What are my chances of getting a TY-300 derailleur to work with a 11-40T 8 speed cassette?

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Bonzo Banana
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Joined: 5 Feb 2017, 11:58am

What are my chances of getting a TY-300 derailleur to work with a 11-40T 8 speed cassette?

Post by Bonzo Banana »

What are my chances of getting a TY-300 derailleur to work with a 11-40T 8 speed cassette.

In the Shimano documentation it says pretty much 11-34T is the maximum range but it has a capacity of 43T

So the rear cassette is 40-11= 29T leaving me 14T capacity but the front is 1x only at I think 42T so is 0 for capacity (42-42).

I've heard of them working with 11-36T 8 speed cassettes but then Shimano are quite conservative but will I have problems with the extra 4T or will the fact I have 1x help. I realise there are different issues here, one is lining up with the cassette and the other is chain tension. I'm guessing I'll be fine with chain tension its just a matter of will it accept 40T.

I don't have the option of a derailleur hanger extension as its the bracket type and the frame doesn't have an integral derailleur hanger.

Although the TY-300 has 6/7 speed printed on it, it is commonly sold with cheaper bikes that have 8 speed cassettes although those are likely direct mount.

Anyone pushed the boundaries of Tourney derailleurs before like this. It is the so called long caged Tourney derailleur but obviously that is still reduced capacity compared to higher up models. Mine is the standard fitting below in the middle. I didn't even know they did a fitting for horizontal dropouts (top right) although have never actually seen one fitted to any bike.

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