'19 Diverge - Larger Cassette Options

I have a '19 Diverge Carbon Comp with Shimano R8000 rear derailleur.  I have a 48/32 up front and 11/34 in back.  Max advertised capacity is 11/34. After a couple of rides these past weeks I feel like I'd benefit from an 11/36 or 11/40. It looks like the way to do this is via the Wolf Tooth Roadlink DM.  Does anyone have any experience with the Roadlink or is there another solution I may be overlooking?

Thanks!!

An r8000 will cover the extra 2 teeth with no probs and maybe the 11-40 without a road link.  There are some YouTube videos showing it, but I've never tried because I live in MN and we don't have much in the way of hills.

Shimano is super conservative with their cassette size recommendations, like to the point where they can't be trusted.

Volsung wrote:An r8000 will cover the extra 2 teeth with no probs and maybe the 11-40 without a road link.  There are some YouTube videos showing it, but I've never tried because I live in MN and we don't have much in the way of hills.

Shimano is super conservative with their cassette size recommendations, like to the point where they can't be trusted.

I second that.  I'm using an Ultegra 6800 GS with a specified high sprocket 11-12 T and low sprocket 28-32 T.  It shifts fine with high sprockets as large as 16 T and low sprockets as large as 40 T.  It also specifies an 11-speed chain but shifts fine with an 8-speed or 9-speed chain.

One issue the OP might experience is total capacity.  With 48-32 T chainrings and a 11-40 T cassette the derailleur will have to wrap 45 T of chain.  My Ultegra 6800 GS is specified for 37 T total.  I haven't had any problems with wrap because I've never had more than a 10 T difference between chainrings or a 24 T difference between cogs.  Also I don't use the 4 smaller cogs with the small chainring.

Well Stu just about covered it well. I too use a medium-long-cage Ultegra 6800 with a 12-36T cassette I cobbled together (removing the silly 11T and installing the 36, leaving all those nice intermediate gears with the stock 34 small ring and a smaller 46 up front; I like the smaller gap up front as I use both often, and the 34/36 combo gets me up hills really nicely. (I had used a true 36/46 for a while but went back to the stock 34 for that extra 6% climbing gearing.) Cross-chaining is only an issue at the extremes. Been working well for several years. Do it!

Thanks for the info. I am just getting my head wrapped around all of this. Reading Wolftooth's site (and based on your input) it sounds like I can easily get from an 11/34 in the back to an 11/36. Woolftooth does state to not exceed the capacity of the derailleur, which I believe on my bike is 39T. If I have a 48/32 up front and 11/36 in back, Isn't that 41T and too much? I do not completely understand the capacity piece except as a number that you calculate. Thanks for the help and patience. 

TimmyR wrote:... I do not completely understand the capacity piece except as a number that you calculate ... 

The capacity is what length of chain the derailleur can wrap up as you go from the small/small combination (least chain required) to the large/large combination (most chain required).  If your derailleur lacks sufficient capacity then the chain will either go slack in the small/small combination (bad) or fail to shift into the large/large combination (worse).  I personally never use the small chainring with the smaller cogs so I don't account for that in capacity calculations.  I do always check the large/large combination, even though I don't intentionally use that I could get there by accident.  I suppose an electronic shifting system could be programmed to avoid extreme combinations but I've never used one.

I didn't think much about max capacity either, but note that with the med-long cage Ultegra 6800 OEM early Diverge setup using 50/34 "compact rings" closed down to 46/34, there's sufficient capacity to run 11/36 cassette. Again, I've chosen to delete the higher-friction 11T cog so as to add on the 36T without removing an intermediate cog, with I think only +1 extra chain link...can't remember.
But it is maxed out, where accidental 34/12 is quite slack, and likewise 46/36 is uncomfortably snug...so I'm not sure if an accidental stock 50 with a 36cog requires an additional link again for the higher capacity. But you should be able to get the Goldilocks chain length to work without Wolfstooth nor other trickery, as Spesh simply understated the capacity...except with the short-cage derailleur.
(They also stated that the max tire width is 35, when I'm able to squeeze 38mm Pana-made tires in there nicely.)

Stu is right, especially riding on bumpy stuff where loose chain can lead to more frame slap and dropped chains.  If this is your RD  https://bike.shimano.com/en-US/product/component/ultegra-r8000/RD-R8000-GS.html you are correct it is spec'd at 39T. The calculation is simply 48-32=16T range up front,  and 34-11=23T in the back, for a combined 39T swing between small-small and big-big on your bike.  Going to 36 on the back with a couple of B screw turns and a slightly longer chain is no biggie, but going to 40 takes you out to a 49 capacity.   I have a 10 spd 2x GRX rig, but the RX400 has a 41T capacity.  The 11 spd GRX 810 derailleurs are listed at 40T capacity and a 34 T max low cog size--pretty close to your RD.

