I think that link you are drawing may be cobblers.
It's often quoted cobblers though.
Its not what I say – its what the TRL state
@tjagain - Can you remember the name of the paper (or at least some key words)? I'm looking for the research on TRL and it's not jumping out at me. There's a lot of research on there!
Its well hidden unfortunatly. TRL pages are hard to find. I'll have a look
I think it was in this one. It was not a central part of the research. also the paper is a bit odd as it found increased accelerations on the head from rotation but dismissed them as of no consequence.
https://trl.co.uk/publications/ppr213
helmet fit were identified as important contributory factors to the level of induced rotational motion and injury potential. The design of helmets to include a broad range of sizes was also concluded to be detrimental to helmet safety,
There has been other work on helmet fit as well by others
the overwhelming conclusion is that a helmet performs better the better it fits for a variety of reasons and the use of shells with cradles is one reason why real life observations do not come close to theoretical protections from helmets
This is the reason why when I do wear a helmet I wear one with a smooth outer shell ( no aero projections at the back) and one that is sized such that I cannot get a finger between head and shell at any point
Thanks for looking that up @tjagain. The paper you've found isn't one that supports your point. As far as I can tell, there is no mention of wearing another layer under the helmet and the conclusions about sizing refer to a child's helmet that has an effective size range that is bigger than its stated size range.
I don't want to start an argument about it, so I'll maybe try to find something again later.
it doesn't mention wearing another layer but it does make the point that a helmet that relies on a cradle to fit ( one size fits all) is less effective. I have seen plenty of other research on helmet sizing and the effects on effectivness
My point is that if you wear another layer under the helmet then the helmet is too large thus leading to it being less effective. I agree its not conclusive and you could certainly see it that wearing the other layer makes no difference when you are wearing it but the corollory of that is that your helmet is too big without the cap. so maybe if you wear a cap all the time then it does not make a significant differnce
My helmet - I cannot wear anything underneath. It does not fit
All you can do is look at the data and make your mind up on that basis
Edit: so to be fair I should have said "may" rather than "does"
Once again - all the research I have seen on helmet wearing and I have looked at a lot of it is poor quality and often contradictory.
it doesn’t mention wearing another layer but it does make the point that a helmet that relies on a cradle to fit ( one size fits all) is less effective
In that paper, the experiments show that using a helmet rated to 56cm on a 57cm head form reduces the helmet's effectiveness, and I think that's what they are referring to in their 'broad range of sizes' statement. It seems one of the helmets tested was able to extend beyond its specified size range so the researchers mention this as a possible factor to consider for future safety standards. I don't think it says what you say it does.
There may well be some data out there that shows that the change in head circumference from a cap (less than 5mm just measured on my head) affects helmet fit enough to impact the effectiveness of a helmet. Until I see it I think I'll use a hat under a helmet for its known benefits: warmer head and better vision. I can't say whether either of those things make me safer (although one could argue they might), but they do make riding a bike at this time of year more enjoyable so I'm more likely to do it.
You never see an F1 driver wearing a cap under a helmet...
Roadies – if having a peaked hat under a helmet is such a great idea, why not just put a peak on the helmet in the first place?
Cap works better, no doubt about it. I'd rather ride with a cap and a peak-less lid when on my MTB. XC will never die ✊
Strangely I’m not sure I’ve ever seen that supposed link before. My feeling on the cobblers nature to it was that mainland continental cyclists traditionally used black shorts despite there being no ban on outfit styles or road racing there and I’ve not seen Rapha or the like eulogising testing up and down the Q10/1 as a way of selling jerseys
Thinking about it my first POC road helmet was supplied with a POC branded cap so they're obviously happy with the combination.
all the research I have seen on helmet wearing is poor quality and often contradictory
Why are you basing your entire contribution to this thread on such research then?
(FWIW I gave up wearing a helmet a few years ago, but it seems an odd line of argument nonetheless.)
Anyway... Bought a basic Prendas cap. It's good and bucket like for coverage, decent medium thickness, would prefer a larger peak but that's by the by.
