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Neck tubes & chin strap

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MarkJ
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PostPosted: 09:39 - 04 Nov 2011    Post subject: Neck tubes & chin strap Reply with quote

The whole Simoncelli helmet thing got me thinking about where I put my neck tube in the colder months. I pull the neck tube up to my bottom lip and then fasten the chinstrap over it tightly, but this might give a little more 'give' on the strap if I crash.

Anyone else do it this way or another? Am I worrying unnecessarily?
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DrDonnyBrago
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PostPosted: 09:52 - 04 Nov 2011    Post subject: Re: Neck tubes & chin strap Reply with quote

MarkJ wrote:
The whole Simoncelli helmet thing got me thinking about where I put my neck tube in the colder months. I pull the neck tube up to my bottom lip and then fasten the chinstrap over it tightly, but this might give a little more 'give' on the strap if I crash.

Anyone else do it this way or another? Am I worrying unnecessarily?



0.5mm of fabric isn't going to make a difference if your helmet fits you properly. How many bikers have beards? I don't recall anybody suggesting beards make helmets fall off. As it happens I do my neck buff up to my throat and use a beard to keep my face warm, I'd have no issue doing it your way if I fastened the strap properly afterwards.

Try removing your helmet without undoing the strap, push up from the back and see if it comes off, loosen it a bit and try again. On my lid/head combination even with the strap undone this wont pull it off, my chin just presses into the front. It needs an upwards motion to come off which is prevented by the chin strap, a tiny bit of slack here doesn't interfere with this. I normally go for enough slack that I can push a finger between my chin and the strap (i.e. resistance but not uncomfortable), makes it comfy but secure.
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DrDonnyBrago
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PostPosted: 10:15 - 04 Nov 2011    Post subject: Reply with quote

I was a little intrigued by how much slack could be induced by the extra diameter of your face with the buff on...


So I've just done a wee calculation to estimate it.

I assumed that the buff in a mildly wrinkled state is about 0.5mm thick (mine is).

My chin where the strap goes makes a semi circle with a circumference of about 16cm = a 32cm full circle.

circumference 1 = 32 = pi x diameter

32/pi = diameter 1

diameter 1 = 10.19 cm.


Diameter 2 = 10.19cm + (2 x 0.5mm) (estimated thickness of a well fitting buff)


Diameter 2 = 10.29cm.

circumference 2 = pi x 10.29 = 32.33cm.

The extra slack in the strap from the buff is the difference in circumference 2-1 divided by two (the buff only covers half of your chin) circumference (c2-c1)/2 = 0.165cm.


So, if your buff was completely compressible (it is not) then you would have a chin strap 0.165cm looser (1.65mm) than if you were not wearing one. As it is not compressible and offers about the same resistance as a bit of your own face this is negligible and irrelevant.


In other words, the extra size of your face added by the buff is negligible, forget about it.
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MarkJ
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PostPosted: 10:39 - 04 Nov 2011    Post subject: Reply with quote

Having re-read my original post it does seem a little Daily Mail ohmygodI'mgoingtodiewon'tsomebodythinkofthechildren. It wasn't something I was really losing sleep over tbh, just wondered if it could make a difference.

My snood is quite thick though, I would imagine more than half a mm. Do you have one of those thin fabric ones?
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DrDonnyBrago
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PostPosted: 10:52 - 04 Nov 2011    Post subject: Reply with quote

MarkJ wrote:
Having re-read my original post it does seem a little Daily Mail ohmygodI'mgoingtodiewon'tsomebodythinkofthechildren. It wasn't something I was really losing sleep over tbh, just wondered if it could make a difference.

My snood is quite thick though, I would imagine more than half a mm. Do you have one of those thin fabric ones?



Mine is a thin one but my chin strap actually goes over a beard, my beard is probably bushier than a snood Wink . The mm estimate was the estimated thickness once compressed by the strap, i.e. the thickness of material after it had been squeezed down. It also assumes worst case scenario of you fastening it with the scarf in place and then the scarf is lost without you adjusting the strap - i.e. it would be a tiny bit too loose. If a helmet can come off your head because the strap is a tiny (i.e. a few mm) bit loose then it probably doesn't fit you very well. The maths I did was basically just a way of illustrating it was minimal, don't read too much into it.

The easiest way to check would be to pull the strap tight with the snood in place, pull the snood out from under the strap without undoing the strap and see if you need to tighten the strap to make it secure again - probably not, at least not by much.


Thinking of it another way, people with double chins and bushy beards don't lose their lids in crashes, so why should a slightly compressible snood make a difference?


Follow these instructions with the helmet done tight and then done tight with your scarf:

https://www.hjchelmets.com/proper_fit.htm
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Rogerborg
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PostPosted: 11:01 - 04 Nov 2011    Post subject: Reply with quote

Weird, I was thinking the exact same thing this morning.

My (slight) points of concern are that I don't tighten the double-D strap correctly due to the padding, and that the fabric might be prone to stretching in an off and letting the strap loose.

Conclusion: maybe, maybe not, but I'm not going to change the way that I wear it, so quit worrying about it.
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Last edited by Rogerborg on 13:38 - 04 Nov 2011; edited 1 time in total
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Okeydokey
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PostPosted: 13:11 - 04 Nov 2011    Post subject: Reply with quote

I spent a very long year working on bike helmet design, as part of the research I found a large number of incidents where the helmet had left the head. The people who did the original research suggested due to the large number of throat/wind pipe lacerations, and the number of helmets that left the head during an accident it was down to the gel coat on the helmet and how efficiently it slid across tarmac.
When it doesn't slide well you have rotational forces that effectively peel the helmet off damaging your neck bit! I did some consultancy work for Everoak, who had the best sliding helmet (Co-efficient of Mju) and their hats were used by the Met at the time.
I have recently bought a second hand helmet.... I know how bad that is but will post more details in another thread soon.
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DrDonnyBrago
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PostPosted: 14:47 - 04 Nov 2011    Post subject: Reply with quote

Okeydokey wrote:
I spent a very long year working on bike helmet design, as part of the research I found a large number of incidents where the helmet had left the head. The people who did the original research suggested due to the large number of throat/wind pipe lacerations, and the number of helmets that left the head during an accident it was down to the gel coat on the helmet and how efficiently it slid across tarmac.
When it doesn't slide well you have rotational forces that effectively peel the helmet off damaging your neck bit! I did some consultancy work for Everoak, who had the best sliding helmet (Co-efficient of Mju) and their hats were used by the Met at the time.
I have recently bought a second hand helmet.... I know how bad that is but will post more details in another thread soon.



There was a helmet doing the rounds that claimed to reduce twisting with an anti rotation membrane. Basically it as a plastic skin on top of the lid with a lubricant underneath such that the skin can move over the helmet.


https://www.webbikeworld.com/r2/motorcycle-helmet/lazer-superskin/

https://www.moonraker-motorcycles.co.uk/product_view.cfm?ID=186


Was an interesting idea, did you look into this sort of thing at all?
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