Derailleur hanger alignment tool taught me a hard lesson on day one

I picked up a used Park Tool DAG-3 at a shop closing sale for $40 last month. Got home and thought I'd test it on my old mountain bike that's been shifting rough for years. Turns out the hanger was bent 4 degrees out of true according to the gauge. I'd been replacing cables, adjusting limit screws, and even swapped the derailleur itself trying to fix it. All that money and time wasted because I never checked the hanger. Do most of you keep one of these on your bench or just eyeball it?

3 comments

3 Comments

eva_lewis1mo ago

Eyeballing it is just asking for more headaches" - yep, did that with a level once on a shelf. Looked straight, hung crook.

betty_shah1mo ago

Eyeballing it is just asking for more headaches down the road, honestly.

dixon.daniel1mo ago

Yeah totally agree with @betty_shah on that one. A buddy of mine once tried to eyeball a fence line and ended up with a corner that was three feet off the property boundary. Had to rip out the whole post and redo the hole, took twice as long.