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

Square taper BB's

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.

Square taper BB's

Old 08-10-19, 11:40 AM
  #1  
oldschoolbike
Junior Member
Thread Starter
 
Join Date: Oct 2017
Location: Ottawa, ON, Canada
Posts: 147

Bikes: 1974 PX-10E sold, 1977 Witcomb stolen, 1980 Roberts 1 speed, 1987 Cyclops 3 x 6 friction triple crank, 2010 Masi Commuter 1 speed, 2017 Ribble 525 2 x 10 with Ergos

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 58 Post(s)
Likes: 0
Liked 25 Times in 16 Posts
Square taper BB's

I realize this may be a hypothetical or even rhetorical question, but here goes:

If square taper bottom brackets are so heavy, flexible, and crude compared to modern hollow axle systems, why does square taper still seem to dominate the track and single speed worlds? I would have thought track and single speed riders would most want the claimed improvements, especially in stiffness, but uptake seems minimal to zero compared to road and MTB riders.
oldschoolbike is offline  
Old 08-10-19, 11:57 AM
  #2  
CliffordK
Senior Member
 
CliffordK's Avatar
 
Join Date: Nov 2014
Location: Eugene, Oregon, USA
Posts: 27,600
Mentioned: 217 Post(s)
Tagged: 0 Thread(s)
Quoted: 18302 Post(s)
Liked 4,470 Times in 3,326 Posts
I think, at least for Shimano, the Octalink is the bottom bracket of choice for track.

The Campagnolo Record square taper bottom brackets were fairly light, with hollow spindles.

Keep in mind that many of the Walmart bikes are made to look like track bikes, but really aren't close.
CliffordK is offline  
Old 08-10-19, 02:12 PM
  #3  
dsbrantjr
Senior Member
 
dsbrantjr's Avatar
 
Join Date: Sep 2010
Location: Roswell, GA
Posts: 8,319

Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 1438 Post(s)
Liked 1,091 Times in 722 Posts
Newer does not always mean better. It might mean cheaper to make or faster to assemble, which saves the manufacturer money. Or it may cater to the "gotta have the latest" crowd,
There is something to be said for older technology which has stood the test of time. How many previous "modern" BB systems have gone extinct, while square taper soldiers on?
dsbrantjr is offline  
Old 08-10-19, 03:20 PM
  #4  
terrymorse 
climber has-been
 
terrymorse's Avatar
 
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 6,959

Bikes: Scott Addict R1, Felt Z1

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3298 Post(s)
Liked 3,389 Times in 1,714 Posts
Originally Posted by oldschoolbike
why does square taper still seem to dominate the track and single speed worlds?
Because square taper is cheap?

High end track cranks do not use square taper:



Sugino SG75 DD2
__________________
Ride, Rest, Repeat. ROUVY: terrymorse


terrymorse is offline  
Likes For terrymorse:
Old 08-10-19, 05:01 PM
  #5  
ThermionicScott 
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,620

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: 3868 Post(s)
Liked 2,559 Times in 1,574 Posts
Originally Posted by oldschoolbike
I realize this may be a hypothetical or even rhetorical question, but here goes:

If square taper bottom brackets are so heavy, flexible, and crude compared to modern hollow axle systems, why does square taper still seem to dominate the track and single speed worlds? I would have thought track and single speed riders would most want the claimed improvements, especially in stiffness, but uptake seems minimal to zero compared to road and MTB riders.
If by "track" you mean keirin, consider that it is the NASCAR of the competitive cycling world.
__________________
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 08-10-19, 05:07 PM
  #6  
HTupolev
Senior Member
 
Join Date: Apr 2015
Location: Seattle
Posts: 4,261
Mentioned: 41 Post(s)
Tagged: 0 Thread(s)
Quoted: 1971 Post(s)
Liked 1,297 Times in 629 Posts
They don't all use square taper.

But, where they do, it's a combination of cheapness, lack of track popularity limiting tech development, and the ability to tune q-factor.
Or, in the case of Japanese Keirin, it's because they have very strict fairness rules dictating that bicycles be built with very specific technologies. Those rules were established over half a century ago, and they've found little reason to change them, so the bikes are still made with the same sorts of old-school designs.

