Crashed

Dagless

For those of you with places to pedal to:
After falling off my upwards gear changes at the smaller end of my rear cassette seem to be getting progressively worse, with the pedal spinning before changing (but no grinding or noisy changing).

Or full story:
Had a bit of a fall last weekend, mostly my fault though I can certainly place some blame on the poor surface: I was on a tarmacced canal towpath with plenty of tree-root bumps, and after a brief look down and back up I tried to avoid a root bump, but hadn't looked ahead enough to the partially collapsed section ahead so my wheels went sliding sideways at different times and I went over and rolled out of it.
I wasn't going too fast (maybe 12-15mph) so minor damage to myself, couple of bruises and scratches but my main concern was a pain in my left wrist, luckily now mostly healed.

Secondary to my wrist concern was the bike, I fell to the right so I broke my mirror (no big deal) scratched the brake lever (a little annoying) and when my back wheel slipped over the edge of the tarmac it must have caused 2 gouges in the rim over the brake surface, wheel is otherwise fine but it will no doubt wear my brake pad down pretty fast, so may look into replacing that.

Also scratched my rear derailleur, which brings me to my problem: On the day I crashed I put the chain back on and rode another 20 miles (albeit slower than I usually would just in case) but everything seemed fine, I think I once noticed a gear change taking a little extra time but otherwise everything was smooth (I had just put on a new chain before the ride, so perhaps that was helping). After a few days of no riding, making sure my wrist was ok, I got back on the bike Thursday & Friday and rear-changing seems to be getting worse.

Going down to an easier gear is fine, but when changing up, specifically in the smaller sprockets from 5th-8th gear (bike is 8 speed on the back with 11-32) it started requiring an extra spin of the pedals on occasion. It was still silent and I don't feel any grinding but after a change the crank will spin as if there is no load before the gear sets in. And today on my way home it wouldn't even change into 8th (11t)

Is this likely to be a bent derailleur hanger? It doesn't really look bent but then I never studied it too close before.
Or will I be able to solve it by re-indexing? maybe the crash stretched the cable a little?
Or the new chain I put on I just did straight from the box, should I have taken a link or two out? Would the extra length cause this. (please forgive my ignorance but apart from cleaning, changing brakes & changing inner tubes I haven't done much bike maintenance)

I am hoping to change the cassette to an 11-28 I just bought but thought I should make sure I can fix this issue first.

ugo.santalucia

One tip: people can't be bothered to read an A4 account of your crash... keep it simple, don't guess don't ramble on, what is the main issue you are trying to resolve?

2 lines max

bondurant

The modern world encapsulated

I like it when people take the time to detail e.g. a build or whatever. Even when people talk about how they crashed there's normally something to take on board.

keezx

Most likely a bent hanger and/or rear derailleur indeed.
Check if the cage is vertical below the sprockets.

Dagless

ugo.santalucia wrote:

One tip: people can't be bothered to read an A4 account of your crash... keep it simple, don't guess don't ramble on, what is the main issue you are trying to resolve?

2 lines max

Well some clearly don't mind, however yes I probably should put the main question at the top, sorry.

Main problem is my upwards gear changes at the smaller end of my rear cassette seem to be getting progressively worse, with the pedal spinning before changing (but no grinding or noisy changing).

Dagless

Keezx wrote:

Most likely a bent hanger and/or rear derailleur indeed.
Check if the cage is vertical below the sprockets.

Thanks.
I presume the cage is the bit that holds the two jockey wheels, it does look fine but I just bought a work stand so should be able to have a look properly and switch through the gears at the same time tomorrow.

PhilipPirrip

The good thing is it still works on the rest of the cassette so it's hopefully not terminal.

I'd check the alignment of the hanger first as they're designed to absorb the energy of a derailleur impact. Just undo the fixing bolt (no need to remove cable or chain) to see if it's straight and if necessary, when I've found one bent, carefully straighten.

I've also had occassions where crashes have caused burrs close to the pivot points on a derailleur that could foul the movement of the parallelogram. A bit of filing or sanding of any roughness sorted it out.

For chain length I'd suggest you refer to the online manual for your rear derailleur. For Shimano they suggest you put the chain on the biggest ring and smallest sprocket to determine chain length but I don't know the instructions for Campag or Sram.

