Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

Bent pedal shafts

Notices
Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

Bent pedal shafts

Old 01-19-16, 11:07 AM
  #1  
MiloFrance 
Not riding enough
Thread Starter
 
MiloFrance's Avatar
 
Join Date: Aug 2014
Location: Capestang, France
Posts: 1,356

Bikes: Lots of French, some British and a couple of Italian

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 241 Post(s)
Liked 106 Times in 54 Posts
Bent pedal shafts

Evening all. Anyone have any tips on straightening bent pedals? I have several pairs, don't want to bin them, can't get comfy riding them...
__________________
I'm on holiday whenever I ride my bike
MiloFrance is offline  
Old 01-19-16, 11:23 AM
  #2  
SJX426 
Senior Member
 
SJX426's Avatar
 
Join Date: May 2008
Location: Fredericksburg, Va
Posts: 8,934

Bikes: '73 Bottecchia Giro d'Italia, '83 Colnago Superissimo, '84 Trek 610, '84 Trek 760, '88 Pinarello Veneto, '88 De Rosa Pro, '89 Pinarello Montello, '94 Burley Duet, 97 Specialized RockHopper, 2010 Langster, Tern Link D8

Mentioned: 63 Post(s)
Tagged: 0 Thread(s)
Quoted: 1364 Post(s)
Liked 1,552 Times in 817 Posts
No. Ever try to straighten a coat hanger? Did they bend while you were using them? If so, they will likely return to the same condition.

If not, you could take a chance with the following approach:

the assumption is that the bend is either toward the crank arm(hit the road while cornering) or the other direction. You need to determine the bend direction to move it in the opposite direction.

Find a steel crank arm that has the same threads. If both pedals axles need to be "adjusted", you will need both sides.

Mount only the axle to the crank arm. Place the crank arm in a vice as close to the pedal with enough clearance to allow you to be able to leverage the axle.

The bend is likely between the threads and the first bearing surface at the smallest diameter of the shaft between those two locations.

find a pipe with an inside diameter that will allow you to slip it over the axle to the point were the bend is.

Make sure it is long enough to be able to easily apply force. Apply force slowly with small incremental changes until straight. Use a square between the crank and the center line of the axle.

Don't know if this would work but this is an approach. Good luck! Looking forward to reading what other brave soles suggest other than replacing the axle.
__________________
Bikes don't stand alone. They are two tired.
SJX426 is offline  
Old 01-19-16, 11:27 AM
  #3  
repechage
Senior Member
 
Join Date: Jun 2006
Posts: 18,006
Mentioned: 121 Post(s)
Tagged: 0 Thread(s)
Quoted: 2622 Post(s)
Liked 1,630 Times in 1,204 Posts
I would not trust one even if you were able to realign one.

Some Lyotard pedals have a reputation for failing even without trauma.
Campagnolo pedal axles can be purchased by themselves.
repechage is offline  
Old 01-19-16, 11:52 AM
  #4  
ramzilla
Senior Member
 
ramzilla's Avatar
 
Join Date: Dec 2014
Location: Fernandina Beach FL
Posts: 3,540

Bikes: Vintage Japanese Bicycles, Tange, Ishiwata, Kuwahara

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 689 Post(s)
Liked 282 Times in 227 Posts
If the pedal shaft is bent then you need to discard it. Once steel reaches it's yield point (bent) it loses most all of it's strength. Every engineer knows this. Sorry but, those pedals are a disaster just waiting to happen.
ramzilla is offline  
Likes For ramzilla:
Old 01-19-16, 12:05 PM
  #5  
MiloFrance 
Not riding enough
Thread Starter
 
MiloFrance's Avatar
 
Join Date: Aug 2014
Location: Capestang, France
Posts: 1,356

Bikes: Lots of French, some British and a couple of Italian

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 241 Post(s)
Liked 106 Times in 54 Posts
Thanks Ramzilla, but there are far more variables than that. I am an engineer.
__________________
I'm on holiday whenever I ride my bike
MiloFrance is offline  
Likes For MiloFrance:
Old 01-19-16, 02:21 PM
  #6  
LeicaLad 
Senior Member
 
Join Date: Jun 2010
Location: Work in Asia, now based in Vienna, VA
Posts: 1,758
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
Liked 35 Times in 22 Posts
Yes, but if you've ever had a pedal suddenly snap as you're mashing up a hill. . , trust me, you would not ride such pedals. period.

