Duck's Tech - Compatibility Notes

[Duck!]

GRX cranks have the chainrings a bit further outboard than road cranks to allow for frames being wider to fit fatter tyres. You might be able to tweak the road derailleur out to suit, but Shimano do recommend pairing with a GRX FD which is similarly spaced outward.

R7000 & related rear derailleurs have much more capacity than Shimano officially state; the short cage version can handle up to a 36T large sprocket, but with a comparitively large 16T chainring difference, cutting back to 34T would be safer. The long version will take up to 40T with a 16T front difference, and an absolute max of 42T with a tighter chainring pairing.

[ausdb]

Hi @Duck
I'm after a little bit of advice if you can help, I'm trying to do a parts bin upgrade to 2 x 10 on an old Orbea flat bar roadie that had low end 3x8
Proposed Cranks are 50-34 Truvativs
Rear derailleur is a XT 10 speed and shifter with a 11-32 cassette
Front shifter probably a XT 2x10 that I already have if possible.
But I'm stuck at the front derailleur should I be looking for a road or mtb one to go with the 50 tooth chainring?

TIA if you can help

[cyclotaur]

GRX cranks have the chainrings a bit further outboard than road cranks to allow for frames being wider to fit fatter tyres. You might be able to tweak the road derailleur out to suit, but Shimano do recommend pairing with a GRX FD which is similarly spaced outward.

R7000 & related rear derailleurs have much more capacity than Shimano officially state; the short cage version can handle up to a 36T large sprocket, but with a comparitively large 16T chainring difference, cutting back to 34T would be safer. The long version will take up to 40T with a 16T front difference, and an absolute max of 42T with a tighter chainring pairing.

Thanks Duck! only asked about grx because I have a gravel bike and am enjoying the gearing on that one. But it looks like a bigger cassette would be the go. Looking specifically at surviving ‘back of Falls’ at 2021 Peaks Challenge.

Pretty sure my road RD is the long version - I assume that, say, a SRAM 1170 11-36 would work ok?
Hard to find larger Shimano cassettes....

Cheers...

[Duck!]

Hi @Duck
I'm after a little bit of advice if you can help, I'm trying to do a parts bin upgrade to 2 x 10 on an old Orbea flat bar roadie that had low end 3x8
Proposed Cranks are 50-34 Truvativs
Rear derailleur is a XT 10 speed and shifter with a 11-32 cassette
Front shifter probably a XT 2x10 that I already have if possible.
But I'm stuck at the front derailleur should I be looking for a road or mtb one to go with the 50 tooth chainring?

TIA if you can help

Road

[Duck!]

Thanks Duck! only asked about grx because I have a gravel bike and am enjoying the gearing on that one. But it looks like a bigger cassette would be the go. Looking specifically at surviving ‘back of Falls’ at 2021 Peaks Challenge.

Pretty sure my road RD is the long version - I assume that, say, a SRAM 1170 11-36 would work ok?
Hard to find larger Shimano cassettes....

Cheers...

Yeah SRAM will work, they use the same sprocket spacing. Shimano don't do anything between 34T & 40T big sprockets. I believe SRAM have done the same as Shimano with their bigger (34+) 11-sp. cassettes and dished them in the back so they fit on a standard 8/9/10-sp. hub, so you'll need a 1.85mm spacer behind it.

[ausdb]

But I'm stuck at the front derailleur should I be looking for a road or mtb one to go with the 50 tooth chainring?

Road

Thanks very much time to start digging through the bits boxes to see what I can find.

[redsonic]

Looking for some help here...
I have a set of XTR BR-M8000 levers and calipers. One of my calipers has a cracked piston, and it looks like Shimano don't do replacements. Shopping around for a new caliper, I am looking at flat mount versions, most of which are road. Is there any problem with compatibility between MTB levers and road hydraulic calipers? What if the new calipers have 4 pistons (the M8000 only has 2). The GRX has the master cylinder located at the caliper, so I assume this would not be compatible. Any other combinations that might trip me up?
Thanks



edited to correct the piston count

[Duck!]

