The new Trixbrix store is now live! If you prefer, you can still use the old store: go to the old version
Large R120 radius of the curve, dedicated to large custom train sets. These curves are one size bigger than R104. These curves allows for very high speeds without derailments.
Detailed explanation of R120 radius
The R120 is the radius measured from the center of the circle to the centerline
between the rails using the LEGO® stud as the unit. LEGO® stud is 8mm. The space needed to have the full R120 circle can be calculated as follows: (120 + 4) * 2 * 8mm = 1984mm = 1.98m. This measures the diameter (2 * radius) of the outer shape of the track - that's why we added 4 studs in the formula.
In general, the formula for calculating the outer diameter of the track circle is:
(R + 4) * 2 * 8mm
See also:
R120 Curved Track Set, 16 Sections, Half Circle
R120 Curved Track Set, 32 Sections, Full Circle
Ballast Plate R120
Curved Track R104