the circumference of your head, see the available sizes shown on the product and select the appropriate one.
The majority of cycling helmets have some form of adjustment for size, usually in the form of a ratchet adjuster to tighten or loosen the straps, some helmets will also come with different thickness pads to further customise the fit.
Read our clothing size guide for more information on sizing.
Please note, all size information is provided as a guide - if you're unsure or need any further assistance you can call us on 01792 799508 ... we're happy to help!
Full Face Helmet Guide
How do I apply for finance?
Spend £99 or more at Tredz and you can spread the cost. Pay monthly over 6-48 months, interest free (dependent on repayment terms and amount).
1Fill your basket with everything you want from Tredz and go to the checkout.
2During checkout, select the finance option you want as your method of payment.
3You will be sent to our finance provider's secure server to complete your application.
4Finance providers PayPal & V12 will use the information provided to make a decision and complete checkout if you are approved.Read more about buying on finance
Flexible finance options
Choose your deposit.
Choose your term.
Lowest monthly cost
for 6 months
Delivery & Guarantee
UK Delivery Information
International Deliveries – Temporarily Suspended 11/11/20
Note: We are still offering deliveries to the Isle of Man, Scottish Highlands, Scottish Islands, Channel Islands, Isle of Wight, Jersey and Guernsey.
Courier Delivery update: Due to the COVID19 situation, we are currently experiencing some delays with deliveries. Our couriers are working around the clock to get your order to you as soon as possible but there is a potential delay of up to 48 hours . Please check your tracking on track your order here.
Please note on the TNT tracking app it may show your delivery status as ‘Collecting’ (as per image below). This means your delivery has left our warehouse and is currently held at TNT main depot and there could be up to a 48 hour delay.
Please keep checking the TNT tracking for further updates. On behalf of TNT we apologise for any delay and inconvenience this may cause.
We are committed to offering fast and free delivery, whether you're ordering bikes, accessories or clothing. Our standard delivery service is FREE in the UK, regardless of the size and on all orders over £20.
Please note that bulky products and bikes shipped to outlying UK regions are excluded from free shipping.
Please note that Pre-Order dates can sometimes change due to updated stock information.
Click here for more UK and international delivery information.
Returns & Warranty
It's easy to return a product with our 365 day, hassle free returns.
We will give you a full refund on any item that is returned to us unused/unfitted, in a resaleable condition and in its original packaging (where possible).
Please note: For hygiene reasons, we cannot accept returns of facemasks, undershorts or underwear if the item has been removed/unsealed from its original packaging.
If your item develops a fault or arrives damaged, please contact us first so we can resolve the issue for you as quickly as possible.
For more information please visit our Returns & Warranty page.
Finance provider options available