Fix a broken front derailleur cage with a broken spoke

[maydog]

My neighbor threw out an old 15 speed Murray in rough shape. I knew someone who could us some cheap wheels so I snatched it up. One of several issues was the front der cage outer plate was snapped off. The stops were adjusted so that the front stayed in the middle ring, but I had an idea. I took a broken spoke from the trash heap and bent it to shape. It works quite well on the stand. Road test tomorrow.

 

[dabac]

As a chain guide, I'd expect it to do OK. As a derailer I'd expect the spoke to wear through in a foreseeable time. How have you secured the spoke at the top end?

 

[maydog]

I wrapped the spoke around the top of the derailleur plate making sharp bends using a needle nose pliers, you should be able to see it in the pictures. Its a very cheap bike, any new components would be more than it is worth. I figure the spoke fix will last long enough.

 

[CAMPYBOB]

You're of Norwegian or Finnish descent aren't you? Ok...maybe Dutch or Scottish! Possibly a combination of all the above.

Being an outer...er...'cage' and only handling the downshifts it should work. Kinda. Now, if only Maydog could equip that Murray (of Ohio!) with a $5 cell phone derived GPS-based power meter!

 

[maydog]

Norwegian, Swedish, Dutch, German and French - what's that have to do with it? It was a trash heap bike that I was able to convert to a useable beater. I let my 10 year old test it out the other day and said it worked "pretty good". This type of repair could be done in the field if, for some reason, your front der exploded. The ghetto derailleur fix is not the most trashy thing on the bike. While small, the bike has to weigh about 40 pounds. The wheels were impossible to true. The brakes are super flimsy, single pivot sidepulls. The front caliper appears to have been bent from too much braking force. The brake levers are 100% flexible plastic trash. It is comical that this was once sold as a "mountain" bike. After adjustment, the brakes do work OK for commuting, I wouldn't let anyone use it anywhere hilly.

 

[CAMPYBOB]

Quote by Maydog:
"Norwegian, Swedish, Dutch, German and French - what's that have to do with it?"

Frugality.

Some nationalities are renown for their frugality.

I still have an old Murray "Roadster" (the 10-speed version of that bike with a double chainring) in the basement and yeah, the stamped steel caliper brakes coupled with the flexible plastic brake levers are only slightly better than dragging your feet ala Fred Flintstone.

 

[lectraplayer]

I used to have a Murray. Fun bike, but as noted, it's a bit heavy. I was starting to get it like I wanted, and then somebody stole it from the back of my truck. I guess I need to "paint" my next one with rust.

 

[alfeng]

[color=C0C0C0] It was a trash heap bike that I was able to convert to a useable beater. I let my 10 year old test it out the other day and said it worked "pretty good". [/COLOR]This type of repair could be done in the field if, for some reason, your front der exploded.

FYI. I guess that I need to jump in here & mention that while it might seem as though the particular front derailleur exploded, there should have been clear signs to anyone who looked at it prior to the derailleur's final usable moment that it was a ticking time bomb WITH forewarning which could-and-should have been avoided ... BECAUSE it is pretty clear that prior to failure the chain was allowed to rub against the inside of the outer cage until it finally wore through ... One can readily presume that the front derailleur's cable was slack when you retrieved the bike ... The failure should not have been a surprise.

 

[maydog]

Looks to have snapped clean off to me - not ground into submission by the chain. Poor materials and design with a dash of misuse by the previous owner I think. The chain shows no sign of being used as a saw.

 

[lectraplayer]

What else do you expect from a department store bike?

 

[alfeng]

Quote:Originally Posted by maydog .Looks to have snapped clean off to me - not ground into submission by the chain. Poor materials and design with a dash of misuse by the previous owner I think. The chain shows no sign of being used as a saw.

Well, you may be right ... So, are you are saying that it is merely coincidence that the "break" is parallel with the chain? By my reckoning, at some point in time, the chain scored through the chrome plating & into the brass (?) outer plate ... Of course, the moment of failure could certainly have occurred before the chain worked its way all the way through the derailleur's outer plate.

 

[CAMPYBOB]

Alf, the inner and outer cages would be made of steel. The bright (decorative) chrome plating is usually deposited over a flash thickness of nickel which, in turn, is deposited over layer of copper to boost adhesion and surface smoothness. I'm guessing the 'brass' you are seeing is a combination of the photography, the yellow cast that nickel has and/or the copper layer shining thru the worn upper layers. If the chain did not saw thru the cage there must have been one decent size imperfection in that sheet of steel.

Usually, I see front cages cracking and breaking at the bends that forms the horizontal bridge for the pivot ears as the result of many forced shifts, poor lubrication and bent components. Anything is possible though. Murray's are pretty much toys and the abuse they see is incredible.

 

[alfeng]

Alf, the inner and outer cages would be made of steel. [COLOR=C0C0C0]The bright (decorative) chrome plating is usually deposited over a flash thickness of nickel which, in turn, is deposited over layer of copper to boost adhesion and surface smoothness. I'm guessing the 'brass' you are seeing is a combination of the photography, the yellow cast that nickel has and/or the copper layer shining thru the worn upper layers. If the chain did not saw thru the cage there must have been one decent size imperfection in that sheet of steel. Usually, I see front cages cracking and breaking at the bends that forms the horizontal bridge for the pivot ears as the result of many forced shifts, poor lubrication and bent components. Anything is possible though. Murray's are pretty much toys and the abuse they see is incredible.[/COLOR]

[COLOR=0000FF]OY!!![/COLOR] THANKS for the correction.