A good engineer should know that, too. Not to be snide, I only mean that safety really suggests you retire/decommission those pedals.
__________________
1959 Hilton Wrigley Connoisseur (my favorite!)
1963 Hetchins Mountain King
1971 Gitane Tour de France (original owner)
* 1971 Gitane Super Corsa (crashed)
* rebuilt as upright cruiser
1971 Gitane Super Corsa #2 (sweet replacement)
1980 Ritchey Road Touring (The Grail Bike)
1982 Tom Ritchey Everest
(replacing stolen 1981 TR Everest custom)
1982 Tom Ritchey McKinley (touring pickup truck)
1985 ALAN Record (Glued & Screwed. A gift.)
LeicaLad is offline  
Old 01-19-16, 03:29 PM
  #7  
busdriver1959
Senior Member
 
Join Date: Feb 2011
Posts: 804
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 56 Post(s)
Liked 7 Times in 3 Posts
Originally Posted by LeicaLad View Post
Yes, but if you've ever had a pedal suddenly snap as you're mashing up a hill. . , trust me, you would not ride such pedals. period.

A good engineer should know that, too. Not to be snide, I only mean that safety really suggests you retire/decommission those pedals.
I'm not an engineer but there must be more variables. How do fork blades get their curve without losing all their strength? I'm not trying to be a troll here. Really want to know.
busdriver1959 is offline  
Old 01-20-16, 06:01 AM
  #8  
SJX426 
Senior Member
 
SJX426's Avatar
 
Join Date: May 2008
Location: Fredericksburg, Va
Posts: 8,934

Bikes: '73 Bottecchia Giro d'Italia, '83 Colnago Superissimo, '84 Trek 610, '84 Trek 760, '88 Pinarello Veneto, '88 De Rosa Pro, '89 Pinarello Montello, '94 Burley Duet, 97 Specialized RockHopper, 2010 Langster, Tern Link D8

Mentioned: 63 Post(s)
Tagged: 0 Thread(s)
Quoted: 1364 Post(s)
Liked 1,552 Times in 817 Posts
@busdriver1959 - The answer to your question is all about material composition, physical configuration (shape), manufacturing process and the resulting mechanical properties.

It is not a given that once steel is bent that it becomes "weaker." More often than not, it becomes stronger but will fail sooner. If you take a piece of sheet metal that you can bend with your hands, you will notice that as you bend it back and forth, the material may actually become some what wavy. The reason is that the first bend becomes "work hardened" and stronger than the rest of the material, so the material bends at a different location. With repeated work hardening as a result of deformation, the material changes its crystalline structure resulting in it being "brittle" prior to failing.

Without knowing the material composition, etc. any answer is speculation as to the results of trying to bend the axle shaft back. There is risk in everything we do, bending an axle back, bending the forks both initially and in repair or riding in traffic.

Again, the mechanical properties of the steel are impacted by the stress and strain it is exposed to. We didn't even talk about the impact of temperature.

In the case of the fork bends, they don't loose all their strength.
__________________
Bikes don't stand alone. They are two tired.
SJX426 is offline  
Old 01-20-16, 07:30 AM
  #9  
Bike tinker man
Senior Member
 
Join Date: Dec 2014
Location: Retired to Penang Malaysia originally from UK
Posts: 344

Bikes: My 1978 Raleigh from new, 1995 Trek, & constant changing & rebuilding of other bike projects.

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 41 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
Considering the pedal shaft is steel & I assume the crank arms you are screwing it into is alloy, I would as above just throw them out, a pedal comes adrift whilst you are pedaling you can pull leg muscles with the sudden release.
Bike tinker man is offline  
Old 01-20-16, 08:17 AM
  #10  
SJX426 
Senior Member
 
SJX426's Avatar
 
Join Date: May 2008
Location: Fredericksburg, Va
Posts: 8,934

Bikes: '73 Bottecchia Giro d'Italia, '83 Colnago Superissimo, '84 Trek 610, '84 Trek 760, '88 Pinarello Veneto, '88 De Rosa Pro, '89 Pinarello Montello, '94 Burley Duet, 97 Specialized RockHopper, 2010 Langster, Tern Link D8

Mentioned: 63 Post(s)
Tagged: 0 Thread(s)
Quoted: 1364 Post(s)
Liked 1,552 Times in 817 Posts
In all fairness, the question was how to straighten them, not what to do with them, likelihood of failure or what might happen if they fail.
__________________
Bikes don't stand alone. They are two tired.
SJX426 is offline  
Old 01-20-16, 08:37 AM
  #11  
repechage
Senior Member
 
