Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 03-30-11, 04:31 PM   #1
gecho
Senior Member
Thread Starter
 
Join Date: Sep 2010
Location: Regina, SK
Bikes: 2009 Trek 520
Posts: 1,100
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Crack in Rear Derailleur

After cleaning my drive train and hanging up my bike I noted this crack in my rear derailleur. Is it something I should worry about? I'm not sure what the purpose of that wing part is, but it doesn't seem to be carrying any loads.

The bike (Trek 520) is less than a year old. I'm guessing the crack is the result of a manufacturing defect. Is getting it replaced under warranty typically much of a hassle?

gecho is offline   Reply With Quote
Old 03-30-11, 04:48 PM   #2
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 29,917
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 346 Post(s)
I suspect that it's a stop to keep the RD from swinging back too far when you remove the wheel. The front side will engage the stop tab when you pull the RD back (or when the upper body spring on some models does so). It's probably cracking from a bit of hard banging into the stop tab, but it's hard to tell from the photo.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is online now   Reply With Quote
Old 03-30-11, 05:05 PM   #3
jimc101
Senior Member
 
Join Date: Oct 2007
Location: West Yorkshire, United Kingdom
Bikes:
Posts: 4,809
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
If it's cracked, it could fail, replace.

For warranty, can't work out how you did it, you would have to ask your dealer
jimc101 is offline   Reply With Quote
Old 03-30-11, 07:57 PM   #4
gecho
Senior Member
Thread Starter
 
Join Date: Sep 2010
Location: Regina, SK
Bikes: 2009 Trek 520
Posts: 1,100
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
I dropped it off at the shop tonight, the head mechanic was intrigued by the crack. He needs to show it to someone else tomorrow to see if it might be covered under warranty. I don't need that thing flying off at 40km/h.

On my first mountain bike I had the stem fail once due to metal fatigue and the handlebars came off in my hand while riding. I couldn't steer but still had the brake levers, which I applied very gently.
gecho is offline   Reply With Quote
Old 03-30-11, 08:33 PM   #5
Burton
Certified Bike Brat
 
Burton's Avatar
 
Join Date: Jan 2011
Location: Montreal, Quebec
Bikes:
Posts: 4,251
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yup as FB mentioned - its a safety feature that puts a bit of extra play in the system and might give you a chance to back off the pedals if your chain`s been derailed.

The upper casting in the Shimano Tourney models is plastic and its not unusual to see that stop completely sheared off due to a drive system mishap that scrapped the derailleur.
Burton is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 04:23 PM.