Circling back around to grx - the 2x grx rear dangler improves functionality with a 46/30 double (or similar large tooth jump), and will happily do 11-36 and 11-42 w/out a goat link thing. It is a very good rear dangler for nerd cranks and/or getting lots of climbing in the back. In typical Shimano fashion, the info on what exactly the parts are meant for or compatible with are hard to find, but if you accidentally buy the “1x” version of the grx rear dangler it will not do very well at all with your double, and result in less good range than an RX8000.
Agreed with Mr. Bonzalez, the grx cranks are good and also come in 165 for shorties and/or people with bad knees. Good cheap option for getting 46/30.
hot take request- if grx 46/30 11 speed cranks (not the fancy pants ultegra level) or new 46/30 rings for my WI cranks (or 44/28 or whatever) were very similar in cost, what would you get?
IDK, I think at some point it becomes about aesthetics if everything else is similar. Some benefit to keeping drive train all shimomo tho, and the ramping on shimano chain rings tends to be good (as opposed to white industries which sucks donkey dick for front shifting). I think if it’s all the same level quality etc…then go with what looks better to you /on your bike.
Personally, I went with easton crabon cranks with their weird (but useful) cinch mechanism, because I get a giant discount ;p
that’s what i meant to write but apparently didn’t in my sleep deprived state- new rings for my WI cranks. i haven’t found the front shifting to be super awful, not shimano good but i don’t shift the front much. also everything else is sram on the bike in question
It’s much stiffer from side-to-side. The 1x SRAM derailleurs are the same way. When they tell you they are 1x only, they are not joking or trying to get you to buy more parts
The main difference that’s relevant for 1x vs 2x performance between the RD-RX812 and the RD-RX810 is the offset of the upper pulley from the pivot of the cage.
The RD-RX810 is built like a traditional Shimano derailleur: with the upper pulley very close to the pivot of the cage (in this case, actually concentric with it). This means that the pulley position is entirely independent of the rotation of the cage; the pulley is in the same position regardless of what chainring you’ve shifted into. The slant of the parallelogram is what makes the upper pulley follow the slant of the cassette.
The RD-RX812 is the 1x-specific version, and has the upper pulley highly offset from the cage pivot - much like SRAM’s 1x derailleurs. Like SRAM’s derailleurs, the parallelogram is slanted less and the rotation of the cage is what places the upper pulley into the correct position as it moves back and forth across the cassette. Imagine you ran this on a 2x setup: In the same cog on the cassette, the upper pulley will be in wildly different positions when shifting between chainrings on a double crank. This fairly obviously leads to shitty shifting.
This difference in upper pulley offset is also the difference between the 12-speed XT and XTR derailleurs: 1x-specific RD-M8100/M9100 vs the 2x-capable RD-M8120/M9120
I haven’t had one in my hands yet to measure, but to me it looks like:
GRX 2x = same top pulley offset as road derailleurs, slant parallelogram
GRX 1x = same-ish offset as 11spd mtb derailleurs, slant parallelogram
XT 1X 12spd = bigger offset, less slanted parallelogram.
I would guess GRX 1X will work with a double, especially if it’s a Shimano mtb jump of 10 teeth, but the 2x version will work more consistently (and has more chain capacity).
Interesting note about the GRX 1x/11-speed MTB connection. I poked at this, and you’re right! The RD-RX812 inner cage plate is, in fact, exactly the same part number as on the RD-M8000-GS. The outer cage is a different part#, but I’d bet a fair chunk of change that it’s a cosmetic difference only.
This implies that it would be trivial to hack together a long-cage RX812 with the SGS cage off the M8000, and have 47T of capacity on a derailleur that works with road levers. Longer cage = less cage rotation for a given difference in front chainrings, so less of a problem for the offset pulley. M8000-SGS was intended for use with the 40/32/22 triples, and is rated for up to 18T difference in front chainrings… this could be rad.
Anyway:
Dumb derailleur hacks aside, agreed.
yeah it’s a little odd that Shimano “1x” derailleurs still have some slant to the parallelogram, while SRAM just did away with it entirely. I think some of the features of the Shimano derailleurs allow for better performance across a wider size range of cassettes, but I haven’t thought about that much yet.
The 12spd XT(R) 1X look almost flat if not flat. They also seem to be the first 1x derailleurs that have 1X in their names - the 8100 is “SHIMANO DEORE XT - Rear Derailleur - SHIMANO SHADOW RD+ - 1x12-speed”. I’d expect a company as conservative as Shimano to put a big fat “1x ONLY” on the product page, but maybe it’s clearly spelled out on a compatibility chart somewhere.
I got a surprise when I compared my new long cage Rival to my medium cage Force. They look like completely different beasts. But TBH, the thing that makes the most difference is the “stop” on the Force which stops the derailer cage from rotating back more like the Rival’s. How does the derailer know if I am in a 32 on the front or a 42? I guess the answer is, in one of these combinations, the chain will be the wrong length? Ultimately I want to go 2x I think.
Aren’t those 1x specific derailleurs? If so, once you cut a chain to the specified length, it is only good for that chainring size*
*Chain length depends on the combo of chainring size/chainstay length. So in theory a chain of X links could be used with different sized rings as long as the bike had adjustable chainstay length too.
Yep. Both 1x. I was just surprised at how different they looked. Functionally the only difference is supposed to be that one will shift to a 36 and the other a 42.
I recently had a shit of a time getting a rear XT shifter that had the proper mounting bit to my XT brakes (which had been purchased prior). I even CALLED FUCKING SHIMANO to make sure I was ordering the right part. I got an ISPEC B shifter, which is of course different than the ISPECII shifter that I needed…and of course I had bought the shifter the shimano guy said would mount to the exact brakes I have.
I got pissed and bought an XT shifter that just mounts to the bar. If Shimano’s stuff wasn’t so good I’d boycott them out of sheer frustration with getting accurate product info. Like, I’m not a super expert of course but I work in a shop and have been actively putting bike bits together for several years - if I have a hard time figuring what works with what I can’t imagine someone w/out the benefit of what little expertise I do have navigating this shit successfully.
it’s real easy, you’ve got I-SPEC A, B, II, and EV, none of them are cross compatible, and there’s no hard and fast rule for what was what. Simple! Really love that Shimano has changed this spec on every single new generation of components since 2011.
