Rethreading chain - after derailleur dismantling (is it necessary to break the chain?

[YorkshireGull]

Novice question probably - so please be kind

Unable to shift to small cogs on rear derailleur...so, I decided to do some cleaning of the derailleur as it was all gunked up. All good so far (except the shifter at the front still seems to be clicking to nothing - so perhaps I need to investigate the chain tension) but I've now created another problem with the chain.

Having dismantled the pulley and jockey wheel and cleaned them, and removing the chain - I can now not of course get the chain back on! The problem is that it is totally slack and fails to snap back into it's normal position. From googling it looks like I need to break the chain to then feed it back through and reconnect. Some posts say it's possible to put it back on (as I have done) by removing the wheels other say it's easier to break the chain.

Any advice appreciated - as I'd prefer to avoid breaking a chain that is/was fine!

I have a Shimano 105 - CN-5700 - Cube attempt.
Have I made a schoolboy error in my haste!

[Painkiller]

no need to break the chain. Can you post a side view pic of what you have going on?. your rear plate and top pulley need to be attached but loose, then set your bottom pully on the inside of chain and place into position making sure it is on the top side of the little bent tab on the plate.

[YorkshireGull]

(09-06-2015, 05:35 PM)painkiller Wrote:  no need to break the chain. Can you post a side view pic of what you have going on?. your rear plate and top pulley need to be attached but loose, then set your bottom pully on the inside of chain and place into position making sure it is on the top side of the little bent tab on the plate.

Thanks Painkiller for your reply. Here is a link to a photo -

(sorry - I could take a better one in the morning as late here and now dark!).PLEASE note that tinypic has flipped the photo so the picture is upside down (aahh!) - But you can see how the derailleur is failed to "set" to it's correct position (I.e. not taught at all). It's like it's on the wrong way round but once you incurl it manually it is the right way round and chain on the right side (as per the other bikes in my garage).

Another link to photo here:
http://tinypic.com/m/iymzy0/1

[Painkiller]

your derailleur looks way hyper extended, does it return to normal with the chain removed again?

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did you install the rear plate proper? I do not see the top pulley in the picture either

[YorkshireGull]

(09-06-2015, 06:29 PM)painkiller Wrote:  your derailleur looks way hyper extended, does it return to normal with the chain removed again?

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did you install the rear plate proper? I do not see the top pulley in the picture either

Hi Painkiller - here are some much better daylight photos - again the pictures are flipped. The back plate is on, and I've double checked the plate is on the right way (or I think it is). I agree - the arm just flops away (the wrong way) - but you can curl it up as it should be by using a hand (!) (see the final photo - which also shows how I've threaded it). The B - adjustment screw is screwed right out (could that have such an influence?).

Any more thoughts based on these better pics?

[Painkiller]

something happened to your spring tension, look at this video and see if yours comes apart like this. do not worry about the pivot bolt spring in the video
https://www.youtube.com/watch?v=L5KWFhzIPoc

[YorkshireGull]

(09-07-2015, 07:18 AM)painkiller Wrote:  something happened to your spring tension, look at this video and see if yours comes apart like this. do not worry about the pivot bolt spring in the video
https://www.youtube.com/watch?v=L5KWFhzIPoc

thanks (again!). The spring tension at one end was bent (not sure if I bent it when working with the derailleur or if this is the root cause of my ORIGINAL problem which is no shifting to the rear bottom cog). I managed to re-set it (but it's come loose again already) so will either try to source a replacement spring (or try to straighten out the "bend" in the end section that has to locate to set the spring). I can now see how to resolve this - so thanks ever so much !

The you tube video is brilliant - thanks for directing me to it.

[Painkiller]

Good deal, you may be able to source a new spring at the local bike shop.