"Worn Out Derailer"

[Vicegrip]

@rcannon100 88885 wrote:

The Kid has been told that his less than one year old derailer is worn out. I have never heard of a derailer wearing out. I have heard of them bending or breaking. He says there is too much play in the derailer and the mechanic showed him. What???

Does any of this make sense? Do derailers wear out? What does that mean and how long would you expect one to last?

What are the symptoms?

[Rootchopper]

I have three bikes with a total of 80K miles. I’m pretty sure they all have their original front and rear deraillers. So I’m skeptical.

Is his derailer a really cheap model? Did his bike fall over on top of it? Did he use his bike as a hockey stick and play goalie.

Take it to a mechanic who you have confidence in. Paul at Bicycle Space, Bailey (the owner) at Papillion, Fred or Carlos at Spokes are a few I trust.

[Anonymous]

I don’t remember too terribly specific details, but yes I replaced the rear derailleur on my hybrid a year or two ago, due to what the mechanic says was wear plus he felt the derailleur wasn’t ideal for the gear range, or I guess being used at the edge of the acceptable gear range. The bike had started to make horrendous noises in the lowest couple of gears. Something about extra play caused by wear plus the borderline mismatch of gears-to-derailleur was allowing enough movement for something to make that terrible racket? (sorry, this is probably way too vague and not-well-remembered to be helpful). Anyway, he gave me several options at the time, one of which was to just live with it. Whatever exactly was going on he did not consider a danger to me or the bike. I did not go that route, as I couldn’t stand my bike sounding like it was going to fall apart any second now whenever I climbed a hill. Replaced it with what he felt was a better choice (deore is what is on there now, i don’t remember if i ever knew what the original was). The horrendous noise went away and did not return.

[Harry Meatmotor]

@acl 88892 wrote:

I don’t remember too terribly specific details, but yes I replaced the rear derailleur on my hybrid a year or two ago, due to what the mechanic says was wear plus he felt the derailleur wasn’t ideal for the gear range, or I guess being used at the edge of the acceptable gear range. The bike had started to make horrendous noises in the lowest couple of gears. Something about extra play caused by wear plus the borderline mismatch of gears-to-derailleur was allowing enough movement for something to make that terrible racket? (sorry, this is probably way too vague and not-well-remembered to be helpful). Anyway, he gave me several options at the time, one of which was to just live with it. Whatever exactly was going on he did not consider a danger to me or the bike. I did not go that route, as I couldn’t stand my bike sounding like it was going to fall apart any second now whenever I climbed a hill. Replaced it with what he felt was a better choice (deore is what is on there now, i don’t remember if i ever knew what the original was). The horrendous noise went away and did not return.

I’m gonna go with a dead b-tension spring. so yes, it’s something that can wear out. the b-tension spring keeps the upper derailleur pulley from contacting the cogs, especially in the lower/larger cogs. most derailleurs have a max cog size capacity, measured in the number of teeth on the cog. in order to run a larger cog at the edge of the derailleur’s capacity, you’ll need to increase the tension on the b-tension spring, which can eventually wear out the spring. the horrendous noise was likely a very grumbly noise, as the upper pulley was making contact with the cogs. the mechanic was right, you could probably live with it but it’d eventually wear out the upper pulley.

other ways that inexpensive derailleurs can wear out are in the pivots, especially the main knuckle pivot (also where the b-tension spring is located). if there’s play in that pivot, the derailleur will likely have trouble staying in adjustment.

[Anonymous]

^^^^^^^^
that all sounds correct, to the best of my recollection

[Author]

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