how precise does the hanger need to be
mines bent a touch, you can see the derailure is not in line perfectly. I've bent them back before with a large adjustable wrench, but how precise does it need to be for 9speed. I used to do this on 8 speed and "close" was good enough. just wondering if I will be hitting my head against a wall without having precision measuring instruments
I remove the der. and hold a long straight edge flat against the hanger (using a 36" length of small, angled aluminum from lowes or hd). It's easy to get within 1/16". Hold the straight edge with one hand and measure the distance to the rim. Rotate the st. edge to find the lowest point and then tweak. Make sure the qr is tight, and the wheel needs to be true.
I have bent RD back on 9 speeds with sucess....If it shifts fine after you bend it back all is good...
Originally Posted by Dichotomous
If not then get a new hanger....
I have done it on the bike becareful.....of on a anvil with a hammer...probably better.
If it is an aluminum hanger, get a spare anyway. Aluminum does not like being bent. It gets weaker and fails completely after a few times.
"it IS possible that you are faster or slower than anybody else who is having at least as much if not more or less fun"
As little as 3 to 5mm out can make a difference depending on the orientation of the bend. Vertical alignment is the most critical, but horizontal alignment can can cause problems if severe enough.
If you can actually see that the derailluer/hanger is out of alignment then it's certainly enough to give you problems. But by the same token, I've seen many hangers that didn't look bad, that were out enough to cause shifting problems with 9 speed and above drive trains. So using some sort of visual aide or an actual hanger alignment tool is usually needed.
"I do whatever my Rice Cripsies tell me to!"
It has to be good enough for the shifting to be crisp and smooth. Folks make like there's a need for super precision, but if you have good eyes and hands you can get it good enough freehand. Ultimately, if you don't have a problem, than not being perfect doesn't matter.
An easier way for a freehand bend is to stick a 6mm hex key through the upper pivot bolt, and use it as a bending lever.
If you want better accuracy remove the RD, and use the adjustable as you have, being careful not to ding the flat area where the pivot bolt mates. You can then check by laying a straight edge against the flat, extending it to the rim and measuring with a ruler or using your thumb as a gauge. Do this at three points around the rim, matching the distance to prove that the face is on plane with the wheel.
The key to solving any problem is to understand and address the underlying cause.
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