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    For stupid fun I put a long cage on a Sram RED 10 speed RD to accept a 32t cassette. Why isn’t it actually accepting 32t?

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    6 Comments

    1. pork_ribs on

      I found a sram red 10 speed mechanical groupset plus two Force derailleurs for $100 *total* so I want y’all to know this story is starting in “why not” territory. (Fwiw it was an old man selling everything… Definitely not stolen goods.) My buddy’s 1991 Trek 1000 already was a shit-shifting freak from my parts bin so when I saw the deal I thought I could set him up with something I consider [talismanic.](https://media.giphy.com/media/v1.Y2lkPTc5MGI3NjExczFoa285cHdvMmIzemI5NGF3MnpzOW02MTBubHlzdjN6YWxxMjAwYyZlcD12MV9pbnRlcm5hbF9naWZfYnlfaWQmY3Q9Zw/jfRGnN954yU7u/giphy.gif).

      I read somewhere if you put on a [Sram Force 22](https://www.sram.com/en/service/models/rd-frc-b1?t=11t26377442) rear cage on this [RED RD](https://i.ebayimg.com/images/g/rjEAAOSwVwFid-N2/s-l1600.jpg) (where the hell is the serial number on this…) it can accept the 32t cassette. Also if your buddy paints little red accents on it with nail polish it looks even cooler. Well the swap went fine and the mech shifts up and down the block wonderfully. Unfortunately, in this video you can see when it’s in the 32t cog (and small chainring up front) it seems like the cassette and guide pulley are making contact. [Here you can see the extra long B screw](https://imgur.com/a/nSPQsQy) trying its very best but it’s not cutting it. Also, when it’s screwed in all the way it’s leaning against the derailleur hanger stop thingy instead of pointing at it so obviously it will bend when under any load. [The old B screw compared to new with the cannibalized rear mech next to it.](https://imgur.com/a/8zHEDXm)

      My question is are there any options to get this thing to accept 32t? I’m guessing there is some sort of road link but that’s an alignment nightmare waiting to happen. Contacting a frame builder is completely out of the question. I guess I’m really just curious if cage length isn’t the end all be all of range compatibility.

      Thanks!

    2. RECAR77 on

      that’s because the cage length only affects the capacity (the amount of slack in the chain the derailleur can take up)

      how big of a cassette the derailleur can clear depends on the distance of the guide pulley from the axle. your cage could be 5 meters long and that distance wouldn’t change.

      I know it doesn’t look as good but you can use the force 22 with 10s shifters as-is. they have the same pull ratio (“Exact-Actuation”)

    4. PeppermintPig on

      Derailleur specifications should indicate two properties:

      1. Tooth capacity range: This refers to the amount of slack the chain can take up.

      2. Cassette clearance value. This is a static value indicating the largest cassette/freewheel that the derailleur is expected to be capable of clearing.

      Check the specifications for both pieces of information. The latter is important for clearing into the low gear.

      If you’re just barely clearing, sometimes the remedy is to shorten the chain if you have available slack to do so because the B screw will not always correct your clearance issues, even if you install a long B screw. Sometimes taking a link out will give you a favorable pulley wheel position in order to clear. Be sure to verify for yourself if the Big-Big combination results in a fully extended derailleur. You shouldn’t ever be in that combination, but you should be able to clear that combo also. Ultimately you do not want to inadvertently cause harm to your drivetrain.

      TL;DR: Shorten chain length for better clearance potential. Don’t forget to reset B screw by winding it out when testing new length, and make sure you don’t fully extend derailleur in Big-Big.

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