Bicycle Mechanics - Rear derailleur not shifting to big gears

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scoots826
11-06-08, 04:27 PM
After a pretty bad crash, I got most of the bike fixed. Trued the wheels, straighten the handlebars and brake levers, new grip tape. I had to adjust the rear derailleur but it won't shift to the two largest cogs. Do I need a whole new derailleur? Or is the arm just bent?

bikinfool
11-06-08, 05:43 PM
Could be a bent derailleur hanger.
operator
11-06-08, 05:45 PM
http://www.parktool.com/repair/readhowto.asp?id=64

scoots826
11-06-08, 06:18 PM
http://www.parktool.com/repair/readhowto.asp?id=64

Thanks for the help. Try reading the whole post and not just the title.
ogbigbird
11-06-08, 07:48 PM
after you check to see if the derailleur is bent, try checking your cable slack and your limitation screws. although it is unlikly that a crash could have changed this setting, stranger things have happened. if the derailleur is bent, go buy a new one unless you think you can just bend it back and you are ok with that. if your derailleur hanger is bent, you may need to take it to a shop to rebenf it if you are not comfortable doing it yourself.

adjustment, then if not, replacement. without pictures, my help can only be general.
scoots826
11-06-08, 08:06 PM
after you check to see if the derailleur is bent, try checking your cable slack and your limitation screws. although it is unlikly that a crash could have changed this setting, stranger things have happened. if the derailleur is bent, go buy a new one unless you think you can just bend it back and you are ok with that. if your derailleur hanger is bent, you may need to take it to a shop to rebenf it if you are not comfortable doing it yourself.

adjustment, then if not, replacement. without pictures, my help can only be general.

I checked all of those settings. Everything shifts great until the second highest gear. The shifter clicks over, but the derailleur doesn't move. How would I attempt to bend the hanger? Its only tiagra so if I mess it up, no big deal. What pictures would you need to see? From the back of the bike, in the lowest cog? Thanks in advance.
Panthers007
11-06-08, 10:46 PM
From behind with the camera looking down to show where the two pulleys are. First shift it as far as it will move so that it trying to get to where it won't go. We need to look at the angle of the derailleur wheels and body and where it attaches to the bike-frame.

Rather like this with the RD oriented on the gears you can't shift to:

http://i424.photobucket.com/albums/pp323/nagognog/IMG_0077.jpg