Rattling around rear derailleur

[Rosslando]

Hi,

I recently came off my bike. It is a boardman comp racer. I think the nut on the left side of the bike took a hit due to a deep scratch on it. It was fairly loose when I went around to check the tightness of the bolts. My bike is generally quite quiet but now has a rattling sound throughout all gears around the rear derailleur cogs. It is also not fluidly moving between gears and I can't get it in the top gear.

Does anyone know what I could do to fault find the problem or direct me to where the problem is situated?

I also tried moving the barrel adjuster to see if it would make any difference but it made it worse if anything.

Thanks

 

[Cycleops]

Hello and to the forum.

Which particular nut was that? Sounds like you might have bent the derailleur, the hanger or both, if the latter just a case of swapping it out. If you could post a pic of the mech from the rear and the hanger that might help.

 

[roubaixtuesday]

Per @Cycleops that sounds like you've suffered damage in the fall, most likely a bent hanger (the hanger is designed to bend on impact to protect the frame).

If it's very minor then fettling the gears may sort it, otherwise you need a new hanger. Beware, there are dozens of varieties...

The park tool website has an excellent guide and video on setting up your gears:

https://www.parktool.com/blog/repair-help/rear-derailleur-adjustment

 

[tom73]

+1 for the link plenty stuff on park tool site not hard to follow or find what what need.
Should help you find out what you need to need.

 

[raleighnut]

I'd say bent hanger, whether it is too bad to align or not you'd need to find out.

 

[confusedcyclist]

You won't likely need a new hanger, unless the hanger itself is damaged. As mentioned before, they are designed to bend, and will bend back, but they will fatigue and snap if this is a recurring thing, or bent to extremes, always avoid dropping or parking your bike drive side down! Try realign the hanger before you change anything else, the procedure is below. Sometimes the derailleur will be visibly bent inward. But I've had totally imperceptible misalignment give me clunky shifting and skipping too. The right tool will make swift work of it.

View: https://youtu.be/tXfvW0L3iLM


Once you've checked hanger alignment, reinstall the derailleur and do a quick check of high and low settings on the derailleur. Then, with the clamp off the cable, shift the shifter to smallest chainring, turn the barrel adjuster all the way in and then back out one or two full turns, re-tension the cable, and ensure proper indexing using the barrel adjuster. it should all run smoothly after that, if not, your derailleur may be damaged.

 

[Ajax Bay]

I think the nut on the left side of the bike took a hit due to a deep scratch on it. It was fairly loose when I went around to check the tightness of the bolts

So is this the end of the QR lever on the left side (opposite the rear mech/cassette)? What other bolts did you check (I can't think of any)?
Does sound like rear mech/hanger alignment but the bike didn't go down that side.

 

[confusedcyclist]

The other thing to check is that the cassette isn't loose!

 

[Rosslando]

Hey,

Thanks guys for all the info. Park tool it is. @Cycleops I've attached a few pics. I think the hanger is slightly bent where the chain finds the first cog. Not sure if you can see it that clearly here.

@Ajax Bay that's right. I don't have a QR lever, this is where the bolt is. Opposite the cassette. I'm not sure what this would effect taking a knock. I thought I might have bent the frame.