Installing the Front Hub Motor

Surly ECR Fork

Surly ECR Fork

The Xiongda front hub motor measures 110mm over the lock nuts so a Surly ECR fork needs to be cold set out an additional 10mm. This is done by using a 12" threaded steel rod 3/8" in diameter.  Fit the rod with four washers and four nuts to sandwitch the fork dropouts and then slowly spread the forks by turning the nuts on either side of the dropouts until it measures about 115mm. Taking pressure off the fork will cause it to rebound a short way so you might need to take it slow and experiment while spreading & taking measurements. The final measurement should be right at 110mm.

To keep the motor from twisting in the fork when in operation, a torque arm is needed. This is a snug fitting steel washer with an adjustable arm to secure it to the fork fender eyelet. The Torque arm takes the additional stress and saves your delicate dropouts from becoming rounded and stripped. Other items worth mentioning are 2m steel washers for the spokes.

The Xiongda motor has 3mm spoke holes but standard 14 gauge bicycle spokes are 2mm. You either need to get custom spokes cut in 12 gauge or use a small washer on each spoke.

The motor is laced with a 3 cross spoke pattern using 36 278mm 14 gauge Wheelsmith spokes and brass nipples.

The wheel is finished off by attaching a 6 bolt 203mm disc rotor and adapter*, rim strip, tube & tire. It is then fitted into the fork and the brake caliper adjusted. This step will sometimes need the use of extra washers as shims to position the caliper properly. Changing the angle of the fork will also change the angle the rotor meets the caliper so this area may need a bit more DIY attention.

* The larger disc rotor is used to raise the caliper higher on the hub for better clearance and also stronger braking.

Installed E-Bike Torque Arm

Continue to Part 4 Completed AWD E-bike (2-motors)