Deore RD-M592 to replace Sora RD-R3000 ?

[mikeymo]

can a deore RD-M592 rear derailleur replace a sora RD-R3000 without any other changes (except new cables?)

Bike has drop bars, with the latest Sora shifters (cables under bar wrap). Cassette is 11-34, chainrings (atm) 48-38-28. There's a barrel adjuster at the cable stop on the down tube.

People say the 592 is "better" than the 591. But the 591 has a barrel adjuster, so maybe (?) easier swap without having to do much with cables.

Thanks.

[UpWrong]

I'm about to do exactly this on my AZUB recumbent trike. My understanding is that Shimano 9 speed kit is mix and match. The trike has an Acera trigger shifter which I won't be changing now. Thanks for reminding me about the lack of cable adjuster on the M592, which is a shadow design.

TBH I don't think it will improve your shifting. I'm doing it to have more derailleur capacity (SGS long cage version going on).

[reohn2]

If both cages are the same length(measure the distance between jockey wheels)it's a straight swap,if the Sora is a short cage mech you'll need to add links to the chain,though from your description it sounds as if they're both cages are the same.

PS,is there a cable adjuster on the downtube?

[mikeymo]

I'm about to do exactly this on my AZUB recumbent trike. My understanding is that Shimano 9 speed kit is mix and match. The trike has an Acera trigger shifter which I won't be changing now. Thanks for reminding me about the lack of cable adjuster on the M592, which is a shadow design.

TBH I don't think it will improve your shifting. I'm doing it to have more derailleur capacity (SGS long cage version going on).

Thanks. Yes, my understanding also is that Shimano 9 speed is all compatible.

I'm doing it for the same reason as you. It gets me another 2 teeth of total capacity.

Cheers.

[mikeymo]

If both cages are the same length(measure the distance between jockey wheels)it's a straight swap,if the Sora is a short cage mech you'll need to add links to the chain,though from your description it sounds as if they're both cages are the same.

PS,is there a cable adjuster on the downtube?

Thanks.

The Sora describes itself as "medium cage", but its capacity is 43. There's no "long cage" version of the Sora RD, so I suspect this is actually it.

Yes, as I said, there's a barrel adjuster on the downtube.

cheers.

[UpWrong]

I have just weighed both mechs on the kitchen scales.R3000 is 275g, M592 is 290g. Approx lengths are 7.5 cm vs 10 cm (between the centres of the jockey wheels).

[mikeymo]

I have just weighed both mechs on the kitchen scales.R3000 is 275g, M592 is 290g. Approx lengths are 7.5 cm vs 10 cm (between the centres of the jockey wheels).

Ah, so you've actually got them in your possession, excellent!! That 15gms difference in weight isn't going to worry me, especially as it may be offset by the loss of the barrel adjuster? That difference in cage length looks like 2 half links, so as another respondent said, maybe a longer chain required (?). Presumably you discover that by trying to change into big-big and seeing what happens.

It would be good to know how this works out for you.

Cheers.

[UpWrong]

I have just weighed both mechs on the kitchen scales.R3000 is 275g, M592 is 290g. Approx lengths are 7.5 cm vs 10 cm (between the centres of the jockey wheels).

Ah, so you've actually got them in your possession, excellent!! That 15gms difference in weight isn't going to worry me, especially as it may be offset by the loss of the barrel adjuster? That difference in cage length looks like 2 half links, so as another respondent said, maybe a longer chain required (?). Presumably you discover that by trying to change into big-big and seeing what happens.

It would be good to know how this works out for you.

Cheers.

The difference in cage lengths is much more than I was anticipating. I am assuming the trike came with the Sora medium cage version. OEM gears were 11-34 cassette with 30/42/52 rings. I have changed to 11-32 cassette with 28/42/53 rings. .It's usual on a recumbent trike to change chain length when fitting to leg length anyway.

I will need to shorten the cables but will only do so when I have checked that it works ok in case I need to revert back.

Deore now mounted so should know soon.

[mikeymo]

I have just weighed both mechs on the kitchen scales.R3000 is 275g, M592 is 290g. Approx lengths are 7.5 cm vs 10 cm (between the centres of the jockey wheels).

Ah, so you've actually got them in your possession, excellent!! That 15gms difference in weight isn't going to worry me, especially as it may be offset by the loss of the barrel adjuster? That difference in cage length looks like 2 half links, so as another respondent said, maybe a longer chain required (?). Presumably you discover that by trying to change into big-big and seeing what happens.

It would be good to know how this works out for you.

Cheers.

