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

Lengthening A Steerer Tube

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.

Lengthening A Steerer Tube

Old 09-16-19, 06:33 PM
  #26  
Kapusta
Advanced Slacker
 
Kapusta's Avatar
 
Join Date: Feb 2017
Posts: 6,187

Bikes: Soma Fog Cutter, Surly Wednesday, Canfielld Tilt

Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 2749 Post(s)
Liked 2,516 Times in 1,422 Posts
You could have just brought it to a bike shop that has a tube stretcher.
Kapusta is offline  
Old 09-17-19, 07:47 AM
  #27  
big john
Senior Member
 
big john's Avatar
 
Join Date: Sep 2005
Location: In the foothills of Los Angeles County
Posts: 25,107
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 8191 Post(s)
Liked 8,851 Times in 4,396 Posts
Originally Posted by Kapusta
You could have just brought it to a bike shop that has a tube stretcher.
I think you need a sky hook with that.

New fork!
big john is offline  
Old 09-17-19, 08:17 AM
  #28  
Last ride 76 
1/2 as far in 2x the time
 
Last ride 76's Avatar
 
Join Date: Nov 2013
Location: Northern Bergen County, NJ
Posts: 1,935

Bikes: Yes, Please.

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 499 Post(s)
Liked 285 Times in 222 Posts
Perhaps bringing it to a company that does carbon repairs, would have been a reasonable solution. I'm not sure that diy is the best way to deal with carbon...
but if you're the guy who modded the trek Y-foil, go right ahead. Some hard knocks are not worth it.
Last ride 76 is offline  
Old 09-17-19, 08:30 AM
  #29  
AlmostTrick
Tortoise Wins by a Hare!
 
AlmostTrick's Avatar
 
Join Date: Feb 2006
Location: Looney Tunes, IL
Posts: 7,398

Bikes: Wabi Special FG, Raleigh Roper, Nashbar AL-1, Miyata One Hundred, '70 Schwinn Lemonator and More!!

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 1549 Post(s)
Liked 941 Times in 504 Posts
Good idea, as unlike carbon fiber, wood does not asplode. But... termites.
AlmostTrick is offline  
Old 09-17-19, 11:35 AM
  #30  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 7,768
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 6882 Post(s)
Liked 10,874 Times in 4,638 Posts
What an incredibly foolish thing to do.


On the bright side: when the whole jerry-rigged fork comes apart and causes a crash, perhaps you will be concussed badly enough to not remember that it's your own fault.
Koyote is offline  
Old 09-17-19, 01:30 PM
  #31  
Steelman54 
Full Member
 
Join Date: Jun 2014
Location: SW Ohio
Posts: 281

Bikes: Allegro Model 77, Gitane Team Pro SLX, Waterford R2200

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 68 Post(s)
Liked 57 Times in 38 Posts
Further thought on this one, the joint is likely a potential crack starter in a fatigue environment (pulling on handlebars while climbing for example). Seems risky to ride for any length of time/mileage.
Steelman54 is offline  
Likes For Steelman54:
Old 09-17-19, 05:20 PM
  #32  
Miele Man
Senior Member
 
Join Date: Jun 2014
Location: Ontario, Canada
Posts: 4,655

Bikes: iele Latina, Miele Suprema, Miele Uno LS, Miele Miele Beta, MMTB, Bianchi Model Unknown, Fiori Venezia, Fiori Napoli, VeloSport Adamas AX

Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1324 Post(s)
Liked 927 Times in 640 Posts
To safely join to ends like that you need to chamfer the inside of one part and the outside of the other part to form a scarf joint. That's what is done in wood to joining two pieces together to make the board longer. IIRC it's 1 to 8 or 1 to 12. So, for example, if the wall thickness of a tube is 1mm then the chamfer would be either 8mm or 12mm depending on which ratio you used. The higher the ratio the stronger the resulting joint. A butt joint is the WEAKEST type of joint.

Cheers
Miele Man is offline  
Old 09-17-19, 05:41 PM
  #33  
79pmooney
Senior Member
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 12,830

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 128 Post(s)
Tagged: 0 Thread(s)
Quoted: 4745 Post(s)
Liked 3,861 Times in 2,510 Posts
It was common for racers many years ago to jam dowel down their steerers when they were racing bikes they didn't trust (and some brands were well known for such failures).
79pmooney is offline  
Old 09-17-19, 05:48 PM
  #34  
79pmooney
Senior Member
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Posts: 12,830

Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder

Mentioned: 128 Post(s)
Tagged: 0 Thread(s)
Quoted: 4745 Post(s)
Liked 3,861 Times in 2,510 Posts
An interesting calculation to make would be the strength in bending and shear of the CF steerer and the dowel of slightly smaller diameter. I'd also do the same with a traditional steel steerer as a reality check. If the work is up to the levels of either the steel or CF, I'd have no worries - if I knew I did a good job. I would not include the epoxy in the calcs but I would use plenty and with real care to get everything bonded and the crak between the steerers filled.

