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 04-04-13, 05:54 PM   #1
jengel
Senior Member
Thread Starter
 
Join Date: Aug 2006
Bikes:
Posts: 59
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Weird vibration

High frequency vibration comes on when coasting. Goes away when I start pedaling. Feels like a vibrating bed machine in my saddle.
Older Cannondale Carbon Synapse. Can't find any frame cracks. Any ideas?
jengel is offline   Reply With Quote
Old 04-04-13, 06:15 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: 29,982
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 370 Post(s)
Since it's only when coasting, it's some kind of freewheel noise. Depending on whether it was always this way, came on slowly or suddenly, or other info, it could be inherent to your freehub (some sound like buzzsaws), lack or lube, or rust ot other issues within the freehub, or much simpler something would up against the hub behind the cassette causing noise or drag when they don't turn together.

If this bike isn't new and the noise is, look behind the cassette, and/or remove the cassette and clean there before taking th ehub apart looking for an internal problem. Once the cassette is off you can test off the bike spinning the wheel while holding the freehub body.
__________________
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 04-04-13, 06:21 PM   #3
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: 28,917
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 95 Post(s)
Does the bike have a "dork disk" (the plastic or metal spoke protector behind the largest cog of the freewheel or cassette). if so and if it has slipped or cracked, that could be your source.
HillRider is offline   Reply With Quote
Old 04-04-13, 06:30 PM   #4
gyozadude
Senior Member
 
gyozadude's Avatar
 
Join Date: Jun 2011
Location: Sunnyvale, California
Bikes: Bridgestone RB-1, 600, T700, MB-6 w/ Dirt Drops, MB-Zip, Bianchi Limited, Nashbar Hounder
Posts: 1,180
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Step on the BB first on one side and then from the other side and check for flex. When you pedal, there is chain tension that flexes the rear triangle toward the drive side and compresses the right chainstay to the BB. When you coast, you might not be compressing that member and it can set up a vibration. It's curious that you feel it coming up through the saddle. That would concerned me. Usually a freewheel vibration wouldn't be that bad.
gyozadude is offline   Reply With Quote
Old 04-04-13, 07:01 PM   #5
dddd
Ride, Wrench, Swap, Race
 
dddd's Avatar
 
Join Date: Jan 2010
Location: Northern California
Bikes: Cheltenham-Pederson racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Posts: 5,069
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
If you're using a high-end Mavic wheelset, the freehub bodies on these require regular lubrication, every couple of thousand miles is a good time to clean up and re-lube.

I do this at home, but you should first know what you're doing.
Loud noises while coasting can also result from a neglected freehub and bushing.
dddd is offline   Reply With Quote
Old 04-04-13, 08:25 PM   #6
cny-bikeman
Mechanic/Tourist
 
Join Date: Apr 2007
Location: Syracuse, NY
Bikes: 2008 Novara Randonee - love it. Would have more bikes if I had time to ride them all. Previous bikes: 1968 Motobecane Mirage, 1972 Moto Grand Jubilee (my fav), Jackson Rake 16, 1983 C'dale ST500.
Posts: 6,322
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
Vibration can mean a lot of things. Is it a buzzing (very frequent, small or imperceptible movement) or more like a pulsing (slower, larger amplitude)? Pedaling may just mask the vibration or can short-circuit whatever harmonic vibration is happening.
cny-bikeman is offline   Reply With Quote
Old 04-05-13, 05:52 AM   #7
Continuity
Senior Member
 
Join Date: Mar 2013
Location: NW UK
Bikes: 1992 Marin Eldridge Grade, 2007 Kona PHD and 199? Trek 1000 (current build project)
Posts: 418
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by dddd View Post
If you're using a high-end Mavic wheelset, the freehub bodies on these require regular lubrication, every couple of thousand miles is a good time to clean up and re-lube.
+1 - Indeed. I found this to be the case when servicing my Aksiums. (although they're not exactly 'high end' )

Do you bother with the recommendation to always replenish the threadlock on the locknuts and and to always use a new 'compressible adjuster washer' like Mavic recommend?

I was happy to find out that somone one Ebay in the US offers fairly reasonably-priced replacements for those weird nylon (or Delrin, whatever) bushings that Mavic use, as well as an 'oversize' version that's a couple of thou of an inch larger so as to fit snugly on hubs that are a bit worn.
Continuity is offline   Reply With Quote
Old 04-05-13, 12:42 PM   #8
dddd
Ride, Wrench, Swap, Race
 
dddd's Avatar
 
Join Date: Jan 2010
Location: Northern California
Bikes: Cheltenham-Pederson racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Posts: 5,069
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Quote:
Originally Posted by Continuity View Post
+1 - Indeed. I found this to be the case when servicing my Aksiums. (although they're not exactly 'high end' )

Do you bother with the recommendation to always replenish the threadlock on the locknuts and and to always use a new 'compressible adjuster washer' like Mavic recommend?

I was happy to find out that somone one Ebay in the US offers fairly reasonably-priced replacements for those weird nylon (or Delrin, whatever) bushings that Mavic use, as well as an 'oversize' version that's a couple of thou of an inch larger so as to fit snugly on hubs that are a bit worn.
I've bought and used the replacement bushings, but even the std-sized ones often need a little relieving to turn smoothly.

For freehub servicing, the compressible washer isn't disturbed. It's under the bearing adjuster ring.

And, for routine axle pulls, I don't use the LocTite on my own axle. But it can help keep things tight over the unknown conditions and possibly longer interval of someone else's hub. I have found them loose on occasion, and have seen many such hubs with bearing-loosening issues and which thus required frequent adjustment. A very low strength of LocTite might help with this on the adjuster ring.
dddd is offline   Reply With Quote
Old 04-05-13, 02:18 PM   #9
jengel
Senior Member
Thread Starter
 
Join Date: Aug 2006
Bikes:
Posts: 59
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks, all, for the help. It indeed was the plastic bushing in the Mavic wheel. I'll order a new piece and be on my way.
jengel is offline   Reply With Quote
Old 04-05-13, 02:19 PM   #10
Continuity
Senior Member
 
Join Date: Mar 2013
Location: NW UK
Bikes: 1992 Marin Eldridge Grade, 2007 Kona PHD and 199? Trek 1000 (current build project)
Posts: 418
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Are you ordering it from the US guy on Ebay who sells them?

And did you try cleaning and lubing the one that's on there now? They
do tend to make a terrible racket when they need TLC.
Continuity is offline   Reply With Quote
Old 04-05-13, 03:28 PM   #11
jengel
Senior Member
Thread Starter
 
Join Date: Aug 2006
Bikes:
Posts: 59
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Continuity View Post
Are you ordering it from the US guy on Ebay who sells them?

And did you try cleaning and lubing the one that's on there now? They
do tend to make a terrible racket when they need TLC.
Yes, I'm ordering from ebay. And the lube is ok. Not making noise. I'll, of course, clean and lube before I put it all back together. There is significant play between the plastic bushing and axle.
jengel 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 09:33 PM.