Roadster roll bars

[HandyAndy]

Originally Posted by Talonmotorsport

Considering the rollbar is mounted to a 16 gauge chassis 3mm ERW seams to be over kill, 2mm CDS is ££££ so 2.5mm wall ERW in either 42mm or 48mm dia?

i don,t wish to sound negative to your thoughts/idea of supplying a roll bar but,

i,m not sure i agree with the above, having been a semi pro bike racer (sorry i know i,m boring) i was always happy to spend extra on a helmet that i felt would offer me the best protection for my head in a crash, & yes i crashed a few times in my career but have never had a serious head injury, & i was always thankful that i didn,t buy the cheapest helmet on the market.

my point being....... i don,t think you can have "overkill" when the roll bar is the last safety device to protect your head in a roll over crash.

My own roll bar was supplied via one of Ash g,s group buy & my back stays are of the same material/thickness, & feel happy with the safety it offers.

said in a polite way i assure you.
cheers
andy

Full cage is the best option for paranoid folk and I fall into that bracket as up front the only thing hard enough to keep your head off the ground is the engine if you only have a rear roll bar.

[Talonmotorsport]

Fair comments Andy and yes you get what you pay for. I come from making NASA Autograss rollcages. Mid mounted engined full space frame saloons and theres no point in making a very strong rollbar if it connects to a tissue paper base. It'll just snap at the weakest part which will be the 16 gauge tubing. I can make FIA spec roll bars and even full rollcages in 38x2 CDS but it's £52 per 5mtr lengh and the idea of the Roadster is 'budget' is it not?

[HandyAndy]

i do understand your points tho i must say i,m in no way qualified in structural strength of chassis designs of any vehicle, as Fabby has suggested, a full roll cage is the "better/safer option" if the car builder wants total piece of mind etc, i was just using my own personal experience of "head safety" to be able to offer ( i hope ) a credible personal point of view.
As you say the Roadster is "to build a sports car on a budget" but doesn,t give a budget figure & so the safety aspect is one area i believe is worthy of spending more rather than less if the individual builder wishes/can afford to.

on a lighter note i prefer the middle diagram of roll bar design

again said in a polite & hopefully constructive discussion manner.

cheers
andy

[squbti]

i was thinking of the third option for my roadster & have cad drawings for 50mm pipe & was going to use stainless but but now also have the second one thanks to ashg
if onyone wants a copy of the cad drawings just let me know.
cheers
samy

[NEroadster]

I may be able to do some FEA Analysis for you if you want only quick and dirty but will give the general principles

[Alphax]

38x2 CDS but it's £52 per 5mtr lengh and the idea of the Roadster is 'budget' is it not?

There is a difference between safety and budget.

Safety is never expensive.

[snapper]

There was a required spec in SVA for roll bay size and thickness so i assume it still applies for IVA