I have a wire running up my front brake line to my handlebars. I used 4 zip ties to secure the wire to the steel covered brake line. The ties dont bind but they are snug enough to hold the wire in place: could this possibly cause any problems with my front brake as far as causing (mild) pressure on the line? Thanks

 

I'm guessing that's for a front fender light?

No, it won't hurt a thing. The rubber brake line would (should) reguire a great deat of pressure to collapse. Only thing that'll hurt then is obviously very sharp objects or constant abrasion on a rough object. Over time, it may leave a "print" on the hose where the ties are, but you have no worries.