What is wrong with my derailleur?

[TheWho]

First ebike ever and first bike in 20 years. My derailleur seems to be rubbing against my cassette and I'm not sure why or what to do.

Any ideas?

 

[Weeksy]

You'll see 3 screws/allen bolts on the back of it... 2 next to eachother, 1 not. (silver one in pic1)

Using the appropriate tool, adjust the 1. It's known as the B screw... That will move your mech away. (Clockwise on bolt)

Strictly speaking there's a set distance etc it should be, but start with that...

It could also be your chain being a link or two too long...

 

[Mik3F]

B limit screw likely needs adjusting

Its usually the one closest to the the top of the mech on its own.

Do you have the SRAM tool for checking it?

 

[TheWho]

Thanks, it looks better. How do I know I've got it in the right place?

 

[Weeksy]

Google B Screw adjustment tool. There's different tools depending on your exact setup and number of gears etc.

 

[Mik3F]

Ideally you need the sram tool to properly check, but you can measure from the cassette to the top jockey wheel

You want around a 5mm gap between the cassette and the jockey wheel

 

[TheWho]

Ideally you need the sram tool to properly check, but you can measure from the cassette to the top jockey wheel

You want around a 5mm gap between the cassette and the jockey wheel

Silly question, which is the top jockey wheel?

(I don't have the special tool.)

 

[Weeksy]

Put bike in gear 1.... biggest cog on the rear.

You'll then see a gap for the one that's nearest the cassette, that wants to be about 5mm from the top of that little wheel to the cassette when looking at it from the same height.

 

[Mik3F]

Silly question, which is the top jockey wheel?

(I don't have the special tool.)

The one closest to the cassette

Shift into the largest cog and then measure from the bottom of the cassette to the top of the jockey wheel closest

Aim for 5mm

Then check t make sure you are shifting up and down the cassette without issues

 

[TheWho]

The one closest to the cassette

Shift into the largest cog and then measure from the bottom of the cassette to the top of the jockey wheel closest

Aim for 5mm

Then check t make sure you are shifting up and down the cassette without issues

Thanks!

I also found this which was helpful (even though I don't have the tool):

 

[Mik3F]

If you find it keeps needing to be adjusted, take the b limit screw out and apply some loctite to it before resetting it

 

[TheWho]

The one closest to the cassette

Shift into the largest cog and then measure from the bottom of the cassette to the top of the jockey wheel closest

Aim for 5mm

Then check t make sure you are shifting up and down the cassette without issues

Okay, when I get the b screw all the way in I can't get to the largest gear.

It's a recently new derailleur, but maybe I've broken it somehow?

 

[Weeksy]

B screw shouldn't be all the way in.... or it's VERY unlikely.

Shift into the biggest cog on the rear and take a side on pic...

If you can't get in that gear, dial out the B until you can and take the side on pic showing position of jockey and bottom of cassette.

 

[TheWho]

At 5mm it's clicking but won't change.

 

[TheWho]

If I dial out the b screw the derailleur gets too close to the cassette and it won't change up.

I've finally got it to the largest gear by pushing it with my hand.

 

[TheWho]

Shift into the biggest cog on the rear and take a side on pic...

Side on:

 

[TheWho]

It seems like the derailleur needs to move closer to the spokes but I can't see a way to adjust that.

 

[Semmelrocc]

Since it could also be cable tension and limit screws, I suggest you start over with a complete derailleur adjustment. I recently found this excellent video explaining it all, step by step:

 

[Pyr0]

There are 2 limit screws on your derailleur which control how far in or out it will go.
In post #4 in this thread, you can just about see them in your photo by the pulley.

 

[Weeksy]

That's way more than 5mm isn't it ?

To move it closer to the spokes you see the other 2 allen bolts... you use one of those

They're the high and low limit screws. They stop the chain going over the top of the cassette or onto the frame (at different ends)
So shift into gear 2.... wind out one of the screws 1 turn anti clockwise, counting each 1/2 turn as you go, so you can go back to start point again, each time you go out 1 turn anti-clockwise see if it'll shift into gear 1.

 

[TheWho]

So this is the direction I think it needs to move in:

 

[TheWho]

Since it could also be cable tension and limit screws, I suggest you start over with a complete derailleur adjustment. I recently found this excellent video explaining it all, step by step:

Thanks for this, it's been very helpful. It's hard to follow the bits about listening to sounds as the cogs on the cassette seem to make a noise at certain parts of the wheel rotation and not others. I e tried to capture it in a video, hopefully you can see the gap between the chain and cog changes as I turn the pedals. What's causing that and is it a problem?

 

[Weeksy]

I think that's just the bike moving as you push the cranks.

 

[Mik3F]

Not sure if its the angle of the pic, but the mech hanger looks bent to my eyes

If it is that will also have an effect on the shifting

Here is what I would do,

Shift to the top gear and then set the limit screw, repeat for the low gear limit screw

This way you can't drop off the cassette (or shouldn't be able too)

Make sure your B limit screw is set as discussed earlier

Try shifting now and see what happens, you can always use the barrel adjuster to fine tune the cable tension if required

 

[JP-NZ]

Not sure if its the angle of the pic, but the mech hanger looks bent to my eyes

Same to my eyes... Getting derailleurs just right is an absolute PAIN in the backside. I would just drop it at the shop and have them do it.

 

[Mik3F]

Another alternative, where in the UK are you

Maybe someone local to you on here can help

 

[TheWho]

Thanks everyone. I followed the video above and now know about 100 times more about dérailleurs than I did before. Got it working. I think I must have knocked the cable adjuster.

Thanks again!

 

[Weeksy]

That's how we all learned it mate. Bit of trial and error, either watching videos or watching a mate do it... Next thing you're knee deep in fork internals and tubeless tape none of it is brain surgery, but can feel like it at first try. Well done.

 

[Mik3F]

Good to hear,

Youtube is great for helping fix bike issues

I was clueless when I first started riding, but now I tackle pretty much everything on the bike myself, as long as I have the required tools for the job