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Fixing Shimano di2 front derailer cage ?

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Fixing Shimano di2 front derailer cage ?

Old 05-21-16, 06:10 AM
  #1  
wayneIII
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Fixing Shimano di2 front derailer cage ?

I was cleaning my bike the other day and noticed My Shimano di2 front Derailer cage was cracked in two at the top right in the middle above where the chain is. Bike mostly still shifts fine but on hard shifts into the big ring the chain can push the cage over a bit and my chain has come off the big ring on a few occasions.

Local mechanic says that part not replaceable, have to get all new front derailer. Is that true? Seems an expensive solution. Was thinking of getting it welded but was told that would take off rust coating of the cage. Any other suggestions or replaced ideas without having to get all new Derailer?
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Old 05-21-16, 06:54 AM
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Essentially your mechanic is correct. The parts are rivetted together and no replacement parts are available. A talented pro bono welder might be able to tack the
parts back together but operating an plasma (TIG/MIG) head near the electronics inside the device may be a problem (probably not but ?) even if the heat does not
damage the plastic. A bad job will just break in a few weeks. Any $ invested will be problematic at best, from lousy cosmetics to failure soon. A flame weld/braze
is not an option unless you remove the cage from the derailler, a dicey job in itself.

A bit of self promotion, if the Di2 set up is 10 spd I have a surplus 10spd Di2 FD for cheap. If yours is 11spd then the 10 spd --may-- work, per this ref:
How to Convert Shimano 6770 Ultegra Di2 to 11 Speed but this is unlikely if yours is not an older 10 spd upgrade.

Last edited by sch; 05-21-16 at 06:58 AM.
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Old 05-21-16, 10:37 AM
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Originally Posted by wayneIII View Post
Was thinking of getting it welded but was told that would take off rust coating of the cage.
It is broken anyway, so what if you lose some rust protection?
How old is the unit, is it possibly still under warranty? You might want to pursue that before doing anything which would void the warranty.
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Old 05-21-16, 11:15 AM
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Where's the break?
At the top front of the metal cage ( red circle ) that joins the outside and inside of the cage?

Or where the cage attaches to the derailleur itself (green arrow) ?



Wow, the front derailleur is pretty expensive. I'd contact Shimano about warranty, like the previous post mentioned.

If it's the front bridge (red circle):
I'd try epoxying a metal reinforcement "U" shaped piece.

I'd get some steel bar from the hardware store (but it's hard to find thick bars there), hacksaw a U cut, and file carefully until it's a press fit. Then cut off the rest of the bar. But the reinforcement needs to be sturdy, since there's lots of force on the cage when shifting. Perhaps a local metal shop could cut a piece to fit, since they have scrap steel and the correct cutting tools. I think it's too small a gap to bend a fairly thick bar into a "U".

The reinforcement can even be wider than the bridge, extending to the front of the outside cage.

Scuff the derailleur cage, epoxy in place, then paint the steel reinforcement.

Last edited by rm -rf; 05-21-16 at 11:22 AM.
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Old 05-22-16, 07:28 AM
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wayneIII
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Originally Posted by sch View Post
Essentially your mechanic is correct. The parts are rivetted together and no replacement parts are available. A talented pro bono welder might be able to tack the
parts back together but operating an plasma (TIG/MIG) head near the electronics inside the device may be a problem (probably not but ?) even if the heat does not
damage the plastic. A bad job will just break in a few weeks. Any $ invested will be problematic at best, from lousy cosmetics to failure soon. A flame weld/braze
is not an option unless you remove the cage from the derailler, a dicey job in itself.

A bit of self promotion, if the Di2 set up is 10 spd I have a surplus 10spd Di2 FD for cheap. If yours is 11spd then the 10 spd --may-- work, per this ref:
How to Convert Shimano 6770 Ultegra Di2 to 11 Speed but this is unlikely if yours is not an older 10 spd upgrade.
PM sent about buying your front der
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Old 05-22-16, 07:35 AM
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FYI it broke almost exactly where the red circle is above.

I truly appreciate all the Great suggestions. I guess I would doubt that shimano would warranty it being that is 3 years old, of all the places where a derailer would brake, that would be the last place I would have thought. My other thought was to put a couble of rivets in it and hold it together that way, for some reason I don't think epoxy would hold, the di2 front der can shift with some power if there is chain suck or anything like that.

THanks again all.
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Old 05-22-16, 08:57 AM
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The above suggestion, to reinforce externally with a bracket, would probably be the best 'kludge' solution. I see no reason why properly used, epoxy wouldn't hold a piece of stock in place, as the stock is holding the cage together, not the epoxy. A rivet would just complicate things, and protrude into the (already narrow) cage.
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Old 05-22-16, 10:55 AM
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Shimano is not big on stocking spare parts, so I doubt you can get the cage separately even If you drill out the rivets .
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Old 05-22-16, 02:12 PM
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WayneIII email sent.

Unfortunately Di2 10 spd stuff is hard to find, basically NOS only.
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Old 05-22-16, 06:54 PM
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Originally Posted by sch View Post
WayneIII email sent.

Unfortunately Di2 10 spd stuff is hard to find, basically NOS only.
Obsolete in 3 years, wow. There's planned obsolescence for you.
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Old 05-23-16, 07:42 AM
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sch
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Not much different than same with DA or Ultegra 9 or 10 spd stuff. 9-10 spd RD/FD/Brifters available, but in lower end groups only or as after marker
stuff from 2d tier suppliers. Di2 doesn't fall in those categories, hence NOS only for 10spd. Shimano made one mistake, not making the 9770 brifters
incompatible with the 9870 deraillers, so 10 spd upgraders can go to 11spd without buying new brifters but that is a small market.
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Old 11-09-17, 05:59 PM
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Originally Posted by wayneIII View Post
I was cleaning my bike the other day and noticed My Shimano di2 front Derailer cage was cracked in two at the top right in the middle above where the chain is. Bike mostly still shifts fine but on hard shifts into the big ring the chain can push the cage over a bit and my chain has come off the big ring on a few occasions.

Local mechanic says that part not replaceable, have to get all new front derailer. Is that true? Seems an expensive solution. Was thinking of getting it welded but was told that would take off rust coating of the cage. Any other suggestions or replaced ideas without having to get all new Derailer?
Hi Wayne, If you didn't manage to get this fixed and you still have the old derailleur then would you be interested in sending it to me to use it for parts - I have a hobby trying to repair these things with spares that I collect. Thanks.
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