E-MTB Microspline Cassette Lockring — Extended-Thread Redesign

Context

A client's e-MTB kept losing the lockring that retains its Microspline cassette, often within a few kilometers of riding. The original part and every aftermarket replacement tried failed in exactly the same way, so buying another lockring was not a fix.

Problem

The root cause was geometric. The lockring engages the freehub with only one turn of thread. On an e-bike, motor assistance adds significant torque through the cassette, and all of that load sat on a single thread flank. It sheared, the lockring backed out, and the cassette was left loose on the hub. The aftermarket parts were already CNC-machined 7075 aluminum, so a stronger material was not the answer: the design itself had to change.

Process / Iterations

From field failure to installed part in eight steps.

1. 01

   Failure in the field

   

   The lockring has backed out of the hub after a short ride. Its single engaged thread is sheared off, leaving the cassette loose.

2. 02

   Not a one-off

   

   Three aftermarket lockrings, three identical failures, all CNC-machined 7075. Changing brand doesn't fix a design that engages one thread.

3. 03

   Redesign in 3D

   

   Remodeled from scratch in Fusion 360. Every interface to hub, cassette and tool is kept; the threaded body is extended to add thread length.

4. 04

   Manufactured

   

   Machined in 7075 aluminum by a partner workshop and gold anodized for corrosion protection and to match the bike's details.

5. 05

   Measured side by side

   

   12.03 mm original vs. 13.95 mm redesign: +1.92 mm of length, which takes thread engagement from one turn to three.

6. 06

   Old vs. new

   

   The three failed lockrings next to the redesign. The difference in thread length is visible at a glance.

7. 07

   Standard tool fit

   

   The internal spline profile follows the Shimano standard, so it installs with a standard lockring tool and needs no special tooling.

8. 08

   Installed

   

   Fitted to the stock hub and cassette, and in service since March 2025 without a single failure.

Solution

3 turns · +1.92 mm · Al 7075

A drop-in lockring with three full turns of thread engagement, spreading drivetrain load over three thread flanks instead of one. Same hub, same cassette, same tool: only the geometry changed. The gold anodized finish matches the bike's other gold details, so the fix reads as a deliberate upgrade rather than a repair.