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PostPosted: November 13, 2017, 4:22 pm 
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Joined: November 13, 2017, 4:06 pm
Posts: 4
Hi all,I am new to the forum and live in South Africa.
I am currently building a locost 7 and have the idea of building a roll cage BUT since the car will be used on the street as well as track days I was told not to build a roll cage because it makes driving on the dangerous because if I were to be in an accident my head would hit the roll cage.

Since the locost 7 is so small been hit by another car surely a rollcage will protect me so much better then just a bar behind my head??


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PostPosted: November 13, 2017, 8:25 pm 
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Joined: December 7, 2012, 8:28 am
Posts: 1391
Location: Sarasota
You can make the roll cage so that your head can't hit it. Just build it taller than your head and just behind the headrest. Most cars have the upper bar really close to your head as it has to be 2: close to your head due to the roof. On a lotus 7 type car you don't have a roof determining where the cage goes.

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PostPosted: November 14, 2017, 8:54 am 
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Joined: November 13, 2017, 4:06 pm
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wrightcomputing wrote:
You can make the roll cage so that your head can't hit it. Just build it taller than your head and just behind the headrest. Most cars have the upper bar really close to your head as it has to be 2: close to your head due to the roof. On a lotus 7 type car you don't have a roof determining where the cage goes.


Okay thank you for the advice. I followed your build with great interest. Some really good ideas.


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PostPosted: November 16, 2017, 6:43 pm 
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Joined: March 30, 2011, 7:18 am
Posts: 1162
Location: central Arkansas
It comes down to "you pays your money and you takes your chances."

Generally your tradeoff is a risk of injury by a cage tube vs. rules compliance, accidental rollover, or a collision with a large animal.

You can wear a helmet, swathe any nearby tubes in padding, or kick the tubes far enough away you're not likely to hit them in a collision... but before you get too worried about it, take a look at the distance to the B pillar on a normal sedan, and how some of them high-mount seat belt mechanisms, or the sharp corners on the sunroof, hidden under the headliner or plastic trim. Maybe the tubes aren't as big a problem as they seem at first.


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PostPosted: November 16, 2017, 11:41 pm 
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Joined: June 8, 2010, 8:02 pm
Posts: 477
Location: White Rock, BC, Canada
It really comes down to your own personal concerns on safety. As with everything else in building a car, there are compromises. You can make the best impact structure in the world, but still die when something small punctures the floor. If main criteria is protecting from other vehicles while not braining yourself on the roll-over protection, I'd go for a 4pt rollbar with "door" bars and 3pt or DOT 4pt belts (not race harnesses).

Couple of points:
-necks/backs stretch a LOT in crashes. Things are closer than they seem.
-proper rollbar padding will not help the helmetless head (it's very dense)
-most people build rollbars/cages too short so they don't look goofy. Myself included to be honest (if I'm going to die, I'm going to die pretty damn it!)
-you can't use head/neck restraints without a helmet. No point saving your head if your neck snaps. You do NOT want neck whiplash. I can promise you that from daily experience for the last 20+ yrs. If you strap yourself in tight with race-harness and get into a frontal collision you will damage your neck. DOT belts stretch to help. https://www.youtube.com/watch?v=g40YatgE_CE

Cheers.

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PostPosted: November 17, 2017, 5:24 pm 
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Joined: July 4, 2006, 5:40 pm
Posts: 1858
Location: Novato, CA
A roll cage really only works with a helmet. If driving on the street with a helmet doesn't bother you, go for the cage.


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