Single Speed with a cassette?- Mtbr.com
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  1. #1
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    Single Speed with a cassette?

    I'm wanting to build up a hardtail. I already have two sets of wheels (29er, 27.5+).

    Here's my question, would there be any problems running single speed with a cassette? I would love to start riding as soon as I can and could delay a derailleur and shifter purchase. I know I could buy a single speed set up for an XD driver but I would like to avoid that expense and would have to put the cassette back on if I wanted to run the wheels on my other bike. The frame I am looking at has sliding dropouts.

    Anything wrong with this set up besides being laughed at?

  2. #2
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    A cassette has cogs that are designed to allow the chain to easily slide off sideways. Chainline is maintained by the derailleur.

    If you are reasonably strong then there a good chance the chain will derail and you then suffer an excruciating TTTII.* Then you can guarantee some mirth amongst your more merciless friends...

    I recommend you get a proper singlespeed cog front and rear.




    *Testicular Top Tube Interface Incident.
    As little bike as possible, as silent as possible.
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  3. #3
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    Quote Originally Posted by Velobike View Post
    A cassette has cogs that are designed to allow the chain to easily slide off sideways. Chainline is maintained by the derailleur.

    If you are reasonably strong then there a good chance the chain will derail and you then suffer an excruciating TTTII.* Then you can guarantee some mirth amongst your more merciless friends...

    I recommend you get a proper singlespeed cog front and rear.




    *Testicular Top Tube Interface Incident.
    Thanks, that makes sense. More money one way or another.

    I think I may go single speed though. I've been wanting to try it out.

  4. #4
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    I want to try out some different gears, and have found these in some cassettes i have laying around.
    Chopped the cassettes to bits and took out the 17 and 18t cog.

    Are you saying this is certain death?

  5. #5
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    Cassette single speed cogs are cheap and wear much better than cogs liberated from a gear cluster.
    "These things are very fancy commuter bikes or really bad dirt bikes, but they are not mountain bikes." - J. Mac

  6. #6
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    Quote Originally Posted by Skorp View Post
    I want to try out some different gears, and have found these in some cassettes i have laying around.
    Chopped the cassettes to bits and took out the 17 and 18t cog.

    Are you saying this is certain death?
    Potential neutering is more likely. (TTTII)

    Nothing to stop you fitting 2 or more singlespeed cogs on a cassette if you want to. I did just that a few years ago when I was going to ride a couple of hundred miles on the road to go to a race. I put a small cog on as well as the normal one so I would have a higher gear for the road.

    Take a look at a proper SS cog and note how high the teeth are. That helps stop the chain coming off. Now look at a cassette cog, see how they are cut right down? That's to facilitate the gear changes and allow the chain to slip of the cog.
    As little bike as possible, as silent as possible.
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  7. #7
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    The only reason that chain should derail on a cassette cog is due to poor chainline.

    If you run a cassette cog with a perfect chainline, you'll have more chain wrap than you did with a derailleur. If cassette cogs magically derailed chains due to their tooth profile, no body would be able to ride them. Short teeth and shift gates are there to facilitate shifting *after* the chain is derailed. I know people that ride cassettes and chain rings with missing teeth.

    That's not to say that I'd ride a cassette cog long term however. It's hard to get a perfect chainline a lot of the time and I'd want to make sure that it was indeed perfect. Single speed cogs are cheaper than cassettes and have more material which will wear better. Taller teeth will help keep the chain on in the case that your chainline isn't perfect and will carry the load from hammering on the pedals a bit better.

  8. #8
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    Quote Originally Posted by Shinkers View Post
    The only reason that chain should derail on a cassette cog is due to poor chainline.

    If you run a cassette cog with a perfect chainline, you'll have more chain wrap than you did with a derailleur. If cassette cogs magically derailed chains due to their tooth profile, no body would be able to ride them. Short teeth and shift gates are there to facilitate shifting *after* the chain is derailed. I know people that ride cassettes and chain rings with missing teeth...
    In theory you are correct.

    Results in actual usage may differ depending on the strength of the rider, the steepness of the climb, and the flexibility of the chainstays.

    Short teeth mean the chain does not have to ride so far off the cog to slip sideways. There is a good reason tall teeth are preferred for singlespeed. For the same reason I recommend not using derailleur chain, or at least using the less sideways flexible chains ie 5-6 speed. They also have the benefit of being less expensive.

    BTW the odd missing tooth is not a problem if the teeth are high enough. Many years ago I used to ride my fixed wheel with a block chain which means every second tooth is missing.





    What I recommended is cheap and proven.

    However some learning experiences are never forgotten, and I encourage experimentation, so...

    EDIT: if you do decide to go with the cogs from a cassette use a higher chain tension and ensure your chainline is exact. This may impact (shorten) the life of your BB and wheel bearings, but it helps ensure the chain cannot lift. With proper singlespeed cogs the chain only has to be snug, not tight, and in fact can be run almost hanging to the ground as often seen in pics of 3rd World bikes.
    Last edited by Velobike; 02-23-2018 at 06:23 AM.
    As little bike as possible, as silent as possible.
    Latitude: 5736' Highlands, Scotland

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