Troy Lee Designs D4 helmet review

Troy Lee Designs' new D4 helmet promises the ultimate in lightweight, full-face protection

Our rating 
4.5 out of 5 star rating 4.5
GBP £500.00 RRP
Side on view of the full-face D4 helmet from Troy Lee Designs in black

Our review

The D4 continues where the D3 left off and delivers on safety, comfort, weight, venting and looks, and I'm a big fan
Pros: Super comfy for prolonged stints on the bike; venting is decent considering the coverage; low weight; looks incredible
Cons: Not cheap; my chin strap started to fray after a few months
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The latest bicycle specific full-face helmet from Troy Lee Designs is crammed full of safety features all in a bid to keep your head as safe as possible when you’re hammering down the hills.


TLD’s original Daytona helmet launched way back in 1996 and quickly became synonymous with the fastest riders in the world. Its iconic silhouette may have changed slightly, as the Daytona’s design progressed through its various iterations (D2, D3 and now D4), but it’s still strikingly obvious where this latest lid has drawn its inspiration.

Okay, the D4 may be a bit more moto-inspired and a little broader than the D3, but the distinctive TLD styling continues to attract and appeal.

Troy Lee Designs D4 helmet details

While the D4 may have taken some of its design cues from the original ’96 lid, it’s thankfully not the case when it comes to safety, where the Californian brand has done its utmost to create one of the safest helmets on the market.

The D4 features a solidly secure double D-ring closure (which is weight-saving titanium in this case) as well as breakaway peak hardware and quick-release cheek pads – which should make it easier for emergency services to remove should they need to.

Then, of course, there’s TLD’s Collar Bone Suspension System – the exposed EPS at the base of the helmet either side of the chin bar.

TLD says that during a heavy crash where the rider’s head is liable to contact their collarbone, potentially breaking it, this exposed section of EPS is designed to crumple in a bid to reduce the likelihood of this happening.

Troy Lee Designs D4 helmet
Troy Lee Designs’ D4 helmet looks good.

On top of that and at the heart of the D4’s safety credentials is its construction, which combines TeXtreme carbon, uni-directional carbon, polycarbonate, EPS and a MIPS liner to better protect against angular impacts.

For those not in the know, TeXtreme technology promises a reduction in weight but an increase in strength. Using its Spread Tow technology, TeXtreme claims it can create thin plies that pack more fibres in the same area when compared to conventional carbon.

Considering all of this, it’s impressive to see that the D4 only weighs 960g in a size medium, which is over 100g lighter than the D3 Carbon MIPS and 300g lighter than Fox’s latest Rampage Pro Carbon MIPS at 1,260g.

Of course, all of that technology comes at a price, and the D4 isn’t exactly cheap at £500. If you can’t quite stretch to this one though, TLD is also offering a composite D4 for £375.

Safety might have been the number one focus for TLD, but it’s clear to see it was keen to get a little more air flowing across the top of the head too.

Unlike its predecessor, this latest lid features a series of big brow ports and six slit vents across the top of the head to better draw in air. The rear exhaust ports forgo the mesh covering used to cover them on the D3.

Troy Lee Designs D4 helmet performance

On the hill, there’s a lot to like about the new D4.

For starters, the ultra-comfy, plush padding and well-proportioned sizing provides a snug, very accurate fit, without any uncomfortable tight spots anywhere around the head.

In back-to-back testing, the Fox Rampage Pro Carbon feels tighter (both brands state that their medium size helmets work with 57 to 58cm heads) and isn’t as comfy as the D4 when worn for prolonged periods of time.

TLD also manages to trump Fox when it comes to venting. The D4 not only feels lighter, but is noticeably cooler when you get moving, which is a real bonus when fully kitted up on warmer days.

I also like that the height of the peak can be altered and shoved up right out of the eyeline – the Fox RPC’s peak is fixed in place and can at times creep in to view.

Internal view of Troy Lee Designs D4 helmet
A look inside Troy Lee Designs’ very comfy new D4 helmet.
Andy Lloyd

While all of this is incredibly positive, my D4 test sample wasn’t without issue.

I’m a big fan of the generously padded straps and love the double D-ring closure, but getting the tension on the strap did get trickier the more I used the helmet. This was because the strap began to fray at the point where it sat in the D-ring when tightened up. The more the strap frayed, the trickier it became to adjust the tension.

I contacted Saddleback (TLD’s UK distributor) and TLD about this issue, and was assured by TLD that I was given an early media sample helmet that wasn’t perfect.

According to TLD, the D-rings on my helmet had edges that were too sharp, which is why my strap frayed. Word is, production helmet D-rings will have more of a chamfer, which should prevent this from happening.

I’ve got a second helmet on test right now to ensure fraying is no longer an issue, so will be sure to update the review as soon as I’ve had sufficient time testing it.


Aside from that little niggle, my time inside the D4 has been nothing but pleasurable. The low weight, improved venting, impressive safety credentials and lust-worthy styling help to make the D4 one of the best full-face helmets on the market.

Product Specifications


Price GBP £500.00
Weight 960g (M) – As tested
Brand Troy lee designs


Helmet type Mountain bike full-face