The difference in cage lengths is much more than I was anticipating. I am assuming the trike came with the Sora medium cage version. OEM gears were 11-34 cassette with 30/42/52 rings. I have changed to 11-32 cassette with 28/42/53 rings. .It's usual on a recumbent trike to change chain length when fitting to leg length anyway.

I will need to shorten the cables but will only do so when I have checked that it works ok in case I need to revert back.

Deore now mounted so should know soon.

Interesting. Did you ever have any problems with the trike as it was originally? Just that 11-34 with 30/42/52 is outside Shimano's specs for the Sora SGS RD. If it was OK it rather supports the contention often expressed here that Shimano's specs are "conservative" and can be pushed a little. And presumably, unless you're using any of the extreme cross chain combinations, you won't run into the limits anyway.

Edit. And your new combo of 11-32 and 28/42/53 is one tooth outside of the specs for the Deore RD. I see there are XT 9 speeds that have a 45 capacity too, though quite a bit more money. And don't go up to a 36 tooth sprocket.

[UpWrong]

Got it working on the bike stand. The b-screw makes a really big difference to shifting quality.

My problem is that with a 20" rear wheel there is a risk of damage to the RD if I get a flat. On some cogs it appears to extend beyond the wheel rim.

It's a new trike so I only tested the OEM set up on the stand, and like I said you adjust chain length after setting the leg length. Chain wrap in small-small gear combos is often not a problem on recumbents with chain tubes because the tubes control the excess chain. My problem was bizarrely the RD forward movement was limited by the chain stay. The knuckle was coming up against the stay and this was limiting capacity because the cage was some way off full extension. The shadow derailleur OTOH comes nowhere near the chain stay and gets full movement.

I still have a small amount of wrap in the small-small combo. I might be able to remove one link but will leave for now. Yes Shimano are a bit conservative in their specification of capacity.

[mikeymo]

Got it working on the bike stand. The b-screw makes a really big difference to shifting quality.

My problem is that with a 20" rear wheel there is a risk of damage to the RD if I get a flat. On some cogs it appears to extend beyond the wheel rim.

It's a new trike so I only tested the OEM set up on the stand, and like I said you adjust chain length after setting the leg length. Chain wrap in small-small gear combos is often not a problem on recumbents with chain tubes because the tubes control the excess chain. My problem was bizarrely the RD forward movement was limited by the chain stay. The knuckle was coming up against the stay and this was limiting capacity because the cage was some way off full extension. The shadow derailleur OTOH comes nowhere near the chain stay and gets full movement.

I still have a small amount of wrap in the small-small combo. I might be able to remove one link but will leave for now. Yes Shimano are a bit conservative in their specification of capacity.

Thanks. That all sounds positive. You've done this with the 11-32 and 28/42/53, yes? So one tooth outside the "official" spec. I'm thinking of going to 11-34 and 46-36-24. And if I can go outside spec I could even change to an 11-36 cassette (or 22 granny). This is the first derallieur bike I've made (or owned, or ridden, for that matter). Do you know where the "above specified capacity" is likely to make itself know more - on the cassette or on the triple? What I mean is, if I'm trying to get the max range by going out of spec, where's best to do it?

My bike's a 700c, so no risk of hitting the deck.

The chain is the same length as I bought it, 116 links I think.

Many thanks.

PS, mum was from Portsmouth, but her parents moved out to Horndean during the war. We had many relaxed holidays next to the south downs. Though Horndean was a lot smaller 40 years ago.

[UpWrong]

Horndean is just up the road. I'm in Waterlooville and the combined population of Waterlooville and Horndean is now in excess of 50K I believe.

You can traditionally go 2 teeth beyond Shimano derailleur specs. I'd suggest going to 36T on the cassette rather than dropping to 22T on the crankset which isn't possible with a 74mm BCD anyway if I recall correctly. Shimano sell 12-36T Alivio cassettes which I have used with the M-592 RD.

[mikeymo]

Horndean is just up the road. I'm in Waterlooville and the combined population of Waterlooville and Horndean is now in excess of 50K I believe.

You can traditionally go 2 teeth beyond Shimano derailleur specs. I'd suggest going to 36T on the cassette rather than dropping to 22T on the crankset which isn't possible with a 74mm BCD anyway if I recall correctly. Shimano sell 12-36T Alivio cassettes which I have used with the M-592 RD.

Thanks, I'll bear all that in mind. Though I'm trying to keep expense down a little, and the current cassette is nowhere near in need of replacing. With the M592, if I keep my cassette (11-34) I could just take the granny ring off my 48-38-28 and replace it with a 24. Which would give me a whopping great 117"-19" range and put me 2 teeth outside the shimano specs.