Spoke Calculator

Details on the fields:

Hub Motor:

The Crystalyte 400 series hub motors come on two flavours. The original design (400F in our drop down) used a steel flange that was symmetric about the hub. When Crystalyte modified their rear hub motor design to use an offset flange pattern to reduce dishing, they also increased the flange size somewhat, as reflected in the 400R option. Older rear wheels without the offset flange should use the 400F.

The dimensions of the Nine Continent motor are fairly consistent across a range of different manufacturers that use a 205mm diameter rotor standard, including the newer Crystalyte HS motor series.

Cross Pattern:

The vast majority of hub motors are laced with single cross, which is more than sufficient. Sometimes larger 700c wheels are done in a double cross pattern. For 20" wheels, it is common practice to do a radial lacing pattern as the sharp angles that result at the nipple with single cross can make the wheel challenging to build.

Rim ERD:

If you are using a 3rd party rim, then you will need to look up or measure the effective rim diameter in order to get the right sized spokes for that rim. There is no "standard" ERD for each size. We have included the measured ERD for the stock rims that are included with the eZee, Crystalyte, and Nine Continent kits. The Crystalyte rim is 'flat', not an aero-style rim, and so would most closely match the majority of single walled or similarly shaped 3rd party rims.


For all around simplicity, the spoke length calculation is done assuming that the rim is centered on the hub. For rear wheels that require dishing (ex, Nine Continent and eZee, but not Crystalyte) then you can simply increase the left side spokes by 1mm, and decrease the right hand spokes by 1mm, and the result will be as good as necessary.

Spoke Count:

Virtually all hub motors use 36 holes so the is is the default in all cases. The exception is the Crystalyte 16" motors, which have a 28 hole flange. Most rims at bicycles stores are for 32 spokes, so be sure if you are using a 3rd party rim to verify that it has 36 holes.

Wheel building:

There are many good print and online references for lacing bicycle wheels. Many will defer to Sheldon Brown, Brandt's Bicycle Wheel Book, and others. However, a lot of the points and details with a conventional bicycle hubs don't necessarily apply to hub motors with their much larger flange diameter. For more information on wheel building please see our wheel building page. Copyright by Justin Lemire-Elmore