Originally Posted by gif4445

I've got a 2018 Specialized Diverge. I modified or replaced about everything on the bike to fit me and my type of riding. On the drivetrain, I replaced the crankset with 165mm cranks. By doing that, I had little choice but to go with a 50/34. Because I do a bunch of climbing, I went with an 11-40 cassette. Of course by adding the 11-40, I needed to replace the derailleur with a long cage and road link. The first thing I discovered was how easily (compared to a medium/short cage) the derailleur got out of adjustment and wouldn't shift into the 40 gear. It has only gotten worse with time. The bike has about 14K miles on it and although at the present it has a new chain and relatively new cassette, derailleur and road link, it will lose adjustment in 50-100 miles. My first thought was to simply blame the fact that the long cage plus road link just stick "out there" too much and succumb to the power put on it through the chain, resulting in bent a derailleur. While this was true some of the time, it wasn't the reason most of the time. Anybody's thoughts and actual experiences are appreciated.

Originally Posted by gif4445

I've got a 2018 Specialized Diverge. I modified or replaced about everything on the bike to fit me and my type of riding. On the drivetrain, I replaced the crankset with 165mm cranks. By doing that, I had little choice but to go with a 50/34. Because I do a bunch of climbing, I went with an 11-40 cassette. Of course by adding the 11-40, I needed to replace the derailleur with a long cage and road link. The first thing I discovered was how easily (compared to a medium/short cage) the derailleur got out of adjustment and wouldn't shift into the 40 gear. It has only gotten worse with time. The bike has about 14K miles on it and although at the present it has a new chain and relatively new cassette, derailleur and road link, it will lose adjustment in 50-100 miles. My first thought was to simply blame the fact that the long cage plus road link just stick "out there" too much and succumb to the power put on it through the chain, resulting in bent a derailleur. While this was true some of the time, it wasn't the reason most of the time. Anybody's thoughts and actual experiences are appreciated.

Originally Posted by cubewheels

My Sensah Ignite road RD with stock medium cage (originally used 32-13t freewheel) was still able to shift with 40 - 11t cassette on all cogs smoothly.

I did not do any mods to the RD, I did not even use road nor goat link. I simply adjusted the B-screw all the way in. The only problem I encountered was inconsistent spacing between the cogs as it was a dirt cheap cassette and I had to insert paper shims in some of the spacer to correct spacing. It shifted smoothly on all cogs since the fix and haven't had any problems so far (over 100 miles of riding with the 40-11t cassette to date).

In many RD designs, the upper jockey wheel moved down when the cage is pulled when downshifting to lower (bigger sized) cogs. The bigger angle the cage swivels as you shift, the more vertical distance the jockey wheel will move as well.... This means a long cage could make things worse because it swivels less angle. It is not a problem for RDs designed for use with >40t cassettes because the linkages are designed to have larger vertical movement and uses long cage without any issues. A road RD's linkages move less vertically but the swiveling action of the cage can help increase vertical movement for 40t cassettes.

You may try removing the long cage and putting back the stock cage and see if that solves the problem. Adust the B-screw all the way in. You may even try doing it without the road link if it's going the clear the 40t cassette. Having the right chain length matters. Setup the chain length shifted in the "small-small" combo (small ring + smallest tooth cog in the cassette). Adjust chain length so the cage is horizontal or slightly upwards with a bit of tension remaining.

Originally Posted by gif4445

Of course by adding the 11-40, I needed to replace the derailleur with a long cage and road link. The first thing I discovered was how easily (compared to a medium/short cage) the derailleur got out of adjustment and wouldn't shift into the 40 gear.It has only gotten worse with time. The bike has about 14K miles on it and although at the present it has a new chain and relatively new cassette, derailleur and road link, it will lose adjustment in 50-100 miles. My first thought was to simply blame the fact that the long cage plus road link just stick "out there" too much and succumb to the power put on it through the chain, resulting in bent a derailleur. While this was true some of the time, it wasn't the reason most of the time. Anybody's thoughts and actual experiences are appreciated.

Originally Posted by cyccommute

I’ve got two bikes with road links on them and have no issues whatsoever with the derailer going out of adjustment. I also have about 10 other bikes with long cage rear derailers of various flavors and vintages (9 speed late 90s to 10 speed around 2010) shifting mountain bikes, road bike, and touring bikes. I’ve never had a problem with any of them going out of adjustment at all. I would even say that I’ve gone years without having to do an adjustment. The only time I have to “adjust” the rear derailer is after a cable change and I don’t do those very often.

Because you can’t shift into the lowest gear, I would suspect a cable problem before any other problem. How many miles do you have on the derailer? I assume that you haven’t been suffering with this problem for 14,000 miles. What “adjustments” have you been making? That will tell us something of what your problem is.

