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  1. #1
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    Single wall rims

    So what will happen if a 230 pounder rides a bike with 36 spoke single walled rims? Lets assume they are properly tensioned. Is this asking for trouble or can we assume they will at the very least be safe?

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    Gears? CliftonGK1's Avatar
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    The wheels will explode and spokes will fly everywhere, killing innocent bystanders and destroying storefronts.

    I have a bike with old Araya single wall 36h rims and it's fine. I weigh 230 - 235, and I've been as much as 250. It's also my utility bike and I carry loaded bucket panniers, a bunch of stuff lashed to the top of the rack/panniers, and a full Wald 157GB of grocery bags up front.
    "I feel like my world was classier before I found cyclocross."
    - Mandi M.

  3. #3
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    excellent, just what I wanted to hear. I just bought some cheap wheels to put on a recycling project I got going on and want to make sure they will be decent

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    Quote Originally Posted by CPFITNESS View Post
    excellent, just what I wanted to hear. I just bought some cheap wheels to put on a recycling project I got going on and want to make sure they will be decent
    The modern wheels I've seen made up on single walled rims have been shockingly bad. You'll do well to make sure they're properly tensioned (no chance they will be by the machine that built them), stress relieved (ditto), and inspect for cracks at the eyelets. The hubs sucked too; take them apart, properly lubricate them, and adjust them.

  5. #5
    Senior Member Wogster's Avatar
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    Quote Originally Posted by CPFITNESS View Post
    So what will happen if a 230 pounder rides a bike with 36 spoke single walled rims? Lets assume they are properly tensioned. Is this asking for trouble or can we assume they will at the very least be safe?
    Contrary to popular belief, cycling stuff that is okay at 199.9999 lbs doesn't just immediately explode in failure at 200.0001 lbs, having said that, if you go back over the last 3 years of wheel threads you will find that a few rims keep getting recommended over and over. For those solidly in clyde territory, it's best to select one of those rims, which are all double wall, BTW rather then picking something else that may not work. If your buying a bicycle which comes with 36 spoke wheels and single wall rims, then you don't need to immediately replace them, but you need to watch them for common issues. Once a week or every 100 miles or so (whichever comes first), you need to wipe the dirt off the rims and carefully check for problems.

    The most common failure for rims is cracking around spoke holes, this is most often found in cheap rims where the spoke holes are punched out and not then reinforced, then this is combined with high spoke tension. The punching process weakens the metal slightly around each hole, and the high tension then causes it to start pull the spoke through the rim, the first stage of pull through is to crack. Cheap rims that are low spoke count are most vulnerable to this, because they get the highest spoke tension. Higher quality rims have the holes drilled out, the drill is kept cool with lubricating oil and it doesn't weaken the metal around the hole. The ideal is a rim that is drilled and then a reinforcing ring is put around each spoke hole.

    Double wall rims, have a reinforcing piece (sometimes more then one) that ties the sides of the rim together, this keeps the sides from splaying out (the rim effectively gets wider), if it splays out far enough the tire can blow off, although you should get cracking at the sidewall or brake rub long before it gets to that point. Because of the reinforcement, double wall rims are far less likely to splay out then single wall rims. Splaying is far more likely to be caused by someone putting insanely high pressure in the tires and keeping the tires at that pressure, so it puts constant force on the rim, then a heavier rider. For example 150PSI in a rim rated for 100PSI max.

    The only other issue is when the spoke tension is not monitored and gets low enough that the rim is allowed to bend out of true to the degree that spoke tension can't pull it back into round, the only way to fix this to replace the rim.

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    thanks for the detailed info. I'm not sure If I'm going to keep this bike. It's an old nishiki I bought off the street for $30. I've cleaned it up and it rides pretty nice on the old heavy and warped steel wheels. I've been searching craigslist trying to find a donor bike that I can strip some aluminum wheels off of but not much luck in finding anything at a good price point so in the end I decided I will outfit it with new wheels and there is a good chance I'll just be selling the bike in a couple of months.

    No I'm not trying to make a profit on it, this is more of an exercise in getting reacquainted with wrenching so I don't mind spending a little bit of time and money on it. also, by buying brand new I can do the freewheel install myself instead of having to take it to my lbs or worry about buying a freewheel tool or whatever. At the end of the day, I think I'll have a pretty smooth riding 14 speed bike that I can probably resell here in NYC for at least75% of what I put into it, and that will be fine with me. otherwise I'll keep it or give it to a friend.

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