SoSmellyAir

In late fall this year I had RD shifting problems which I incorrectly attributed to excessive wax on chain, but those problems went away after the RD cable snapped and forced me to replace it.

This aspect is definitely worth looking into if only to avoid (1) being stranded when the RD shift cable finally snaps and (2) the difficulty of extracting a snapped RD cable from an STI lever.

cxwrench

[QUOTE=gif4445;22353029
Sometimes I can see the RD appears to be bent, other times no. I do know that the tool the LBS uses to bend the RD back, does not work according to procedure for this Long cage derailleur.[/QUOTE]
You're not making any sense here.

gif4445

Sorry, when I say "RD looks to be bent", I'm meaning it's out of line and actually roadlink and/or hanger is bent.

gif4445

I meant RD is out of line and roadlink/hanger is bent.

70sSanO

If the hanger is bent the RoadLink will only make it worse.

John

squirtdad

Just checking is it the RD-R8000-GS derailleur ?

that is the on speced to handle 11-34, 39 tooth capacity and 16 tooth front difference

OP is pushing that by 6 teeth beyond max rear cog and 6 teeth beyond wrap capacity, which is significant

using a roadlink does not change this at all

it would seem if it can be adjusted to work and then goes out of adjustment, it could very well be that this exceeding the limits is putting stress on some area of the system.

Can the chain handle big/big and small/small equally well? I know from mis sizing a change that a barely working Big/Big caused some issues for me

cyccommute 

However that would only have an effect on set up. It’s not something that can be adjusted and then go out of adjustment. If the hanger is bent, it would be difficult or impossible to adjust properly.

As an example of pushing the limits I’m using a Shimano RD-M950 rear derailer. Shimano says that it is speced to handle an 11-34 cassette, and a 43 tooth total difference and a 22 tooth front tooth difference. I’m using it with a Road Link on an 11-36 cassette so I’m 3 teeth beyond the specifications. I’ve used it with a 48/36/20 crankset which means I’m using it for a total capacity of 53 teeth and a 28 tooth front ring difference which should be way beyond its capacity. I’m a However even with the 20 tooth inner and the very wide range crank, I’ve never had any adjustment issues with the derailer. The chain gets a bit slack in the highest two cassette gears but I wouldn’t use those any way. I am now using a 44/34/20 crank puts the total capacity at 49 which is only 6 teeth beyond the wrap capacity. That hasn’t changed anything in terms of adjustment.

A RoadLink may not change the capacity but it will change the maximum size of the low gear. That’s the reason to use them.

Not in my experience and I’m going far beyond the specifications of the system. There is no stress on the system that should cause a slow degradation of the shifting.

70sSanO

Just wondering… Did the issue start after removing the rear wheel and then reinstalling it?

John

gif4445

No. This whole thing has been gradual for the most part. From not needing adjustment for well over a thousand miles, to needing adjustment after 50-60 miles. There have been replacements made to most of the drivetrain however during this time.

cxwrench

Max cog and capacity generally go together. If you exceed the max cog size on a 1x, you also exceed the capacity. If you exceed the max cog size on a 2x and don't decrease the difference between chainring sizes, you exceed the capacity.

70sSanO

What baffles me is having to continually adjust the limit screws. With solid attach points and RD pivots, the limit screws never need to be touched.

Technically, once a RD is set up the limit screws no longer have a function with STI shifters since the cable and shifter ratchet pawls control now far the RD moves. It is nice to have them set as a precaution, but that is it.

My gut feel is the hanger/attach surface is not flat enough so it is not completely solid and may slightly shift back and forth, but I have no way of knowing and it is just a wild guess.

John

Calsun

With my Trek 5200 with its 53/39 chainings I have used a 12-25 cassette since I bought the bike 20 years ago. At 71 it is still fine for the hills with the 39/25 combination and no need to ever stand in the pedals or even drop my heels. I have a long cage derailleur on my two mountain bikes but they have 1x drivetrains.

gif4445

I did a couple things after some semi-careful thought. The first was to order a 46-30, 11-36 cassette and brifters. Supposedly the 46-30 was available immediately. It will probably be a wait on the other two items. It will be interesting to see what difference taking the road link out will make. While I'm waiting on those, I will be waiting on a new Roubaix, which I ordered the same day. Most likely a lengthy wait for most of my items, but we have another few months of winter left. If I have everything by the middle of summer, I'll be happy.

venturi95

My thoughts: you are over capacity and bending something with a seeming harmless cassette/chainring choice. I would recommend using a narrower ratio set up as an experiment and see if that takes care of your alignment woes.

gif4445

The LBS is installing a 46/30 and an11-36 cassette this week. We will see how that goes.

tFUnK

Not much to add other than to say I have 1x and 2x setups with medium cage RDs using RD extenders, accommodating 36t, 40t, and 50t max cogs. No shifting issues but I'm not racing nor am I doing a ton of miles.