105 Rear deraileur trouble

Emrock

I had a minor fall on my Canyon Ultimate the other day. So I was stationary, it was clipless related, and the bike seemed fine apart from some cosmetic damage to the bar tape, saddle and my knee. However when setting off again my gears had started to jump and skip, especially when moving down the cassette, which I assumed is due to the fall as I had recently indexed them and shifting had been very good up until that point.

I have indexed again and seem to be hitting an issue where I can only set it up to shift smoothly in one direct not both. I have looked at the alignment of the rear derailleur and it does seem a tiny bit skew. Also I have noticed a couple of scratched on the derailleur presumably from the fall.

Anyway can anyone suggest a next step? Should I look at replacing the hanger (which to the naked eye looks undamged) or replace the entire rear derailleur? Or is the potentially a quicker raiser fix?

SHHH

In this case I'd put it in a stand so the wheel can spin freely. Detach the RD cable and push the RD with your hand and see if it moves through all the gears normally. Troubleshoot from there.

In my experience it's unlikely that the main RD mech/spring gets damaged, more likely the hanger spring if anything. Check that the hanger and hanger spring is undamaged.

svetty

Hanger is likely mis-aligned. Buy an alignment tool and over the years it will save you a lot of hassle and cost.

Another good reason to unclip on the left foot and not your right

timothyw

As above, the hanger is bent. Very unlikely you've bent the derailleur itself with a clipless incident I'd have thought.

Take it to your lbs and get them to align the hanger, or order yourself/borrow the tool and do it yourself.

You could just buy a new hanger, but the possibility is that a new one would need alligning anyway.

Bobbinogs

RD's are fairly simple things and don't often go wrong in terms of alignment. I would replace the hanger. It will cost £20 and take 5 minutes and, if it doesn't work, then the old one can be kept as a spare for touring, etc. If the indexing is still going awry on the way down the block (from bigger to smaller cogs) then it could be a simple case of a snagged cable not moving as smooth as it should. Hence, if the hanger doesn't work, I would look to disconnect/remove the cable and then ensure that it is in good shape and moves smoothly, and that the friction areas (under the BB, for example) are well lubed.

svetty

Bobbinogs wrote:

RD's are fairly simple things and don't often go wrong in terms of alignment. I would replace the hanger. It will cost £20 and take 5 minutes and, if it doesn't work, then the old one can be kept as a spare for touring, etc.

TimothyW wrote:

You could just buy a new hanger, but the possibility is that a new one would need aligning anyway.

It's always worth having a spare hanger so getting another one is a good idea but as TimothyW says it would still need aligning if you fitted one now so not of much help with the present problem.

Mad_Malx

TimothyW wrote:

You could just buy a new hanger, but the possibility is that a new one would need alligning anyway.

Is this right? Last time I had this problem it was sorted immediately I swapped hangar.

Sometimes they can crack when damaged/bending back too.

k-dog

Yes, alignment has as much to do with your frame as the hanger so just putting a new one on doesn't mean it will be aligned.

SHHH

I don't think you need to align a 105 hanger, I could of course be wrong.

Mad_Malx

That's useful to know k-dog- I'm just going through the chainset on another bike trying to find the source of skipping, after ruling out chain, cassette, indexing.
Time to buy a tool. Got a whole garage full of bikes for the family and keeping them all smooth is a bit like painting the forth road bridge.

SHHH

Sorry, I just read what I wrote earlier and it makes no sense. What I really meant was it's either a bent hanger or a bent cage. Doh. In my experience I've never had to align a hanger, but then maybe I've just been lucky when installing new derailleurs?

Bobbinogs

SHHH wrote:

... In my experience I've never had to align a hanger...

Me neither, I feel like I am missing out

It would make sense though if swapping the hanger didn't solve the problem but I think that is a long way from saying that a hanger needs alignment after replacing.

Emrock

Thanks for the replies everyone, very helpful. I am leaning towards buying a replacement hanger to see if that does the trick, also as having a spare is no bad thing. However if we are talking alignment, which tool would you suggest I look into getting to align properly? I'm keen to do my own maintenance, but I would rather not shell out too much on very specific tools, when I have other priorities. So is it worth getting an alignment tool?

I did inspect the hanger (with rear mech removed) and it didn't appear damaged or out of line, plus the carbon frame seems fine. However the sloppiness in my shifting is very slight so it is perhaps not visible to my eyes. However that and the fact that the only visible scratches are on the mech itself still leave me with a lingering fear that the derailleur could be to blame. Is there any way besides swapping them out to discover whether it's the derailleur or hanger that is to blame?

SHHH

Definitely don't buy an alignment tool to start with. Very unlikely that the RD/spring is damaged. I'd still try what I mentioned in my earlier response, which is to remove the RD cable and make sure it moves through the sprockets normally. If it does, then reattach the cable and adjust the tension. It's slightly odd that it's only skipping down the cassette. I'd have thought that a bent hanger/cage etc would cause it to skip both ways. In my experience with "sticky" derailleurs, when gears don't shift down, it's usually because of dirt and a blast of WD-40 works well. But you said it shifted well up until the fall, so perhaps not the case here. Worth trying though.