Going from 11-34 to 11-40

[B4_Ford]

I’m in the process of putting together a parts bin build on a Fierte IT. Groupset is a 105 R7000 series except for the rear derailleur, which is an RX-800. Front chainrings are 50-34. I was going to install a CS-HG700 11-34 cassette, but then I started to consider an XT 11-40. The extra gearing would be useful for the hills and mountains around me (I’m kind of old with a bad hip so I need all the help I can get). Has anyone run this sort of setup and will it work well or is this a fool’s errand? Biggest cassette I’ve ever run is an 11-34.

[truth]

I've done this works great. I'm using a wolftooth roadlink but I'm not sure it's necessary.

[Old School]

do it. Very forgiving. (but don't throw away any links if you shorten the chain....you might need them back)

[kytyree]

You might consider the Sram 11 speed 11/36 as well, I had that for awhile with an ultegra drivetrain and it worked just fine without a roadlink or something like that.

[DreamInColor]

Ironically, I had just watched this video before I saw your thread. I’d love to set up one of my road bikes with this configuration (11-42 in the video I believe) as I also live in a very hilly area and typically don’t care about going all out on the descents.
https://m.youtube.com/watch?v=wrh3_4EdBDw

[DeBike]

I have used an XT 11-40, 11 speed cassette with 105 7000 GS rear derailleur and crank set with 46-36 rings. No issues, works just fine, no add on.

[Hilltopperny]

I ran that combo back in 2018 on my Drifter. It works fine and gives you a lot of extra gearing for the steep long hills.

Sent from my Pixel 6a using Tapatalk

[Carbonita]

I've also run 11-40t 11s for ~14k miles with r7000 mid cage, and now rx800 for the past year. No der extension link needed. Test fit a gifted 11-42t yesterday, bottomed out the b-screw (body screw 1 full turn more than 40t), but it shifts fine on the stand. Also running 46 30 rings up front. Yeah, doc says I have a terminal case of O.L.D.

Update: shifting is fine on a hilly 60 miler. Big big (46 42) has the der near max, but just say no.

[bewheels]

Regarding the use of something like a Wolftooth roadlink - regardless of the cassette size, the main determining factor as to whether an extension link is needed is the shape and orientation of the drive side dropout which varies between brands, models, or even production runs (or each frame, if custom).

One frame/drop out may need an extension link to use a 32 tooth cog.
Whereas another frame/drop out may need one once the cog hits 40 teeth.

As Carbonita did, it is a good idea to do a test fit and see what happens. Though it would also be good to take it for a test ride as well. As we have all experienced, just because it works on the stand doesn't mean it works smoothly and quietly on the road when under pressure and going over rough surfaces.

[basilic]

the GRX 11s RD works well with 11-40

[NYCfixie]

Originally Posted by basilic

the GRX 11s RD works well with 11-40

The GRX812 can use an 11x40 but is for a 1x11 setup and cannot wrap enough chain for a double crank. The body also pivots differently and is more like a MTB derailleur so there may also be clearance issues with a bigger cassette in a 2x1 setup.

The GRX810 is for a 2x11 setup and is rated for 11x34 max (though most say an 11x36 is fine as mentioned above).

The GRX810 is essentially the same as the Ultegra RX800 rear derailleur. The RX800 was announced before GRX came out but once GRX was announced the RX800 was no longer needed since most GRX parts are compatible with road parts: https://bike.shimano.com/en-US/infor...ad-compon.html

[B4_Ford]

Looks like I’m going to need a Wolftooth road link to pull this off on the Fierte. I yes fitted everything tonight with the 11-40 and there isn’t enough clearance for the 40 tooth, even with the b screw all the way in.

[zennmotion]

Originally Posted by B4_Ford

Looks like I’m going to need a Wolftooth road link to pull this off on the Fierte. I yes fitted everything tonight with the 11-40 and there isn’t enough clearance for the 40 tooth, even with the b screw all the way in.

You can get a knockoff "derailleur hanger extension" for much less on ebay if you want to try it out. I have a cheap one and it works fine.

[B4_Ford]

Originally Posted by zennmotion

You can get a knockoff "derailleur hanger extension" for much less on ebay if you want to try it out. I have a cheap one and it works fine.

Wolftooth is $22 on Amazon. I think it falls within my budget.

[B4_Ford]

Not sure if the Roadlink or Roadlink DM is better. Instinct say the DM as it has one less point of failure.