Cycling Equipment · Public discussion

rims!?

Started by Strelok · · Last activity · 9 posts · 948 views

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Cycling Equipment
Published
16 October 2011
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28 February 2012
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Strelok
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  1. This is is a difficult thing to decide on! everyone seems to be putting down mavic nowadays. so i am thinking of avoiding them. with dt the rims don't seem suited for touring unless expensive IIRC.

    so, i was looking at sun ringle.

    first, can rhynolites be use with disc brakes?

    also, how good is the MTX 31 rim? will it be too wide for some 26x1.5 Schwalbe marathons? I've seen one review on MTBR.com and it was some knucklehead saying they sucked.

    what fair priced (below $50) rim would you look for for loaded touring? i need them in 26 inch and will be lacing them to 36 hole xt hubs and straight gauge dt spokes.

  2. Any, and every rim can be used with disc brakes. It's a non-issue, the rim couldn't care less if the brake track remains unused.
    It's the other way around, a disc brake rim may not be possible to use with rim brakes, as it may not have the required brake track.
    But I wouldn't use straight gauge for a touring wheel. I'd use a thinner gauge on NDS, and on the non-brake side of the front, to get less of a tension difference. May not be required, but it won't hurt.
    I haven't built one for ages, but one stock recommendation for longevity is to look for rims that are double-eyeletted. That's when the eyelet links both walls of the rim together as one unit, distributing the load.

  3. I wouldn't go too hard on mavic. In fact, I'd probably recommend a set of X719, or similar, for a set of disc wheels. Their sealed spoke bed makes them quite strong. More of a pain to put together but they'll defintiely take the heat. To be honest, you won't find much in the way of bulletproof reliability (which is what you need for touring) at low price points. "Don't spoil the ship for a penny's worth of tar"

    There is also a slight error above which needs correcting: spoke thickness has no effect on spoke tension. Tension is set by wheel geometry and your hand on the spoke key, nothing more.

    We tend to use thicker spokes in high tension areas becuase high tension requires a high level of torque on the spoke when tightening. A thicker spoke is less likely to twist (or rather, the twist is not of a high degree) when tensioning. Bringing a thinner spoke to high tension will lead to a much higher degeree of twist. And the more the twist, the harder it is to compensate for. So it's much easier to use thicker spokes in high tension situations.

  4. Quoted post said:

    Originally Posted by tafi [IMG]/img/forum/go_quote.gif[/IMG]

    There is also a slight error above which needs correcting: spoke thickness has no effect on spoke tension. Tension is set by wheel geometry and your hand on the spoke key, nothing more.

    We tend to use thicker spokes in high tension areas becuase high tension requires a high level of torque on the spoke when tightening. A thicker spoke is less likely to twist (or rather, the twist is not of a high degree) when tensioning. Bringing a thinner spoke to high tension will lead to a much higher degeree of twist. And the more the twist, the harder it is to compensate for. So it's much easier to use thicker spokes in high tension situations.

    Well, fine. Let's call it strain instead. Or load vs cross section.

    Either way, using a thinner gauge on the spokes farthest away from perpendicular compared to the wheel axle improves the odds for a durable wheel.

    Spoke wind-up is entirely a builder's issue. Awareness, ability and attention to detail will sort that out. This is the first time I've ever heard thicker spokes being favored primarily to avoid wind-up.

  5. Getting back to Sun Ringle, I'm quite enthusiastic about the brand. I've been working on a lot of old mountain bikes with Rhynos, lately, and I've yet to find one seriously out of true.That certainly speaks for the builder as well as the rim, but the rim certainly has something to do with it. Also, I've been building strong and reasonably light training wheels for myself using Assaults and M14As. Sun rims are excellent bang for not a whole lot of bucks.

  6. Quoted post said:

    Originally Posted by dabac [IMG]/img/forum/go_quote.gif[/IMG]

    Well, fine. Let's call it strain instead. Or load vs cross section.

    Sorry dabac but this is wrong too. The thinner spoke under the same tension will experience higher stress (tension force per unit cross section area) in its midsection.

    Quoted post said:

    Either way, using a thinner gauge on the spokes farthest away from perpendicular compared to the wheel axle improves the odds for a durable wheel.

    I agree with you in principle. But it has nothing to do with the static loads you are talking about, and everything to do with fatigue causd by dynamic loads (loads which are always changing).

    The increased stress suffered by thin gauge spokes is not really a problem. Even a thin spoke is capable of taking a lot more load than the rim ever will. The extra stress is more than offset by the fatigue resistenace imparted by the butting (shaping) of the spoke. The butting reduces the impact that stress raisers (threads and elbow) have on spoke fatigue life.

