B Screw Adjustment

[Lovacott]

Hi,

When I was indexing my gears last week, I noticed that the derailleur was a fair bit lower than the largest cog on my freewheel.

If I gave it a little shove inwards with my hand, gear changes were a lot quicker and smoother.

So I loosened off the B screw and nothing happened?

If I tighten the B screw, the derailleur moves further down and back, but if I loosen it fully, it gets nowhere near the maximum recommended 5mm gap (more like 15mm).

I don't want to loosen and adjust the hanger to derailleur connection until I fully understand the consequences.

Here's a picture.

 

[fossyant]

Just leave it be. Its not that important unless you've got some of the high end kit like 12 speed.

You won't get it that close with a basic mech.

Drive chain could do with a clean.

 

[Ajax Bay]

Go for it ("loosen and adjust the hanger to derailleur connection") if the 'system' allows a change of angle. It'll either be better or worse or no difference and you can return to the status quo if judged best. Provided a gap between largest sprocket and guide pulley wheel remains (the 5mm quoted sounds right) I can envisage no adverse consequences.
This is a 'working bike' (daily) @fossyant - I think that your observation is unreasonable and anyway based on tenuous evidence.

 

[Lovacott]

Drive chain could do with a clean.

It's a weekly job for me.

 

[Lovacott]

Go for it ("loosen and adjust the hanger to derailleur connection") if the 'system' allows a change of angle. It'll either be better or worse or no difference and you can return to the status quo if judged best. Provided a gap between largest sprocket and guide pulley wheel remains (the 5mm quoted sounds right) I can envisage no adverse consequences.

I had a rear tyre blowout a few weeks ago and I think I may have dislodged the derailleur whilst I was doing the repair.

Since then, my indexing has been fine but the changes have been very slow (click click click click click change).

The cables are all good, the mech moves on demand when I change gear but the chain is hesitant to shift.

But when I shove the derailleur forward with my free hand by a few millimetres, changes are as sweet as.

I've never tried B screw adjustment before (didn't know it existed until this morning).

 

[Lovacott]

Go for it ("loosen and adjust the hanger to derailleur connection")

Never touched it before but I did just now and it didn't need loosening at all. It was just off hand tight at best.

As soon as I tightened it fully, my gear changes worked like magic.

There must have been just enough slack to allow sideways movement in the derailleur which made the gear changes hesitant.

I've had the bike for 6 years and it's probably the only part I've never looked at or replaced.

I gave the bike a bloody good clean as well.