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To cut a long story short, I have a full suspension mountain bike. Its rear derailleur mech (see title) is broken, had a trip round the spokes and age has degraded the main springs. I therefore need to replace it. Now, its old, and you can get the model, but its new, old stock so I want to upgrade the rear mech, not just replace.

So I need a Shimano rear mech, for 7 speed rear wheel, that bolts directly to hanger that is part of frame (Direct Attach). Can someone suggest how to select a replacement mech? I am happy with the rest of the system, which is Dual SIS, and grip shift.

Thanks in advance,

Jawapower

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    I made a small edit so your question asks for selection advice rather than directly asking for a product recommendation - which i believe was your intention. This is to ward off close votes which product recommendation questions tend to attract. – Argenti Apparatus Nov 29 '18 at 13:30
  • I'd recommend to look up what direct mount is and make sure you don't confuse it with standard mount. Most direct mount derailleurs come with an adapter to standard mount, but you need to know whether to use it or not. – ojs Nov 29 '18 at 18:20
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Specific product recommendations are off topic here, but I can tell you that pretty much any Shimano MTB 7, 8 or 9 speed derailleur will work.

The reason for this is that the shifter controls the amount of cable pulled for each gear change. The derailleur has an 'actuation ratio' which is the ratio of lateral movement to cable length pulled. Shimano 7, 8 or 9 speed derailleurs all use the same actuation ratio and the shifters are responsible for pulling the correct amount of cable for the 7, 8 or 9 speed sprocket spacing.

Derailleurs from the Tourney TX (the highest Tourney level), Altus or Acera lines will be a step up from your current derailleur.

You will need to check the specs of the derailleurs you consider, specifically: the max largest sprocket that can be accommodated and and the 'total capacity' which is the max (difference in size small and large chainrings) + (difference in size small and large cassette sprockets), measured in teeth. and represents how much chain slack the derailleur can take up.

Specs can be looked up on Shimano's site here: http://si.shimano.com/#/

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    Thanks, I wasn't after a "product placement" type of response! You answered exactly as I wanted... The main thing I'm unsure about is the "replacement rear mech" needs to be (direct attach) some of the Shimano I have looked at haven't said if they are/are not direct attach. Is there a number or letter in the mech name or that indicates its direct attach? and will bolt straight to the inbuilt hanger on the frame..? – Jawapower Nov 28 '18 at 23:44
  • That's interesting, had to go into Archive to find my RD-TY22, and it says for "6 Speed" only, yet mines a 7 speed...!! Now I haven't had bike from new, perhaps the rear mech has been replaced with the wrong one in the first place, what do you reckon? It really doesn't like shifting into or out of 1 or 7.....? – Jawapower Nov 29 '18 at 0:10
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    @Jawapower Many Tourney derailleurs are really 6/7 speed. Like I said there is actually compatibility of rear derailleurs across lines with different 'speeds' because the same actuation ratio was used. if you are having shifting difficulties replacing the cable and housings can also help. – Argenti Apparatus Nov 29 '18 at 0:25
  • Hi, done all that, new cables, inner and outer, derailleur stripped down, de-greased, de-mudded, de-belly button fluffed, de-wire wooled (yes) re-greased, assembled, oiled, and still poor performance, the grip shifter/s are fine and positively move the cable both ways.. I think the main springs are worn, strained and the parallelogram is slightly warped.. So a new mech is essential.. I think...... – Jawapower Nov 29 '18 at 1:02
  • Found this one in a sale, says "attach direct" we'll Att. Dir. It's the Shimano Cambio Post. 6/7v RD-TY300 Tourney TX Att. Dir. Do you think this will work...? – Jawapower Nov 29 '18 at 22:03

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