No one ever talks about...

[Kevan]

derailleur hanger alignment gauges.

What's this tool about?

How's it used?

The LBS bossman in tweakin' the ol' bike used this thing for almost a second then moved on with his other check-sees.

What gives?

[Ginger]

Kevan, some people crash, bounce their derailleur off of stuff, drop their bike on the drive side, don't use spacers in shipping, things like that. All that abuse can cause rear derailleur hangers to bend a little. A little bit of a bend in a rear hangar can cause shifting problems. Any time you've got a frame that you're looking at for the first time, it doesn't hurt to throw your derailleur alignment gauge on and do a little check. It's kinda fun too.

The park tool site has a pretty good description of the tool

http://www.parktool.com/tools/DAG_1.shtml

and how to use it
http://www.parktool.com/repair_help/DAG.shtml



The checker doesn't work so well with removable derailleur hangers which is why you probably don't see it used often.

And I have seen a titanium frame with a bent deraillure hanger, but only one. Much more likely to find that issue on a steel frame.

[Matt Barkley]

Dag!

[Kevan]

okay maybe I came across a little too naive with my initial post, certainly the name of the tool answers the basic question; I was looking more for detail. Thank you Ginger for the website offering, it helped.

Okay, I know what this thing’s for, really.., but how many of you basement grease monkeys have this thing, use this thing with any regularity, or have other alternative approaches that answer the same questions as this tool does. Costing 50 bucks I would think this gauge hangs low on everyone’s wish list.

The Calfee which was being checked has a substantial Ti dropout cut from a fairly thick (1cm?) sheet of Ti. I would think a steel or aluminium hanger would be much more subject to bending than this thing, and that by just witnessing how the shifting is working.. you would have confidence that all was square.

Anyways, I was just curious.

[OldDog]

I have a Park hanger tool and even have a clue as to how to use it, as it was standard practice to check the hanger alignment on new production bikes (we delt in Schwinn, Fuji, Gitane and the occastional Kabuki back in the 70's, early 80's) during the assembly stage, during my shoprat years. Not a toll the home mechanic would pull out very often, unless your in the habit of droping your bike alot. Or, like me, you still ride an old steel mtn bike and bend your hanger often. I got mine from a gentlemen closing up shop, I purchased his shop tool set for a sneeze.

A great Father's Day present for that cycling dad who has everything.....A Park tie would be nice too.

[Frank]

The derailleur hanger has been the item on the frames I buy most likely to get "unadjusted" during transit. It is especially vulnerable on a complete bike that is shipped because the rear derailleur sticks out and makes it easier to bump. It can get moved if the frame is dropped or box pushed from the side (even when there has been a dropout protector). I use the tool when I build up a frame so when I start to get the drivetrain put together I am working from a good starting point on the rear derailleur.

First complete bike I bought the derailleur got pushed over some during shipping. Luckily I caught it when I was first going for a ride as I heard the spokes barely hitting the derailleur when in the 27 cog on the rear. Adjusted the derailleur hanger and went on to log thousands of miles on the bike.

[Ti Designs]

Try wrenching for a team of beginner riders some time - the derailleur tab alignment tool gets used a lot during contact week! At the shop we see a fair amount of use for that tool, people come in with the rear wheel missing most of it's right side spokes, the upper pivot of a derailleur and...

I have the mother of all derailleur tab alignment tools. I had a customer who managed to bend a 12mm thick 6/4 dropout. The guy from Paragon asked me to take pictures 'cause he's never heard of such a thing. Anyway, a wheel axel to hold the dropouts with an offset port-a-power 6 ton ram did the repair. The alignemtn tool itself is kinda simple, a home made version is simple and somewhat easy to make. The tab is threaded M10x1, which happens to be the same thread as most rear axles ('cept Campy, Joytech and Zeus). Some bar stock, a hub axle, a couple of track nuts and some quality time with a drill press and you too can have your very own alignment tool...

[Ginger]

Yeah...ya did Kevan.

Steel mountain bike here. Steel cross bike too. And I've used it on the CSi as well. for some reason I tend to fall drive train side down...not cool.

You're right, mostly you can eye up a rear hanger and see if it's rideable, but if you've got an odd shifting issue, I always check the hanger before continuing. Without the tool, you can check if the bike's hanger is bent, but getting it bent back correctly in both planes is a PITA.
I've freehanded a check on the trail before using a stick...but I'd rather ride a single gear than to mess with a bent der hanger on the trail again.

I have one buddy who carrys a DAG in the back of his truck to group rides because sooner or later on open-invite group rides, someone dumps a bike on its drivetrain.

[Kevan]

Now them's some answers. Thank you, and I promise to have my OJ before posting anything beyond Sandy's understanding.

[NateM]

Notice on the Park site that it says,"However, there are some hangers that do not repair well. Extremely thick hangers and titanium hangers are difficult and sometimes impossible to repair." Which I suppose means dont try to bend them. Both Serotta and Calfee seem to fit this advice. The hanger on my Ser Ti is slightly bent but the mechanics at the nearby shops wont fool with it.I have a DAG but I leave the ti bikes alone.Maybe next time I'm in Boston I will visit with our friend Ti Design for a little tweak to the right.

[Peter]

I own one. Great for mountain bikes which are invariably getting dumped on the trail.

Here's the concept: the derailleur pulleys have to be in the same plane as the gears for good shifting. The tool assumes the rim and the cogs are in the same plane, and uses the rim as a reference.

Here's how to use the tool: Put the chain on the small cog and remove the derailleur from the hanger-no need to remove the derailleur cable or the chain.

Screw in the tool. Rotate the wheel until the valve is at 6 o'clock. Place the indicator against the side of the rim adjacent to the valve. Slide the indicator up towards the hub, out of the way, and rotate the valve to 12 o'clock. Rotate the tool to follow, and slide the indicator up towards the rim face again. The gap/negative gap you now see is TWICE the distance the hanger needs to be bent. Use the tool t tweak the hanger. Go back and forth between 6 and 12 until the gap is within 4mm. Then, rotate the valve and tool to the 9 o'clock position (viewed from the gear side) and measure/adjust there as well. You do NOT need to check the 3 o'clock position because the 6, 9, and 12 positions constitute the three points needed to describe a plane, and the idea is to get the derailleur aligned in a parallel plane with the cogs. Besides; it's a real hassle to get the indicator tool past the seatstays or chainstays.

This tool has more than paid for itself for mountain bike repairs (steel frames). I wonder how things would fare on a bike with Ti dropouts bonded to carbon tubes- could you break the bond or crack the tubes while trying to tweak the Ti dropouts?

[hypnospin]

rd indruction manuals did (still do?) spec using these before set up & adjust. good for the steel frames with steel dropouts. handmade frames can be less accurate than the robot made new frames, and these things could be off in any axis.
use at your peril on any but old school steel, or risk snappin' stuff off. if not now then down the road.




I have a Park hanger tool and even have a clue as to how to use it, as it was standard practice to check the hanger alignment on new production bikes (we delt in Schwinn, Fuji, Gitane and the occastional Kabuki back in the 70's, early 80's) during the assembly stage, during my shoprat years. A Park tie would be nice too.

[weisan]

The alignemtn tool itself is kinda simple, a home made version is simple and somewhat easy to make. The tab is threaded M10x1, which happens to be the same thread as most rear axles ('cept Campy, Joytech and Zeus). Some bar stock, a hub axle, a couple of track nuts and some quality time with a drill press and you too can have your very own alignment tool...

Whenever I hear "home-made tools", my ears perched up. Kind Ti-Master, any pictures....pleassseeee.
:D

weisan