    Quoted post said:

    Spoke wind-up is entirely a builder's issue. Awareness, ability and attention to detail will sort that out.


    Only up to a point. Tensioning involves tightening the nipple on the spoke. But before you overcome friction in the thread, the spoke will twist somewhat. Typically you twist the nipple until it begins to turn independently of the spoke end, and then back off to remove the twist imparted to the spoke. To acheive high tension, however, you must be careful not to aplly too much shear stress. If the spoke yeidls in torsion then its buggered. This is not a problem for 1.8mm mid section spokes but can be an issue when you get down to 1.5mm (revolutions). Oiling nipple threads will ony get you so far. There is a limit.

    You're also ignoring the extra time and effort that has to be put in to a wheel with thinner spokes, by the wheelbuilder, to compensate for the twist. The extra time costs money which most customers (not being technically minded) do not understand, therefore it is common to just use plain gauge spokes as they do the job most of the time and are easier and faster to work with.

    Quoted post said:

    This is the first time I've ever heard thicker spokes being favored primarily to avoid wind-up.

    Well there's a first time for everything. The fact remains they are easiest to build with, so unless a customer has a preference for butted spokes, I would always go for plain gauge becasue the wheel will be finished faster. The only other reason to use thicker spokes is lower cost. They are not as durable, are no stronger and are heavier than butted spokes.

  7. Quoted post said:

    Originally Posted by tafi [IMG]/img/forum/go_quote.gif[/IMG]

    Sorry dabac but this is wrong too. The thinner spoke under the same tension will experience higher stress (tension force per unit cross section area) in its midsection.

    I have a feeling that you are deliberately misunderstanding me.
    So I shouldn't have said tension. My bad. It's an ugly habit, but real widespread. It's also kinda encouraged by the Park tensiometer. But we've already been there.
    In the follow up I posted" load vs cross section". Can't see much room for misunderstanding there, but then again, I'm not trying that hard.
    I have to admit that "tension force per unit cross section area", sounds more posh, and obviously I didn't write that.

    But why do you feel compelled to point out that " thinner spoke under the same tension" when I've already admitted to sloppy use of language? And tried to clear it up too?

    And sure, you can call the dynamic loads the spoke killers all you want, but the way they are controlled in a bicycle wheel is by the static preload. Get the dynamic load to be a sufficiently small part of the static load and the problem goes away. If you have another theory, please share. Or harp away at another poorly chosen phrase, if that's your preference.

    I'm not saying that "increased stress suffered by thin gauge spokes" is a problem. It isn't, true enough, but apart from being part of general wheel knowledge, I can't see the specific connection to this thread.

    You say "The extra stress is more than offset by the fatigue resistenace imparted by the butting (shaping) of the spoke. The butting reduces the impact that stress raisers (threads and elbow) have on spoke fatigue life"

    I really don't think it's the shape of the spoke that's the key. It's the total available cross section for each side of the wheel, how it matches the tension, and lets the spoke maintain sufficient preload for good fatigue resistance.

    Setting DS tension as 100%, my last build according to Spocalc would end up with 59% NDS tension.
    So I use 1.8 mm DS spokes and 1.5 mm NDS spokes. If 1.8 mm cross section area is 100%, the 1.5 mm spoke end up at 69%

    100% tension at 100% area vs 59% tension spread over 69% area seems like a well matched set to me.

    I kept the spoke count, used thinner spokes, and as a result the stress as seen by each spoke is pretty darn close.

    But I could have gone another way - triplet lacing. I could have used a 36H rim and a 36H hub. but only laced 2/3 of the NDS holes. That'd have given me 59% tension spread over 67% cross section area. That difference is probably beyond what the TM-1 can measure, or I can build for that matter.
    Sure, there's an unknown as to how the rim would react to each 5th hole being empty, but I reckon the spokes would do fine.
    Anyhow, I'm outta here. Have a ball with whatever language or terminology lapses you're able to find

  8. I've used Mavic 717 rims (36h) for loaded touring for years and have never had a problem, other than wear and tear. They are very good rims.

  9. I wonder if guys are interest in carbon bike rims?
    700c tubular and clincher we supply.

    price of 100$, i think we have some types for your reference.
    our company site: sonata.en.alibaba.comsonata.en.alibaba.com it is our shop on Alibaba.com

    Tubular: 24mm, 38mm, 50mm, 60mm, 88mm
    Clincher: 20mm, 22mm, 50mm, 60mm, 88mm.

    Best regards
    kyle Foo
    "][email hidden]
    Sonata Composite Sport Co.,ltd

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