Ben
79pmooney is offline  
Old 09-17-19, 06:24 PM
  #35  
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: 18320 Post(s)
Liked 4,489 Times in 3,338 Posts
Keep in mind, 20 years ago, nearly all bikes had a simple friction lap joint in the steering.



Granted, most of the steer tubes were steel, and they weren't without issues, such as the internal expanders on the left causing cracking of some stems.

Nonetheless, the style was even raced, and many riders actually survived.
CliffordK is offline  
Old 09-17-19, 06:33 PM
  #36  
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: 18320 Post(s)
Liked 4,489 Times in 3,338 Posts
Originally Posted by Miele Man
To safely join to ends like that you need to chamfer the inside of one part and the outside of the other part to form a scarf joint. That's what is done in wood to joining two pieces together to make the board longer. IIRC it's 1 to 8 or 1 to 12. So, for example, if the wall thickness of a tube is 1mm then the chamfer would be either 8mm or 12mm depending on which ratio you used. The higher the ratio the stronger the resulting joint. A butt joint is the WEAKEST type of joint.

Cheers
One thinks of modern carbon fiber bike frames being monocoque, but in reality, they are made of many lap/chamfer joints that are epoxied together at the factory. And, they are strong enough to hold the bike together.

In this case, a chamfered joint would be strong, if precisely machined, and backed by an internal sleeve.
CliffordK is offline  
Old 09-17-19, 06:40 PM
  #37  
Mad Honk 
Senior Member
 
Join Date: May 2019
Location: Bloomington, IN
Posts: 2,939

Bikes: Paramount, Faggin, Ochsner, Ciocc, Basso

Mentioned: 114 Post(s)
Tagged: 0 Thread(s)
Quoted: 1285 Post(s)
Liked 1,837 Times in 1,110 Posts
So If you want to reinforce a carbon tube why not epoxy in a steel section. Far safer and less likely to fail. JMHO, MH
Mad Honk is offline  
Old 09-17-19, 07:35 PM
  #38  
rosefarts
With a mighty wind
 
Join Date: May 2015
Posts: 2,555
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1073 Post(s)
Liked 841 Times in 475 Posts
Use aluminum instead of dowel and pin both tubes in addition to the epoxy.

Decent idea, wrong material used.
rosefarts is offline  
Old 09-17-19, 07:56 PM
  #39  
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: 18320 Post(s)
Liked 4,489 Times in 3,338 Posts
Originally Posted by rosefarts
Use aluminum instead of dowel and pin both tubes in addition to the epoxy.

Decent idea, wrong material used.
Galvanic Corrosion will either bond everything together... or cause it to shatter.
CliffordK is offline  
Old 09-17-19, 08:25 PM
  #40  
rosefarts
With a mighty wind
 
Join Date: May 2015
Posts: 2,555
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1073 Post(s)
Liked 841 Times in 475 Posts
Originally Posted by CliffordK
Galvanic Corrosion will either bond everything together... or cause it to shatter.
I've spent a lot of time bolting climbing routes in a seaside locale. I probably have personally experienced galvanic corrosion more than most here.

I stand by my earlier statement. Epoxied aluminum inside a head tube simply will never see enough moisture and electrolytes to worry about.
rosefarts is offline  
Old 09-17-19, 08:38 PM
  #41  
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: 18320 Post(s)
Liked 4,489 Times in 3,338 Posts
Originally Posted by rosefarts
I've spent a lot of time bolting climbing routes in a seaside locale. I probably have personally experienced galvanic corrosion more than most here.

I stand by my earlier statement. Epoxied aluminum inside a head tube simply will never see enough moisture and electrolytes to worry about.
The issue is specifically carbon fiber + aluminum.

I'm not quite sure what other conditions are necessary, as the two are frequently bonded together, sometimes with problems, often not.

If there is a well formed oxide layer on the aluminum, plus a thick epoxy layer, tit may be adequate to protect the aluminum.

Nonetheless, the issue could be avoided entirely by choosing compatible materials such as carbon fiber.

Wood also would not be susceptible to the corrosion, but could have other issues, especially with moisture if not well sealed.
CliffordK is offline  
Old 09-17-19, 08:56 PM
  #42  
cecu
Member
 
Join Date: Jul 2019
Posts: 33
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Liked 6 Times in 5 Posts
Just to add to this, the dowel and the bonded carbon fibre being "strong" isn't necessarily a good thing.
It needs to take in consideration the way a force is dissipated on a given "original" piece/section.


By adding a dowel and/or a piece of bonded carbon fibre to a section, if the strength of said section is different from the original, you're also changing the way forces/stresses are dissipated, creating weak spots.

As said above by a few people already, this does not sound very safe, especially given that a failure of such component is pretty catastrophic.
cecu is offline  
Old 09-18-19, 09:01 AM
  #43  
RubeRad
Keepin it Wheel
 
RubeRad's Avatar
 
Join Date: Aug 2011
Location: San Diego
Posts: 10,238

Bikes: Surly CrossCheck, Krampus

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked 3,400 Times in 2,511 Posts
Originally Posted by CliffordK
Keep in mind, 20 years ago, nearly all bikes had a simple friction lap joint in the steering.


