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

Multiple bearings on one shaft

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.

Multiple bearings on one shaft

Old 06-07-23, 08:20 AM
  #1  
Full Member
Thread Starter
 
Join Date: Mar 2019
Posts: 352
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 183 Post(s)
Liked 14 Times in 12 Posts
Multiple bearings on one shaft

Asking once again since wasn't able to find anything about rear hubs with more than 4 bearings such as Bitex BX103R. It has been said that more than one bearing at one end of the shaft should be avoided as a way to increase the load capacity since it's impossible to match the bearings.
https://www.eng-tips.com/viewthread.cfm?qid=292906
sysrq is offline  
Old 06-07-23, 09:19 AM
  #2  
Senior Member
 
FBOATSB's Avatar
 
Join Date: Jul 2014
Location: Central Indiana
Posts: 2,159
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 915 Post(s)
Liked 516 Times in 345 Posts
I would think your concern is totally unfounded for anything as simple as a bicycle. That link of yours refers to high stress high speed bearings like in turbines that have to have zero flex. These issues come up here from time to time. Bitex hubs are pretty bombproof from what I read.
I copy/pasted this statement directly from that link you posted: "I think what it boils down to is that my hasty assumption of uniform load sharing among multiple bearings is correct only in the case of a perfectly rigid shaft. Elastic flexure completely disqualifies this multiple bearing approach in reality. I really should have seen the impracticality of this approach earlier."
FBOATSB is offline  
Likes For FBOATSB:
Old 06-07-23, 10:05 AM
  #3  
Full Member
Thread Starter
 
Join Date: Mar 2019
Posts: 352
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 183 Post(s)
Liked 14 Times in 12 Posts
Originally Posted by FBOATSB
I would think your concern is totally unfounded for anything as simple as a bicycle. That link of yours refers to high stress high speed bearings like in turbines that have to have zero flex. These issues come up here from time to time. Bitex hubs are pretty bombproof from what I read.
I copy/pasted this statement directly from that link you posted: "I think what it boils down to is that my hasty assumption of uniform load sharing among multiple bearings is correct only in the case of a perfectly rigid shaft. Elastic flexure completely disqualifies this multiple bearing approach in reality. I really should have seen the impracticality of this approach earlier."
Might be true since there is no reason to think it's all for marketing purposes only by Bitex.
Kinda seems pointless to argue without having in depth understanding of engineering.
https://www.meadinfo.org/2013/01/dup...ement%E2%80%9D.
sysrq is offline  
Old 06-07-23, 10:47 AM
  #4  
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,644

Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)

Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3873 Post(s)
Liked 2,576 Times in 1,583 Posts
Perhaps the steel shell helps reduce flex.

The bicycle industry has a long history of doing "suboptimal" things and getting away with it. Before getting upset that it doesn't work in theory, maybe you should find out if it works in practice?
__________________
Originally Posted by chandltp
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
RUSA #7498
ThermionicScott is offline  
Likes For ThermionicScott:
Old 06-07-23, 11:24 AM
  #5  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 39,086

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: 5990 Post(s)
Liked 2,922 Times in 1,622 Posts
I'm not sure I understand your question.

Are you looking for a serious engineering analysis on a bike forum?

In any case, your question may br the result of confusion about the design.

The double bearings sharing load considerations don't apply here if you're looking at the rear hubs.

These do have 4 bearings, but they're doing different jobs. 2 bearings support the hub, and 2 support the freehub. So, each is a classic 2 bearing design.
__________________
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  
Likes For FBinNY:
Old 06-07-23, 12:41 PM
  #6  
Full Member
Thread Starter
 
Join Date: Mar 2019
Posts: 352
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 183 Post(s)
Liked 14 Times in 12 Posts
Originally Posted by FBinNY
I'm not sure I understand your question.

Are you looking for a serious engineering analysis on a bike forum?

In any case, your question may br the result of confusion about the design.

The double bearings sharing load considerations don't apply here if you're looking at the rear hubs.

These do have 4 bearings, but they're doing different jobs. 2 bearings support the hub, and 2 support the freehub. So, each is a classic 2 bearing design.
Bitex BX103R has 6 bearings, one on each end of on the outer sides of the axle and four in the middle.

Last edited by sysrq; 06-07-23 at 12:51 PM.
sysrq is offline  
Old 06-07-23, 12:44 PM
  #7  
Full Member
Thread Starter
 
Join Date: Mar 2019
Posts: 352
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 183 Post(s)
Liked 14 Times in 12 Posts
Originally Posted by ThermionicScott
Perhaps the steel shell helps reduce flex.

The bicycle industry has a long history of doing "suboptimal" things and getting away with it. Before getting upset that it doesn't work in theory, maybe you should find out if it works in practice?
In practice there is no way to tell without measuring the actual load of each bearing. Hopefully it's not just a needless weight being carried around.
https://principle-eng.co.uk/duplex-bearings/

Last edited by sysrq; 06-07-23 at 12:58 PM.
sysrq is offline  
Old 06-07-23, 01:19 PM
  #8  
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,644

Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)

Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3873 Post(s)
Liked 2,576 Times in 1,583 Posts
Originally Posted by sysrq
In practice there is no way to tell without measuring the actual load of each bearing. Hopefully it's not just a needless weight being carried around.
https://principle-eng.co.uk/duplex-bearings/
What is your investment in this hub? Something you're thinking of buying, or it just crossed your radar and now it bugs you?

