Originally Posted by
Wilfred Laurier
stem and bars should be proportional
so for very wide bars you should have a very long stem
bitd 150mm and 160mm were common so look for something like that
whatever you do dont go less than 120mm
for obvious reasons

The stem length and bar length are completely unrelated. Stem length is related to the reach of the rider and the length of the top tube but not the width of the handlebar. Would you suggest a 40mm or 50mm stem for a 440mm road handlebar? I regularly run flat handlebars that are wider than 680mm and I wouldn't run a stem much longer than 130 because that's what fits my reach. As I said above, 780mm mountain bike handlebars are very common today and you won't find too many 150mm modern stems...like none. It's hard to find any over 130mm.