Transcontinental Race No. 8 - TCR8 - #TCRN08 - 2022

That's what I found too re: cranks.

I've raced with 40T and 42T using an R8000 Ultegra RD (the newer shadow mount one). Works fine. I think the 46T might need a WolfTooth Roadlink but I don't own one to test it out.

42T got me around Transiberica with no recurrence of the knee troubles that plagued my last TCR. I was just thinking on gravel lower would be better.

Doesn’t solve the power meter issue, but I have successfully put a GRX 46-30 chainset onto my otherwise Ultegra Di2 setup.

Currently running with an 11-34 cassette but it should work with the 11-40 I had on previously.

Chain is slack in the bottom two cogs but Di2 won’t let me cross chain anyway.

Yeah, it's an easily solved problem if I change cranks. But we've been through a lot, me and Roty Rotor...

ah you want to try the 11/46 cassette. If you have a 12 tooth difference on the front like a 46/34, then I think you can push the 1x GRX rear mech to do 46 with the mod I mentioned on page 1 of this thread. The point of the long cage XT mod is to take up the chain slack. The body of that GRX should handle the jump to 46.

Di2 GRX RD is £200 though whereas a Wolftooth for my R8000 is maybe £20-30.
I'll probably not bother to be honest.
Wanna take trainers and flats so my lowest gear will be... 2x Feet™

I have successfully put a GRX 46-30 chainset onto my otherwise Ultegra Di2 setup.

Interesting, as they say you'd need the GRX front mech for those with the wider chainline.

aha, the plot thickens -> Di2.
An expensive experiment that may not work.
The path to a new crankset starts to appeal when comparing the costs innit?
If you did take that on, you might be the first person ever.
Mixing an 11/46 with a 2x front is already quite an uncharted territory.

was hard pressed to find a difference between the mechanical R8000 & GRX front mechs.
Pulled out the vernier (with battery but sans cap of course) and measured.
The cage shape is a tad different, everything else was the same.
My conclusion? R8000 mechanical front mech can handle it all, GRX is braze on only and thus may need clamp = more cash for no reason.

I sold my old Wolftooth. I think I need the newer DM version now anyway. They're about £25 but aren't meant to work with the 46T

"Optimized for use with 11-36t, 11-40t, and 11-42t 11-speed cassettes
Will improve performance with 10-42t 11-speed cassettes, but not to factory levels"

It's right at the limit, just shifts far enough to get into the big ring and not rub, limit screw (or whatever it is) is all the way in.

Well that's lovely. I actually have the 5801, but the shape is very much the same as r8000.

What's the biggest cassette people have had working on standard R8000 (med cage)? Got a 34 on there now but bigger would be nicer.

What is r8000? Ultegra?
If so 40 is fine. I have wolf tooth but not sure I need it. @hippy has 40t without wt

42T without Wolftooth during Transiberica

Yeah... got last version of ultegra di2. thx

When I bought the GRX crank I included the front mech + clamp.
Turned out the R8000 mech worked just fine.
The GRX + clamp was an extra €20 over the R8000.

Surely there is sound technical reason Shimano states the R7000 & 8000 are incompatible.
Maybe we just got lucky with our bikes?
Kudos to Shimano mechs for being so forgiving.

I think the only difference is that there is a larger Q factor on the cranks and the derailleur is further out to give room for wider tyres. There's a bit of adjustment on a mech which I guess most of the time covers the change and they just want to cover their backs?

but what was the difference in teeth on your front rings? You run a 34/48 right?

In my testing on an 11/42 rear, once you add the extra chain links, and have a 16 tooth difference up front, the R8000/RX800 rear mech starts to be unhappy in the smaller cogs due to the short cage length. Like when running small to small front and rear rings.
If you have 34/48 = 14T or a 34/46 = 12T, the mech stretches its leg more, has more spring tension and thus keeps the chain more taut.

Shimano are very conservative with their limits. There's probably a couple of frames/scenarios out there that didn't work so they make that the rule. Same as their RD tooth limits.

For that race I think it was 34/46.

I have my Di2 setup in semi-auto mode which means you can't cross-chain the small chainring to the two smallest cogs. Why would you want to do that anyway?

With 12T difference up front, everything is pretty happy. so @atz, keep that in mind.

I'll give it some thought. Don't want to be buying new chainrings, I'm not THAT bothered, it's just to make life easier.

You can try the Sram PG1170 11/36. I recommended this to someone and they are happy.
If I remember right, they didn't even have to add any chain links, guess it was long enough already. B screw adjust and done.

But not sure if 2 teeth will bring enough though, especially around here!

Just noticed this.
Silly me still using thumbs, palms, water and levers. So old skool.
Holding out for the mini version. Maybe we can ask Silca to make one...
https://www.challengetires.com/product/accessories/tools/2818

1 Attachment

Any tyre where they recommend a special tool to fit it, is not on my shopping list (I mean a second time as I already have a set).