Bent rear mech hanger on titamium frame

Jakecp · June 2007

Managed to crash on the Dragon Ride yesterday, and although I was able to finish, have bent the rear mech hanger on my Van Nicholas Zephyr. These frames don't come with replaceable hangers, as apparently the titanium is tough enough not to bend - apparently not!

My question is, can you bend titanium back as you can with steel, or will it fatigue like aluminium?

basta pasta

Unknown · June 2007

oops. ti can be bent back and it should be fine. worth getting to decent shop that has a hanger bender thing. So it gets bent back straight

Mleh Mleh Mleh

Garybee · June 2007

Have you got a frangible (weak link) mech hanger bolt?

Hypocrisy is only a bad thing in other people.

hazeii · June 2007

Bending Ti hangers straight is no problem - it happened to me on a Ti frame, the LBS checked with the importers then bent it straight.

pbiggs · June 2007

The frame would come with a replaceable hanger if it couldn't be bent back. Every manufacturer knows that's a vulnerable part that's likely to get bent one day, whatever they say about stiffness.

The hanger should be nice and thick to survice bending back & forth a few times.

~Pete

mercsport · June 2007

Titanium is remarkable stuff . When I rear ended a car about 4 or 5 years ago the carbon forks snapped in two and the head tube angle became vertical with a neat crease where it joined the down tube and a slow curve on the top tube . Eighteen months later , after an exasperating time with an ally frameset that I replaced it with , I put a long bar of engineers mild steel into the head tube ( a nice fit ) , clamped it in a vice and heaved the frame to near perfection again .
I have to say that I couldn't tell the difference between when it was new and after . It became my main bike again until just last month when , on the top of the Brecons , the down tube snapped under the strain of a tub of lard ( me ) and a couple of large panniers . It was after all a racing frame and didn't snap at where I'd creased it in the smash .
I don't think it would be a sweat straightening your hanger out again .
...' thinks '....yet the Litespeed frame I bought recently has a screwed on rear hanger ?

Edit : As I've just loaded a link to a web album illustrating the break I might as well put it in here :

http://picasaweb.google.com/f.bruce.mil ... eedBuildUp

P.S. I suppose it must be connected in some way to the original creasing which was immediately at the head/down tube junction . But note the distance away from there at the eventual break .

Bruce

MattBlackBigBoysBMX · June 2007

Titanium isn't that remarkable.
If the frame has creased, then it has exceeded it's elastic limit and weakened greatly. Bending it back would weaken it more.
Not recommended.

Edit to add: straightening the drop-out, done carefully, should be fine though.

Wheelies ARE cool.

Unknown · June 2007

And THEN fit a break-away bolt!

d.j.
"Not much to see,
Not much left to lose"

rgisme · June 2007

Been there, done that. It should be possible to bend it back no probs. As others have said an LBS should have the right tool to get it back in proper alignment easily - and probably in a few seconds.

mercsport · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by MattBlackBigBoysBMX

Titanium isn't that remarkable.
If the frame has creased, then it has exceeded it's elastic limit and weakened greatly. Bending it back would weaken it more.
Not recommended.
<hr height="1" noshade id="quote"></blockquote id="quote">

BTW , ' Remarkable ' , .. yes !! Other than steel what other material would have allowed me straighten everything out to continue riding for the next few years until the catastrophe noted above ? It's the sort of repair that was taken for granted in the days of steel framed bikes and almost routinely done by any bikesmith back then . ( Of course steel frames are still very much with us ! )

Jakecp · June 2007

Thanks for advice - will take it to my LBS and get bent back. Not sure if it has a frangible mech bolt - what's one of these and how do I tell?

Nasty crash, 4 or 5 of us went down, and one guy went to hospital with a potential broken collar bone. Really lucky to be able to carry on and finish - my body is feeling the price today though, very glad not to leave my desk...

basta pasta

Unknown · June 2007

"a frangible mech bolt - what's one of these and how do I tell?"

In the days when alu mtbs did NOT have replaceable hangers, one could buy mech bolts designed to shear off if the mech took a hit. Not seen some for a while, but worth an internet search (or ask on singletrackworld?).

d.j.
"Not much to see,
Not much left to lose"

MattBlackBigBoysBMX · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by mercsport

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by MattBlackBigBoysBMX

Titanium isn't that remarkable.
If the frame has creased, then it has exceeded it's elastic limit and weakened greatly. Bending it back would weaken it more.
Not recommended.
<hr height="1" noshade id="quote"></blockquote id="quote">

BTW , ' Remarkable ' , .. yes !! Other than steel what other material would have allowed me straighten everything out to continue riding for the next few years until the catastrophe noted above ? It's the sort of repair that was taken for granted in the days of steel framed bikes and almost routinely done by any bikesmith back then . ( Of course steel frames are still very much with us ! )
<hr height="1" noshade id="quote"></blockquote id="quote">

Decades ago, bikes weren't built from heat treated tubes with 0.5mm wall thicknesses.
Me thinks you were lucky.[;)]

Wheelies ARE cool.

mercsport · June 2007

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by MattBlackBigBoysBMX

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by mercsport

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by MattBlackBigBoysBMX

Titanium isn't that remarkable.
If the frame has creased, then it has exceeded it's elastic limit and weakened greatly. Bending it back would weaken it more.
Not recommended.
<hr height="1" noshade id="quote"></blockquote id="quote">

BTW , ' Remarkable ' , .. yes !! Other than steel what other material would have allowed me straighten everything out to continue riding for the next few years until the catastrophe noted above ? It's the sort of repair that was taken for granted in the days of steel framed bikes and almost routinely done by any bikesmith back then . ( Of course steel frames are still very much with us ! )
<hr height="1" noshade id="quote"></blockquote id="quote">

Decades ago, bikes weren't built from heat treated tubes with 0.5mm wall thicknesses.
Me thinks you were lucky.[;)]

Wheelies ARE cool.
<hr height="1" noshade id="quote"></blockquote id="quote">

I can't pretend to understand it but it seems that Ti. is at its best being worked COLD .
A couple of links for you , but a search will reveal tons more .

http://stinet.dtic.mil/oai/oai?&verb=ge ... =AD0724606

http://www.litespeed.com/2006/tech_shape.aspx

rjsmith · June 2007

SRP make alloy breakaway bolts. I bought a few not long ago. Use them on Scott carbon bikes where there is no detachable hanger so didn't want to crash and bend carbon!
Quite easy to fit them into mechs. I use them in my Dura Ace mechs.

Bent rear mech hanger on titamium frame

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