Two issues here, I think - impact resistance and friction resistance. Armour will help protect against the knocks, but however it is added you will still need some material (thick leather, Kevlar/aramid, thick cordura etc) over it that's going to stand up to the friction of sliding down the road at speed. Under a jacket that doesn't have fitted armour, you could wear one of these
http://www.knox-armour.co.uk/product...uct=crossshirt
However, the material to which the armour is stiched isn't claimed to offer friction resistance, so I think anyone would still be well advised to wear it under a jacket that will stand up to the potential rough and tumble.
As I understand it, Kevlar is used principally to protect the skin from friction damage and is an expensive material, paticularly the knitted variety. I've not heard of anyone sewing it onto regular clothing on a DIY basis although no doubt a skilled machinist could do the job. Given the likely cost and effort involved probably better to go with purpose made products. I see from your link, for instance, that Draggin Jeans make Kevlar liners to be worn under regular trousers. You would still want to think about adding knee and hip, and perhaps coccyx, armour for impact resistance.
Linear Mode
