Gravel / Gravé / Gnarmac / Groad / ATB

I’ve been running an XTR rear derailleur with Dura ace shifters for pretty much 3 years and it’s been flawless. I was about to switch to SRAM, but honestly everything 12 speed I see as little benefit for a not inconsiderable outlay of both cash and effort.
So looks like I’ll be copying Hippy and building a Di2 Crux. Yey!

Going to kick off with 11-40 x 38 as that’s what I have right now. I might increase the front ring to 40 or 42, but need to loose a few kg and get my knees back in the game before I start flexing.

Well yeah, but I already have a lot of 11s Di2 stuff so it'll take a long time before I need to go the whole hog upgrade. Just wondering if it's worth it from the off. I should look at the difference between 11s and 12s for the parts I need. Haven't had time to do a groupset bits price compare yet.

I've been running 42T with 11S GRX and 11s Ultegra (no wolftooth) for ages. I'd presume the 12s stuff would allow me to do the same thing. It's not within Shimano spec but none of my bikes have been within spec for the last 10 years.

Ah, yes, we had this discussion in another thread! I'd forgotten all about that fact. I don't really want Ultegra even though it'll be primarily a road bike I think. I'll run 30/46 up front and will want to use a 42T cassette still. I don't want to gear higher other than the times I stick a 36T back on when I'm not climbing for a while.

In stuff like 7 Serpents and El Piri I'll definitely still want my 30x42T low gearing. I'd event try and squeeze a 46T on with Wolftooth maybe but I haven't tried that yet. Sounds like sticking with 11S GRX is the way to go.

Yeah, but one might have trouble finding a 12s 42t cassette, the usual suspects don't make them. But it does seem they do exist and more might appear later.
https://cooolstore.com/gb/cassettes/8193-kcnc-cassette-mtb-12s-9-52-sram-compatible-4710751036574.html

I think the best thing to do currently is grab 11s bits except maybe the newer calipers? Can you mix newer GRX calipers with older GRX - presume so?

Yes. Looked into this and seems fine. I’m installing 105 12s calipers on 105 11s levers next week.

Can’t be bothered reading to see if this is relevant but I’m using a non-Shimano 11-46 cassette with a 12s GRX mech, works fine.

12sp 105 di2 seem cheap. Unless the ad is wrong wiggle are doing a rear Der for£99

Front Der is £85

Wiggle

Nice. Is the cassette a Rotor or the ZTTO they sell in Aliexpress or are there others?

This one from AirBike. It's a bit of a boat anchor at ~650g but works fine.

there are so many 11spd di2 rd. i feel like i'll be able to find new stock for at least like 5 years. whether my inbred consumerism allows me to verify this idk, but i think this isn't really an issue in the timescales i operate in at least.

yes it works. i have br8100 on the back of my st 9150 set, uses the same hose/fittings, easier to bleed makes it worth it imo.

I recall having this very problem last year more than once. Costumers with fried RDs and nothing in stock at Shimano with crazy waiting times. You can always find something online, but not for a warranty replacement.

Nice.

So, when I'm looking for bits, it looks like I'm going for all the usual 11s GRX stuff (must remember to buy the RD-RX817-GS 1x RD that works 2x 42T) but looking for BR8100 or 12S series (flat mount or is that not a thing with 8100?) calipers.

These ones...
https://bike.shimano.com/en-EU/product/component/grx-12-speed/BR-RX820.html

What's the 'better bleed process' all about?

Yeah or if not those calipers, then I'm pretty sure the road ones are identical apart from branding

https://bike.shimano.com/en-EU/product/component/ultegra-r8100/BR-R8170.html

https://bike.shimano.com/en-EU/product/component/shimano105-r7100-di2/BR-R7170.html

@yeahdext and @hippy as well as anyone else building a Crux, the widened chain stays that allow for wider tyres, leave little clearance to a PM with external battery, in case that's relevant for you.

I run a 4iiii 105 PM which leaves 1-2mm clerance to the chain stay. Pretty sure something will jam there at some point and either rip the battery off or damage the chain stay, but that might be just me.

This picture is not my Crux, but just to give context, that's more or less what it looks like.

IIRC I've still got Ultegra calipers on the Tripster with GRX levers so I reckon you're probably right - why would they change the physical properties (inc production cost) when they work interchangeably?

My dislike of crankarm powermeters (aka RNGs) finally pays off! :D

fondles P2M

Quarq here!

Challenge I have at the moment; my Hope BB does not have a 'tube' how the heck I'm meant to keep my Di2 and Hydro hose safe I don't know.
Well I do, it's another BB. Sigh. My Sl7 I had some zip tie hack that appears to have held. But not possible on this it would appear.

I used a plastic sleeve made from a yoghurt pot for a few years

just buy a CK and then never have to touch your bb again

Until you need to service it. Which you need to do regularly since the bearings are not user replaceable, nor are they magic

Knew you'd both have blingier PM than me, but thought I'd mention. Bike is really fun tho, definitely more CX geo than gravel, which I am really pleased about