Rohloff developed the HG/IG Check tool to be able to quickly determine the condition of Shimano HG or IG cassette sprockets. The tool will indicate when the cogs are on the verge of being too worn out, therefore preventing chain skipping. Cassette cogs should be checked before long trips or before replacing a chain to determine if the new chain will skip on the old cogs.
The HG/IG Check can be ordered under the following part number:
3100 HG/IG check
How to Use the HG/IG Check
The enclosed handle (6) should be fixed at the drilled hole at the end of the grip (3) in the direction of the side with the logo (Fig. I).
Place the Rohloff HG/IG Check on each sprocket of the HG-IG Shimano cassette block that you want to check.
Sprockets with tooth numbers between 12 and 21 should be measured as follows: place the last link of the measurement chain (2) on the sprocket with the test roller (5) inclining slightly outwards and press it against the measurement chain (Fig I). With the other hand forcefully press the handle (approx. 10 kg (22 lb)) in the drive direction and swing the test roller (5) into the tooth pocket while the measurement chain (1) is under load .
If the test roller (5) moves freely in the tooth pocket (Fig II), your HG-IG sprocket is still working well. This indicates that even a new chain will run well on this used sprocket
If the test roller (5) hooks on the tip of the tooth or if you need to use some force to move it into the tooth pocket, the sprocket should be replaced
If the measurement chain (1) slides from the sprocket profile while the handle (6) is under pressure (Fig. III), the amount of wear is excessive. Sprockets with more than 21 teeth are rarely worn out, so they should not cause any problems while in use. Therefore, a check up is normally not necessary. Nevertheless, you can check whether the measurement chain (1) slips off the tooth profile while putting pressure on the grip (6) (Fig III). If it stays in the profile, the sprocket is still okay. If it slips, problems can be expected under heavy load.
The HG/IG check is a great addition to any tool kit and we would recommend this tool if you are serious about your bike maintenance