Schwinn Calante and 4 cross spoke pattern.

Our pastors ride together for exercise, and they ride to a yearly conference somewhere in Indiana. One of them has an old Schwinn that I have worked on several times. The rear wheel has broken spokes several times. The spokes that break are the forward facing spokes on the side opposite of the gears. The non-drive spokes have less tension than the drive side, and the forward facing spokes get relaxed when torque is applied while riding. This constant tension-relaxing bends the spoke at the head and it eventually breaks. Why does this wheel break spokes more than other wheels? I think this must be due to the unusual cross 4 pattern. This causes the spokes to be at a more severe angle to the hub and therefore get relaxed more. I'm not 100% sure of this, because another pastor had a similar problem, and I changed the non-drive side to 2 cross pattern, and he still broke spokes. I ended up replacing wheels for both of them. Hopefully they won't have problems on this years long ride.

Cross 4 spoke pattern (each spoke crosses 4 other spokes) with broken forward facing spoke on the non drive side.