Question about HO track outside diameter.

This has probably been asked before but I have a small spot where I may be able to put a small loop of HO to run some On-30.  I would like to use Bachmann track with the built in road bed.   Anyone know what the outside diameter is for the tightest curve possible?    Thanks. 




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Original Post

What’s the radius of said tightest curve? I thin the base is like 1 1/2 inches or 1 5/8 inches wide so add 7/8 to the radius and multiply by 2. The radius will be from the center of the track that’s where the 7/8 comes from.

MTH Authorized Service Tech

President Chief Operations Officer, The Lenny Lines


I love my trains!!!


A standard small curve in HO is 18" radius; adding in extra for the base of the EZ-Track, you need roughly 38" for the circle.

You can go two alternate routes if you are willing to give up the EZ-Track roadbed.

1st, you can find some 15" radius sectional track: t he diameter will be close to a circle of O31.

2nd, you can get flextrack and make the circle the diameter you need.

An important consideration, just as in O, is minimum radius for the equipment.  MOST B-mann locos will handle 18" radius.  MANY will do the 15".  SOME will do 12".  A FEW will do as small as 10" or maybe a wee bit smaller.  Their freight rolling stock will easily do the 15"; some will do the 12".  You can custom build cars to do the 10".  The passenger equipment will go a little smaller than 18". 

There is a detailed chart out there on the web listing minimum radius for each B-mann piece:

The charts lists B-mann's numbers and actual test data from users.

Frisco, MoPac, and T&P near Rolla, MO

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