Duck's Tech - Compatibility Notes

[Duck!]

Not a Shimano hub. Probably Formula. OEM spec & bluddy near impossible to find aftermarket.

[piledhigher]

Not a Shimano hub. Probably Formula. OEM spec & bluddy near impossible to find aftermarket.

May be the end of this 20+ year old wheel.

[MichaelB]

Question re what Shimano cranks will fit with 73mm BSA BB !!!

Building up a bike and want to run a GRX600 crank or similar.

Will the Shimano cranks like CX50/70 or GRX series fit the 73mm wide shell with the outboard bearing BB ? Or do I need a MTB crank/BB386 compatible version ?

Also, what is difference between Shimano road BB and MTB BB ?

Ta

[Duck!]

MTB or road triple crank for you. GRX & CX-series cranks are basically road cranks, and the spindle length is too short for the wider BB shell. MTB cranks have a longer spindle to allow for wider frames, plus the option of BB-mounted "E-Type" front derailleurs or chainguides. Road triples are also longer & spaced out to fit the extra ring on, so will have a bit in reserve to fit the wider shell. 4703 Tiagra could be an option, then play around with chainrings to suit.

BB386 cranks won't work, they're the same spindle length as standard road (86mm shell, same as road press-fit, and same assembled width as 68mm BSA outboard), just with a 30mm diameter spindle.

The only real difference between road & MTB bottom brackets is the extra assembled width of the MTB versions.

[MichaelB]

MTB or road triple crank for you. GRX & CX-series cranks are basically road cranks, and the spindle length is too short for the wider BB shell. MTB cranks have a longer spindle to allow for wider frames, plus the option of BB-mounted "E-Type" front derailleurs or chainguides. Road triples are also longer & spaced out to fit the extra ring on, so will have a bit in reserve to fit the wider shell. 4703 Tiagra could be an option, then play around with chainrings to suit.

BB386 cranks won't work, they're the same spindle length as standard road (86mm shell, same as road press-fit, and same assembled width as 68mm BSA outboard), just with a 30mm diameter spindle.

The only real difference between road & MTB bottom brackets is the extra assembled width of the MTB versions.

PFBB.

Shimano MTB Cranks seem to be 38/28 (on 96/64 PCD) combo's as biggest chainrings Some more googling to do ....

[Duck!]

If you can dig out an older generation you may find something with a 40T big ring.

[MichaelB]

Confirmed - 73mm shell width.

I suppose this wouldn't work as it's 9/10sp whereas I'm wanting to run 11sp ?

It looks like I'm pointed down the direct mount route (or get creative with a file and 2.5mm from each side )

Aside from the chainring stuff, the assumption is that the FD-CX70 would still work with the much smaller chainrings ?

[Duck!]

I suppose this wouldn't work as it's 9/10sp whereas I'm wanting to run 11sp ?

BCD will be your problem; Shimano don't use 96mm.....

[MichaelB]

I suppose this wouldn't work as it's 9/10sp whereas I'm wanting to run 11sp ?

BCD will be your problem; Shimano don't use 96mm.....

Running into all sorts of problems ....

If I run a Shimano MTB cranks with 38/28, I can get roughly the same low gear with an 11-34 cassette, but lose out on the top end (by ~ 5km/hr at 90rpm.

Not huge, but not brilliant either. Googling to do ....

[Duck!]

That's why I suggested something like the 4703.... Same bolt pattern as the rest of Shimano's current road/cross range, with the longer spindle to fit the wider shell. Turf the little ring (or keep it & turf the big one), there'll be options to get the rest of the combo you're after.

[MichaelB]

That's why I suggested something like the 4703.... Same bolt pattern as the rest of Shimano's current road/cross range, with the longer spindle to fit the wider shell. Turf the little ring (or keep it & turf the big one), there'll be options to get the rest of the combo you're after.

Something like this Altus Triple 44/32/22 and ditch the inner 22 ?

Looking at the Shimano Techdocs, there is the 11sp FC-M9020-3 (656g) & M8000-3 with 40/30/22 (773g) w 96/64 BCD.

There is also the Trekking option of FC-T8000 with 48/36/26 (or 44/32/24) on 104/64 PCD, but it's a heavy beast at 868g.

Affordability and availability are an issue though on the 11sp options

[Duck!]

That could also be an option.

[MichaelB]

That's why I suggested something like the 4703.... Same bolt pattern as the rest of Shimano's current road/cross range, with the longer spindle to fit the wider shell. Turf the little ring (or keep it & turf the big one), there'll be options to get the rest of the combo you're after.

