Brake and Derailleurs cables and liners

Mar 30, 2020
I'm totally new here and to all of this.
Inspired by online photos (and with a bunch of time, thanks to Covid 19), my kids and I have made 4 tall bikes from all their old bikes. The first three break by pedaling backwards. The fourth is made from adult bikes and has no breaks...other than turning uphill.... and similarly I don't know how to hook up the derailleurs. I haven't been able to make any of the scrap bits and pieces work for hand brakes or the drrailleurs.

Break cables, brake liners, derailleur cable, derailer can one size fit all?
What tools and components should I shop for? I'm seeing many more art bikes in my future, and we are not running any races or trying to make it cross country and wondering if there is good economical way to buy in bulk.
Is there a good video to watch on brakes and/or derailleurs for high bikes (not just replacing existing equipment)?

Any hot tips, tricks or tool recommendations would be much appreciated.

Thanks y'all.
Oct 19, 2012
Wakefield, UK
If the distance between handlebars and brakes / derailleurs is the issue look to buy tandem inner cables. The outer can be bought by the meter off ebay.