Small weight differences aren't very important in track because there aren't any climbs, and "stiffness" concerns with steel square taper spindles are silly marketing nonsense.
HTupolev is offline  
Likes For HTupolev:
Old 08-10-19, 07:05 PM
  #7  
dsbrantjr
Senior Member
 
dsbrantjr's Avatar
 
Join Date: Sep 2010
Location: Roswell, GA
Posts: 8,319

Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 1438 Post(s)
Liked 1,091 Times in 722 Posts
Another reason to use square taper would be on a long tour, where replacements are much more likely to be readily available than the latest-and-greatest BB du jour.
dsbrantjr is offline  
Old 08-10-19, 07:25 PM
  #8  
Bigbus
Very Senior Member
 
Join Date: Mar 2018
Location: Always on the Run
Posts: 1,211

Bikes: Giant Quasar & Fuji Roubaix

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 413 Post(s)
Liked 343 Times in 244 Posts
I like square taper simply because it's what I'm familiar with, availability of parts, and most importantly, it's what I know how to work on.
Bigbus is offline  
Old 08-13-19, 06:36 PM
  #9  
terrymorse 
climber has-been
 
terrymorse's Avatar
 
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 6,959

Bikes: Scott Addict R1, Felt Z1

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3298 Post(s)
Liked 3,389 Times in 1,714 Posts
Just say "no" to square taper. It's junk technology that eats crank arms, and possibly injures the rider.

If the crank arm becomes loose, which happens when the fixing bolt gets loose or falls out, the crank arm is ruined.

If the fixing bolt is over tightened, which happens a lot, the crank arm "walks" up the taper. The crank arm develops a crack from being overstressed, then it breaks off without warning—usually when the rider is standing on the pedals—sending the rider to the ground.

Just. Say. No.
__________________
Ride, Rest, Repeat. ROUVY: terrymorse


terrymorse is offline  
Likes For terrymorse:
Old 08-13-19, 06:58 PM
  #10  
Marcus_Ti
FLIR Kitten to 0.05C
 
Marcus_Ti's Avatar
 
Join Date: Sep 2014
Location: Lincoln, Nebraska
Posts: 5,331

Bikes: Roadie: Seven Axiom Race Ti w/Chorus 11s. CX/Adventure: Carver Gravel Grinder w/ Di2

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 2349 Post(s)
Liked 406 Times in 254 Posts
Originally Posted by terrymorse
Just say "no" to square taper. It's junk technology that eats crank arms, and possibly injures the rider.

If the crank arm becomes loose, which happens when the fixing bolt gets loose or falls out, the crank arm is ruined.

If the fixing bolt is over tightened, which happens a lot, the crank arm "walks" up the taper. The crank arm develops a crack from being overstressed, then it breaks off without warning—usually when the rider is standing on the pedals—sending the rider to the ground.

Just. Say. No.
Spindle arms can come loose to. Hence all the photos out there of riders with Hollowtech2 arms stuck to riders feet and not the bike.

Post-sq-taper designs have had durability issues as well....HT2 arms coming apart, short-lived BB life due to poor sealing compared to sq-taper. etc.


Not at all saying spindle isn't better....but almost all the issues taper cranks have spindle cranks have had as well....exception being that 3-piece cranks can be adjusted for an out of spec BB shell--with 2-piece cranks the shell must be machined nearly perfectly. But, spindle cranks can be nearly a pound lighter while being much stiffer.

Last edited by Marcus_Ti; 08-13-19 at 07:01 PM.
Marcus_Ti is offline  
Old 08-13-19, 07:11 PM
  #11  
rccardr 
aka: Dr. Cannondale
 
rccardr's Avatar
 
Join Date: Jul 2009
Posts: 7,839
Mentioned: 234 Post(s)
Tagged: 0 Thread(s)
Quoted: 2144 Post(s)
Liked 3,373 Times in 1,193 Posts
Originally Posted by terrymorse
Just say "no" to square taper. It's junk technology that eats crank arms, and possibly injures the rider.

If the crank arm becomes loose, which happens when the fixing bolt gets loose or falls out, the crank arm is ruined.

If the fixing bolt is over tightened, which happens a lot, the crank arm "walks" up the taper. The crank arm develops a crack from being overstressed, then it breaks off without warning—usually when the rider is standing on the pedals—sending the rider to the ground.

Just. Say. No.
Hunh.
Wonder why, over several decades & tens of thousands of miles, none of this has ever happened to me. Ever.
__________________
Hard at work in the Secret Underground Laboratory...
rccardr is offline  
Likes For rccardr:
Old 08-13-19, 07:16 PM
  #12  
terrymorse 
climber has-been
 
terrymorse's Avatar
 
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 6,959

Bikes: Scott Addict R1, Felt Z1

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3298 Post(s)
Liked 3,389 Times in 1,714 Posts
Originally Posted by rccardr
Hunh.
Wonder why, over several decades & tens of thousands of miles, none of this has ever happened to me. Ever.
Luck.
__________________
Ride, Rest, Repeat. ROUVY: terrymorse


terrymorse is offline  
Likes For terrymorse:
Old 08-13-19, 07:22 PM
  #13  
rccardr 
aka: Dr. Cannondale
 
rccardr's Avatar
 
Join Date: Jul 2009
Posts: 7,839
Mentioned: 234 Post(s)
Tagged: 0 Thread(s)
Quoted: 2144 Post(s)
Liked 3,373 Times in 1,193 Posts
Originally Posted by terrymorse
Luck.
Mmmmmmmmm.....that's a lot of luck.
__________________
Hard at work in the Secret Underground Laboratory...
rccardr is offline  
Likes For rccardr:
Old 08-13-19, 07:30 PM
  #14  
terrymorse 
climber has-been
 
terrymorse's Avatar
 
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 6,959

Bikes: Scott Addict R1, Felt Z1

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3298 Post(s)
Liked 3,389 Times in 1,714 Posts
Originally Posted by rccardr
Mmmmmmmmm.....that's a lot of luck.
Some people live charmed lives. Others, not so much.

