Jumping Gears

zoomaj

Hello all

Thank you for helping me with my bottom bracket post, I am also suffering from another problem in regards to changing my gears. I have had bike shops look at them. Which they seem to have fixed temporarily but the problem always comes back. Which is why I want to take matters into my own hands this time to understand the matter on a deeper level.

Now when I change gears it always does change from 1-8, the chain goes up and down the cassette but it is very abruptly. The chain almost just drops onto the next cog and it is not very smooth at all.

I have just tried cycling in gear 5 which is what the bike responded too. But after 25 seconds of riding it ghost shifted onto the 3rd cog from 5.
But I don't understand how this happened as when I initially changed gear it was actually on gear 5. Halfway into cycling it then changed to gear 3. Is this an indexing issue? On the work stand the gears do almost work perfectly. But in practice under stress and load, it's far from a perfect smooth experience.

I have also changed my chain which was 0.75 worn according to the chain tool.
Any advice would be appreciated on how to make them buttery smooth without any delayed ghost shifting.

zoomaj

Gears on the 5th but on the cassette it's showing as 3. But it was initially on gear 5 when I changed gear then dropped to the 3rd cog 25 seconds after cycling

zoomaj

The same also happened on gear 4, it stayed on gear 4 then jumped to gear 5 then jumped back to gear 4 then again to gear 5 then again to gear 4!. It kept repeating this pattern every 25 seconds going up and down the cassette. Obviously very dangerous on the road when cycling at high speed.

zoomaj

On the derailer iv jjst noticed it doesn't sit directly under the cassette. It's about 2-3mm to the right which could explain the unexpected shifting as its pulling the chain to the right. Any ideas how I could resolve this issue? Do I have a bent derailer? Or could the spring be loose?

zoomaj

Here it is on the smallest gear and you can see the derailer is not lined up at all. Any help or assistance would be appreciated. Thank you

zoomaj

The chain seems to be so much to the right hand side in the derailer and a big gap on the left which is not equal distance in the middle. Iv checked out my kids bikes and the chain sits perfectly in the middle with equal gap in the derailer.

So there is definitely something wrong on mine unfortunately.

I will check the above videos thank you

JBA

zoomaj said:

Gears on the 5th but on the cassette it's showing as 3. But it was initially on gear 5 when I changed gear then dropped to the 3rd cog 25 seconds after cycling

You are thinking the gears the wrong way around. The largest sprocket is 1st gear and the smallest is 8th.
In the photo above the chain is on the 6th sprocket.

Follow the guides that Oxoman linked to and start from scratch setting the limits and then indexing the gears. Take your time and be methodical.

zoomaj

I have just changed the derailer on my bike and it is running very close to the cassette, and ideas on what to do here? It's OK when I pull it away by hand. I have adjusted the b screw but it seems so close to the cassette and not working smoothly at all

zoomaj

Right guys quick update. I put the derailer on incorrectly. I have now sorted it and shifting is 90% accurate. I just need to index the gears hopefully everything should be OK.

According to the park tool video above. My derailleur had sloppy pivert points as well as bent jockey wheels. So nothing was aligned.

Thank you everyone for your help and assistance in this matter