Custom Pedals?

Discussion in 'rec.sport.unicycling' started by gerblefranklin, Feb 5, 2005.

  1. I recently did a poorly landed 5+' drop, and bent my right snafu pedal
    (or possibly my profile crank, however unlikely). I have also bent the
    spindles on a set of wellgos and I'm not sure, but also another snafu. I
    am tired of breaking stuff, as there's no reason to do so. So my
    question is a rather simple one:

    How feasable is it to fabricate one's own pedals? What features would
    one want in them, and what materials would you use? Sealed cartridge
    bearings, or custom seals?

    I'm thinking of a 4130 chromoly spindle, or titanium, depending on which
    is cheaper to heat treat. As for the material of the body, I am thinking
    aluminum and rubber. Possibly magnesium if it's easy enough to obtain,
    but aluminum seems the best bet both for strength and durability and
    accessibility.

    As for the bearings, I'm thinking custom o-ring seals on the outside
    would be more than easy, and on the in-side a rubber flap that srings on
    the axle to keep mud and grit out. A good packing of grease on the other
    side could provide a backup protection. I think cartridge bearings, such
    as on Wellgo b-37s, are inferior because of their lateral weakness.

    As for the pedal body designs, I was considering a custom,
    non-symmetrical design. On the left (pedalgrab side) pedal, one side
    would be amply pinned, while the other side would have a small
    triangular reccess in it with rubber lining so as to facilitate
    stability on round rails. The edges would be pinned for grip in wood. I
    don't grind, and have no need for good sliding. On the right side, a
    normal, symmetrical parralleogram design seems ideal. Plenty of pins of
    course.

    Please, if you have any input on the topic, I'd like to hear it.


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  2. munimanpete

    munimanpete Guest

  3. yea i thakn u shuld maek it 4 me 2
















    OMG!!!


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  4. john_childs

    john_childs Guest

    You might want to consider the 'Gack Juggernaught'
    (http://www.gackbmx.com/juggernaut.html) pedal. It's expensive, but
    looks very strong. The axle is oversized and maintains that oversized
    diameter for the entire axle (except for the 9/16" threads). MSRP is
    something like $130.

    Ryan Atkins was using a pair of 'Specialized platform pedals'
    (http://www.specialized.com/SBCEqProduct.jsp?spid=9826) at the CA Muni
    Weekend. He was using last year's model. This years model has some
    changes to improve durability. You could ask him how they've been
    holding up. They're supposed to be strong. MSRP is $82.99.

    You can only get so strong with pedals. The limiting factor is the
    9/16" threaded pedal hole. You can make the rest of the axle oversized,
    but you still have to make the threads 9/16".

    Making your own pedals would be expensive and time consuming. And you'd
    have unpredictable results and probably a few design duds at first.


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  5. john_childs wrote:
    > *You might want to consider the 'Gack Juggernaught'
    > (http://www.gackbmx.com/juggernaut.html) pedal. It's expensive, but
    > looks very strong. The axle is oversized and maintains that oversized
    > diameter for the entire axle (except for the 9/16" threads). MSRP is
    > something like $130.
    >
    > Ryan Atkins was using a pair of 'Specialized platform pedals'
    > (http://www.specialized.com/SBCEqProduct.jsp?spid=9826) at the CA Muni
    > Weekend. He was using last year's model. This years model has some
    > changes to improve durability. You could ask him how they've been
    > holding up. They're supposed to be strong. MSRP is $82.99.
    >
    > You can only get so strong with pedals. The limiting factor is the
    > 9/16" threaded pedal hole. You can make the rest of the axle
    > oversized, but you still have to make the threads 9/16".
    >
    > Making your own pedals would be expensive and time consuming. And
    > you'd have unpredictable results and probably a few design duds at
    > first. *



    I imagine there would be many duds. I have time, not money, sadly. I was
    thinking about that limit of the threads, and i guess there's no real
    way around that. Still, it'd be nice to have a pedal that actually grips
    round rails when you pedalgrab them. It's really frustrating to end up
    doing a crappy grind when you are trying to pedalgrab something.


