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 01-31-09, 04:04 PM   #1
Drwecki
Senior Member
Thread Starter
 
Join Date: May 2007
Location: Madison, WI
Bikes: Tease Fixed Gear, Schwinn World Traveler 72, 60's Hawthorne
Posts: 373
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Loosing sprocket hold

I have a buddy who rides his vintage road bike on centuries and he has a problem where he'll be riding along really fast and he looses the chain/sprocket connection. It's not while shifting either? I think he needs to put a new chain on, but more expert advice is needed, what should we watch out for when we are repairing it?

Brian
Drwecki is offline   Reply With Quote
Old 01-31-09, 04:08 PM   #2
HillRider 
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Posts: 28,854
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 66 Post(s)
What do you mean "loses"? The chain skips on the cogs? The chain shifts to a different cog?

The problem could be a worn chain, worn freewheel/cassette or a bad shifter. What kind of shifter does he have; friction, indexing? Where are the shifters mounted?

More info is needed.
HillRider is offline   Reply With Quote
Old 01-31-09, 04:12 PM   #3
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Bikes: Rans Rockst (Retro rocket) Rans Enduro Sport (Retro racket) Catrike 559, Merin Bear Valley (beater bike).
Posts: 26,631
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 92 Post(s)
His drive train is probably worn out.

As bicycle chains wear they get a little longer. Then they wear the sprockets to fit the longer, worn chain. Eventually they'll start to "skip" usually at bad times.

Chains are easy to check. Hold an accurate ruler against the taut chain. On a new chain you'll find 2 rivets that are exactly 12" apart. I replace just the chain when 2 rivets are 12 1/16" apart. If the 2 rivets are 12 1/8" apart you need a new chain and freewheel/cassette.

Chainrings are also easy to check. New front chainrings are rounded over the tops of the teeth. If your chainrings are pointy, you need new ones. Sometimes it's cheaper to replace the whole crankset.

Rear cogs take a kind of shark fin look when they wear, but it might take a practiced eye to spot it.
Retro Grouch is offline   Reply With Quote
Old 01-31-09, 06:33 PM   #4
Bill Kapaun
Senior Member
 
Bill Kapaun's Avatar
 
Join Date: Feb 2007
Location: Mid Willamette Valley, Orygun
Bikes: 86 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds.
Posts: 9,279
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
It may be that the cogs are slipping because the pawls disengage?
http://sheldonbrown.com/freewheels.html#lube
Bill Kapaun is offline   Reply With Quote
Old 02-02-09, 11:25 AM   #5
noglider 
aka Tom Reingold
 
noglider's Avatar
 
Join Date: Jan 2009
Location: West Village, New York City
Bikes: too many
Posts: 27,139
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 245 Post(s)
Worn chain and/or teeth is/are far more likely than worn pawls. The former occurs commonly. The latter is very rare, though it does happen.

Replace the chain first, as it's cheap and easy. If the teeth are badly worn, the problem will then get worse. At that point, replace the affected sprockets.
noglider 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 08:49 AM.