msu2001la

The top pulley on my Tiagra rear derailleur somehow came off during a ride this morning. I was hammering pretty good when it came apart, and the chain+derailleur wrapped up around the rear cassette and the whole drivetrain jammed up. I was able to back pedal and get the chain unstuck from the rear cassette, but had to walk home because every time I tried to pedal forward the derailleur would wrap back up around the cassette.

I just moved, so I'm trying out a new local shop in Chicago.

The mechanic said he thought I'd just need a new pulley and bolt, and was nice enough to pull parts off of another derailleur he had in stock and put them on. When he went to adjust it after putting the new pulley on, he shifted the chain into the spokes while it was on the stand. Horrible grinding noises, cursing, etc. I was on the other side of the shop looking around trying to not make him nervous.

He tells me he thinks that the derailleur hanger is bent, and that he can't get it to shift right. Says the hanger probably needs to be replaced. Another mechanic comes over and looks at it and says that the derailleur itself is bent and the whole thing may need to be replaced. The 2nd mechanic starts looking at the spokes/wheel and talks to the first mechanic about how the wheel might be bent because a few of the spokes seem a little loose. He asks me if the derailleur went into the wheel when it came apart (it didn't), and I'm thinking that any wheel damage is from what just happened when he shifted into the spokes.

So, does all of this sound right? Pulley comes off and completely destroys the derailleur, derailleur hanger and now the wheel needs work?

I told the guy I was okay with a new derailluer if that was the only option, but I'd prefer to repair what is there. I figured you could just grab the cage and bend it back...

Any thoughts?

Jeff Wills

Yeah, it could happen. Jamming the chain between the cassette and spokes can damage spokes to the point that they'll soon break. (Been there, done that.)

When things went bad while you were riding, where did the chain end up? Did the mechanics see actual damage on the spokes?

BikeWise1

Shifting into the spokes on the stand didn't hurt anything.

First thing I look at when a bike comes in like yours is hanger alignment. Then derailleur condition and then chain. Yes, the chain may be shot as well if it is twisted anywhere.

You probably need a new rear derailleur, derailleur hanger alignment, or hanger if replaceable and possibly a minor wheel true and chain.

Sometimes you can bend a derailleur, sometimes not. Depends on which plane the bending occurred in. If they bent it back and it later broke, you'll be in worse shape. Tiagra derailleurs aren't that pricey. Get a new one.

msu2001la

The shop was able to bend the derailleur back into spec and also bend the hanger back. They installed a new pulley+pin and it's good as new, shifting nicely.

He charged me $65 to fix the existing derailleur, adjust everything and also give the whole bike a quick once over. Not exactly cheap (seems like I could've gotten a new derailler for just a little more), but he got me going again pretty quickly.

Apparently, no wheel damage though he may have trued the back wheel up a bit.

wunderkind

A brand new Tiagra RD is $50.

cny-bikeman

Given that he did more than just the derailleur that is not way out of line. He should have been more careful so as to not shift into the spokes, though

msu2001la

Plus installation...

I'm sure I could buy a Tiagra RD for cheaper than $50 on-line somewhere. I seem to recall seeing Ultegra RD's for like $75.

Alas, it was the Friday morning of a holiday weekend and this guy managed to fix my bike and get me on my way by Friday afternoon. I could've saved a few bucks, but with my skill-set, it would've taken me a good chunk of Sautrday to get a new RD on, adjusted and ready to roll. Plus I don't have tools to bend a bent hanger back into place.

Esteban32696

I don't know all that he did, or how long he worked on it,,, but from what you mentioned, $65, doesn't seem out of line. Glad you are back on the road.

tmac100

This happened to me while touring in outback Australia in 2006. I hitch-hiked with the bike 700 km and then had the bike shop in Katherine NT fix things: new derailler and replaced the broken spokes (I had the exact spares as the wheels are 4X laced). Fortunately the hanger was OK. Thanks Arvon Stacey for building such a robust set of wheels and touring bike :-)