I went from 11/34 to the 10 sp version of this 11/40 cassette  https://sunrace.com/product/csms8-eax/  and added the Wolftooth GoatLink, replaced an original KMC chain with an Ultegra (used every last link, so no chain trimming), and it shifted better than the original.  I was pushing about 350lbs of total bike, rider, gear and trailer weight up and down reasonably steep chunky gravel sections.  Like Stu, I try to avoid cross-chaining, as it increases wear and friction.  After cruising up a shallow climb with a tailwind or drafting in a group ride in the big ring on a 46/30 and the 3rd or 4th biggest cog of that cassette, have I gotten lost in my thoughts, scenery or conversation  on a stretch I normally ride on the small ring and shifted to big-big when the slope kicked up?  Yup, and more than once.  If the chain were too tight, that would put huge stress on derailleur and not be great for chain, cog and chainring.  

There was a reason MTBs used to come in 3x9 with 22-34 low gear ratios.  My new 30-40 low gear still isn't as low as my old 26'er low gear, but it sure beats 30-34 or 30-36 on the steep stuff with a load.

As you noted, Wolftooth on the Roadlink page https://www.wolftoothcomponents.com/products/roadlink?_pos=1&_sid=2c7e2e0dc&_ss=r calls out the capacity issues.  On the RoadlinkDM page they say, "Optimized for use with GRX ultra wide range drivetrains when using the GRX 810 (RX810) rear derailleur."

The Goatlink  page https://www.wolftoothcomponents.com/products/goatlink has some charts about chain wrap and engagement improving with the Goatlink vs just cranking in the B screw to clear the larger cogs, and you probably get pretty close to the same effect with the RoadlinkDM. The B-screw approach works for a couple of extra teeth, but it reduces the number of teeth the chain is resting on if you go all the way to 40T, so chain and cogs will wear faster.   If you don't change chains more frequently, stretched/worn chains wear chainrings faster. If you can't find Roadlink DM, Goatlink is officially for MTB rigs, but I pinged them at the time because RoadlinkDM hadn't come out yet, and they said the Goatlink should be fine, they just hadn't tested it.

You can absolutely try an 11-40 cassette with your current crankset and derailleur.  The Roadlink DM is the correct extender, though you may not need it.  For the minor expense you could try it both ways to see which you prefer.  If it was not clear, the Roadlink only assists the derailleur to reach the out of spec 40T cog.  It does nothing to increase the capacity of the derailleur.  Just be sure you size the chain for the 48x40 combination to avoid damage and go from there with your experimentation.  A couple of notes from my experience:  The big benefit, apart from the relief on long, steep climbs is not needing to shift the front as much.  I can use the entire cassette on the big ring, only shifting to the small ring on the front when the climbs will be lengthy (perhaps the usability of the big-big combination is a benefit of the extender).  Chain drops can be avoided by going to the noisy extremes on the cassette (big-big and small-small) before shifting the front.  

TheSubaruGuru wrote:I didn't think much about max capacity either, but note that with the med-long cage Ultegra 6800 OEM early Diverge setup using 50/34 "compact rings" closed down to 46/34, there's sufficient capacity to run 11/36 cassette. Again, I've chosen to delete the higher-friction 11T cog so as to add on the 36T without removing an intermediate cog, with I think only +1 extra chain link...can't remember.
But it is maxed out, where accidental 34/12 is quite slack, and likewise 46/36 is uncomfortably snug...so I'm not sure if an accidental stock 50 with a 36cog requires an additional link again for the higher capacity. But you should be able to get the Goldilocks chain length to work without Wolfstooth nor other trickery, as Spesh simply understated the capacity...except with the short-cage derailleur.
(They also stated that the max tire width is 35, when I'm able to squeeze 38mm Pana-made tires in there nicely.)

Thanks! I am running 48/32 up front and an Ultegra R8000 Shadow Medium Cage in the rear. My LBS believes I need a Wolftooth Road or Goatlink (they mentioned Goatlink...my understanding is it'd be a Roadlink DM). I am not skilled in adjusting my derailleur or I'd just take a shot at it and see what happens, so I'm researching all options. It makes sense to me that as long as you avoid the extremes you'd be fine. I worry a bit that in the midst of suffering I'd accidentally go big-big or small-small and set myself up for failure. 

Interesting this is popping up now.  I'm in search of an 11 speed 11-36 cassette as I presently run a 48/31 up front and looking to get lower than 31/34 for climbing.  We have gravel rides in my area with diets of 5000' of elevation gain. I can't seem to find Shimano/SRAM in this combo. 

GSParkes wrote:I can't seem to find Shimano/SRAM in this combo. 

SRAM 11-36 here.  I knew they existed....   I used to run one.

https://www.jensonusa.com/SRAM-PG-1130-11-Speed-Cassette-11-36T-11-Speed?pt_source=googleads&pt_medium=cpc&pt_campaign=&pt_keyword=&utm_source=bing&utm_medium=cpc&utm_campaign=CP%20%7C%20MF%20%7C%20BNG%20%7C%20SHOP%20%7C%20NBR%20%7C%20All%20Products&utm_term=4585444531557096&utm_content=All%20Products

I've deleted the OE 11t cog and installed a 36t instead. As long as you have the normal long-arm rear derailleur it'll be ok. Add a tooth or two to the chain. Done this both on my 2014 Roubaix and 2015 Diverge. 34/36 works fine for my moderate hills.