That's a nice diagram, but it seems odd to me that it depicts the wedging action happening at the butted section. In practice, wouldn't it be in the non-butted section, where more linear contact is available?
RubeRad is offline  
Old 09-18-19, 09:33 AM
  #44  
Unca_Sam
The dropped
 
Unca_Sam's Avatar
 
Join Date: Oct 2018
Location: Columbus, OH
Posts: 2,406

Bikes: Pake C'Mute Touring/Commuter Build, 1989 Kona Cinder Cone, 1995 Trek 5200, 1973 Raleigh Super Course FG, 1960/61 Montgomery Ward Hawthorne "thrift" 3 speed, by Hercules (sold) : 1966 Schwinn Deluxe Racer (sold)

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 1739 Post(s)
Liked 1,014 Times in 696 Posts
Originally Posted by RubeRad
That's a nice diagram, but it seems odd to me that it depicts the wedging action happening at the butted section. In practice, wouldn't it be in the non-butted section, where more linear contact is available?
I remember the diagram, and I think it's from Sheldon's website discussing proper mounting of quill stems. You're right. This is a diagram of a too long stem or high butted section preventing the wedge/expander from binding adequately.

While I enjoy reading how we could solve this issue, no one has considered the cost/benefit. A new fork costs $170 on up. What does it cost to machine an identical conical chamfer into the tube and donor steerer and epoxy with a carbon overlay? If it were wood, you might key the chamfer because the only resistance to rotational shear would otherwise be the glue bond, I'm not sure if that's helpful in a layered material like carbon fiber. Unless you're looking at $250+ for a new fork, I'd think replacing is the most cost effective option.
Unca_Sam is offline  
Old 09-18-19, 09:53 AM
  #45  
rosefarts
With a mighty wind
 
Join Date: May 2015
Posts: 2,555
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1073 Post(s)
Liked 841 Times in 475 Posts
FWIW, this works for steel steerers. They are brazed, not epoxied, and the inner sleeve is also steel.

Probably not as strong as the original and definitely a bit heavier but when talking about something that is orders of magnitude stronger than necessary, it works.

For this carbon fork, it all depends on how I was planning to use it. Commuting on relatively slow roads, usually alone, preferably out of traffic - do what I said earlier with an aluminum sleeve and pins.

50+ mph descents, pack rides, proximity to traffic, rough surfaces - new fork.
rosefarts is offline  
Old 06-20-20, 12:27 PM
  #46  
hrdknox1
Junior Member
Thread Starter
 
hrdknox1's Avatar
 
Join Date: Apr 2014
Posts: 184
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 85 Post(s)
Liked 53 Times in 40 Posts
The wood dowel snapped and I crashed descending at a high speed. Fortunately this catastrophy resulted in only road rash and soreness for me, but it could have been much worse. Obviously the stress endured by the steerer tube is much greater than I anticipated.
See my original post " Lengthening a steerer tube".


Last edited by hrdknox1; 06-21-20 at 09:22 AM.
hrdknox1 is offline  
Likes For hrdknox1:
Old 06-20-20, 02:03 PM
  #47  
RubeRad
Keepin it Wheel
 
RubeRad's Avatar
 
Join Date: Aug 2011
Location: San Diego
Posts: 10,238

Bikes: Surly CrossCheck, Krampus

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Liked 3,400 Times in 2,511 Posts
Wow -- I'm glad you learned that lesson instead of me!

What kind of wood was the dowel? I imagine your average home despot dowel, which is light as air, is not that strong.
RubeRad is offline  
Old 06-20-20, 02:30 PM
  #48  
Pop N Wood
Senior Member
 
Join Date: Jun 2020
Location: Maryland
Posts: 1,379

Bikes: 1982 Bianchi Sport SX, Rayleigh Tamland 1, Rans V-Rex recumbent, Fuji MTB, 80's Cannondale MTB with BBSHD ebike motor

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 667 Post(s)
Liked 529 Times in 355 Posts
Wow. just wow.

Glad you walked away.

Brave of you to come back and post the results. There was obviously some difference in opinion so maybe your hard learned lesson will help others.
Pop N Wood is offline  
Old 06-20-20, 02:53 PM
  #49  
icemilkcoffee 
Senior Member
 
icemilkcoffee's Avatar
 
Join Date: Aug 2009
Posts: 2,592
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 1541 Post(s)
Liked 1,702 Times in 956 Posts
Originally Posted by hrdknox1
.... I purchased a cheap fork ($48) off eBay .....
I would have just used that Ebay fork!
icemilkcoffee is offline  
Old 06-20-20, 03:07 PM
  #50  
hrdknox1
Junior Member
Thread Starter
 
hrdknox1's Avatar
 
Join Date: Apr 2014
Posts: 184
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 85 Post(s)
Liked 53 Times in 40 Posts
Originally Posted by RubeRad
Wow -- I'm glad you learned that lesson instead of me!

What kind of wood was the dowel? I imagine your average home despot dowel, which is light as air, is not that strong.
Yep, The Home Depot.
hrdknox1 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.