I have a steel bike with 1 inch steerer tube made out of steel. I have about 55mm of spacers below the stem and above the top of headset. Is is safe to run my bike with that many spacers below the stem? I use it for mixed terrain riding, mostly road with occasional gravel mixed in.
Common threadless steel steerers have essentially no practical limit for this in either 1" or 1-1/8". There of course is a theoretical limit, but it's going to be a very large number, way over 12"/300mm. There have been a few companies over the years to make thinwall fancy alloy steel steerers (Alpha Q/Reynolds was a fairly popular one) that do have limits, which was published info.