Reddit reviews Park Tool Derailleur Hanger Alignment Gauge
We found 4 Reddit comments about Park Tool Derailleur Hanger Alignment Gauge. Here are the top ones, ranked by their Reddit score.
The Derailleur Hanger Alignment Gauge can help solve a multitude of derailleur shifting problems, most notably with index shifting systemsThe DAG-2 is made of heavy-gauge steel and is chrome plated for long shop lifeA longer, narrower alignment boss to fit a wider variety of bikes
Look to see of the der pully holder is parallel with the plane of the wheel. If it looks good, it might still have shifting issues, but is safe to ride (barring problems with limit screws, etc).
To really be sure (like when chasing down small shifting anoynances that only happen at one end of the range), its best to use the same alignment tool used to fix the problem. It screws into the der hanger and has a movable probe that you set touching the rim; then you simply rotate the guide and check to see if the probe just touches the rim in all spots. If not, you use the arm of the tool to lever the der hanger around until it does. Mind you, if you wheel is (badly) out of true, there's no point to this.
https://www.amazon.com/Park-Tool-Derailleur-Hanger-Alignment/dp/B0028YWHPW
http://www.amazon.com/Park-Tool-Derailleur-Hanger-Alignment/dp/B0028YWHPW/ref=sr_1_cc_1?s=aps&srs=2529177011&ie=UTF8&qid=1377571554&sr=8-1-catcorr&keywords=park+derailleur+hanger+tool
Derailleur hangers are meant to bend before your derailleur because they are much cheaper than a new derailleur. So yes, if it's been bent in a crash you can try and bend it back to straight.
If your derailleur hanger is made of steel it can generally be bent back to straight with a DAG tool fairly easily. If it's aluminum, you can bend it back a few degrees, but generally they snap. Aluminum is much more brittle and will strain harden much quicker than steel, so once it's bent, it's usually done.
If you break a hanger, just buy a new one from your LBS. They range from $5 to $50+ depending on your bike. Most are pretty cheap and are very simple to install.
No, you should not.
There is a special tool for this that my bike shop used on my der hanger.
I understand your desire to make the repairs yourself, but the hanger needs to be aligned with a millimeter or so, which you can't achieve with a hammer.
It's a task that will only need to be performed once, so it doesn't make sense to purchase the tool for it, when any bike shop would gladly do it for nearly free.
However, this is the tool they'll use: http://www.amazon.com/dp/B0028YWHPW