replacing rear mech jockey sprockets

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shobo
Posts: 55
Joined: 11 Aug 2019, 9:34am

replacing rear mech jockey sprockets

Postby shobo » 5 Sep 2019, 6:41pm

Hi all,
My 105 rear mech jockey sprocket (the outermost one) has worn down. Only 6000 or so miles done I think.
I've never replaced jockey sprockets before, but I thought it could be done. Maybe my imagination.
Anyway, I don't see how to get the old one out. Where there could be an allen bolt, it looks like the sprocket is permanently fixed in.
Same for the arm holding both sprockets.
So I will have to replace the entire rear mech.
Thoughts ?

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foxyrider
Posts: 4511
Joined: 29 Aug 2011, 10:25am
Location: Sheffield, South Yorkshire

Re: replacing rear mech jockey sprockets

Postby foxyrider » 5 Sep 2019, 7:04pm

Look at the back?
Convention? what's that then?
Airnimal Chameleon touring, Orbit Pro hack, Orbit Photon audax, Focus Mares AX tour, Peugeot Carbon sportive, Owen Blower vintage race - all running Tulio's finest!

Brucey
Posts: 35543
Joined: 4 Jan 2012, 6:25pm

Re: replacing rear mech jockey sprockets

Postby Brucey » 5 Sep 2019, 7:53pm

the upper ('guide') pulley and the lower ('tension') pulley are mounted on most shimano mechs using M5 bolts. They are easily replaced. As suggested above, if you look at the LHS of the cage plate of most recent incarnations of 105 you will see the head of the (countersunk) bolt for the upper pulley.

This is RD-5700

https://si.shimano.com/pdfs/ev/EV-RD-5700-3042A.pdf

but other 105 models are similar. What exact model is yours?

FWIW if the teeth have gone from the guide pulley there are only two likely reasons for this

1) the pulley bearing wasn't lubed properly and/or
2) the gear adjustment was poor enough that the chain was scuffing the pulley at the side in normal use.

BTW when properly maintained, these pulleys (even quite cheap ones) can last 20000 miles, easy.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

shobo
Posts: 55
Joined: 11 Aug 2019, 9:34am

Re: replacing rear mech jockey sprockets

Postby shobo » 5 Sep 2019, 8:15pm

you passed the test, guys. Sprocket extracted.
Where's the best retailer to get a replacement ?
btw its the lower sprocket. The upper sprocket has very little wear.
Thankyou.

Brucey
Posts: 35543
Joined: 4 Jan 2012, 6:25pm

Re: replacing rear mech jockey sprockets

Postby Brucey » 5 Sep 2019, 9:00pm

SJS have a good choice but other places are cheaper. Ultegra/XT pulleys are a step up in quality (for most but not all 105 variants).

edit; BTW the lower pulley on a 105 mech can wear quite rapidly if you spend too much time running cross-chained (i.e. big-big or small-small)

cheers
Last edited by Brucey on 5 Sep 2019, 9:11pm, edited 1 time in total.
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cycleruk
Posts: 5201
Joined: 17 Jan 2009, 9:30pm
Location: Lancashire

Re: replacing rear mech jockey sprockets

Postby cycleruk » 5 Sep 2019, 9:09pm

Some Shimano lower pulleys are direction specific. There is usually an arrow showing the direction of rotation.
If you get it the wrong way round it may be slightly noisy.
Other brands may not be fussy.
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