Join Date: Jun 2006
Posts: 18,006
Mentioned: 121 Post(s)
Tagged: 0 Thread(s)
Quoted: 2622 Post(s)
Liked 1,630 Times in 1,204 Posts
True enough. once the pedals get straightened the probability greatly increases that they get used again. I really think that is unwise.
repechage is offline  
Old 01-20-16, 09:08 AM
  #12  
rootboy 
Senior Member
 
rootboy's Avatar
 
Join Date: Apr 2005
Location: Wherever
Posts: 16,755
Mentioned: 90 Post(s)
Tagged: 0 Thread(s)
Quoted: 554 Post(s)
Likes: 0
Liked 123 Times in 72 Posts
Metal fatigue. Not something to be taken lightly in a component used to transfer power to a drive train.
Especially if the component fails, and you run the risk of castrating yourself.
rootboy is offline  
Old 01-20-16, 09:49 AM
  #13  
Salamandrine 
Senior Member
 
Join Date: Oct 2015
Location: Los Angeles
Posts: 6,287

Bikes: 78 Masi Criterium, 68 PX10, 2016 Mercian King of Mercia, Rivendell Clem Smith Jr

Mentioned: 120 Post(s)
Tagged: 0 Thread(s)
Quoted: 2317 Post(s)
Liked 584 Times in 421 Posts
Mechanic here. I won't argue engineering.

They are pretty difficult to straighten. Best I've could ever do was straighter than they were before. It's generally not worth the trouble.

Anyhow, don't try to do it on the crank arms unless it's a really cheap bike you don't care about. You are more likely to bend the crank arm then the pedal shaft. *

Best case: disassemble the pedals, screw the axle into a big chunk of steel that is tapped to take the pedal. Put that into a huge vise, and straighten the axle with a heavy pipe. (of course most people would use an old steel crank arm instead of a custom chunk of steel)

*BTW, sometimes it's the crankarm that is bent, not the pedal.

Last edited by Salamandrine; 01-20-16 at 10:15 AM.
Salamandrine is offline  
Old 01-20-16, 11:17 AM
  #14  
CroMo Mike 
All Campy All The Time
 
CroMo Mike's Avatar
 
Join Date: Nov 2013
Location: Richmond, Virginia
Posts: 1,388

Bikes: Listed in my signature.

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 156 Post(s)
Liked 74 Times in 51 Posts
A competent machine shop could straighten them but the cost would make buying new a better option. As a home machinist I chucked several different good condition pedals in the lathe and found they weren't real straight anyway.
CroMo Mike is online now  
Old 05-07-22, 07:54 PM
  #15  
dnbdonaldson
Newbie
 
Join Date: May 2022
Posts: 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by ramzilla View Post
If the pedal shaft is bent then you need to discard it. Once steel reaches it's yield point (bent) it loses most all of it's strength. Every engineer knows this. Sorry but, those pedals are a disaster just waiting to happen.
It actually gets stronger when bent but also more brittle (cold worked). More likely to shear b/c it is brittle.
dnbdonaldson is offline  
Old 05-07-22, 11:00 PM
  #16  
Steel Charlie
Full Member
 
Steel Charlie's Avatar
 
Join Date: Apr 2009
Posts: 392
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 134 Post(s)
Liked 144 Times in 87 Posts
Bin them. Pedals are cheap. Life is too short to putz around with such an easily replaced POS that was obviously poor quality to begin with.
Not to mention bent pedal shafts will eat your ankles and knees.

Last edited by Steel Charlie; 05-07-22 at 11:03 PM.
Steel Charlie is offline  
Old 05-07-22, 11:58 PM
  #17  
scarlson 
Senior Member
 
scarlson's Avatar
 
Join Date: Jun 2010
Location: Medford MA
Posts: 1,904

Bikes: Ron Cooper touring, 1959 Jack Taylor 650b ladyback touring tandem, Vitus 979, Joe Bell painted Claud Butler Dalesman, Colin Laing curved tube tandem, heavily-Dilberted 1982 Trek 6xx, RenÚ Herse tandem

Mentioned: 69 Post(s)
Tagged: 0 Thread(s)
Quoted: 881 Post(s)
Liked 1,184 Times in 629 Posts
Such zombie
Very resurrect
Much dogpile

