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

How screwed am I with a rounded off crank bolt?

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.

How screwed am I with a rounded off crank bolt?

Old 02-05-16, 05:12 PM
  #1  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
How screwed am I with a rounded off crank bolt?

Hello All:
I need to change the cranks out on a CycleOps Phantom stationary bike for a client. The cranks are on tighter than anything I have every encountered. I got the left one off but the allen bolt rounded off trying to get the right one off.
Solutions? Anything short of a grinder and a new BB would be very much appreciated.
By the way, the crank will be thrown away so I can certainly afford to damage it.
Cheers,
Jim
Attached Images
File Type: jpg
IMG_2738.jpg (85.7 KB, 84 views)
JimboMartin is offline  
Old 02-05-16, 05:21 PM
  #2  
corrado33
Senior Member
 
Join Date: Jun 2013
Location: Bozeman
Posts: 4,135

Bikes: 199? Landshark Roadshark, 198? Mondonico Diamond, 1987 Panasonic DX-5000, 1987 Bianchi Limited, Univega... Chrome..., 1989 Schwinn Woodlands, Motobecane USA Record, Raleigh Tokul 2

Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 1125 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Since it's a stationary bike... hammer a slightly oversized allen/torx in there and crank on it. (Possibly imperial allen.) If that fails, grind the head of the bolt and the part of the crank arm off then remove the rest of the bolt with a pair of vice grips.
corrado33 is offline  
Old 02-05-16, 05:50 PM
  #3  
dsbrantjr
Senior Member
 
dsbrantjr's Avatar
 
Join Date: Sep 2010
Location: Roswell, GA
Posts: 6,234

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

Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 652 Post(s)
Likes: 0
Liked 46 Times in 42 Posts
You could epoxy a sacrificial hex driver into the rounded-out recess.
dsbrantjr is offline  
Old 02-05-16, 05:54 PM
  #4  
AnkleWork
Senior Member
 
Join Date: Jan 2013
Location: Llano Estacado
Posts: 3,327

Bikes: old clunker

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 540 Post(s)
Likes: 0
Liked 25 Times in 15 Posts
Heat?
AnkleWork is offline  
Old 02-05-16, 06:05 PM
  #5  
Crankycrank
Senior Member
 
Join Date: Jan 2009
Location: San Diego, CA
Posts: 1,342
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 184 Post(s)
Likes: 0
Liked 10 Times in 7 Posts
Drill the bolt head off and use a crank puller as usual. Grip rest of the bolt with vice grips and it may screw out easily if you want to save the BB.
Crankycrank is offline  
Old 02-05-16, 06:19 PM
  #6  
_ForceD_
Senior Member
 
_ForceD_'s Avatar
 
Join Date: Jul 2015
Location: Rhode Island
Posts: 1,012

Bikes: Several...from old junk to new all-carbon.

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 391 Post(s)
Liked 9 Times in 7 Posts
Have you considered a screw extractor such as those at this link:

Straight Flute & Spiral Flute Extractors by Vermont American | Zoro.com

Dan
_ForceD_ is offline  
Old 02-05-16, 06:20 PM
  #7  
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 7,285
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 537 Post(s)
Liked 19 Times in 16 Posts
There are now extractor sets made for just such occasions. I have this set and have had a 100% success rate with it.
9 pc Metric Extractor End Hex Key Set | Princess Auto
Dan Burkhart is offline  
Old 02-05-16, 06:26 PM
  #8  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks Guys! Epoxy idea is very clever! Yes, I had thought of an easy out and may go that way. The bolt is not solid so it should be easy to drill all the way through. Drilling the head off seems like a good idea too because the thing is on so amazingly tight.
Still thinking and open to other suggestions.
EDIT: I guess I could try the epoxy solution first. If it doesn't hold then I can still drill it.
Cheers,
Jim

Last edited by JimboMartin; 02-05-16 at 06:35 PM.
JimboMartin is offline  
Old 02-05-16, 07:00 PM
  #9  
wschruba 
Senior Member
 
Join Date: Sep 2015
Location: New Jersey
Posts: 1,570
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 465 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
If you're throwing the crank out anyway, the fastest way will be to use a mini hacksaw (or a grinder, doesn't matter) diagonally across the crank, just above the eye, about halfway through, then cold chisel to break the last bit. Once you have relieved the tension on the bolt, it will come out with almost zero resistance, and the crank shortly after.