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  6. john_childs

    john_childs Guest

    gerblefranklin wrote:
    > *I imagine there would be many duds. I have time, not money, sadly. I
    > was thinking about that limit of the threads, and i guess there's no
    > real way around that. Still, it'd be nice to have a pedal that
    > actually grips round rails when you pedalgrab them. It's really
    > frustrating to end up doing a crappy grind when you are trying to
    > pedalgrab something. *


    One design feature to strengthen up the area around the 9/16" threads is
    to put a lip all the way around the area where the pedal spindle makes
    contact with the crank. Look at the spindle for the Specialized pedals.
    There is a lip all the way around next to the threads. That lip snugs
    up to the crank and gives more support around the threads. Lots of
    other pedals put the flats there for pedal wrench. That gives less
    support in that crucial area and makes it more likely for the pedal
    spindle to flex or bend there.


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  7. onetrack

    onetrack Guest

    it dosen't seem like pedals would be too hard to make. the only high
    tolerance areas are where the bearings seat on the pedal body and
    spindle. if you could get a solid block of aluminum and cromo rods then
    had the high tolerance areas CNCed for you (expensive) then everything
    else could be done with simple tools.

    if you took a pair of exhisting pedals you could tap one side so that
    rubber from an old tire or something could be bolted on. that might be a
    cheap solution to your crappy grinds.


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  8. vanman2004

    vanman2004 Guest

  9. onetrack wrote:
    > *it dosen't seem like pedals would be too hard to make. the only high
    > tolerance areas are where the bearings seat on the pedal body and
    > spindle. if you could get a solid block of aluminum and cromo rods
    > then had the high tolerance areas CNCed for you (expensive) then
    > everything else could be done with simple tools.
    >
    > if you took a pair of exhisting pedals you could tap one side so that
    > rubber from an old tire or something could be bolted on. that might be
    > a cheap solution to your crappy grinds. *



    I have considered bolting rubber on. I don't really feel like putting
    the time into my trashed pedals as they are.

    Making the bearing races isn't that hard. A lathe with a good radius
    cutter can do it in a jiffy. That or a bridgeport with a special fly
    cutter. The shop I'm at has both, so there's no worries there.

    I'm thinking of just drawing up a set of plans and putting them on the
    internet, though, so as to let someone else make them. I have enough
    projects on my hands as it is.


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  10. Skippii

    Skippii Guest

    If you were to make one-piece crank arm& pedal together, you could
    probably make an incredibly strong pedal, since you wouldn't be limited
    by the 9/16th threads.

    But your chances of making a better crank and better pedal than what's
    already out there at the same time are pretty slim, I'd say.


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  11. spyder

    spyder Guest

    gerblefranklin wrote:
    > *I'm thinking of just drawing up a set of plans and putting them on
    > the internet, though, so as to let someone else make them *


    You realize once you do that, you're leaving yourself wide open for
    total uni to step up and offer to do it for $25 + labour!:D


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  12. Skippii wrote:
    > *If you were to make one-piece crank arm& pedal together, you could
    > probably make an incredibly strong pedal, since you wouldn't be
    > limited by the 9/16th threads.
    >
    > But your chances of making a better crank and better pedal than what's
    > already out there at the same time are pretty slim, I'd say. *

    A friend of mine wanted to make a splined pedal-crank connection.

    Andrew


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  13. johnfoss

    johnfoss Guest

    andrew_carter wrote:
    > *A friend of mine wanted to make a splined pedal-crank connection. *

    Why? Trying to figure out if he just doesn't understand why we use
    splines where we do...

