Deore LX rd-m570 capacity

[Tolsey31]

Hi,

Can anyone help with this please? Before I get the new chain out does anyone know if the above derailleur will take 38t? By offering it up and simulating chain tension it looks like it might, but it's close.

Thanks!

 

[hamster]

Do you mean a 38T rear or 38T difference of chain wrap?

Shimano always quote limits which are guaranteed good. If you mean a 38T rear sprocket, I would suck it and see, knowing that a £5 mech dropper from eBay will fix it if not. You will need to screw in the B-tension as far as it goes.

 

[Tolsey31]

Thanks for quick response. It's a 38t cassette. I'd never even heard of a mech dropper so every day's a school day. Cheers.

 

[hamster]

this sort of thing
https://www.ebay.co.uk/itm/31395797...Knoe_AeqWn-F-2ekK6uvPYWmBjw8Wmw8aApEmEALw_wcB
If your frame has a long mech hanger you may well get away with not needing it.

 

[joglo]

this sort of thing
https://www.ebay.co.uk/itm/31395797...Knoe_AeqWn-F-2ekK6uvPYWmBjw8Wmw8aApEmEALw_wcB
If your frame has a long mech hanger you may well get away with not needing it.

My experiences with such a a thing, typically called road link, goat link or wolf tooth, isn't good, because of the bigger distance from the top pulley to the smaller cogs the gear shifts are not very exact any longer...

You could give it a try without, just optimize the chain length, as short as possible (I would assume with such a cassette you may want to try a setup with single chain ring in the front, right?). You also could use a longer b-screw.
Those tricks may help.

I'm successfully using LX 550 and 563 rear derailleurs with 11-36 cassettes, but failed with 11-40. Both in a 1xX setup, without front mech.
It always depends also a bit on the frame and regular hanger.

 

[Tolsey31]

Hi, it's for a standard 3 front ring setup so I think I'll just give it a whirl...I thought I was buying a 36 as that's what it was listed as ha ha.

 

[Repacker]

From https://productinfo.shimano.com/download?path=pdfs/archive/2005_SPECIFICATION.pdf

• Total cap: 43
• Max front diff: 22
• Large sprocket max: 34
• Small sprocket min: 11

 

[Tolsey31]

Thanks - that concludes the matter I think!

 

[hamster]

The Shimano recommendations are conservative, and are pretty much guaranteed to work. You can usually stretch things rather further, although it then may not work on every frame. things like mech hanger drop length become significant.

That said, if the OP really wants a much lower bottom gear, then switching to a smaller chainring at the front is far simpler.

 

[Tolsey31]

I managed to get shifts up to the 38 ring, but the rest of the cassette was impossible to dial in so I'm taking my medicine and getting an 11-34.