'B' srew lack of adjustment

stevenw

Hi, Out for a ride on Sunday and noticed that after about 20 miles, when in the lowest 2 gears there was a rubbing noise from the jockey wheel/cassette. Sure enough, the jockey wheel is too close to the cassette. Here's the problem, I have adjusted the 'B' screw all the way in and it is making no difference. I can see the derailleur move just a tiny amount but its not enough. I also tried a longer srew, but just put the derailleur at an odd angle. Derailleur l Shimano 105 and 10 speed.
Thanks
Steve

Mister W

What size cassette and rear mech have you got? Is the cage touching the biggest cog when you're on the next one or is the problem just with the jockey wheel?

If you can post some pics that would be even more helpful.

stevenw

The bike is a Specialized Roubaix, 11-28t and short cage. When I'm in the bottom 2 gears(the big cogs) on the cassette, the guide wheel is just too close to the gear directly above it and is making a lot of noise, even with the the adjuster fully screwed in. It seems to me like the coil spring inside has lost some of its tension so that when you turn the screw the spring isn't strong enough to take up the slack, if that makes sense. I will see what i can do about photos.
Thanks
Steve

alfablue

Is your chain too long? On big ring and small sprocket, the jockey wheels should be vertically aligned.

stevenw

I bought the bike 2nd hand last year and have ridden it quite a bit with no probs. That doesn't mean to say the that the chain isn't too long, just that this problem only occurred on Sunday, or at least thats when I first noticed it!!
Edit: It looks to me as if the chain is the original .
I must be missing something obvious somewhere :?

alfablue

Its just that the position of the guide wheel (top jockey wheel) in relation to the sprockets is a function of both chain length and B screw, and chain length can have the biggest effect. Have you put the chain on small sprocket and large chain ring and are the jockey wheels vertical?

Other possibilities, q/r has come loose and wheel has moved in dropout; mech hanger is bent; mech is loose in mech hanger.

alfablue

Have a look at this:

http://www.bikeradar.com/gear/article/w ... ace--26312

in particular
7: Adjust chain length
and
9: To B or not to B

Cleat Eastwood

alfablue wrote:

Is your chain too long? On big ring and small sprocket, the jockey wheels should be vertically aligned.

That must be your first port of call. Just because its the original chain doesnt mean it hasnt worn.

I had a similar problem with my allez. it was one link too long. it totally ripped the mech and hanger off.

I wouldnt ride it tillit was sorted if I was you.

stevenw

Thanks for all the replies. Will get back to it tomorrow. Will set everything to the "base" settings and see how it goes. Thanks again.
Steve