Shimano RX100 ST-A550: 2x8 STI Levers – Repair and Refurbishment

Shimano RX100 ST-A550 STI 2x8

The Shimano RX100 ST-A550 are road STI levers integrating braking and shifting for a 2x8 drivetrain. They are among the first generations of Shimano integrated controls widely used on 1990s road bikes and remain sought after for restorations and vintage bikes still in regular use.

Common Problems with ST-A550

With age, the original grease can harden and retain dust. The internal pawls can then become sluggish or get stuck. Typical symptoms include a lever that no longer clicks, irregular shifting, slow return, or a mechanism that works in one direction but not the other.

Therefore, a lack of clicking does not necessarily mean the lever is broken. On many ST-A550s, a thorough cleaning and appropriate lubrication can restore normal operation.

Repair and Reconditioning

Reconditioning involves disassembling the necessary components of the mechanism, removing old grease and deposits, checking the pawls, springs, and pivots, lubricating correctly, and then reassembling the lever. Each mechanism is then tested to verify the shifting of all gears.

Shimano RX100 ST-A550 Features

Group: Shimano RX100
Reference: ST-A550
Type: integrated brake/shift STI levers
Drivetrain: 2 chainrings / 8 rear speeds
Compatibility: Shimano 8-speed road drivetrain
Usage: road bike
Period: 1990s

Buy Reconditioned Shimano RX100 ST-A550

Available pairs change regularly depending on the levers I acquire, repair, and recondition.

View currently available Shimano RX100 ST-A550

Have ST-A550 Levers Repaired

If your Shimano RX100 ST-A550 levers are no longer shifting correctly, you can contact me with the exact reference and a brief description of the problem. Defects related to hardened grease, seized pawls, or a dirty mechanism are often repairable as long as no essential part is broken.

Frequently Asked Questions

Are Shimano RX100 ST-A550 8-speed?

Yes. The ST-A550 is designed for a Shimano 2x8 road drivetrain.

Is an ST-A550 that no longer clicks necessarily broken?

No. Old, hardened grease or a seized pawl can prevent the mechanism from working correctly. Disassembly, cleaning, and lubrication can often solve the problem.