Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Effect of bearing precession on hub cones

Notices
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.

Effect of bearing precession on hub cones

Old 03-28-10, 07:55 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Aug 2005
Location: New Hampshire
Posts: 1,221

Bikes: Niner RLT 9 RDO, Gunnar Sport, Soma Saga, Workswell WCBR-146

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 114 Post(s)
Liked 19 Times in 19 Posts
Effect of bearing precession on hub cones

I have a theoretical question that isn't related to any specific problem I'm having, but it occurred to me as I was repacking a hub the other day.

There are numerous threads and articles around describing what bearing precession is, especially as an explanation for why pedal and BB thread directions are reversed on opposite sides of the bike.

My question is, does this effect apply to hub cones on threaded axles? For example, looking at my 105 rear hub from the left side, the hub shell rotates counterclockwise as the bicycle moves forward. If I'm thinking about it correctly, this would result in a slight clockwise torque on the cone. With a right-hand threaded axle, I believe this would tend to pull the cone away from the locknut. Since the only thing holding the cone in place is friction against the locknut, I would think this would create a vicious cycle where that friction force is reduced, leading to more creep in the cone, leading to even less friction, etc., while simultaneously increasing pressure against the bearings (bad).

So, assuming I've got it right, is this ever a problem in real hubs? And if not, why is it a problem in pedals and BBs but not hubs? I would think it would make more sense to use a left-handed thread on the left side of the axle, and vice versa.
Metaluna is offline  
Old 03-28-10, 08:18 AM
  #2  
Senior Member
 
Join Date: Sep 2004
Location: boston, ma
Posts: 2,896
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 1 Time in 1 Post
yes hub cones do become loose over time. whether its from precession or insufficient torque when adjusting the hub i dont know
reptilezs is offline  
Old 03-28-10, 08:27 AM
  #3  
Senior Member
 
Join Date: Sep 2008
Location: Loveland, CO
Posts: 7,251

Bikes: Cinelli superstar disc, two Yoeleo R12

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 1107 Post(s)
Liked 562 Times in 448 Posts
If the locknut is tightened properly, it should never be a problem. Precession forces are very small and would never loosen a cone. Very few modern hubs even use threaded cones these days - only cheap bikes with the old 10mm threaded axles.

Some people will swear that precession forces are large enough to loosen the right side BB cup on an Italian threaded frame, but I contend that they are not. If a cup were to loosen for some other reason like the BB face not being square to the threads, or being under-torqued, those forces can eventually unscrew the cup, but not until it's fairly loose from other causes.

The opposite situation never occurs. You don't find BB cups that have tightened themselves due to precession. If you were to hand tighten a BB cup, it will never get tight, all by itself.
DaveSSS is offline  
Old 03-28-10, 09:52 AM
  #4  
thompsonpost
Guest
 
Posts: n/a
Mentioned: Post(s)
Tagged: Thread(s)
Quoted: Post(s)
Lock nuts, the clue.
 
Old 03-28-10, 09:52 AM
  #5  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 39,096

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

Mentioned: 141 Post(s)
Tagged: 1 Thread(s)
Quoted: 5993 Post(s)
Liked 2,927 Times in 1,624 Posts
As DaveSSS said these forces are miniscule, and aren't a meaningful factor in why hub bearings get loose, if they do. They're most important in pedals because of the large twisting force as the pedal spindle is flrxed back and forth with respect to the rotating crank, but otherwise can be pretty much ignored.

Hubs where the bearing adjustment is well secured by a cone/keyed washer/locknut arrangement, or other secure system can go many thousands of miles without getting loose. Eventually they'll develop play because of wear, as will any bearing, but that's about it.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

Just because I'm tired of arguing, doesn't mean you're right.

“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  
Old 03-28-10, 11:13 AM
  #6  
Senior Member
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,555

Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1533 Post(s)
Liked 725 Times in 515 Posts
IMO left-hand threads on bikes are virtually pointless.
Kimmo is offline  
Old 03-28-10, 11:23 AM
  #7  
Senior Member
 
Join Date: Apr 2006
Location: Sioux Falls
Posts: 223

Bikes: Bianchi Road bike, Nashbar Ultegra triple cyclocross, Raleigh full XT hybrid, lugged steel Schwinn, Full rigid Diamondback MTB

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Kimmo,

I have a little experience with peddles and respectfully disagree. My kids have had issues with the peddles on their trailerbike. It seems that they were having fun peddling backwords. I didn't know it because I am usually cruising fast enough, and the trailerbike is geared low enough, that they couldn't "contribute" anyway. What they did find is that after a period of peddling backwords the pedal would fall off. Others have had this same experience with onoccupied trailerbikes. While I do understand that this probably wouldn't have happened if I had checked the torque of the pedels before the ride, I think that we would see many more people losing pedals if the left didn't have left handed threads.
labrat is offline  
Old 03-28-10, 11:26 AM
  #8  
Senior Member
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,555

Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1533 Post(s)
Liked 725 Times in 515 Posts
By 'virtually' I mean completely pointless as long as the bearings aren't binding and everything's nice and tight. It could be argued the threads should be the other way round so then you know when something's wrong, cause bits fall off.

BTW it's pedals.

Last edited by Kimmo; 03-28-10 at 11:29 AM.
Kimmo is offline  
Old 03-28-10, 11:30 AM
  #9  
thompsonpost
Guest
 
Posts: n/a
Mentioned: Post(s)
Tagged: Thread(s)
Quoted: Post(s)
Kimmo, he got it right at least twice.
 
Old 03-28-10, 11:35 AM
  #10  
Senior Member
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,555

Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1533 Post(s)
Liked 725 Times in 515 Posts
I'm guessing he didn't know when he was right, since he employed three different spellings.

BTW, before anyone has a go, that comment re the threads being the other way round was kinda tongue in cheek
Kimmo is offline  
Old 03-28-10, 11:50 AM
  #11  
thompsonpost
Guest
 
Posts: n/a
Mentioned: Post(s)
Tagged: Thread(s)
Quoted: Post(s)
Yeah, I gave it a thought, too.
 
Old 03-28-10, 12:16 PM
  #12  
AEO
Senior Member
 
AEO's Avatar
 
Join Date: Jun 2007
Location: A Coffin Called Earth. or Toronto, ON
Posts: 12,257

Bikes: Bianchi, Miyata, Dahon, Rossin

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 5 Times in 5 Posts
only on some raleigh bike hubs does it matter

left side only has the single cone nut for the bearings with no lock nut.
if you insert the wheel in backwards, the hub tightens itself to destruction.
if you insert it in the correct way, the cone can't unwind because the fork dropouts and axle nut are holding it in place.
__________________
Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
AEO is offline  
Old 03-29-10, 12:02 AM
  #13  
Senior Member
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,555

Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1533 Post(s)
Liked 725 Times in 515 Posts
Originally Posted by AEO
left side only has the single cone nut for the bearings with no lock nut.
O_O

Sketchy...
Kimmo is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
jjames2b
Bicycle Mechanics
17
04-09-15 09:50 PM
RandomTroll
Bicycle Mechanics
3
10-16-14 10:39 PM
Ryrog
Singlespeed & Fixed Gear
7
05-08-11 07:49 AM
jamesj
Classic & Vintage
1
08-05-10 07:04 PM
5b00
Bicycle Mechanics
8
06-02-10 10:51 PM

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.