For what you want to run, 18" radius.
I am running 15 inch radius on my HO layout with one siding on 14 inch which is very tight, the only problem with these radius is I am limited to 8 wheel drive locos, and the longer freight cars under bodies have to be modified so the trucks can turn sharper. Been running on this setup for 2 years now and havent had any derailments
Doug
Check out this page:
http://www.ldsig.org/ldsigwiki/hints-tips/curve_radius_rule-of-thumb
If you have spurs with a tighter radius than the main line, just use a 'handle' of cars which can take that radius and keep the loco off that track. You might have to keep a couple of 'designated spacer' cars handy for that use.
Embargoing locos from certain tracks is normal prototype practice. On my own layout, ALL Kokutetsu locos are barred from operation on Tomikawa Tani Tetsudo track. They would derail at the first curve, and it's in a very inconvenient location.
Chuck (Modeling Central Japan in September, 1964)
I have been running my Bachmann freight trains on 18" for about a year and never a problem. Sometimes I wonder why. All my other trains mess up from time to time but the freight train - never - fingers crossed.
Chris.
Loco Guy - is a state of mind - not an affinity to locomotives.
Sit back and enjoy your track...
Main Line (oval) radius 18". Spurs about 14".
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
A curve with a radius of 14" is definitively too narrow for either loco! Bachmann states 18" or larger for "best performance", which should be read as 18" being the minimun radius for reliable operation.
New to designing track plans, i am starting to plan and build a small On30 logging layout using 2 4'x4' islands connected by a 24" wide by 6' long straight run between, camp on one end mountain and logging operation at the other end. Looking at the Michigan-California Lumber co plan in the June 2015 MR i am confused by the stated minimum radius of 18". I believe that would be a circular track diameter of 36". Looking at the plan and by the 1 ft grid it looks like the inner circle is about 28". Am i correct that this would be a 14" minimum radius? Will Bachmann 2 truch Shays and there Climax run on this?