Bicycle Mechanics - Derailler hitting spokes.

I had a little bit of a tumble today, not too bad, but when I got back home to start checking the back I noticed that my rear derailler hits the spokes before it even makes it to the largest cog (Sora 8speed on a Trek 1000). I noticed when looking for behind that the part of the derailler that holds the two jockey wheels bends towards the bike at a few degrees. I compared to a friends brand new bike and his is perfectly perpendicular to the ground. I figure I have to get this back verticle again. Is that even possible or is the derailler shot?

Cheers

Check to see exactly what's bent. Is it really the cage? Or is it the derailleur hanger?

You can usually bend the cage back if it's not too badly deformed, although you'll probably still have problems that at least will require retensioning the cable and maybe re-setting the limit screws.

If it's the hanger, I believe the 1000 has a replaceable derailleur hanger. You can't usually bend 'em back on an aluminum frame.

Not a bad idea to have the shop check the alignment of the rear triangle, too.

RichC

Excuse my ignorance but you could tell me exactly what the hanger and cage are.

The cage is the part with the jockey wheels in it.

The hanger is the part of the frame the derailleur bolts to.

In situations like this a bent hanger is actually more common than a bent derailleur. Aluminum doesn't take well to being bent, which is why alu frames usuually have replaceable hangers. On a steel frame, you can generally just bend the hanger back.

RichC

How do I check between the bent hanger versus a bent derailler, what should I be looking for to differentiate between the two?

The hanger should itself be perpendicular to the ground. If it is, then the bend is in the derailleur.

RichC

Chances are, your hanger is bent. Usually, the hanger will bend before any major damage is done to the derailleur. Your LBS has a simple hanger alignment tool which can bring it back to alignment.......or you can try eyeballing it back. Remove your derailleur first.

It looks like the hanger is where the bend is. I think I'd be happier with the LBS doing it rather than me eyeballing it. What sort of labour time are we looking at?

Originally posted by Spire
It looks like the hanger is where the bend is. I think I'd be happier with the LBS doing it rather than me eyeballing it. What sort of labour time are we looking at?

Assuming the hanger (sometimes it's the whole dropout) is replacable, replacing one is pretty is pretty easy but does of course require removal and reinstallation of the derailleur. My guess is that it's at most a 30 minute job. Having trashed three hangers on my MTB already, I've gotten pretty good at it and can probably do it in about 15 minutes.

I don't remember what I paid for my old Parks hanger alignment tool, but generally once the derailleur is off it only takes less than 5 minutes to tweek the hanger back to alignment. Before I had the tool, I used to just eyeball it using a straightedge and that seemed to work quite well as well...

you can do it yourself. all you have to do is remove your derailer..

remove the hanger, and replace it with a new one.. bolt the derailer unto the new hanger..

Adjust the limit screws and the tensioners...

and your done..

I might also make the suggestion to have the right side spokes on the rear wheel inspected as well. If the derailleur was striking the spokes, it might have nicked them, and you don't want one of those to break on a ride.