105 rear derailleur hanger

[shouldbeinbed]

Folks.

My new to me bike is approx 10yo with 105 rear mech, garaged and unused for several years - its my 1st 105 mech & I'm not sure if it is slightly damaged or if the hi/lo adjusters just need a tweak.

The jockey wheel cage just catches on the spokes in 1st gear but it runs smoothly up and down all gears otherwise. The chrome hanger attached to the frame looks bent in slightly.

Should it be bent or is it just badly adjusted screws?

I'm at work so no pics yet but if there's no definitive answer by tonight I'll put a pic up to show what i mean.

thanks in advance

 

[MattHB]

you need to adjust the screw above the H and L adjustment screws to give the dérailleur more clearance.

have a look at sheldons site for some more guidance. I think he calls it the 'Angle adjustment' screw

 

[shouldbeinbed]

you need to adjust the screw above the H and L adjustment screws to give the dérailleur more clearance.

have a look at sheldons site for some more guidance. I think he calls it the 'Angle adjustment' screw

The B screw? I'll give it a twiddle. Thanks

 

[RecordAceFromNew]

Don't touch the B screw. It has absolutely nothing to do with your problem.

If you look at the rear mech from behind, with the bike vertical, is the mech vertical? If not, is it because the hanger is bent or the mech is bent?

If hanger is bent, is it alloy or steel? and by how much?

If neither looks bent, you need to adjust the L screw - that can stop the rear mech moving further inboard than it should.

Health Warning - do not ride the bike in present condition - mech dragged into spokes is a big deal.

 

[MattHB]

Surely not enough clearance on the mech is B screw?

 

[HovR]

Health Warning - do not ride the bike in present condition - mech dragged into spokes is a big deal.
.

In addition to RAFN's warning, if the hanger is bent and it's alloy, I'd strongly suggest not riding it even with the L screw adjustment preventing the derailleur touching the spokes. I'd also strongly suggest not trying to bend an alloy hanger back to straight.

In every single case I've seen where an alloy hanger has taken a decent knock, even if it appeared fine (or it was bent back to straight), it snapped a few miles down the line, normally when the rider was standing on the pedals, resulting in a nasty fall.

 

[RecordAceFromNew]

Surely not enough clearance on the mech is B screw?

The B screw is for adjusting clearance between top jockey wheel and the larger/largest cog on the cassette. The OP has clearance issue between mech and spokes!

 

[fossyant]

Surely not enough clearance on the mech is B screw?

No. The B screw adjusts the distance of the jockeys from the cassette teeth. If the hanger is bent, like it sounds, then this needs sorting. If it's steel then its a quick fix.

 

[shouldbeinbed]

Aw now that's not fair. I was about to go an have a tinker The jockey wheel mech looks to be straight aligned and theres no chatter or clackety gear changing up or down the range, just this catch onto the spokes in top cog. The bit I wonder if its bent is the little chromed hanger that bolts the derailleur body into the frame, It looks as if it is bent inwards more than I would normally expect, but I I'm no 105 expert and the park tools e.g. bike does look quite similar from the rear end there. (Cant you tell I've ridden hub gear bikes for a while now), I do suspect it would take a hell of a force to bend that bit without mangling the rest of the rear end.

I think I'll try the L screw in the first instance and if that doesn't fettle it, will reconvene for Plan B

 

[MattHB]

The B screw is for adjusting clearance between top jockey wheel and the larger/largest cog on the cassette. The OP has clearance issue between mech and spokes!

Oops I misread the post! Sorry!

 

[RecordAceFromNew]

For a 10 year old bike with 105 and your description, it is most likely that you have a shiny alloy hanger, like one in pic below.

Such hangers are thinner at the back and are designed to bent when knocked (to save the frame or rear mech bending instead). Recommended practice is to replace if alloy (try a magnet). To get the right one you need to know what frame you have - they come in numerous sizes and shapes. Should cost around a tenner.

 

[fossyant]

To test, get the chain possibly in the big ring and a middle sprocket. You'll want the 'cage' to be fairly in line - i.e. one jockey over the other.

go to the back of the bike and crouch down. The cage should be at right angles to the floor, and not bent inwards/outwards.

Put bike in gear where it catches spokes, and go take another look from the back to identify issue - which bit of the cage is catching ? Check for loose spokes as well !

 

[lpretro1]

The hanger is specific to the bike frame not the derailleur. Looking at he pic the one you have is a fairly common one - try here http://www.gear-hanger.co.uk/ Yours looks like No3 but check against the picture. If you have set the derailleur correctly and the thing is still not straight then change the hanger.

 

[shouldbeinbed]

For a 10 year old bike with 105 and your description, it is most likely that you have a shiny alloy hanger, like one in pic below.

Such hangers are thinner at the back and are designed to bent when knocked (to save the frame or rear mech bending instead). Recommended practice is to replace if alloy (try a magnet). To get the right one you need to know what frame you have - they come in numerous sizes and shapes. Should cost around a tenner.

Yep and with a bit more time in the comfort of my kitchen tonight I'm more sure now that it is this hanger that isn't sitting right. I shall dismantle it over the weekend and see what is what.

thanks all for the advice.