It's unlikely the impact will have affected the cable length.

Dagless

PhilipPirrip wrote:

I'd check the alignment of the hanger first as they're designed to absorb the energy of a derailleur impact. Just undo the fixing bolt (no need to remove cable or chain) to see if it's straight and if necessary, when I've found one bent, carefully straighten.

Ah, so it might be fixable without a new hanger, i'll give that a go.

PhilipPirrip wrote:

For chain length I'd suggest you refer to the online manual for your rear derailleur. For Shimano they suggest you put the chain on the biggest ring and smallest sprocket to determine chain length but I don't know the instructions for Campag or Sram.

Thanks, yeah it's Shimano... just looked up a park tool vid for that.

clickrumble

ugo.santalucia wrote:

One tip: people can't be bothered to read an A4 account of your crash... keep it simple, don't guess don't ramble on, what is the main issue you are trying to resolve?

2 lines max

Well I liked reading the account of your crash, hope you've got the bike sorted out too!

veronese68

Skim read because I'm lazy. Most likely to be the hanger, they are designed to give first to protect more expensive components. I will say I don't think anyone can tell by eye if a hanger is straight. It's a small part and being twisted by one degree will make a difference. It's worth getting a proper tool, borrowing one or getting it checked by your bike shop. Even a new hanger is not necessarily a guarantee of straightness.

Dagless

I think I've got it working ok, only taken a couple of loops round the block but all the gears I am likely to use seem to work, I'll know for sure tomorrow. It won't go into 1st from the big chainring but I shouldn't be doing that anyway (don't think I have ever used 2nd from the big chainring either, I normally drop down to the middle ring or small ring when in 4th/5th at the back)

Although I did take it all off to have a look I ended up basically just bending it back into a place that looked about right then started from scratch with the limit screws & indexing.

One thing I will ask though: Is the cage that holds the jockey wheels supposed to always be parallel to the bike? As when I took the wheel & chain off and went through the gears top to bottom it looks to me like it makes a slight arc. So the lower jockey wheel is closer to the spokes than the top jockey in 1st gear, vice-versa in 8th gear.

pilot_pete

Sounds like a bent hanger and bent cage from your description. I'd be surprised if 'bending it back to a place where it looked about right' proved to be a full solution. In my experience even a bend which cannot be detected by eye can lead to less than optimal shifting.

The correct solution is to use a derailleur alignment tool to ensure the hanger is straight. Beg, borrow, steal one or just take the bike into your local shop and ask them to straighten it. Probably charge you very little as it would only take 5 mins max. If the hanger is badly bent (and now bent back by you) it may need replacing for a new one. You will still need to check the alignment of a newly fitted hanger to eliminate mis-alignment from your gear set up woes.

With a correctly aligned hanger you can then move on to other possible issues such as the bent cage, derailleur body damage, cable inner and outer issues, possible shifter damage and the obvious derailleur set up and adjustment.

PP

Dagless

Pilot Pete wrote:

Sounds like a bent hanger and bent cage from your description. I'd be surprised if 'bending it back to a place where it looked about right' proved to be a full solution. In my experience even a bend which cannot be detected by eye can lead to less than optimal shifting.

The correct solution is to use a derailleur alignment tool to ensure the hanger is straight. Beg, borrow, steal one or just take the bike into your local shop and ask them to straighten it. Probably charge you very little as it would only take 5 mins max. If the hanger is badly bent (and now bent back by you) it may need replacing for a new one. You will still need to check the alignment of a newly fitted hanger to eliminate mis-alignment from your gear set up woes.

With a correctly aligned hanger you can then move on to other possible issues such as the bent cage, derailleur body damage, cable inner and outer issues, possible shifter damage and the obvious derailleur set up and adjustment.

PP

Thanks, I wasn't really expecting it to be a permenent solution but I haven't had any problems in the past week (approx. 80 miles). In part I am wanting to learn more about maintenance & repair on this bike before I buy a proper road bike next year. (this bike is more of a hybrid style)

I will see how it goes for now, will probably need new tyres in a month or two so I'll get the hanger etc checked out at the same time. Or if I get problems before then I'll get it checked.