Lost: two gears... Help please adjusting derailleur

[James Up Hill]

I should really appreciate some help from you clever people, please!

I have lost the ability to select the top two gears.

I came off my bike yesterday (a SMIDSY event; idiot pulled out in front of me and whilst I could stop just before I hit him, I ended up on the tarmac), and although the bike went down on the left side (rather than the derailleur side) I haven't been able to find my top two gears since.

I have undertaken a full readjustment of the rear derailleur (in my less than totally skilled fashion).

The 'low gear' screw is in the right place. The 'high gear' screw won't come out far enough to be able to reach the top two gears.

The 'selector' now goes between 3 and 7 and will not go down to 1 or 2. The gear wheel goes between 1 and 5 and will not go up to 6 or 7.

I cannot see that anything looks out of true/bent.

It's a B'Twin Triban 500.

Thanks in advance!

[richardfm]

Have a look at this video to ensure you are following the correct procedure to adjust the derailleur https://www.youtube.com/watch?v=UkZxPIZ1ngY and this one to work out whether or not the hanger is bent https://www.youtube.com/watch?v=tXfvW0L3iLM

[gaz]

The 'selector' now goes between 3 and 7 and will not go down to 1 or 2. The gear wheel goes between 1 and 5 and will not go up to 6 or 7.

It can be difficult to understand online requests and apologies if I've misunderstood. Traditionally rear gears 1-7 are left to right as viewed from the rear, 1 being the largest sprocket and the lowest gear, 7 being the smallest sprocket and highest gear. This should correspond to the shifter labelling, i.e. 6 & 7 are the two smallest sprockets.

The 'low gear' screw is in the right place. The 'high gear' screw won't come out far enough to be able to reach the top two gears.

If you can't reach sprocket 1 the 'low gear' screw may be in the wrong place and if you've moved it there's a good chance the 'high gear' screw is in the wrong place too.

I was about to link to Park Tool but I've been beaten to it.

[pwa]

Just to eliminate the simple and most easily checked, there isn't a gear cable outer casing that has pulled out of a "stop" on the frame and is just resting on it rather than sitting fully in it? If so, it needs popping back in.

It could easily be a minor problem with the cable.

[DevonDamo]

If you lost the gears as a result of the crash, it's possible that something is bent, even though it doesn't look it. The usual suspect would be the derailleur hanger - the small piece of metal which screws into your rear drop outs and which the derailleur is bolted onto. These often get bent in crashes, but it's rarely visually apparent. There's a particular tool which you use to check whether your hanger is straight - basically, a long arm that screws in in place of the derailleur and you then rotate through 360 degrees and check it isn't moving out or in. Do a bit of googling and youtubing to find it.

That said, although it's happened to me a couple of times, a bent detailleur hanger hasn't resulted in me losing gears. It usually means your gears try to change when you backpedal. I bought the special tool to check/adjust mine, but it might be worth asking a friendly bike shop if they'll check it for you.

[pwa]

Presumably as the bike hit the deck the bars swung round as far as they would go, further than normal, and my guess is that something happened to the cable / cable housing at one of the stops on the frame or at the lever, resulting in cable being pulled a little even when you try to get the smallest sprocket. A careful inspection of the whole length of cable would be a good first step.

[James Up Hill]

Hello

Thank you all for comments.

" 7 being the smallest sprocket and highest gear. This should correspond to the shifter labelling, i.e. 6 & 7 are the two smallest sprockets."

Yes, indeed. Just like a car (I assumed). Highest gear, highest speed.

Even with the tension in the gear cable reduced to completely floppy it won't reach the two highest gears (smallest wheels). This suggests to me that it is something in the derailleur mechanism itself.

[pwa]

Hello

Thank you all for comments.

" 7 being the smallest sprocket and highest gear. This should correspond to the shifter labelling, i.e. 6 & 7 are the two smallest sprockets."

Yes, indeed. Just like a car (I assumed). Highest gear, highest speed.

Even with the tension in the gear cable reduced to completely floppy it won't reach the two highest gears (smallest wheels). This suggests to me that it is something in the derailleur mechanism itself.

Agreed. Not being able to get the mech over the smallest sprocket even with no tension in the cable makes the problem one at the mech / hanger. It was worth checking though.

It can be difficult to see, but can you see if the H (high) limit screw is touching the part of the mech it has to in order to stop the mech going further? If it is, it needs to come out (unscrew) further. If it isn't, something else is preventing the mech moving towards the small sprocket.

[roubaixtuesday]

Hello

Thank you all for comments.

" 7 being the smallest sprocket and highest gear. This should correspond to the shifter labelling, i.e. 6 & 7 are the two smallest sprockets."

Yes, indeed. Just like a car (I assumed). Highest gear, highest speed.

Even with the tension in the gear cable reduced to completely floppy it won't reach the two highest gears (smallest wheels). This suggests to me that it is something in the derailleur mechanism itself.

Agree. And as others have said, a bent hanger may be most likely.

But losing two gears suggests a pretty big out of alignment which should be visually obvious.

Can you post pictures, especially from the rear, of the gears how they are when the cable has no tension on it?

[James Up Hill]

Thanks for your message. Please see the attached photographs.

[roubaixtuesday]

Nothing looks obviously bent. My guess would be that cable is stuck in the kink, or somewhere else.

I suggest removing the cable entirely from the derailleur as a next step. If that doesn't engage the smallest cog, then it's something in the derailleur itself.

[scottg]

the kinked housing and cracked end cap can foul the cable.

[Brucey]

the cable is borked and the mech looks bent to me.

cheers

[James Up Hill]

Thank you.

One screw is backed all the way out in order to access fifth gear (without that it was only reaching fourth after last week's accident). The other is where it is in order to prevent the chain from being tangled up in the wheel.

Assuming Brucey is right (quite likely) does this mean a new mech, or can it be bent straight again?

[roubaixtuesday]

Thank you.

One screw is backed all the way out in order to access fifth gear (without that it was only reaching fourth after last week's accident). The other is where it is in order to prevent the chain from being tangled up in the wheel.

Assuming Brucey is right (quite likely) does this mean a new mech, or can it be bent straight again?

It would be surprising if the derailleur bent without the hanger bending.

But, as I and others suggested, the cable is a much more obvious culprit, and detaching it to test will take you all of 30 seconds. Try that first?

A new derailleur according to Google is about £15.