Replacing Cable Guides to Improve Shifting

samfailed

I've been having issues with sticky downshifting on my 2018 Giant Defy Advanced 2 for some time. I've replaced the cable inners and outers on several occasions but I face the same problem each time. The cable is obviously sticking somewhere meaning the derailleur will not return to the smallest cog on the cassette. I can force it do so manually by pulling on the exposed bit of cable but otherwise it's impossible.

I've tried everything else so I thought it might be worth replacing the cable guides that take it through the frame and under the bottom bracket. There's plenty of muck, grim and water that probably makes it way in and that could be causing an issue somewhere along the line? I've found the replacements online (only £2.50!), is this worth a go or am I missing something more obvious and easier to fix?

thistle_

What gear shifters do you have? ( https://forum.bikeradar.com/discussion/13115581/r7000-rear-mech-cable-route-warning-potentially-difficult-content#latest )

The 2018 Defy looks like it has internal cable routing. Check whether the thin plastic sleeving that the gear wire goes through also goes through the cable guide, it stops the cable getting gunked up.
If you have sleeving here already, the cable should be pristine as long as it the sleeving hasn't got damaged and a new cable guide probably won't make much difference.

photonic69

Have you replaced the cable guides in shifters? There are reports of them wearing through and snagging the inners. I did mine a couplel of months back. Quite cheap considering if they wear out the cable starts chewing up your shifter body which is far more expensive to replace.

https://www.sjscycles.co.uk/gear-spares/shimano-strs505-sl-cable-guide-a-right-hand-y03n75000/

and

https://www.sjscycles.co.uk/gear-spares/shimano-strs505-sl-cable-guide-b-right-hand-y03n74000/

You'll find corresponding ones for the LHS shifter.

EDIT: Mine were 105 ST-RS505 hydraulic shifters. The plastic cable guides for yours will be slightly different but still applicable

samfailed

Replaced cable guides and made no difference as thistle pointed out.

Had a look at the cable guides in the shifters, removed them and tested and it made no difference.

Stuck now, no idea what could be the issue, replace the whole shifter perhaps?

MattFalle

have you tried flushing out the whole shifter with GT or WD or similar, re-oiling with a light oil to see if that helps?

ilovegrace

I had this problem front and rear shifting on an inter cable routed Felt Z5.
Tried everything from new shifter to new front mech , it would work for a while then back to square one.
Had enough in the end , stripped the bike of parts and the frame is hung up in the garage.
I have a Look 566 external cable routing for 6 years and never had a shifting problem.
Sorry cant be of any help but like a car , when are they costing to much to keep?

photonic69

Have you tried Jagwire Road Elite cables? It has an inner sheath that can go from the first stop near the head tube all the way to the rear derailleur. It adds an extra bit of slipperiness. Very useful over the bottom bracket plastic cable guide. It’s a bit more pricey but if it works it works. Used this on my all weather commuter.

https://jagwire.com/products/diy-cable-kits/elite-sealed-road-shift-kit

carl_p

I'd try a plastic liner running through the cable guide rather than bare cable. Perhaps a bit of Cable Magic too. Have you tried adjusting the limit screw, can you actually make the chain jump off the small cog?

samfailed

PROBLEM SOLVED!

If in doubt, take it to your LBS. They sorted it for me very quickly so I could ride with my club on Sunday, despite the fact they have a three week waiting list for most repairs! It seems it was the end of the outer had become frayed and squished at the point where it enters the frame. However, it would have never have worked after I had been fiddling with it because I managed to wrap the gear cables around the brake hose inside the frame, oooops.