Gege-Bubu

I would like to check my derailleur hanger alignment, but have no special tool like DAG

Is there a way how to check and fix the alignment ?
Or can I make DIY DAG?

shelbyfv

You can thread the axle of a spare wheel into the hanger (remove the derailleur.) Google it.

Andrew R Stewart 

Place a straight edge in between the rear wheel's cogs. Have the straight edge hang down past the der cage. Compare the cage to the straight edge. To straighten one can use a long handled allen wrench placed in the der's mounting bolt and maybe add a pry tool (screwdriver) behind the hanger and between the hanger and the small cog of the rear wheel. As most needs to align a hanger are to pry it out this method is a quick and easy one which will use the der cage as the gage (and it's the cage that counts as far as the chain's smooth running goes.) Andy.

Andrew R Stewart 

I sure wouldn't want to use a 3/8x26tpi axle to do this straightening method with. Any one who asks the OP's question is also likely unable to know about threading compatibilities and the importance to maintain said compatibility when stressing a soft alloy threaded part (the hanger). But otherwise a good suggestion. Andy.

GeorgeOwnwell

To expand, hangers are threaded 10x1, the same as most rear axles. You can use a spare wheel and remove the QR skewer and thread the exposed threads on one side of the axle into the hanger. Snug it up with a wrench and then align the "straightening" wheel with the wheel in the bike making it as even as possible. Imgur: The most awesome images on the Internet

eddy m

You don't want to use a wheel to bend the derailer hanger, but it works well enough to measure the alignment. It also works better if you can adjust the spare wheel's axle enough to engage all the threads of the hanger.

em

JohnDThompson 

Indexed shifting is fussier about hanger alignment than friction shifting, and the more cogs in the cluster the fussier it gets. By all means try this method first, but if shifting is sub-par afterward, take it to a shop with the proper tool.

fietsbob

it is all about having an arm at precisely 90 degrees to its axis, the hanger bolt, and a reference pointer also square to that arm ,



that allows you to accurately measure that the hanger is at precisely a right angle to the plane of the wheel-cassette assembly


if making the arm out of Bamboo works for you , fine , but the holes thru it have to be done accurately ..

Aubergine 

FWIW I have managed to straighten a few bent hangers by eyeballing their alignment. One was on my Old Peugeot # 2, and the other was on a new Schwinn (a department store bike.) Both bikes shift properly now.

eddy m

I'm not surprised by that. The spec for alignment is something like 1/8 inch out at the rim. I can't eyeball that but I can try and error into it.

em

Andrew R Stewart 

Never heard of this 1/2" run out spec before. I aim for 10% of that. Andy.

Dan Burkhart 

True. as you would well know( but others might not), a 3/8 x 26 axle will very easily thread into a M10 x 1 hanger, but the fit is very sloppy and likely to do damage when the force is applied.

dedhed

I've used an adjustable wrench and also have a 10 X 1 bolt about 2" long i can use and eyeball them. I've only done this on 7 speed and less friction shifting so it has been "good enough"

Andrew R Stewart 

If using a bare axle (10x1) or bolt as the inserted lever a nut that can be tightened against the hanger will further support it and reduce any in the threaded hole oblonging. Andy.

3alarmer 

[h=1]LifeLine Derailleur Hanger Alignment Tool[/h]
$35.22





...in a rational world, this is about what the Park tool would sell for. I honestly cannot get good alignment on a hanger without the tool, maybe I'm just not good at eyeballing it. I work on a lot of olde stuff, and they go out in a variety of directions, sometimes twisted, sometimes just a simple off from the vertical plane of your wheel. But like I said, without the tool, I just have trouble checking all the various planes of dysfunction.

ultraman6970

35 is cheap for that tool but if the OP wants to check that once each 10 years well... I do use the 2 axles and a caliper technique, works great!

ps: never occur to me to use a whole wheel too, it makes your life easier at the time of torquing the hanger in place.

CliffordK

Except for Campagnolo which uses (or used to use) 10mm X 26 tpi.

I made my own tool... HEAVY DUTY. Well, it became obvious, even a steel derailleur hanger is pretty soft, so it doesnt' take much to bend it. I did find a stock 10x1 bolt would only thread partway into the hanger, but enough that it would work for both leverage and measurements.

Unfortunately I've misplaced the tool at the moment, but it seems to be fine to just get pretty close.

eddy m

I mis-typed that. I use 1/8 difference top to bottom, front to back. That's about 1 degree. It's almost impossible to see a 1 degree difference, but it's easy to measure a 1/8 gap. A gap of 10% of 1/2 inch is less than 1/2 degree, more than perfect enough.

em

Kopsis

I'm all for DIY, but if one doesn't have the right tools and won't use them often enough to justify the investment, why not just let the LBS handle this? It's a quick (i.e. inexpensive) procedure and most shops could really used the business this time of year.

Gege-Bubu

Thanks everyone for input!
I tried to use threaded rods, wheels, carpenters squares, levels, etc
All came down to me "eyeballing." And it never came perfectly straight. For example, I use the wheel to check alignment, fix the bent a little, then check it with rods - out of alignment. Fixed again, eyeballing, looks ok. Checked alignment with wheel - out of alignment!
Someone may say that having it perfectly straight it is not a big deal, but I am having trouble shifting some gears (not all) of my 11 speed group.

I could go to my LBS to fix it, but if I will need to do it again, or need to build a new bike, - the tool will be handy.

So, the right answer to my question was given by 3alarmer:
"Don't try to DIY, because it will not work, buy the tool"
Thanks for the link! Now I need to figure out whet else to buy for $14.77 to have a free shipping.
maybe I will buy some socks.

3alarmer 

...they always get me that way too.

cny-bikeman

I straightened untold number of hangers in my bike career. I also did a good bit of frame/fork alignment, and have a very good eye. Nevertheless, when it comes to straightening a hanger on cassettes with 8 or more (esp.10+) cogs, eyeballing and DIY solutions are not always sufficient. I was unable to solve an inconsistent shift problem on my own bike that I knew was alignment related until I was able to put a DAG on the hanger.

noglider 

I've straightened hangers by eye. Sometimes that was good enough. I now own the tool. If doing it by eye doesn't work, buy the tool or bring the frame to a shop.

davidad

I have used a spare wheel to straighten bent steel hanger with out problems before I bought the tool.

Gege-Bubu

Well, I got Merlin tool yesterday and tried it this morning before I started my trainerroad session.

The hanger was obviously bent, not 1", but good 1/4" off between top and bottom position of the arm.
It took me about 15 min to set my bike stand, get all the tools, and fix the hanger, and put all stuff back into garage.
I was trying to fix it without the tool for a good hour, and never got it right.
Now my shifting is smooth as butter.

I think, this job is the one of the things that must have the tool. No rod or wheel would give me precise alignment. Maybe some one can do it, but i cannot
I like it, because it let me straighten it in no time.


Thanks !