Had a derailleur hanger tool for 2 years before I realized it had a built-in alignment gauge

I was straightening my hanger by eye like always and bumped the tool on the bench. Noticed this little indicator arm I'd never touched. Always just used the threaded part. Anybody else miss something obvious on a tool for way too long?

2 comments

2 Comments

juliawalker14h ago

wait hold on, that little arm isn't actually an alignment gauge in the way you're thinking. most hanger tools have a little tab that just shows if the hanger is straight relative to the tool's own body, but it doesn't measure alignment against the frame or dropout. you still need to double check with a proper gauge or at least look down the line from the back of the bike. i made that same mistake and ended up torquing my hanger the wrong way for weeks before someone at the shop set me straight.

the_robert10h ago

Aw man, I gotta disagree a little here. On the Park Tool gauge at least that arm does actually reference off the wheel rim, so it's measuring more than just the tool's own body. I've lined mine up against a proper alignment gauge before and it matched up close enough for most work.