madteg
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| posted on 13/11/10 at 10:14 PM |
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Helmet lifting of head
Why does my crash helmet try to lift of my head at about 140mph. and also how can i stop it.( on the track of corse)
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Mark G
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| posted on 13/11/10 at 10:18 PM |
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Do the strap up!
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austin man
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| posted on 13/11/10 at 10:20 PM |
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get one that fits you sounds like its too big for you
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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handyandy
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| posted on 13/11/10 at 10:20 PM |
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I,d say if its actually lifting that much then its too big.
cheers
andy
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JacksAvon
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| posted on 13/11/10 at 10:22 PM |
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I would guess it is an offence under the road traffic act to play with your helmet at such speed.
Or,are you just telling us you have travelled at such speed and have no idea of aerodynamics
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madteg
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| posted on 13/11/10 at 10:24 PM |
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Its a good fit and the strap is done up tight.
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handyandy
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| posted on 13/11/10 at 10:29 PM |
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quote:
Originally posted by madteg
Its a good fit and the strap is done up tight.
Possibly caused by the wind hitting your screen & coming up from around the side of your cockpit, maybe some side screens would help...maybe???
I,ve ridden bikes at 180mph (on track) & just a tiny adjustment of head position behind the screen would either make the air flow over the helmet
smooth or like someone was trying to pull my head off 
Maybe the side screen idea would help.
cheers
andy
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mangogrooveworkshop
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| posted on 13/11/10 at 10:30 PM |
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Buy a windscreen
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scootz
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| posted on 13/11/10 at 10:35 PM |
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Is it a motorbike helmet, or a car helmet... I read somewhere that it can make a difference.
Particularly (apparently) if it's a 'sports' bike helmet as it's designed for airflow passing over your noggin whilst
it's buried low-down by the tank!
On the face of it, it makes some sense, but could equally be a pile of poo...
It's Evolution Baby!
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eddie99
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| posted on 13/11/10 at 10:43 PM |
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Get a Car racing helmet that has aerodynamics on it, bike helmets always tend to lift up as car purpose helmets don't. As bike helmets are
designed for you to be facing more downwards.
http://www.elitemotorsporteng.co.uk/
Twitter: @Elitemotoreng
Facebook: http://www.facebook.com/pages/Elite-Motorsport-Engineering/153409081394323
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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paulf
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| posted on 13/11/10 at 10:43 PM |
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That would cut the top speed by acting as an air brake and thus solve the problem.
Paul
quote:
Originally posted by mangogrooveworkshop
Buy a windscreen
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chris mason
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| posted on 13/11/10 at 10:43 PM |
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assuming it's a bike helmet, Buy a car helmet 
Huge difference to how they work with wind at speed in a kitcar, speaking from experience.
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madteg
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| posted on 13/11/10 at 10:47 PM |
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looks like i have to get a new helmet then. Thanks guys.
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matt_gsxr
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| posted on 13/11/10 at 10:49 PM |
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I get this too, although in my case the helmet goes "light" before 140mph.
I've always put it down to the fast air over the top of the helmet being at lower pressure (standard sort of wing effect).
Single seater helmets often have a sort of "bill" that I guess is designed to counteract this effect. They can also have spoilers and
stuff.
I guess the bit at the bottom serves some aerodynamic purpose.
Solution is to drive slower, or maybe put a DIY spoiler on the top of your helmet (although be careful with glues on these things).
Personally I quite like the effect.
Matt
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locoR1
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| posted on 13/11/10 at 10:51 PM |
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Will be the bike helmet in a car! At 140mph im assuming you are talking about the back straight at Bedford?
I have a car helmet V2 pro with the lip round the bottom for down-force to keep your head on lol but also half doors and mine was fine!
wasn't as fast as you though i hit the rev limiter at 137mph
 
Description
Check out my CB500T Cafe Racer build diary
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Mark Allanson
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| posted on 13/11/10 at 10:55 PM |
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I wore a bike helmet once in my car - to SVA and back. At anything above 70mph, it was like someone trying to pull me out of the car by my head - I
just wear goggles now, which is fine up to max speed
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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Peteff
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| posted on 13/11/10 at 11:10 PM |
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If your helmet pulls it's too big, nothing to do with it being a sports bike helmet or any other bike helmet. Full face helmets for sit up bikes
and crotch rockets are exactly the same and if they are too big they will lift whatever you drive, car, sports bike or cruiser even if you strangle
yourself with the strap.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Mark Allanson
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| posted on 13/11/10 at 11:17 PM |
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quote:
Originally posted by Peteff
If your helmet pulls it's too big, nothing to do with it being a sports bike helmet or any other bike helmet. Full face helmets for sit up bikes
and crotch rockets are exactly the same and if they are too big they will lift whatever you drive, car, sports bike or cruiser even if you strangle
yourself with the strap.
Noooo, my helmet is as tight as a *****'s **** from ******!! It is just the aerodynamics of a big round thing sticking up in an uninterrupted
fast air flow!
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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craig1410
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| posted on 13/11/10 at 11:21 PM |
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Yeah I got this as well although not since I fitted an aeroscreen. The aeroscreen is just high enough to stop air hitting my neck and then presumably
pushing up inside the helmet. Now the airflow hits at about eye-level and the buffeting is much reduced and the helmet no longer lifts. Do you have an
aeroscreen of any kind?
You know you should have made the title of this thread, "Helmet suction at high speed". You would have had loads more people reading it...
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RK
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| posted on 13/11/10 at 11:22 PM |
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http://www.soloracer.com/zeroninez9akr.html
http://www.soloracer.com/zamprz31.html
I've got the second one. Most comfortable thing you'll ever put on your head. And LIGHT.
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wilkingj
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| posted on 14/11/10 at 12:54 AM |
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I agree with Mark on tight helmets.
I have Big Head, and found it difficult to get a helmet that was large enough just to get on, let alone be loose!
Its all in the aero dynamics.
Try a fly screen first! It makes a lot of difference, and a bit of plastic temporarity fitted to the car (LOADS of Gaffa Tape?) for a test will cost
you nowt. Decent helment doesnt come cheap. It will at least help you to decide if its a helmet aerodynamics job or not.
Final parting shot... Try a couple of Bungee cords from your Helmet to the underside of the seat. That will stop your helmet rising at high speeds
Its a Lo-Cost solution as well.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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snapper
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| posted on 14/11/10 at 08:02 AM |
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If you look in the Demon Tweeks car parts catalog you will find aerodynamic parts forcrash helmets
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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BigLee
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| posted on 14/11/10 at 10:06 AM |
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Make a splitter out of plywood and glue it to the top of your helmet. That should help the airflow! Something A3 sized would be fine!!!
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andrew
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| posted on 14/11/10 at 10:42 AM |
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i have the same problem even have to tape visor shut , tried various helmets , have aroscreen , the wind just seems to hit in wrong place , the faster
you go the more you have to tilt your head down ,if i get i cured i will let you all know
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ReMan
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| posted on 14/11/10 at 10:53 AM |
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This tHE sole reason I fitted the fly screen to my car
It started lifting at around 70
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