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I have a MTB with a mashed up Tourney RD-TY-300, due to a badly rusted chain. I might be able to bend it back into alignment, but seems unlikely, or would require a lot of work and finesse that I don't have the patience for. So, I thought about buying a "new" second hand one, cheap on eBay.

However, I have come across the fact that there are two types of hangers, direct and standard mount. As this MTB is a cheap kids bike, and looking at the hanger, it would seem to be a standard mount (photo to follow), as the mount hole is close to the axel.

So, are all Tourney RD-TY-300 derailleurs the same and can fit each mount, or are there two types that I should watch out for, when making my purchase: one for standard and one for direct mount? It would seem logical, as the required "reach" would seem to be different (or does the stretch of the spring just mean that it sorts itself out in either case?).

Also, as this page, Standard Mount vs. Direct Mount Derailleur Hangers, states,

  • If you have a standard mount rear derailleur, you can only use it with a standard mount hanger.
  • If you have a direct mount hanger on the frame, you can only use with a direct mount derailleur with the b-link removed.
  • If you have a direct mount rear derailleur, you can use it with a standard deralleur hanger (with b-link), or use it on a direct mount hanger (without b-link)

However, I have been unable to ascertain whether the RD-TY-300 comes in two flavours, and the eBay listings don't seem to specify which one either. I could just go ahead and buy one, and see if it fits, but I don't want to have to deal with returns, etc..

Can anyone point me to a Shimano datasheet (or exploded diagram) that shows the two types and whether they have different codes..?

Also, are long and short cages a related factor?

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Here is a link to the Shimano Specifications for the RD-TY300. It includes pictures that will clarify what exactly you need.

Essentially, there is a lot of confusion in regards to rear derailleur mounting since the advent of bicycles designed for "direct mount" rear derailleurs. Especially since Shimano utilizes the term, "direct attachment, conventional" for the common type of rear derailleur where a bolt, as a captive part of the rear derailleur, threads into the bicycle side derailleur hangar.

The TY-300, is a low tier model designed for budget bikes. These are bikes whose design may not include a derailleur hangar-neither built in nor replaceable. Thus, Shimano and other manufacturers of budget parts have a piece attached called a "claw" that allows you to mount the derailleur at the rear drop-out utilizing the rear axle and nut to secure it. The claw and compatible frame also have a small fixing screw and hole to help fix the derailleur to the frame.

As you can see in the above link, the "versions" of the TY-300, refer to the type of mount that is attached to it: two types of claw hangars and conventional "direct attach" bolt system for those bikes that have a derailleur hangar.

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