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So, OH has been having slight shifting issues and as there is a pretty big scar on the side of the rear mech I thought it might be worth investing in an alignment tool and checking it out.
I bought an x tools one after someone here recommended them on a recent thread and set about checking and bending. Sure enough the hanger seems bent which results in about 5mm of difference at the rim.
Question is, do you try to get it perfect or is a couple of mil close enough? The tool is well made but does have a bit of play around the pivot which results in about 5mm of play at the rim end so I'm not sure of the accuracy. I'm trying to hold it against the play while measuring.
A couple of mm at the rim is a tiny amount at the hanger. I'd say that's good enough. My park tool has a little play but you can bounce it between the limits if you want it super precise but it's not essential. The difference between bent and pretty straight is night and day, the difference between pretty straight and perfect is far less noticeable
@nickjb Cheers! Out of interest, how much difference at the rim would you expect to cause problems?
I think I read somewhere (poss the park tools blue book) that so long as you are within about 5mm it shouldn’t affect shifting performance. I’ve got a pretty decent tool 😳 but even that has a certain amount of play so getting it perfect would be hard work.
As an aside it’s one of the best investments I’ve made - I try to use it every few months, and often it is surprising what a difference it makes even if there have been no obvious knocks..
^^ Absolutely agree, I've got the cheap tool the op has but it's been used a fair amount and I wouldn't be without it now.
It's been worth its weight in good particularly on 12 speed stuff.
the Parktool video (advert heavy at start) suggests a 3mm max gap is ok and translates this to being 0.5mm out at the hanger also includes a useful warning to have a spare hanger available which reminds me I'm pretty sure I have one but couldn't find it 🙁
Yes spare hanger is also a top tip actually. Good point about the 12 speed stuff actually which is perhaps more sensitive to this kind of thing.
Thanks folks! All good advice. Must buy spare hanger.