Cramic

Hi all,

I ride a Giant TCR pro disk 1 with a Shimano Ultegra gear system.

Today, regards the rear derailer, when I try to change gears nothing happens the first time and I have to click it again to get the gears to shift. Both up and down and not the same gear each time.

At times during my 45 minutes ride home it would work as usual, going up and down through the gears ok. Next time and it would get stuck on a gear and I’d have to press the shifter once or more times to get it to shift.

I’m planning to get it looked at in the local giant store over the weekend, but have a couple of longish rides for Monday and Tuesday and would like to get it sorted before then.

If the store can’t take a look is there any simple tricks I can try at home? Bear in mind my mechanical know how is quite limited. Also does this sound like a common problem and what is it?




I’ve attached a couple of pics in case there’s something obvious I’m not seeing.

Thanks in advance!

alcjphil

Probably time to change cables

JohnDThompson 

The cable housing looks to be in poor condition. Disconnect the cable from the derailleur and check the housing ends and ferrules. Plastic ferrules can crack, and housing ends can splay; both issues will degrade shifting. Be sure to check all the housing, not just the piece going to the derailleur. If you find damage, trim or replace the housing, and replace the ferrules, if cracked. Get metal ferrules, if possible. Check that the cable can move smoothly through the housing.

Crankycrank

Agree with everything already mentioned but before doing anymore shifting check if the cable is fraying near the cable end. You can do this by shifting into the smallest cog while pulling on the cable itself, apply the brake so you can see where the cable goes into the shift lever mechanism and look for frayed strands. If they are frayed, continued shifting can result in a jammed cable which can be a real PITA to remove or worse, a broken piece of cable can work its way into the shifter gear and break something.

Andrew R Stewart 

Agree whole heartedly that the description mimics what a cable friction issue causes. BTW given the road rash on the der I would also do a hanger alignment check too. Andy

Iride01 

Do you have bare cable running down the outside of the down tube? If it gets very slack, even just briefly when you shift the small paddle, the it will indicate some binding in the cable between it and the DR. If it doesn't immediately move when you shift the small paddle, then there might be binding somewhere between it and the shifter. Maybe a frayed cable inside the shifter.

If you have slack in the cable when you are in the 11 tooth cog, then you need to take up that slack with the barrel adjuster or reposition the cable in the pinch bolt.

And if your bike won't shift to all the gear combinations, then seriously, get it fixed. I can't believe how many people will tell me their bike shifts perfectly, then later in the conversation they'll admit they can't get into the very high or low gears. Duh!

KerryIrons

Not probably. Look at the last picture - you can see the rust on the casing metal. Total cable & casing replacement if the OP wants things to work right.

Cramic

Thanks all, excellent advice. I feared it may be the case the cable/housing simply needs replacing and trouble shooting it at home appears beyond me.

Two further questions:

1) Big job and is the store likely to be able to sort in a day?
2) Given the problem only just became noticeable, is it likely to fail further in three approx. 50km rides on Sunday, Monday, and Tuesday? What’s worse case scenario, just stuck in one gear?

Thanks again!

alcjphil

Worst case scenario is that the cable breaks at the shifter and is impossible to remove

smd4

Replacing cables is a job everyone should be able to do on their own. If you have to take it to a shop, they can probably have the job completed by the time you go grab yourself a cup of coffee.

kcjc

Sounds like the cable is fraying at the shifter end and doesn't the cable housing look funny? It look like brake housing with coiled shell as opposed to shifter which are linear. A shop should be able to change it out in an hour or so. It take me normally around an hour to do mine including fishing out frayed cable bits and new bar tape or about half an hour for just cable replacement (including fishing out frayed bit but reusing existing housing and tape, my semi-annual routine).

Hope the route is flat because when it brakes, you'll be stuck on the smallest cog unless you carry the right allen key to move the limits.

smd4

I thought the same thing, but I'm not even sure compressionless cable can make that tight a bend.

Andrew R Stewart 

Shimano has offered precut housing, for the last loop to the der from a CS stop, that used brake casing windings. Although the stuff I've seen has been less then 4mm OD IIRC. I also suspect the shown casing is not SIS spec. Andy

maddog34

dude.. you NEED A NEW CABLE AND CASING.. that is the Obvious thing... and i'd bet that the rest of the cables/casing are in similar Bad condition. Change them or risk injury.. your choice.

maddog34

Worst case? the cable breaks as you are in Climb mode and suddenly it shifts into high gear... OUCH! And you COULD CRASH from the sudden near Stoppage of the Cranks.... and, as i said elsewhere, the OTHER CABLES may be near failure too.. ever lost your brakes on a steep downhill? It SUCKS. and HURTS. fix it or be hurt.. your choice. and getting the remainder of a Broken/Frayed shift cable out of a brifter is a real Hassle... Replacing cables/casings is Standard Maintenance.

SoSmellyAir

Yes, needed for Shadow RDs, i.e., RD-R7000, RD-R8000, RD-R9100: SHIMANO Shift Cable Housing for Rear Derailleur | SHIMANO BIKE-EU

Link to buy one (plus shipping): Shimano OT-RS900 Rear Derailleur Shift Cable Housing Excel Sports | Shop Online From Boulder Colorado

Link to buy ten (free shipping): Shimano OT-RS900 Derailleur Cable Housing 10 pieces of 240mm Black (northwestbicycle.com

oldbobcat

Definitely time to change cables.

kcjc

Interesting. I forgot the older SIS stuff I used back in the 80s until after reading your response and Google it. Didn't know that stuff is still around and being used on indexed shifting. I seen to remember linear was a must when I moved to DA 7400 and Chorus back in the late 80s.

kcjc

Thanks. Good to know as I haven't needed to service my R9100 equipped bike yet. Not happy needing to stock another cable type.

Lombard

Change cables and housings.