Is there a rule of thumb with regards to how many spacers you use between the headset and stem, or is is a ride it and see what you think kind of calculation?
Ta
No rule at all - spacer count is irrelevant as it's dependent on fork length/head tube length/ headset height and then depends on what position you want on the bike.
I would normally measure saddle height and then how far below the saddle the bars are (or at least their relative position) and start off based on that.
purely a personal setup thing.
you could run none, and cut your fork down, but that makes the fork harder to sell on or reuse.
you could have loads, and ride like a tourer.
my trance has a 7 1/2" head tube, so i run none at all, with the stem upside down to normalise it 🙂
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if it a bike youve bought or already own then move them around to suit til the bar height feels right. If youre fitting new forks its well worth keeping the steerer a bit longer and using spacers for resale (or even if you end up putting the forks on a different frame).
for comparison my Nomad has a 130mm headtube, the On One 456 I owned had an 80mm headtube. I ended up with all the spacers on the On One's forks above the stem which looked a bit naff, but not as naff as having to buy a new fork when I sold the On One a few weeks ago...
initial build before lowering stem, but keeping steerer tube a reasonable length
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