Very short travel minimalist suspension fork for rails-to-trails riding I would like to convert a MTB frame to an XC bike for riding on former railroad tracks that have been converted to trails that present a mix of surfaces: fine gravel, dirt road with crushed stone, grass, poorly maintained broken and eroded concrete pavement, and long stretches of well-maintained macadam.
To that end, is there a 27.5&quot; tapered-steerer suspension fork (disc mounts) with very short travel,  perhaps only 25mm-50mm?
A rigid chromoly fork would probably do but I cannot find one that fits the frame without using a tapered-to-straight headtube adapter.
P.S. I'd prefer to avoid carbon, if possible.
It sounds like you don't really need a suspension fork. The surfaces and conditions you describe are what gravel bikes are designed for - those don't have suspension forks, they just rely on larger tire volume and lower pressure (compared to road bikes).
Short travel suspension forks do exist, but if your frame is designed for a longer travel fork the required axle-crown length will very likely be longer than that available on a short travel fork. (Obviously the for longer travel the frame head tube needs to be higher to give the wheel somewhere to go when the fork compresses.)
Short travel forks will also be lower end and therefore lack adjustment and will be heavy.
I'd go with a rigid fork if you can find one the correct length. Of course another option is selling the MTB and buying a (used possibly) gravel bike.