Shimano FH-RM40 135mm Rear hub

Add this hub to your bench

Hub Data
Manufacturer Shimano
Model FH-RM40
Position Rear
Axle Type 10mm
OLN 135 mm
Spoke Interface Type J-Bend
Brake Compatibility rim brake
Drive Interface Shimano 7 (30.9mm)
Internal Gearing none
Dynamo Type none
Spoke Hole Diameter 2.6 mm
Left Flange Diameter 45.3 mm
Right Flange Diameter 45.3 mm
Left Flange Offset 33 mm
Right Flange Offset 22.5 mm
Mid-Flange Offset -5.3 mm (to the left)
Weight 0 g
Hub ID 541
Record Status Public
Created Sep 9, 2019 12:11pm
Contributed By Karl Stoerzinger
hub dimension diagram
PLEASE NOTE: Shimano publishes hub dimensions in a relatively confusing manner on They seem to provide the outside-to-outside flange spacing, and an overall offset of the flanges as a whole. Wheelbuilders are interested in the distance from the midpoint between locknut faces to the middle of the flange (not the inside or outside face). When necessary, I convert Shimano's data into useful spoke calculation dimensions with some simple arithmetic, and factor in 3mm thick hub flanges (an approximation). The formula is to divide spacing by two, add or subtract the overall offset, then subtract half of our assumed 3mm flange thickness. Please check the notes to see if the values for this part are derived from Shimano's published data or actual measurements of a hub specimen. -Karl
9/9/19 -- A very inexpensive cassette hub with virtually no bearing seals. Not made to be pretty or durable. Not to be confused with the FH-RM40-8, which seems to be the same hub shell with an 8spd freehub body and thinner left axle spacer to still achieve 135mm spacing, but at the expense of more dish in the wheel. -Karl