All Shimano hydro brakes are interchangeable, although there can be some minor hiccups with different hose-caliper connections.

You will have problems fitting a flat-mount caliper to a frame or fork designed for IS or post-mount.

[redsonic]

Thanks for that, Duck.

You will have problems fitting a flat-mount caliper to a frame or fork designed for IS or post-mount.

I have a flat mount frame and fork, and was using the adapters to post mount calipers, and thought I might as well make the front caliper flat mount if I was changing.

[Duck!]

All good then on that front.

The M8000 caliper uses a banjo bolt hose connection, whereas the flat-mounts use a straight olive & barb compression connection, the same as at the lever. You'll need to cut the banjo fitting off (therefore shortening the hose a tad) and fit the compression fittings. The barb insert is specific to the model of hose, BH90 in the case of the XT.

[redsonic]

The barb insert is specific to the model of hose, BH90 in the case of the XT.

Thanks again for the help Duck. I have gone with GRX 810 calipers and have BH90 hose. Does that mean that the extra BH-59 olive and insert/barb I ordered is not compatible? Is the colour (brass for BH-59 vs silver for BH-90) the only visual way to tell which is which?
It looks like you are going to save me from leaky brakes!

[Duck!]

The BH59 barb is too large for the BH90 hose; the "high power" BH90 hose has a smaller internal diameter and thicker wall than BH59. The olive and compression nut are the same for both hoses.

[redsonic]

[cyclotaur]

Thanks Duck! only asked about grx because I have a gravel bike and am enjoying the gearing on that one. But it looks like a bigger cassette would be the go. Looking specifically at surviving ‘back of Falls’ at 2021 Peaks Challenge.

Pretty sure my road RD is the long version - I assume that, say, a SRAM 1170 11-36 would work ok?
Hard to find larger Shimano cassettes....

Cheers...

Yeah SRAM will work, they use the same sprocket spacing. Shimano don't do anything between 34T & 40T big sprockets. I believe SRAM have done the same as Shimano with their bigger (34+) 11-sp. cassettes and dished them in the back so they fit on a standard 8/9/10-sp. hub, so you'll need a 1.85mm spacer behind it.

SRAM 1170 11-36t fits and works perfectly.

[metalrideroz]

Does anyone know the compatibility of various hollowtech crank arm fixing bolts?
Crankset i'm using is fc-3450 and uses this type,
https://ebike.hu/kepek/24zZ/shimano-hol ... 614000.jpg

For some reason the tool I have doesn't fit properly, tool is this one,
https://www.merlincycles.com/assets/ima ... _tools.jpg

The tool fits the bolt on the fc-m677 and fc-m770 cranksets on my other bikes fine.

What other fixing bolts are compatible if I can't find an exact match? Can I use one from any hollowtech road crankset?

[Duck!]

Shimano have used a couple of different wall thicknesses for their two-piece (they're not all Hollowtech) crankset spindles, with corresponding bolt diameter sizes, so you'll need the right one for that aspect. However the tool interface is (or is supposed to be) the same for all tension bolts, so any bolt tool should fit.

PS, I have exactly that tool in my workshop kit, and have never had a problem with it not fitting certain bolts. The old bolt hasn't possibly been deformed by overtightening?

[metalrideroz]

Shimano have used a couple of different wall thicknesses for their two-piece (they're not all Hollowtech) crankset spindles, with corresponding bolt diameter sizes, so you'll need the right one for that aspect. However the tool interface is (or is supposed to be) the same for all tension bolts, so any bolt tool should fit.

PS, I have exactly that tool in my workshop kit, and have never had a problem with it not fitting certain bolts. The old bolt hasn't possibly been deformed by overtightening?

Duck always with the knowledge!
Ok, i'll get a replacement bolt then. I had always assumed the tool was universal, no idea why this particular bolt says otherwise, it looks as new. I hammered the tool in and it made its own fit haha. It wasn't fitting otherwise, way too tight of a fit.

[Calvin27]

Hey anyone know what sort of compatibility there is for GRX400 FD?

