Why do we use riser bars anyway? Why not just put more spacers beneath them and raise height that way?
I assume there is some good reason for it, but I’ve never known what it was.
20 years ago you could only get 2 types of bars, flat bars that were 580mm wide for xc or riser bars that were 680mm for everything else. As most bike frames had similar head tube lengths this worked quite well, if you wanted to do more gnarr you probably also wanted a higher front end so it didnt matter.
Then 29ers happened and people wanted flat bars for trail riding as suddenly your front end was 75mm taller. And XC riders realised 580mm bars were shit.
And short stems mean a few degrees of rise no longer adds a substantial ammount of height so we’ve gone back to risers.
You cant put too many spacers under the stem otherwise you’re putting stress on the steerer tube it wasnt designed for. Theres probably other ways to measure it but generally there shouldn’t be more spacers than stem. And minimising it is probably better.
They also made your bike look like a motorbike, which is probably why they persisted in the first place rather than headtubes getting taller.