On an old road bike the freewheel mechanism sometimes gets stuck in the "coasting" mode, i.e., the pedals spin but the bike doesn't accelerate. When spinning the cassette by hand it still works as expected, however with more friction than I would expect. So I am assuming the cassette needs to be removed, the freewheel mechanism cleaned and oiled an put together. I tried opening the lock ring of the cassette with a Parktool fr-5.3 tool which does not fit (the tool is too small in its outside diameter and the number of splines doesn't match). I don't find any tool online for 10 splines, could any one tell me where to find the right tool and what it is called? I am attaching a picture of the cassette / lock ring. enter image description here

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    Do you have calipers to measure the larger internal diameter?
    – Chris H
    Jan 7, 2023 at 16:50
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    @ChrisH Photoshop scaling suggests 28.6mm. Jan 7, 2023 at 19:25
  • Congrats on hitting the HNQ !
    – Criggie
    Jan 8, 2023 at 4:11
  • @Criggie what does HNQ stand for? ChrisH, I have calipers but they are out of battery, I will make a drawing of it as soon as I can, I will try to hack a tool together for this just for fun (I have no experience in metal working, so I treat this as a learning project now).
    – tim0s42
    Jan 8, 2023 at 17:42
  • HNQ is "Hot Network Questions" - the panel on the right hand side of screen showing posts that are doing well.
    – Criggie
    Jan 8, 2023 at 21:09

2 Answers 2


I have no idea what the correct Suntour tool is for this. This design only was made for a brief window.

One plan is to make a 2-notch tool out of a beater socket with the appropriate OD. Carefully grind it without letting it get too hot; even though you're only using it twice, you might have to really reef on it for removal. Grind wrench flats on the outside so you can hold it on with the QR while turning the lockring with a big adjustable wrench.

I believe I've also seen this flavor (30mm) of BMX 2-prong FW remove ground down for this need. They're cheap.

enter image description here

Ultimately you have the decision whether any of this is worth it, since when it eventually wears out, replacements are vanishingly scarce and also not really compatible with available indexing shifters/RDs. Unless you have a lot more time than money it's probably better to cut bait.

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    The teeth are starting to look worn anyway, so if no compatible cassette is available, it might be new wheel (or hub) time (re. the last paragraph)
    – Chris H
    Jan 7, 2023 at 20:27

I would go with vise grips, plumber's pliers, or a grinder and remove it destructively.

Then you replace the whole cassette with a more modern one, which will have a standard modern lock ring.

Cassette teeth are a wear item so it needs replacing eventually.

The risk here is whether the freehub's spline pattern matches modern cassette's splines. If not, you may need to replace the freehub, or the whole hub, or possibly the entire back wheel.

Another option is to find an old socket whose outer diameter fits the larger of the two bore diameters, then grind, file, or mill ten slots for the teeth. This might be a one-time tool, so there's little point making it pretty.

The choice comes down to whether you will save this cassette and re-use it later, and the cost of a new cassette/chain vs the cost of your time and tools.

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    I've always found lockrings for a given freewheel/freehub to be consistent (but I haven't done a lot with freewheel hubs), so a modern cassette might not fit, and a cluster that fits might need the odd old tool. It looks rather like one I've got, but I've mislaid the tool and both wheels that take it are at work
    – Chris H
    Jan 7, 2023 at 18:47
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    There is no replacing this cassette with a modern one. It's from the era after Suntour came out with their own cassette/freehub design but before they went under. Jan 7, 2023 at 18:48
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    Thanks a lot for this insight, this means even if I manage to source the right tool somehow, in a year at most I will have to replace the hub - so I am not sure if it is worth putting more time into this - I will just replace the wheel with a spare for now :)
    – tim0s42
    Jan 8, 2023 at 0:09

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