Originally Posted by Iride01

You don't state what RD you got. If long cage and short cage are the only thing you think matters for sizing your drive train and shifting components then it's no wonder that you got something that doesn't work.

Give some more details about what you have and where you want to be and maybe something can be worked out. But you may have wasted some money and now have to lay out some more.

Originally Posted by 70sSanO

I don't have extensive experience with using a RoadLink, but I have them on a couple older mtb's and don't have any issues; but my smallest cogs are 13t.

The one thing a RoadLink does well is getting the RD to shift into a larger than spec cog. The one thing it doesn't do well is shift into smaller cogs.

The fact that your shifting is coming out of adjustment and not shifting into the 40t, is more of an indication that it is not setup correctly, a bent hanger, or your shift cable is fraying. I'm not sure of the "bent" RD other than an improperly sized chain or forced shifting under extreme stress.

For a road bike, I'd have to agree with shelbyfv and get a 46/30 crankset in 165mm, a compatible long cage RD, and an 11-36 cassette. You will actually end up with a lower ratio in the 30/36, than the 34/40. The only question is if you are really pushing a 50/11. I suspect that the need for a 34/40 means the 50/11 is only used bombing downhill or not at all.

John

Originally Posted by BTinNYC

gif4445,
what RD are you using?

Originally Posted by Litespud

what “power put in through the chain”? The only part of the chain experiencing “power” is the upper stretch between the cassette and the crankset. The RD is simply managing the slack

Originally Posted by cxwrench

shelbyfv and Litespud are correct. OP is confused about how drivetrains in general and rear derailleurs in particular function. Long cage derailleurs aren't any harder to set up than any other derailleur. Length of the cage makes no difference. The extra length of the cage is to wrap chain, nothing more. Many long/medium cage derailleurs have the same big cog spec as their short cage versions, the long cage wraps the extra chain needed for a triple up front. Road links on the other hand will allow a derailleur to clear a larger big cog but don't make the cage any longer so you can't wrap the extra chain you need for the bigger cog AND shifting will suffer on the smaller cogs because the upper pulley is now too far away from the cogs. This is even stated on the Wolf Tooth website. And of course the derailleur doesn't feel any power put through the drivetrain as it's situated before the cassette. All it does is manage slack and guide the chain onto the proper cog.

Originally Posted by shelbyfv

Since you have gone beyond spec it's not surprising you are having problems. Get a 46-30 crank, 36t cassette and ditch the road link. EDIT- I got curious and found that you can get 165mm cranks with 46-30 from FSA and Shimano GRX. Looks like you can both have your cake and eat it.

Originally Posted by gif4445

I replaced the shifting cable about 300 miles ago. Old one looked fine. Lightly lubed up some areas along the way, underneath BB, brifter. No affect. The derailluer has about 1500 miles on it. I've been successful in adjusting the derailleur back to working flawlessly, as has my LBS. But the problem returns and lately it returns around the second ride out.

Originally Posted by gif4445

I'm thinking this is the next step. And it fits my riding. 50-11 is used only on the downhill, so although there will be times it will be missed, it won't be much. The last I checked with my LBS, parts were non-existant. Thinking I may have to go after this myself. What sources do you use or suggest?

Originally Posted by cyccommute

Since you can get the derailer to work flawlessly and then it degrades, I don’t see your problem as being with the equipment nor with being beyond Shimano’s specifications. You aren’t that far beyond the specification and, in my experience, Shimano’s specification are very conservative.

Are the adjustments to get the bike back to working to the cable tension?


I’ve gone through a recent spate of the front derailer slowly degrading and it turned out to be a slipping cable at the anchor bolt. Going to a thicker cable seems to have solved the problem. The thicker cable lets the anchor cable bit into the cable better and keeps it from slipping. The issue was (is) progressive with the shifting deteriorating over time. It also occurs at the point where the cable tension is at its highest, i.e. high gear on the front derailer. The cable tension is highest in the low gear on the rear.

Originally Posted by Iride01

Your Shimano Ultegra RD-R8000 has a low sprocket max of 34 teeth. Sure with a hangar extender you can fudge that to handle your larger40, 48 or 50 tooth cog. But then somethings is going to suffer in it's performance because now the DR is physically further away from the 11 tooth cog.

While in my younger days I experimented all the time with making stuff that shouldn't work together work together, I now just find it easier to stay within the designers specs.

It might just be that finicky is what you should expect with a groupset that is being run out of spec and for the demands of your particular riding. Maybe you should get the component groups that are made for the 11-40 or whatever size rear you are wanting to run.

Originally Posted by gif4445

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.