Schwinn Airdyne, AD3 and AD4, Loose Wedge Pins? Inspect the Bottom Bracket and Crank Assembly

Some Schwinn Airdyne exercise bikes use a wedge pin for the crank arms. It is necessary to inspect these parts for wear.

Bike models with the wedge pins include the AD3 and AD4 Airdyne models.

Over time and with use, the wedge pin will become loose and needs to be tightened.

When the wedge pin becomes loose it creates space between the parts it holds together.

If the parts are loose in the assembly, they begin to wear each other down.

If this happens, any of the parts in the assembly can need replacing along with the wedge pin. This means all parts are suspect in this state.

Why do the crank arms of the Schwinn Airdyne with wedge pins become loose? The loose parts in the assembly have worn each other down. This keeps them from tightening.

This causes the wedge pin to no longer do its job. The holes the wedge pin fills become enlarged. The wedge pin no longer wedges the pieces together. This can even lead to broken wedge pins.

Why have to take it apart more than once for this repair? It is best to replace the entire assembly.

When the wedge pins no longer tighten or break, when your crank arms are loose no matter what, the entire crank assembly with the bottom bracket should be replaced. The crank and bottom bracket assembly is the Sportsmith item P14100.