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 10-15-11, 11:52 PM   #1
Shilun
Senior Member
Thread Starter
 
Shilun's Avatar
 
Join Date: Jun 2005
Location: Taiwan
Bikes:
Posts: 142
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Noise from back wheel when using 13T cog

My bike has developed a chattering/rattling sound when going over rough or bumpy road surfaces, but only when in the 13T cog! It appears to be coming from the area of the rear wheel. Smooth roads are OK, as are all the other cogs. I've tried to reproduce the sound at home on a bike stand, but without success. Any thoughts?
Shilun is offline   Reply With Quote
Old 10-16-11, 06:51 AM   #2
eric1514
Member
 
Join Date: May 2007
Location: Sedona, AZ
Bikes: 1968 Raleigh SuperCourse
Posts: 44
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Chain slapping on the chainstay?

Eric
eric1514 is offline   Reply With Quote
Old 10-16-11, 09:06 AM   #3
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: 29,685
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 232 Post(s)
Quote:
Originally Posted by eric1514 View Post
Chain slapping on the chainstay?

Eric
+1,

only on small sprockets + only on bumpy roads = chain hitting chain stay.

This is most likely, especially of it's worse when coasting vs pedaling.
__________________
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 offline   Reply With Quote
Old 10-16-11, 09:09 AM   #4
2manybikes
Dog is my co-pilot
 
2manybikes's Avatar
 
Join Date: Jun 2003
Bikes: 2 many
Posts: 15,559
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 52 Post(s)
Yes. ^^^^^^
2manybikes is offline   Reply With Quote
Old 10-16-11, 11:30 AM   #5
eric1514
Member
 
Join Date: May 2007
Location: Sedona, AZ
Bikes: 1968 Raleigh SuperCourse
Posts: 44
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Now, as to the cause.

1) Very worn out chain is now longer than it was.
2) Rear wheel is not pulled back as far as it had been in the past; either it is slipping forward or was not installed correctly.
3) Rear derailleur has swung forward.
4) Broken spring in rear derailleur tensioner.

Good luck,
Eric
eric1514 is offline   Reply With Quote
Old 10-19-11, 09:45 PM   #6
Shilun
Senior Member
Thread Starter
 
Shilun's Avatar
 
Join Date: Jun 2005
Location: Taiwan
Bikes:
Posts: 142
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks for all your help. I checked over and over for chain slap, but just couldn't find where or how it was occurring. Finally, I gave up and took the bike to my local LBS. He took off the rear cassette, fiddled around for a while, and announced that he had cleared a small piece of grit from inside the hub. And with that, the problem disappeared. Why it only revealed itself while riding on the 13T cog, however, remains a mystery.

Thanks again for taking the time to respond.
Shilun is offline   Reply With Quote
Old 10-21-11, 05:53 AM   #7
kingsting
Bicycle Repairman
 
kingsting's Avatar
 
Join Date: Sep 2010
Location: The Land of Three Mile Island
Bikes: Many
Posts: 598
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The grit was allowing the cassette to move forward with the wheel, making the chain slack on the top and allowing it to hit on the stay. Because of the gear ratio, it required less friction to do this in the small cog compared to the larger ones.
kingsting is offline   Reply With Quote
Old 10-21-11, 02:50 PM   #8
deermouse
Member
 
deermouse's Avatar
 
Join Date: Oct 2007
Location: Boulder, CO
Bikes:
Posts: 36
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I suspect the grit was wedged between the 13 tooth gear and the next gear. The grit probably prevented the chain from properly laying on the 13 tooth sprocket. The next larger sprocket held the chain a little higher so it didn't cause a problem.

Just my guess, but good work from the LBS.
deermouse 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 05:35 PM.