Drilling the head of the bolt can be practical, as well, if you have a way of fastening the crank such that it doesn't spin. 11/32 is the most common fractional size that will guarantee a clean break. Once you have the bolt extracted, can then work on removing the crank--the advantage above is that it omits a step by cutting the crank's eye, relieving the bolt, and removing the press fit of the spindle at the same time.
wschruba is offline  
Old 02-05-16, 07:54 PM
  #10  
Bike tinker man
Senior Member
 
Join Date: Dec 2014
Location: Retired to Penang Malaysia originally from UK
Posts: 329

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

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 37 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
My humble opinion:-
I doubt if you have rounded off the recessed allen head, if epoxy then would be stonger enough to hold, also depending on your expertise & being able to get a good drill at it, remember that the bolt head is hardened, there is a good chance the drill will go off to one side, as above I think best option is to hachsaw / grind the crank arm away then vice grips on the bolt.

I have to say I've not used those flute extractors before thats a new one for me, one always learns reading other members comments.
Bike tinker man is offline  
Old 02-05-16, 09:03 PM
  #11  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks wschruba. I'm having a little bit of trouble imagining how you make this cut with a grinder. Sorry to be so slow but you could describe it again in some slightly different way?
Epoxy is setting now so I'll give that a try tomorrow evening. If it doesn't work I'll try drilling or grinding.
Thanks,
Jim
PS The cranks are steel, not alloy.

Originally Posted by wschruba View Post
If you're throwing the crank out anyway, the fastest way will be to use a mini hacksaw (or a grinder, doesn't matter) diagonally across the crank, just above the eye, about halfway through, then cold chisel to break the last bit. Once you have relieved the tension on the bolt, it will come out with almost zero resistance, and the crank shortly after.

Drilling the head of the bolt can be practical, as well, if you have a way of fastening the crank such that it doesn't spin. 11/32 is the most common fractional size that will guarantee a clean break. Once you have the bolt extracted, can then work on removing the crank--the advantage above is that it omits a step by cutting the crank's eye, relieving the bolt, and removing the press fit of the spindle at the same time.

Last edited by JimboMartin; 02-05-16 at 09:10 PM.
JimboMartin is offline  
Old 02-05-16, 09:34 PM
  #12  
dwmckee
Senior Member
 
dwmckee's Avatar
 
Join Date: Jun 2008
Location: Pittsburgh, PA
Posts: 1,576

Bikes: Co-Motion Cappuccino Tandem,'88 Bob Jackson Touring, Co-Motion Cascadia Touring, Salsa Carbon Warbird, Ritchie Titanium Breakaway, Felt Surplus 70 MTB, Dahon Folder, Frances Cycles SmallHaul cargo bike

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Epoxy is way softer than the steel that stripped out and very unlikely to work if it is really tight. I'd go with drill the head and use an extractor.
dwmckee is offline  
Old 02-05-16, 09:45 PM
  #13  
velocentrik
Senior Member
 
Join Date: Sep 2015
Location: Front Range, Colorado
Posts: 128
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 71 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by JimboMartin View Post
Hello All:
I need to change the cranks out on a CycleOps Phantom stationary bike for a client. The cranks are on tighter than anything I have every encountered. I got the left one off but the allen bolt rounded off trying to get the right one off.
Solutions? Anything short of a grinder and a new BB would be very much appreciated.
By the way, the crank will be thrown away so I can certainly afford to damage it.
Cheers,
Jim
Sounds to me, without knowing what tools you used, that someone used an SAE allen when a metric was required, previously.

There are specific bits and tools made to extract bolts and screws. Any competent qualified professional bike shop will be able to handle this. Any serious personal bike garage eventually finds the need for those extractor tools.
velocentrik is offline  
Old 02-05-16, 09:54 PM
  #14  
wschruba 
Senior Member
 
Join Date: Sep 2015
Location: New Jersey
Posts: 1,570
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 465 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by JimboMartin View Post
Thanks wschruba. I'm having a little bit of trouble imagining how you make this cut with a grinder. Sorry to be so slow but you could describe it again in some slightly different way?
Epoxy is setting now so I'll give that a try tomorrow evening. If it doesn't work I'll try drilling or grinding.
Thanks,
Jim
PS The cranks are steel, not alloy.