https://www.sheldonbrown.com/brandt/...ng-cranks.html
__________________
Ride, Rest, Repeat. ROUVY: terrymorse


terrymorse is offline  
Old 08-13-19, 07:38 PM
  #15  
HTupolev
Senior Member
 
Join Date: Apr 2015
Location: Seattle
Posts: 4,261
Mentioned: 41 Post(s)
Tagged: 0 Thread(s)
Quoted: 1971 Post(s)
Liked 1,297 Times in 629 Posts
Originally Posted by terrymorse
If the fixing bolt is over tightened, which happens a lot, the crank arm "walks" up the taper. The crank arm develops a crack from being overstressed, then it breaks off without warning—usually when the rider is standing on the pedals—sending the rider to the ground.
The crank arm "walks up" the taper with every installation, even if it was torqued properly. This is a form of long-term wear for square-taper cranks. But, it typically takes a very large number of installations for a failure to occur, either from a bottom-out of the taper or a fatigue crack.

Excessive torque will move the starting point for that installation cycle slightly farther up the taper, which means that the crank will suffer more of that permanent wear than it should have. In today's cartridge-BB world of very infrequent re-installations, this almost never becomes a problem in the first place.
To cause a problematic amount of added walk-up on a single installation from overtorque, you'd have to go really nuts. Like "bust out a huge cheater bar for no reason" nuts. The kind of behavior that will wreck any kind of crank interface.

(What is a big problem for taper interface wear is when someone misinterprets the walk-up as loosening of the fixing bolt, and repeatedly re-tightens the bolt after every few rides. Each time this is done, it restarts the walk-up cycle and puts a re-installation worth of wear on the interface.)
HTupolev is offline  
Likes For HTupolev:
Old 08-14-19, 07:26 AM
  #16  
rosefarts
With a mighty wind
 
Join Date: May 2015
Posts: 2,546
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1070 Post(s)
Liked 837 Times in 472 Posts
Terry, I think you're being a little dramatic.

To the OP, it's a little heavier and required multiple sizes to be made. The nee outboard ones are lighter and streamline the manufacturing process.

Square taper bearings almost always last longer.

Broken cranks or flex has nothing to do with it. Maybe marketing.
rosefarts is offline  
Likes For rosefarts:
Old 08-14-19, 08:16 AM
  #17  
3alarmer 
Friendship is Magic
 
3alarmer's Avatar
 
Join Date: Nov 2010
Location: Sacramento, CA
Posts: 22,898

Bikes: old ones

Mentioned: 304 Post(s)
Tagged: 0 Thread(s)
Quoted: 26212 Post(s)
Liked 10,180 Times in 7,062 Posts
Originally Posted by terrymorse
Just say "no" to square taper. It's junk technology that eats crank arms, and possibly injures the rider.

If the crank arm becomes loose, which happens when the fixing bolt gets loose or falls out, the crank arm is ruined.



Just. Say. No.
...no.
3alarmer is offline  
Old 08-14-19, 08:55 AM
  #18  
ThermionicScott 
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,620

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: 3868 Post(s)
Liked 2,559 Times in 1,574 Posts
Originally Posted by HTupolev
In today's cartridge-BB world of very infrequent re-installations, this almost never becomes a problem in the first place.
That's what I'm hoping for with all of my old bikes. After installing cartridge BBs, the cranks just stay on, year after year.
__________________
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 08-14-19, 10:42 AM
  #19  
davidad
Senior Member
 
Join Date: Feb 2009
Posts: 6,660
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 582 Post(s)
Liked 171 Times in 138 Posts
Originally Posted by terrymorse
Just say "no" to square taper. It's junk technology that eats crank arms, and possibly injures the rider.

If the crank arm becomes loose, which happens when the fixing bolt gets loose or falls out, the crank arm is ruined.

If the fixing bolt is over tightened, which happens a lot, the crank arm "walks" up the taper. The crank arm develops a crack from being overstressed, then it breaks off without warning—usually when the rider is standing on the pedals—sending the rider to the ground.

