B-Screw problem!

declan1

Hello!

My 105 5700 shifting has never been quite as good as I expect it to be - I presume this is due to the fact that the jockey wheel is about an inch from the largest sprocket, no matter where the b-screw is in its adjustment range.

I know people always have problems where the jockey wheel touches the cassette, but in my case it's too far away!

Any help would be much appreciated!

pinno

Internal spring gone? Chain too short? Rear mech not flush in its mounting? Does it need lubrication? Do you need to take the circlip off the hanger bolt and gently see if there's crud/rust internally preventing it from sitting properly?
Is the cable outer between the chainstay and rear mech too short?

Unless squeaky clean, modern indexing can be pernickety.

declan1

It's been like this since I put it on brand new. It's only a few hundred miles old. Chain length was set using Sheldon's method.

The shifting is acceptable, but it's not how I would like it. I sometimes have to push the lever a little bit further than the click (when changing up the cassette) to make it change.

P.S. I know how to index gears hehe

andrewjoseph

is the bottom of the B screw in contact with the tab of the mech hanger or has it somehow gone past? sometimes when not paying attention putting on a rear mech i have done this. you need to pull the mech right up when tightening, then let it drop down onto the tab. then adjust to get correct clearance, about 5mm at the minimum.

declan1

Yup, it's touching the tab.

I think I've found the problem - the outer cable housing for the rear mech is too short - it starts to bend as soon as it exits the mech barrel adjuster. If I push forward on it, the mech moves closer to the cassette.

extrusion

The b screw on my 105 derailleur does nothing. Zilch. On my 9 speed mtb the screw moves the jockey wheel very noticeably, on the road bike i cannot see any difference at all!?

onbike 1939

extrusion wrote:

The b screw on my 105 derailleur does nothing. Zilch. On my 9 speed mtb the screw moves the jockey wheel very noticeably, on the road bike i cannot see any difference at all!?

The effectiveness of the B screw does depend to some extent on the configuration of the frame. However sometimes lack of effect is caused by the lack of a good contact with the small tab giving it no purchase. I usually replace the screw with a more robust Allen-headed bolt at the first opportunity and make sure when adjusting that I pull the RD against the spring tension and away from the tab. To leave the RD in position when adjusting can cause the screw to bend.