This is obviously not a picture of the spindle eye, but more importantly than that is that it is the right profile so you can see what I mean. Because of limitations of space, you usually can't cut a slot parallel with the spindle, hence cutting one on an angle. You can cut as deep as you feel comfortable doing, but I suggest about halfway, since the cold chisel won't really have any issues breaking a weakened part that is 1/2" thick or so. The depth of the cut provides a measure of protection to the spindle, since splitting something with a chisel is not an exact science. Your goal, after all, is not a clean, perfect cut, it's just to force the eye apart. When that happens, you will hear a loud pop, and the eye portion of the crank will be quite hot.

It is prudent to take a few precautions doing this:

1) put a small block/brick underneath the crank, so any force you are imparting with the chisel/hammer goes into the ground, not the bearings.

2) don't hold the chisel by hand, that's a sure way to break you hand if you miss. Use a vise-grip to hold it, instead.

3) Eye protection, for real.

I use a 5 pound hammer (commonly called an "engineer's hammer"); just about any cold chisel (note that this is a type of metal-working chisel) will work fine, considering that you just need a hardened wedge, having started the slot with the hacksaw.

You want a 'mini hacksaw', though you can also just take a hacksaw blade wrapped in tape, to save a few bucks if you have to. Your hand will really hurt by the time you're done, and it will go quite slowly, though. If that's worth $5 to you, so be it.

You should absolutely try other avenues first, but a hacksaw blade holder, cold chisel, and engineer's hammer are all things that anyone should own if they make a habit of working on machines.

*edit*

If it helps you to think of it this way, you are performing the large scale, freehand version of using a nut splitter.
Attached Images
File Type: jpg
Untitled drawing.jpg (46.6 KB, 24 views)
wschruba is offline  
Old 02-05-16, 10:02 PM
  #15  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
In this case it was a metric allen key but a cheap one. My bad for using it.
JimboMartin is offline  
Old 02-05-16, 10:02 PM
  #16  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks, I get it now!
JimboMartin is offline  
Old 02-06-16, 09:49 AM
  #17  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I should probably mention that this is an ISIS bottom bracket with a larger bolt. OD of threads is 12mm and the ID of the recess on the back side is 7mm.
Also, I may have brought this on myself by working out in the 25 degree garage. I will bring the next two inside and let them warm up before I try to remove the cranks.
Cheers,
Jim
Attached Images
File Type: jpg
IMG_2739.jpg (73.3 KB, 11 views)
File Type: jpg
IMG_2740.jpg (96.3 KB, 14 views)
JimboMartin is offline  
Old 02-06-16, 10:21 AM
  #18  
wschruba 
Senior Member
 
Join Date: Sep 2015
Location: New Jersey
Posts: 1,570
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 465 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
@JimboMartin

If it's an ISIS spindle, the method I posted won't work; you'll have to cut half the eye off (one of those cuts on either side of the crank arm), if you can't remove the bolt.

An EZ-out is ideal in this situation, again, if you can drill a hole into the bolt. You will need a large tap handle to install the EZ-out, and can then use a large adjustable wrench to remove everything. A big tap handle is ideal for removal, however, as the EZ-out is hardened, and if you break it off with uneven force from a wrench (this is mostly as a result of not getting it in concentric with the bolt, though), you will be in another world of misery (see above). You'll want an EZ-out sized for the inner diameter of the bolt, in this case, and cost is important, no $10 sets. Bring the bolt to an auto parts store, and buy the individual one that has the taper grabbing about 1/3 of the way into the hollow in the back of the bolt you got off (so, about 1/3 up the flutes, it should measure ~7mm).

