hobkirk

I just replaced my RD cable. I've done this 10 times, I've replaced my FD and RD several times. So this seemed routine (except for a bunch of time dealing with a frozen cable adjuster, but problems like that are pretty routine themselves).

The gears shifted great on my workbench (bike upside down) but when riding the RD was reluctant to shift into the smallest gear with the lever having no tension (feeling cable behind adjuster on downtube). It seems like the RD spring isn't pushing the RD carriage all the way out. Everything is well lubed and the I don't find any binding in the RD in-out action.

1. Does this mean I need to overhaul the RD (or replace it)?
   Is this practical for someone asking these questions? I've got tools, I use to own/manage a car repair business, but I ran the desk and rarely worked on cars.
2. Next time, is there any easy way to retrieve the head and frayed threads that remain in the housing? Or, what am I doing wrong?

• I click the shifter to 1st gear (11-tooth), then push lever to side to expose the "fill me" hole for the new cable.
• But I was greeted by the frayed cable attached to the head, and the head was buried deeper.
• My first try was pushing it out with the cable end of the new cable. No go.
• I eventually did something that exposed the head and I was able to pull it out, but I don't really know what I did.
• Tools - I was using micro pliers, tweezers, ice pick, and a bungee cord to lock the lever in position.
• I couldn't find anything useful at Park Tool.

I use a Shimano XT RD (661? 771? it's 9-speed on a MTB) on my 10-speed road bike (2008 Roubaix). I'm old and fat, I want big gears, and at the time Ultegra had a 28-tooth cassette limit (I have 11-34). This setup has worked fine for at least two years.

THANK YOU!
Doug

PS - I do absolutely know that PM is the ideal solution. Just replace the cable every 6 months. But there are always complications (broken pelvis, knowing I am about to replace the shifters with newer Ultegra 6700 levers that are sitting in the box).

dsbrantjr

What is the condition of the cable housings, especially the last loop leading into the derailleur? I generally replace the housings as well as the inners since a groove gets worn into the housings and it does not always play well with a new inner cable as it sits differently or can be a slightly different diameter, or perhaps a housing end has gotten dislodged and is not seated correctly.

IthaDan 

B bolt and chain length (too little of the former and too much of the latter) can make a RD reluctant to drop to the smallest cog.

hobkirk

• I did not replace the housings nor even rotate the rear one. (I'm about to do all new levers, routing the shift cables under the bar tape, hopefully in the next week.)

• The B-bolt is bottomed and has been since day 1 (at least 10K miles ago). I did check clearance Big/Small and Small/Big to see if B was a problem.
• The chain is about 700 miles old and length is perfect (slightly longer than needed for Big/Big).

Bike Gremlin

Not going all the way out could be the limit screw. Did you check without cable attached, does it move enough?

If it moves enough out without cable, then it is cable tension.

Outer limit screw should allow the pulley wheel to move just past the middle of the last sprocket.
Inner limit screw should align rd pulley exactly below the largest (first) sprocket.

Andrew R Stewart 

Shimano is well known for their weak parallelogram return springs, I have seen dozens which were so. With good cable conditions, proper limits and B adjustments the der will be very sluggish when moving the last bit onto the high gear cog(s). Often with the cable detached the der will shift relatively OK but with cable in play not so, and again this is with new cables and casing (as replacing cable and casing is pretty much the first thing a pro wrench does that a customer will have no problem with).


Testing this with a new rear der clears up the shifting just about every time. One can even feel the return spring tension lack when moving the der by hand and comparing to a new one.


But all the above answers do need to be gone through and I'll add that a sloppy bushing in the guide pulley also hinders accurate shifting as does a chain with well worn side to side flexibility.


As for fishing out the frayed and broken off cable head- I usually start with trying to shift the lever into the high gear position and using a very thin pick push the head out from the cable/casing port. Andy.

grizzly59

The weakish spring in the deraileur has to overcome any drag in the cable system + drag due to crud in the deraileur mechanism + pull the chain over. Some RD's have a slotted screwhead showing inside the parallelogram that can be turned a notch and increase the spring force. If you have compressed air, shield the rear tire with cardboard or the sports section, spray the RD down with WD40, mineral spirits, etc., let it sit 5 min, and blow it all out. You can't get oil on your brake tracks! Drop of oil on the mech pivots, wipe it down. If your cable is catching inside the housing you need to replace that. Cables tend to wear through teflon liners on bends of the housing, any doubt replace. Recheck the limit screws. When you're trying to shift to the smallest cog is your cable still tight, or a bit of slack? That's all I can think of.

hobkirk

THANKS! You nailed it, as always.

I twisted the rear cable housing 180° and reassembled it with no other changes. The RD had zero reluctance going all the way out.

I just got back from a 31-mile loop through Sudbury, Concord, Carlisle, and Acton, through a MA park and by cranberry bogs. And snick, snick through the gears, smooth as silk. So, like I said, "Thanks!"

Andrew R Stewart 

So by twisting the casing loop 180* you made the inner cable contact a new portion of the casing's inner liner, the unworn section that was the outer portion. Basically the same as replacing the casing with new with one difference that pro wrenches need to heed. That is that if this doesn't work mid term and the repair comes back the customer will ask, and rightfully so, why didn't the shop just replace the cable and casing? for only $10 more this could have saved the customer from coming back, from having a bad experience when riding.


So here's the difference from a home mechanic working on his own stuff and a shop working on their customer's bike. One more reason that a shop charges what it takes to warranty their work, or at least the better shops do this.


Glad your bike works well for now. Do pay attention to the shifting into the small cog as the miles continue to add up. Andy

hobkirk

Andy, I agree with you 100%! Sometimes I think my unspoken ideas are implicit.

• I rotated the cable housing as a quick fix because I know I'm going to change it shortly. I posted the result to show the people who suggested cable housing that they were right, and "thank you."
• I ran my own car repair shop for 14 years. I absolutely understand the difference between pro shop service and DIY. This happened on a Saturday afternoon, the rudest time to visit my LBS, and I was going out for a ride, etc., etc.
• By the time I'd fished out the cable head and dialed it all in, it was too late to ride. But maybe I could ride Sunday before the rain. So I asked here, hoping a pro tech would save me inconvenience (I could have ridden w/o the 11 cog).

I apologize to Andy and anyone else who may have felt slighted. I always have a respectful attitude when I ask Q's in this forum. And I very often discover something I had never considered.

Andrew R Stewart 

hobkirk- I wasn't trying to leave the impression that I had been slighted or dissed at all. Like you my posts can have a meaning some miss. I try to give advice to those who are just reading. Who might have the same issues or just wish to better understand the issue at hand in a deeper sense. I have been told this can come over as condescending. If I sounded like that here I apologize.

My mentioning the difference between home and pro approaches to repair was to help the many who never see the pro side to understand why we do what we do sometimes. Not to disrespect your fix, which was a good solution that I will remember and pull from my mental file in the future. Andy