Just. Say. No.
I,m sorry, but you don't have a clue. If a sq. taper crank is torqued properly it will not walk up the taper until it cracks un less someone keeps retorquing the bolt.
The reason for the newer BBs is strictly marketing to people who need the "new and improved model". Otherwise there wouldn't be so many.
davidad is offline  
Likes For davidad:
Old 08-14-19, 11:26 AM
  #20  
ThermionicScott 
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,620

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: 3868 Post(s)
Liked 2,559 Times in 1,574 Posts
Originally Posted by davidad
I,m sorry, but you don't have a clue. If a sq. taper crank is torqued properly it will not walk up the taper until it cracks un less someone keeps retorquing the bolt.
The reason for the newer BBs is strictly marketing to people who need the "new and improved model". Otherwise there wouldn't be so many.
Terry isn't drawing attention to the fact, but he knew the guy who wrote that stuff.
__________________
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 08-14-19, 05:23 PM
  #21  
TiHabanero
Senior Member
 
Join Date: Nov 2012
Posts: 4,429
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1724 Post(s)
Liked 1,346 Times in 703 Posts
The greats of pro cycling used square taper without issues. I have had square taper on every bike since the beginning of time, and have had zero issues. I know some seriously powerful riders that use square taper without issues. I even use, God forbid, Shimano UN52 square taper BB with Campagnolo Nuovo Record crank, and have had zero issues. Been using it for 20 years this way.

Marketing BS for sure.
TiHabanero is offline  
Old 08-14-19, 05:30 PM
  #22  
terrymorse 
climber has-been
 
terrymorse's Avatar
 
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 6,959

Bikes: Scott Addict R1, Felt Z1

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3298 Post(s)
Liked 3,389 Times in 1,714 Posts
Originally Posted by davidad
I,m sorry, but you don't have a clue. If a sq. taper crank is torqued properly it will not walk up the taper until it cracks un less someone keeps retorquing the bolt.
Please note that I stated "if the fixing bolt is over tightened". I stand by my statement. Even a crank arm assembled with the specified fixing bolt torque will walk up the taper, as evidenced by the looseness of the fixing bolt after some use. The bolt becomes loose because the arm has moved up the taper during use. If the cyclist is lucky, that will not be enough to initiate a fatigue crack.

As you state, re-tightening the fixing bolt will continue the crank arm's journey up the taper, increasing the possibility of a fracture.

And believe it or not, I do "have a clue". Would you like to compare CVs?

Originally Posted by davidad
The reason for the newer BBs is strictly marketing to people who need the "new and improved model". Otherwise there wouldn't be so many.
Two words: proprietary & patents.
__________________
Ride, Rest, Repeat. ROUVY: terrymorse


terrymorse is offline  
Old 08-14-19, 06:12 PM
  #23  
3alarmer 
Friendship is Magic
 
3alarmer's Avatar
 
Join Date: Nov 2010
Location: Sacramento, CA
Posts: 22,898

Bikes: old ones

Mentioned: 304 Post(s)
Tagged: 0 Thread(s)
Quoted: 26212 Post(s)
Liked 10,180 Times in 7,062 Posts
...it's a wonder more people haven't been killed by square taper BB's.
3alarmer is offline  
Likes For 3alarmer:
Old 08-14-19, 06:24 PM
  #24  
terrymorse 
climber has-been
 
terrymorse's Avatar
 
Join Date: Dec 2004
Location: Palo Alto, CA
Posts: 6,959

Bikes: Scott Addict R1, Felt Z1

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 3298 Post(s)
Liked 3,389 Times in 1,714 Posts
Originally Posted by ThermionicScott
Terry isn't drawing attention to the fact, but he knew the guy who wrote that stuff.
I suspect you're thinking of this guy. I knew him when he had hair (yes, I'm old).
__________________
Ride, Rest, Repeat. ROUVY: terrymorse


terrymorse is offline  
Likes For terrymorse:
Old 08-14-19, 07:46 PM
  #25  
Mad Honk 
Senior Member
 
Join Date: May 2019
Location: Bloomington, IN
Posts: 2,919

Bikes: Paramount, Faggin, Ochsner, Ciocc, Basso

Mentioned: 114 Post(s)
Tagged: 0 Thread(s)
Quoted: 1273 Post(s)
Liked 1,806 Times in 1,094 Posts
I guess I'm a bit old skool on this one. 3 RAAMs, and a bunch of time at the Major Taylor in Indy, and countless hours in the saddle for commutes and daily cycling and no failures in my square taper bottom brackets. I volunteer at a local bike project and I see a lot of over tightened crank arms but none that have ever failed. Maybe wee need to re-think putting aluminium crank arms on steel spindles. For my 200 pound body though they work quite nicely. Smiles, MH

Last edited by Mad Honk; 08-15-19 at 08:43 AM. Reason: correction
Mad Honk is offline  

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.