Derailleur Hanger Alignment Tool

[Pedropete]

FWIW and AFAIK, they all develop play at the bushing eventually. I've used Park (older version), Shimano and my current Unior and they've all done the same thing. I've also used someone else's Abbey HAG and it had the same issue. Most important things to remember (and assuming the tool's beam doesn't deflect like some cheapo Amazon/ebay specials):

• Always reference at the valve regardless of orientation of the tool: rotate the wheel forward to avoid dragging the derailleur backwards
• Keep the tool in tension, ie. allow for any play by taking up the slack before advancing the indicator to the rim
• Take readings at 12-6 then 9-3 before making any adjustments
• Creep up on your correction with small adjustments: this'll avoid overshooting and having to come back again, overworking the material
• Accept that no matter how careful and/or experienced you are, some hangers will fail. Some crack, some snap clean off and others turn to plasticine, so try and have a spare on hand for any hanger you plan to realign

Other bits to consider regarding hangers:

• More speeds = less tolerance of misalignment. 5-8-speed will tolerate quite a lot; 9 slightly less but still pretty easygoing, 10-11 gets trickier and 12-13-speed will have you questioning your life choices
• Hangers can weaken and bend simply through use, especially with consistently bad shifts or poor geometry
• Don't assume a new bike's hanger will be straight as they often aren't
• Have a spare hanger for any bike you own. Label it and and keep it in your tool bag. For the sake of £10-£15, you'll be back on the road much faster

 

[Fastpedaller]

"FWIW and AFAIK, they all develop play at the bushing eventually." That's one reason why I used a spare track hub to make my tool (as described some posts above. The other reason being low cost.