My youngun is into track days and I notice that all seem to insist on full leathers or 2 piece fully zipped, all understandable,but wont allow any type of textile although many now claim to have better protection than traditional leather gear. Do they know something we don't ? Are textiles over rated or just too many types. That said a cheap set of leathers might not be up to much either God I remember doing track days not that many years back (or so it seems) in pretty basic kit !
point you might be going faster in place on a track but equally they're built as safe as possible for racing ie one way, nee stone walls, telegraph poles and dozy car drivers etc etc
I used to do a lot of track days & minimum requirement every track I went to was fully zipped together leathers (ones with the short zip across back were not deemed as suitable), plus of course motorcycle boots, leather gloves & a full face helmet with gold ACU sticker. I think the argument for leathers over textiles would be the slide factor, as in leathers slide to a stop whereas textiles are more likely to grip and send you end over end, this is just my opinion & no doubt there will be differing ones.
I think the reason for this is , most accidents on a track result in a slide and is generally harmless, textiles have too many pockets/flaps which can snag or cause drag and so make you to flip, then limbs will start impacting on tarmac, direction will change etc thus causing damage. Flip front, again there's a join which is a weak point causing a break resulting in a snag which could potentially twist the neck. then again I could be wrong
Drag racing with the ACU, you could only use a 2 piece suit if the zips were stitched directly to the leather, which counts out most 2 piece suits. I think they've changed it again since I was racing and it's one piece suits only now. Apparently Arai don't make flip top helmets because they're not as strong.... Although they do open face helmets though.