Per the Techdocs, the 4703 only shows compatibility with the 68 & 70mm shells ?

[Duck!]

That's because they don't cross road & MTB with their specs. Being a triple it has a longer spindle, with spacers to fit to the road BB width.

[MichaelB]

That's because they don't cross road & MTB with their specs. Being a triple it has a longer spindle, with spacers to fit to the road BB width.

Ah, OK.

So grab a 4703 that comes with 50/39/30, and then get the CX sized chainrings (e.g. 46 outer & 34 middle) to fit ? Then sell off the chainrings I took off ?

Sorry for all the dumb questions, but double checking that 10sp chainrings work with 11sp chains ?

[Duck!]

As per the first page of this thread, chainrings aren't fussy.

[MichaelB]

Ta. 46 outer Chainrings aren't cheap or plentiful.

Solve one problem, create another

[MichaelB]

...
Something like this Altus Triple 44/32/22 and ditch the inner 22 ?

....

Had a second look at this one, but it's square taper BB and 180mm Q-factor

[MichaelB]

OK, some more interweb trawling ....

Would any of these chainrings fit on a Deore XT M8000 Crankset (normally 38/28) ? (not that they are the best option or right price, but they give me other options ...

Outer chainrings (96mm PCD)
M672 40T
M8000 40T
M7000 40 T
Metra M5000 46T
M4000 40T

As for inners, it looks like the 28T is the biggest Shimano one for 64mm PCD.

I reckon I could live with the 40/28 or 42/28 combo (yeah, not much change from the 38/28), but then might even look at the 36/26 M8000, and change it to 40/26 or 40/24, and still run the 11-36 or 11-34 cassette ....

[Duck!]

Forget the Metrea, you'll need to do a lot of reshaping work on the mount tabs to make it fit anything other than the U(not M)5000 crank. Additionally, due to the huge jump from the small ring shifting will be rubbish; 18T is too wide for any 2x front ddrailleur, and the cage shaping of a 3x model will not play nicely with the 2x rings.

[MichaelB]

OK, so now the chainrings (from the above posts) have arrived. In that package, I ordered the right chainring bolts for the 64PCD inner per the Shimano EV's.

But the 42T that will be mounted as a single ring, what are the correct length bolts ? Just use the same ones as suitable for 1x ?

Such as these ? 6.5mm vs 8.5mm ?

Alloy Chainring Bolts

[Duck!]

Yes, use the shorter bolts as for a 1x.

[Calvin27]

Hi @Duck!,

I have a 5701 RD 10sp which barely manages a 30t cassette. Looking at casette options now and looks liek there is an ultegra 12-30 for $80 but then the prices seem to drop a fair bit for 11-32 and 11-34. I've always wanted a wider range and now that the bike is doing off road duties the wider cassette is appealing.

So question is what derailleurs are compatible and further more where do I even buy these - no one seems to stock 10 speed anymore and the stuff that is available is goeblocked!

My options look like (appreciate compatibility notes here)
- 5701 GS which can do up to 32t. I like this option but given my current RD is rated to 30t and struggles, I'd like a bit more.
- 10 speed Tiagra SS/GS (I think these might be different pull, but the SS rated to 33t whouls do the job.
- 10 speed GRX (not sure if compatble, pretty sure it's based off the tiagra pull)


Thanks in advance.

[Duck!]

If you can find a 4600-series Tiagra derailleur, that will take up to 32T, and works on the same pull ratio as your current stuff. 4700 & GRX is derived from 11-sp. and is incompatible. For fitting bigger sprockets you need to look at so-called "9-sp." derailleurs, which work on the correct pull ratio. R3000 Sora will take 34T, while "Shadow" type MTB models will fit 36T comfortably.

[10speedsemiracer]

Hi @Duck!,

I have a 5701 RD 10sp which barely manages a 30t cassette. Looking at casette options now and looks liek there is an ultegra 12-30 for $80 but then the prices seem to drop a fair bit for 11-32 and 11-34. I've always wanted a wider range and now that the bike is doing off road duties the wider cassette is appealing.

So question is what derailleurs are compatible and further more where do I even buy these - no one seems to stock 10 speed anymore and the stuff that is available is goeblocked!

My options look like (appreciate compatibility notes here)
- 5701 GS which can do up to 32t. I like this option but given my current RD is rated to 30t and struggles, I'd like a bit more.
- 10 speed Tiagra SS/GS (I think these might be different pull, but the SS rated to 33t whouls do the job.
- 10 speed GRX (not sure if compatble, pretty sure it's based off the tiagra pull)

The other option is to look at the crankset.


Thanks in advance.