At one time, I had a Bachmann Spectrum 2-10-2 and a BLI 2-10-2 on my old layout which, at one time, had 22" and 24" radius curves. The Bachmann could handle the 22" radius curves, but the BLI could not.
Rich
I remember when I was laying it out, I kept running my BLI 2-10-4 through it until it stayed on the track. I only use the track to turn things and the speed only has to be brought down to a crawl as it goes through the 4 to 5 o’clock position. I may modify that before the ballast and ground cover go on but it does its job the way it is. My Hudsons go around easy peasy. My Rapido passenger cars go around when pulled but not pushed.
The Bachmann USRA 2-10-2 has 57" drivers and a rigid wheel base of 21’.
A Santa Fe 3800 class has 63" drivers and a rigid wheel base of 22’.
A C&O T-1 2-10-4 has 69" drivers and a rigid wheel base of 24.3’.
That may not sound like much difference, but it is when doing the geometry of going around a curve.
Even my Reading T1 4-8-4 with 70" drivers only has a rigid wheelbase of 19.25’ compared to a UP FEF with 80" drivers and a 22’ wheelbase.
Even with my 36" radius minimum curves, the Bachmann 2-10-2 at 21’ is my longest rigid wheelbase. I will not go above that for both operation and appearance.
Sheldon
My Bachmann spectrum 2-10-2 is one of my finest smooth running engines on my fleet.
I don’t need to worry about it negotiating tighter radius curves as I don’t have any but I did notice the center wheel doesn’t have a flange on it for this reason.
Probably not noticeable in N-Scale unless you pointed it out to someone. I don’t know if you’d get away with this cosmetically in HO though.
TF
The real locomotives had blind center drivers, as did many/most other 5 coupled steam locomotives.
Sheldon