I doubt any engineering analysis or advanced laboratory testing went into the design. They were probably faced with bearing failure on one side with their most demanding customers, made room for another one, and that solved the problem well enough.
__________________
Originally Posted by chandltp
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
RUSA #7498
ThermionicScott is offline  
Old 06-07-23, 01:40 PM
  #9  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 39,086

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: 5990 Post(s)
Liked 2,922 Times in 1,622 Posts
Originally Posted by sysrq
Bitex BX103R has 6 bearings, one on each end of on the outer sides of the axle and four in the middle.
So you are asking for an engineering analysis. Unfortunately vastly more specific info would be needed.

However, here's some grist for your mill.

While a single larger bearing I'd generally preferred to paired smaller bearings, that doesn't mean the second is necessarily bad. For example, as may apply here, dimensional constraints may drive the decision, especially if a roller bearing isn't a good option.

OTOH often what's claimed based on engineering is more about marketing. With a long and proven history of simpler designs, I tend to keep my hype filter set on high.

Personally, I wouldn't consider the added bearings a reason to buy the hubs. However, I wouldn't consider that a reason not to either.

Buy products based on reputation and proven performance. Consider performance in the field the best confirmation that the engineers made good calls.

Last edited by FBinNY; 06-07-23 at 01:49 PM.
FBinNY is offline  
Likes For FBinNY:
Old 06-07-23, 02:04 PM
  #10  
Senior Member
 
Troul's Avatar
 
Join Date: Oct 2013
Location: Mich
Posts: 7,651

Bikes: RSO E-tire dropper fixie brifter

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked 3,165 Times in 2,011 Posts
i'd consider the extra bearings to be harder to maintain to clean & grease, unless the design took that into consideration.

What I'd entertain to try is the standard ball bearings in the normal places & then a set of needle bearings positioned in the center (whether one or two sets depending on serviceability] .
__________________
-Oh Hey!
Troul is offline  
Old 06-07-23, 06:34 PM
  #11  
Senior Member
 
CliffordK's Avatar
 
Join Date: Nov 2014
Location: Eugene, Oregon, USA
Posts: 27,549
Mentioned: 217 Post(s)
Tagged: 0 Thread(s)
Quoted: 18459 Post(s)
Liked 4,564 Times in 3,390 Posts
Here is the Bitex hub

https://www.bitexhubs.com/htm/pd_detail.php?no=BX103R

The 6 bearings will increase the friction slightly. The inner bearing will likely stay clean, but won't experience a lot of stress either, most of which will be borne by the outer bearing.

The bearings shouldn't need a lot of maintenance, other than occasional replacement.

Perhaps low quality bearings will wear into each other quickly.
CliffordK is offline  
Old 06-08-23, 10:26 AM
  #12  
Full Member
Thread Starter
 
Join Date: Mar 2019
Posts: 352
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 183 Post(s)
Liked 14 Times in 12 Posts
Originally Posted by ThermionicScott
What is your investment in this hub? Something you're thinking of buying, or it just crossed your radar and now it bugs you?

I doubt any engineering analysis or advanced laboratory testing went into the design. They were probably faced with bearing failure on one side with their most demanding customers, made room for another one, and that solved the problem well enough.
It seemed to be the next quietest and cheapest hub available after Shimano with cartridge bearings so had no other choice but to go all the way and order some touring wheel for possible upcoming 1600km tour.
sysrq is offline  
Old 06-08-23, 04:50 PM
  #13  
Full Member
Thread Starter
 
Join Date: Mar 2019
Posts: 352
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 183 Post(s)
Liked 14 Times in 12 Posts
Originally Posted by FBinNY
So you are asking for an engineering analysis. Unfortunately vastly more specific info would be needed.

However, here's some grist for your mill.

While a single larger bearing I'd generally preferred to paired smaller bearings, that doesn't mean the second is necessarily bad. For example, as may apply here, dimensional constraints may drive the decision, especially if a roller bearing isn't a good option.

OTOH often what's claimed based on engineering is more about marketing. With a long and proven history of simpler designs, I tend to keep my hype filter set on high.

Personally, I wouldn't consider the added bearings a reason to buy the hubs. However, I wouldn't consider that a reason not to either.

Buy products based on reputation and proven performance. Consider performance in the field the best confirmation that the engineers made good calls.
Well, Bitex has been said to have acceptable reputation, but nothing much is found about this particular model among reviews and discussions (Bitex BX103R) or any other hub with more than 4 bearings.
sysrq is offline  
Old 06-08-23, 05:42 PM
  #14  
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 39,086

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: 5990 Post(s)
Liked 2,922 Times in 1,622 Posts
Originally Posted by sysrq
Well, Bitex has been said to have acceptable reputation, but nothing much is found about this particular model among reviews and discussions (Bitex BX103R) or any other hub with more than 4 bearings.
I think you get my point. You simply will not get meaningful technical advice unless you pay an engineer to direct a hub and give you an opinion. Even then it's only an opinion.

So you're buying the hub based on info given, which may be material or just hype. But, as you note, the company enjoys a good reputation, so trusting them is probably OK.

OTOH I think you're overly concerned, and probably can do equally well with just about any decent hub.

1600km is not a very long trip, and many here, including me, have taken much longer tours on much less special hubs. Touring or not, my hub service interval is roughly 10k kilos.

So. You probably won't go wrong with these hubs, but you may be spending more than you need to.


BTW ---- Have a great trip, and make plenty of memories.
FBinNY is offline  

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.