It's for a budget build that I have been riding for 2 years hence the choice of 10 speed. The rear I'm pretty happy with. The FD/shifter seems to shift like a turd. Can't tell if it's the shifter or the FD but keen to fix this. All the cable tension and setup are done properly and it shifts perfect, but just feels terrible compared to my other bikes (even compared to the terrible 5700 105).

Anyway, keen to address this as soon as possible. Thinking a left hand shifter replacement and/or FD. Would something like GRX600 be a marked improvement or even compatible (with or without a new FD)? I know the outlay I'm looking at about $500+ retail to get this but it's that bad lol. Bike is a bit of a spare parts gravel bike, but full Ti frame so I'm happy to drop some coin on it even if it is 10 speed.

[Duck!]

How's the cable condition, both inner & outer? Worn cabling will have a significant effect on shift feel. Aside from 10-sp. vs 11-sp. indexing in 400, there is no functional difference between the GRX levels and their donor road parts, just materials.

[Calvin27]

How's the cable condition, both inner & outer? Worn cabling will have a significant effect on shift feel. Aside from 10-sp. vs 11-sp. indexing in 400, there is no functional difference between the GRX levels and their donor road parts, just materials.

Cable condition is good. The routing is ok and smooth too. I was more thinking that grx400 shifter might have some compromises since it's tiagra level stuff. I've got two mates who expereinced the same thing, they came from ultegra and 105 hydro gruppos on their roadies, surely can't be coincidence all three of us complain about lousy fd shifting? Would move to a grx600 left shifter but those stocks are bone dry and i'm nto willing to gamble $500 for a 800 series. Would r7020 left shifter work?

[ft_critical]

Drivetrain:

....

Hi Duck, all,

For my son... His Scott Scale 965 has SRAM NX 1x11 and I need a new chainring, cassette and chain. The derailleur is actually GX, but everything else is NX.
What options do I have to replace these items? The cassette is an 11-42 I believe.

In particular, will Sunrace, Shimano work?

Thank you for your help,

FT

[Duck!]

Yeah, sprocket spacing is the same across all brands of 11-sp, so anything will fit as long as it has the 11T top gear. Anything with a smaller top sprocket needs a different freewheel body (XD driver), which may not be available for some hubs.

The chainring may need to be a bit more specific, because there are a few different mounting types.

[ft_critical]

Yeah, sprocket spacing is the same across all brands of 11-sp, so anything will fit as long as it has the 11T top gear. Anything with a smaller top sprocket needs a different freewheel body (XD driver), which may not be available for some hubs.

The chainring may need to be a bit more specific, because there are a few different mounting types.

Thanks Duck. Appreciated.

I found the same 30t 94bcd chainring in SRAM.

[MichaelB]

Hiya Duck,

Currently running 50/34 and 11-32 cassette on a short cage (SS) RD Di2 setup.

It works fine on the 32 tooth, but when on the 34 chainring and smallest sprocket allowed, the chain is loose, which points to a total tooth count issue.

Whilst it works fine, as I get older and slower, I’m less and less likely to go to a smaller top cog, and I still like climbing, I’m looking at my options.

As I understand it, they are;

1 - live with what I have (cheapest)
2 - get a GS/ Long cage RD (best). I’ve secured a new RD815 GRX for a great price and looking at some S/H R8050-GS RD’s
3 - put the GS lower pulley cages (Part No’s Y3HR00040 & Y3HR98060) on the existing SS RD, and make a Franken-GS version.

There are two issues with option 3 - they are like hens teeth and shipping is typically A$100 from the available suppliers (on US ones found so far) and as has been mentioned by Duck! Before (afaik) that there are geo differences between the GS and SS versions to deal with the larger sprockets.
There is also conflicting info on the interwebs as to whether option 3 actually works (regardless of the cost and availability of the lower cages).

Any thoughts/good advice re Option 3 ?

As for option 2, apart from a bigger large sprocket capability, is there any issues using the GRX RD vs the 8050-GS version (asthetics and weight aside ) ?

Cheers

[Duck!]

What model is the current RD?