A center punch dead center of the bolt is important to minimize your chances of drilling the pilot for the EZ-out off center, which greatly increases the chance of breaking it off. Those bolts are usually made of high grade (10.9-12.9) steel alloy. You do not need a carbide drill bit, but it will cut easier than a cheaper one (cobalt alloy, at the minimum). They should both be used with cutting oil, and the carbide one very carefully (drill dead straight), as minor deflection will break the bit/chip the flutes very easily. To minimize your chances of breaking the drill bit, center punch, drill a small pilot, then follow with the large bit after. If your drill doesn't plug in to the wall (or have a 1/2" chuck for a battery op), it probably won't have the power necessary to get through a hardened bolt.

If your epoxy attempt doesn't succeed, and the alternative would have you running out to buy a whole bunch of tools, you may want to cut your losses and call around to a few trusted shops. A competent mechanic could remove it fairly quickly, but then again, I've talked to more than my fair share of coworkers or other 'mechanics' that I wouldn't let near a broken wood screw, let alone what you're got.

Last edited by wschruba; 02-06-16 at 10:25 AM.
wschruba is offline  
Old 02-06-16, 10:38 AM
  #19  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Great tips, thanks!
JimboMartin is offline  
Old 02-06-16, 11:07 AM
  #20  
desertdork
just pokin' along
 
desertdork's Avatar
 
Join Date: Aug 2008
Location: the desert
Posts: 1,095
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I used a "Bolt-Out" or "Bolt-Grip." Sold individually and in sets. Grabs the outside of the bolt head. Out in a jiffy.
desertdork is offline  
Old 02-06-16, 11:20 AM
  #21  
CliffordK
Senior Member
 
CliffordK's Avatar
 
Join Date: Nov 2014
Location: Eugene, Oregon, USA
Posts: 22,485
Mentioned: 166 Post(s)
Tagged: 0 Thread(s)
Quoted: 8515 Post(s)
Liked 72 Times in 64 Posts
Originally Posted by desertdork View Post
I used a "Bolt-Out" or "Bolt-Grip." Sold individually and in sets. Grabs the outside of the bolt head. Out in a jiffy.
I think that is what I was going to suggest. You'll need to try to pull the rubber washer/gasket out.

CliffordK is offline  
Old 02-06-16, 11:35 AM
  #22  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 41,928

Bikes: 8

Mentioned: 188 Post(s)
Tagged: 0 Thread(s)
Quoted: 6833 Post(s)
Likes: 0
Liked 215 Times in 179 Posts
that ^^ would be OK for the hex head bolt he doesn't have.

For the hex socket recess ... drill it out in the center, insert tapered extractor , its fluted

and so that turning it CCW it gets biting in tighter..

heat-gun the arm and it will expand.. a little.

Last edited by fietsbob; 02-06-16 at 11:39 AM.
fietsbob is online now  
Old 02-06-16, 11:42 AM
  #23  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
And these will grip a round head? Cool!
Update: For some reason, probably the cold, my epoxy did not set at all. So I went ahead and drilled for an easy out. At the hardware store I picked up cobalt bits as well as the easy out. Just to see what would happen I decided to try drilling with a regular bit and had no problem at all. Clearly not hardened. Right now I am heating it up a bit and will try the easy out. I have to say that I am pretty wary of breaking the easy out so if it doesn't come loose with moderate torque I plan to just drill off the head with a half inch bit.

Originally Posted by desertdork View Post
I used a "Bolt-Out" or "Bolt-Grip." Sold individually and in sets. Grabs the outside of the bolt head. Out in a jiffy.
JimboMartin is offline  
Old 02-06-16, 11:55 AM
  #24  
exmechanic89
Senior Member
 
exmechanic89's Avatar
 
Join Date: May 2015
Location: Richmond VA area
Posts: 2,725

Bikes: '00 Koga Miyata Full Pro Oval Road bike.

Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 474 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Absolutely no way epoxy will be strong enough for this task. I'd go with the one of the other suggestions..
exmechanic89 is offline  
Old 02-06-16, 12:15 PM
  #25  
JimboMartin 
Senior Member
Thread Starter
 
Join Date: Dec 2013
Posts: 245
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 26 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Update #2 : The center of that bolt may not have been hardened but the head is for sure. Can't make any progress at all with a hand drill and a cobalt bit from Ace. Trying to rig up a big table to put the whole thing on my drill press now.
JimboMartin is offline  

Thread Tools
Search this Thread

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

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.