Measurement 1
Rim ERD
The effective rim diameter, measured at the bottom of the nipple seats. It is given in the rim's technical datasheet (e.g. 600 mm for a 28" rim).
Spoke length calculator
Standard hub or Bafang motor, rim, lacing pattern: get the exact length of your left and right spokes, then order them cut to the millimetre.
The 4 measurements you need
Can't find your model in the list? Measure these four values with a calliper or look them up in the manufacturer's datasheet.
Measurement 2
Flange pitch circle diameter (PCD)
From the centre of one spoke hole to the centre of the opposite hole, on each flange. On a hub motor, it is much larger than on a standard hub.
Measurement 3
Centre → flange
The distance from the middle of the axle (between the locknuts) to the middle of each flange, on the left and right.
Measurement 4
Lacing pattern
3-cross for a standard 32- or 36-hole hub; 1-cross, or even radial at the front, for a hub motor.
Your spokes, your wheel, your kit
Everything is done in our workshop in Prilly, near Lausanne: custom-length spokes, hub motor wheel building or complete wheels.
Single or in bulk
DT Swiss spokes cut to length
DT Swiss spokes cut to the millimetre according to your calculation, black or silver, 2 mm or 2.34 mm, with or without nipples.
E-bike
Lacing your hub motor
Send us or bring in your hub motor: reinforced spokes, tensioning and truing by the workshop.
Most popular
Complete built wheel
Hub, rim and DT Swiss spokes: we calculate, lace, tension and true the wheel. CHF 130 for building.
Conversion
Bafang electric conversion kits
Mid-drive motor or hub motor already laced into a rim: turn your bike into an e-bike.
Spoke Length Calculator
How do you calculate bicycle spoke length?
Spoke length depends on four measurements: the rim's ERD, the flange diameter (PCD) of the hub, the distance from the hub centre to each flange, and the number of spoke crosses. On a rear wheel or a disc-brake hub, the flanges are not symmetrical, so the left and right spokes are not the same length.
Spokes for Bafang hub motors and e-bikes
A hub motor has much larger flanges than a standard hub. It is usually laced 1-cross, or even radially at the front, with heavy-duty spokes to withstand the torque. Our workshop in Prilly, near Lausanne, cuts DT Swiss spokes to the calculated length and can build the complete wheel for you.
Frequently asked questions about spoke length
How do you calculate spoke length for a bicycle wheel?
You need the rim's ERD, the hole circle diameter of each hub flange, the distance from the hub centre to each flange, the number of spokes and the number of crosses. The calculator on this page works out the length for both the left and right sides.
What is a rim's ERD?
ERD (Effective Rim Diameter) is the diameter of the rim measured at the seat of the spoke nipples. It is given in the rim manufacturer's technical data sheet. It is the most important value in the calculation.
Why are the left and right spokes not the same length?
On a rear wheel (cassette) or a hub with disc brakes, the flanges are not the same distance from the centre. The spokes on the side closer to the centre are slightly shorter.
How many crosses for a Bafang hub motor wheel?
Hub motors have large flanges, so they are usually laced 1-cross, and sometimes radially at the front. Too many crosses make the spoke run over the motor casing.
Should the calculated length be rounded?
Yes, round to the nearest millimetre. Our DT Swiss spokes are cut to the millimetre, so there is no need to choose a shorter or longer standard length.
Can you calculate and build the wheel for me?
Yes. For a complete wheel or for lacing your hub motor, our Prilly workshop calculates the exact length, laces, tensions and trues the wheel. The build costs CHF 130 per wheel.