I've straightened pedals before. Within reason it's fine. Some vintage pedal axles are quite soft and amenable to all sorts of massaging with minimal loss in durability. I like to use something that spins the axle so I can see what direction the wobble is in. A drill chuck or a lathe or a milling machine. One reason to do it is if you have a pedal that's impossible to get a replacement for, such as the '50s Dural Bramptons whose axles I fixed.
__________________
Owner & co-founder, Cycles RenÚ Hubris. Unfortunately attaching questionable braze-ons to perfectly good frames since about 2015. With style.
scarlson is offline  
Old 05-08-22, 08:55 AM
  #18  
oneclick 
Senior Member
 
Join Date: Feb 2020
Posts: 2,122
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 787 Post(s)
Likes: 0
Liked 839 Times in 515 Posts
Originally Posted by rootboy View Post
Metal fatigue. Not something to be taken lightly in a component used to transfer power to a drive train.
Especially if the component fails, and you run the risk of castrating yourself.
Bending - as in making a permanent bend - is NOT "fatigue".

Engineers (as well as some people who are NOT engineers) know this.
oneclick is offline  
Old 05-08-22, 12:29 PM
  #19  
SurferRosa
se˝or miembro
 
SurferRosa's Avatar
 
Join Date: Dec 2018
Location: Pac NW
Posts: 6,405

Bikes: Old school lightweights

Mentioned: 77 Post(s)
Tagged: 0 Thread(s)
Quoted: 2681 Post(s)
Liked 3,792 Times in 2,014 Posts
What is a pedal "shaft"?
SurferRosa is offline  
Old 05-08-22, 12:38 PM
  #20  
zandoval 
Senior Member
 
zandoval's Avatar
 
Join Date: May 2010
Location: Bastrop Texas
Posts: 3,481

Bikes: Univega, Peu P6, Peu PR-10, Ted Williams, Peu UO-8, Peu UO-18 Mixte, Peu Dolomites

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 575 Post(s)
Liked 904 Times in 583 Posts
It's possible but...

Originally Posted by Salamandrine View Post
...generally not worth the trouble.
And you know this... Ha
__________________
No matter where your at... There you are... Δf:=f(1/2)-f(-1/2)
zandoval is offline  
Old 05-08-22, 12:45 PM
  #21  
repechage
Senior Member
 
Join Date: Jun 2006
Posts: 18,006
Mentioned: 121 Post(s)
Tagged: 0 Thread(s)
Quoted: 2622 Post(s)
Liked 1,630 Times in 1,204 Posts
Originally Posted by scarlson View Post
Such zombie
Very resurrect
Much dogpile

I've straightened pedals before. Within reason it's fine. Some vintage pedal axles are quite soft and amenable to all sorts of massaging with minimal loss in durability. I like to use something that spins the axle so I can see what direction the wobble is in. A drill chuck or a lathe or a milling machine. One reason to do it is if you have a pedal that's impossible to get a replacement for, such as the '50s Dural Bramptons whose axles I fixed.
and you could probably Make replacements given enough time.

I think the trick for a repair would be to replicate the heat treat.
performing a Rockwell hardness test would provide an indication to the extent of the original part.
the Lyotard 460? Pedals with the stepped, axle, spindle, shaft, your choice of name, are the parts I have seen enough of to at least be wary of. Most of these parts are now pretty old, age is not the issue but abuse in service. The abrupt steps in diameter are not the most low risk design.

I am conservative and gravity storm averse.
repechage is offline  
Old 06-21-22, 09:01 PM
  #22  
ramzilla
Senior Member
 
ramzilla's Avatar
 
Join Date: Dec 2014
Location: Fernandina Beach FL
Posts: 3,540

Bikes: Vintage Japanese Bicycles, Tange, Ishiwata, Kuwahara

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 689 Post(s)
Liked 282 Times in 227 Posts
A bent pedal shaft is fine as long as your going downhill or cruising along a flat road with the wind at your back. But, soon as you climb out of the saddle in order to climb a steep hill watch out. That's when the shaft will snap off and, probably result in a nasty injury.

Without destructive testing how would we ever know...............................RAMZILLA
ramzilla is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
srinath.the.man
Bicycle Mechanics
6
03-11-16 08:32 AM
Wozza2014
Bicycle Mechanics
12
01-10-15 12:05 PM
ilikebikes
Classic & Vintage
20
07-12-14 09:01 PM
Hiyawaan
Clydesdales/Athenas (200+ lb / 91+ kg)
11
12-31-13 02:19 AM
Turtle Speed
Bicycle Mechanics
15
08-14-13 09:51 AM

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.