i have a 2016 Caadx fitted with a Tiagra 4700 and a 12-28 cassette. I got the rear cassette changed to an 11-32 but it does let me go into 1st or 2nd gear when the chain is on the large cog at the front. I have checked the Shimano compatibility chart and it should work but when I try to change it just rubs and does not let me do anything. Does anyone have any ideas?
Rear derailleur problem
- Thread starter 8765fi
- Start date
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Globalti
Legendary Member
You shouldn't be using the large-large combination anyway, it's called cross-chaining and it's the mark of somebody who lacks mechanical sympathy. It will wear the chain fast because you're forcing it to change direction too abruptly. Quite possibly also the chain won't go up onto the two biggest cogs because you've reached the limit of the derailleur and the chain is too tight.
midliferider
Guru
- Location
- Northampton
My understanding is that you will need to adjust the cable strength and re tune the gears.
sgl5gjr
Senior Member
- Location
- Huntingdon
Take it you sorted out the chain length to match the new set up?
roadrash
cycle chatterer
- Location
- sitting on the edge of wigan pier
if that's the problem then loads of videos can be found on youtube on how to measure the correct chain length .
Ajax Bay
Guru
- Location
- East Devon
Shimano spec
I assume you have the GS version of the RD-4700 as the SS (short cage) version is spec'ed to max 28t sprocket.
I read this as the front derailleur (FD) not being indexed correctly. As the OP changes up the cassette it gets to a point where the chain rubs on the inner cage plate of the FD. If this is the problem you just need properly to index your FD.
I assume the chain does go on the largest sprocket (at the back) when the chain is on the small chainring (at the front)?
It is possible, though, that if the chain was already a bit short with the 12-28 cassette on, the chain would just be too short for the 32. But it should at least go on the second largest which will be 27 or 28 (which is another clue as to this not being a chain length problem). Only one more link (one inch) is needed if the length was right with the 28t - but best to get the length right from first principles, as others have suggested. AASHTA
When on the large ring and the third largest rear sprocket, what o'clock does the cage (with the jockey wheels) on the rear derailleur (RD) describe (eg 5, 6, 7)?
Finally, you probably need to screw in to its fullest extent the 'B screw' (the end of which presses against the hanger and tilts the RD). When in the largest sprocket, the top jockey wheel should be circa 8mm minimum below the large sprocket teeth.
Since you presumably have 4700 STIs as well, you may wish to scan this thread on woes with 5700 (same under bar tape cable routing).
