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PostPosted: Fri May 17, 2013 1:33 am 
rBoTM Winner
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Joined: Wed Dec 12, 2012 10:18 pm
Posts: 2373
Location: California
patineto wrote:
Oh the water works, in fact it works so well it burst my Klein forks after only 2 hours in the cold.


Ouch that hurts so sorry that happened to you

All of these solutions seem a little extreme to me. As I understand with aluminum the problem with removing a dent, as with a bent tube or drop for that matter, is tensile strength. Steel has great tensile strength, it can be bent and straightened fairly easily, but aluminum tends to break. Hence the fill the dent and paint solution.


Steven


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PostPosted: Fri May 17, 2013 2:13 am 
Retro Guru
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Joined: Thu Aug 19, 2010 7:09 am
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Location: SoCal, US
patineto wrote:
Oh the water works, in fact it works so well it burst my Klein forks after only 2 hours in the cold.
Well at least the dent on the other side got fixed.


What did you end up doing with these forks??


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PostPosted: Fri May 17, 2013 3:40 am 
Old School Hero

Joined: Thu Jun 10, 2010 4:46 pm
Posts: 159
Location: Salt Lake City Utah USA
mkozaczek wrote:
patineto wrote:
Oh the water works, in fact it works so well it burst my Klein forks after only 2 hours in the cold.
Well at least the dent on the other side got fixed.


What did you end up doing with these forks??


I good friend of mine reweld them for me about three years ago..
Image

Can you say the Most expensive commuter bike you have ever seeing, three years running no problems at all..
Image


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PostPosted: Fri May 17, 2013 7:12 am 
King of the Skip Monkeys
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Location: Moomin Valley
theres the hydraulic fluid method too - seal it and pump it up! Its on RB somewhere...


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PostPosted: Fri May 17, 2013 7:15 am 
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Location: Platsa, Messinias, Greece
I've used frame blocks with some success on steel frame tubes and I can't see why you couldn't try it on aluminium. Obviously the tube has to have a circular cross-section and the dent has to be in a place where there are no braze-ons that would get in the way and where there's room to clamp the frame blocks in place.
I made my own from a block of seasoned beech but any hardwood would do - split it, clamp or bolt the two halves back together and drill the required size of hole on the centreline of the split (I needed 28.6mm so I used a 1 & 1/8th" Forstner bit in a pillar drill).

*Edit* - I have used the hydraulic method but not on bike frames. You'd need to machine blanking plugs (with O ring sealing) to go in the head tube & BB shell and bottle bosses would probably be a problem, as although you could blank them off with an M5 screw and washer, you might well blow them out of the frame or distort the tube around them.
Anyway, I filled the tube with oil and used a grease gun to pressurise it.


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PostPosted: Fri May 17, 2013 8:54 pm 
Old School Grand Master
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Joined: Mon Jun 14, 2010 9:06 pm
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Location: Herts UK
i would try using 2 part epoxy to glue on a plate that has bolts welded/attached to it. then using blocks of wood to spreadthe fore and a metal part, pull the dent out by screwing on nuts to the screws. remove the plate by disolving the epoxy with solvent.


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PostPosted: Fri May 17, 2013 10:42 pm 
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Joined: Wed Sep 21, 2011 9:29 pm
Posts: 1770
Location: yorkshireland
I have used the extendable hose on a hoover to pull out squashed cones on a pair of hifi speakers but have always left bike dents well alone. It always seems like a pointless exercise which usually ends up leaving a weaker tube.


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PostPosted: Sat May 18, 2013 10:52 am 
Old School Hero

Joined: Sun Apr 28, 2013 8:56 pm
Posts: 209
Location: Flipping between Wigan and Lincoln
lewisfoto wrote:
patineto wrote:
Oh the water works, in fact it works so well it burst my Klein forks after only 2 hours in the cold.


Ouch that hurts so sorry that happened to you

All of these solutions seem a little extreme to me. As I understand with aluminum the problem with removing a dent, as with a bent tube or drop for that matter, is tensile strength. Steel has great tensile strength, it can be bent and straightened fairly easily, but aluminum tends to break. Hence the fill the dent and paint solution.


Steven


Agree with this completely.

Cold working aluminium will work harden it to a certain extent & this can lead to stress risers within the material.

Whatever caused the dent in the first place counts as cold working (the hardening may not be much at this point but could be enough to mean the dented section won't be the "path of least resistance" for the hydraulic/ice based methods) and getting said dent out with any of the methods on this thread also counts...

YMMV but personally I wouldn't trust a dented alu frame unless I was using it only in a low-stress environment.


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PostPosted: Sat May 18, 2013 3:11 pm 
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Joined: Mon Oct 08, 2007 7:47 pm
Posts: 1748
Location: Fairfax, California
I posted this fix last year to a similar question-- A long time ago I had a chrome plated Eddie Soens track bike frame with a large dent in the top tube. Joe Breeze fixed it for me. He had a fitting he had made which was a solid plug to insert in the head tube. This plug had an L shaped hole through it that went from the top (when inserted in the head tube) to a right angle turn to come out at the middle of the top tube. The hole in the plug had a relief cut and an O-ring inserted for a seal on the inside hole and was drilled and tapped for an automotive grease fitting on the outside of the top hole. With a drill he made a hole inside the head tube into the top tube and lined up the fitting with it. Then he filled the top tube of the frame with oil, re-inserted the fitting and used a grease gun full of oil on the other end of the fitting (the outside top) and pumped up the pressure until the dent popped out! All that was left was to drain the oil out of the top tube and reassemble the now perfect bike-even the chrome was perfect!


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