    Yes, like skippi says, you can always think big and take in the whole
    picture. If the threads are the weakest point on a set of pedals,
    perhaps unicycling will move to a larger size someday. You can customize
    some existing cranks, or make your own. Or go the whole nine yards and
    make the whole hub and crankset. Tom Miller made some super-strong
    one-piece cranksets for abusive unicyclists many years ago. Not sure how
    they compared to todays' splined stuff, but they were a sensible
    solution before we had access to splines.


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  14. I did some research into the technology used to fabricate crank splines
    a few months ago, and it's well beyond most well-equipped machine shops'
    capability to do so. The technology is the same as is used for making
    the bronze blocks that Bridgeport ACME leadscrews thread into. I would
    need access to a specially equipped tool called a broaching machine. All
    they do is cut stuff like splines. In order to build my own unified
    pedal/crankset, I'd have to furst build a broaching machine that could
    cut splines with an accuracy of +0.0000", -0.0005". That's far more
    difficult than simply finding alternative methods of pedal designs.

    A 1 piece pedal/crankset desgin has many drawbacks:
    -If you break the spindle on one of your pedals, you are thoroughly
    screwed.
    -It limits you in material choices, since you must use the same material
    for the pedal spindle as you use for the crank.
    -You have to temper the pedal spindle and crank to the same hardness,
    which isn't neccessarily ideal.

    I'm sure there are other drawbacks, but those seem the most obvious. I
    think that tianium would be a nice material for a pedal spindle, but I
    imagine it would be awful for cranks (although it'd be the closest we
    ever came to built in shock absorbers due to flex). I have never heard
    of splined titanium cranks, and I bet there's a reason for this. There
    is the chance that the technology doesn't yet exist to broach profile
    splines (special because they are extremely small) into titanium. I have
    heard that titanium flexes so much that in order to make accurate bottom
    brackets for titanium bikes, you must start with a giant, oversized
    block of titanium to minimize flex. Then, once the BB is cut, you
    machine the rest of it down. That isn't feasible for a crank.

    I like John Childs' point about the ring on the specialized pedals. I
    noticed how the wrench surfaces on my snafus DO weaken the spindle, but
    it doesn't seem that the threads were where my pedal bent. It seemed to
    bend at the inner bearing race.

    I am fine with Evan taking a shot at making the pedals, since he won't
    succeed at his current rate.


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  15. john_childs

    john_childs Guest

    The titanium pedal spindles I've seen have all been for the weight
    weenie cyclists who are more concerned about grams than strength. The
    titanium pedal spindles had max rider weight limits and were not
    designed for hardcore use. They are aftermarket titanium spindles
    designed to replace the stock steel spindles in specific pedals.

    You'd have to make the titanium spindle larger in diameter than the
    steel spindle to get the same strength. CrMO steel is better when
    you're going for strength.


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  16. Since I read 'this thread' (http://tinyurl.com/6y36t) I've always been
    under the impression that per unit of material, titanium was 2x as
    strong as steel or chromoly. It will flex far more, but ultimately be
    just as strong if not stronger.

    But then again, I guess I'm wrong. Thanks John.


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  17. vanman2004 wrote:
    > *No, it is much stronger per gram/pound/stone/whatever, but the
    > titanium pedals etc. are all made for lightweight cyclists because
    > titanium is ideal for that sort of thing. In other words, there is
    > much LESS material in stuff made of titanium because it's designed for
    > lightweight "weenies". *



    By that logic there shouldn't be any reason not to make a ful thickness
    ti pedal spindle. It would be far stronger and be of comparable weight.
    What made you think I'm designing my own pedals for weight savings?


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  18. Ken Cline

    Ken Cline Guest

    "gerblefranklin" <[email protected]> writes:

    > By that logic there shouldn't be any reason not to make a ful thickness
    > ti pedal spindle


    Titanium, feh. Get your mitts on some Aermet alloy - the stuff they
    use in F-18 landing gear. It's crazy strong, somewhere around 3 times
    as strong as CrMo if I read the specs right. Basically off the chart.
    Excellent durability and good corrosion resistance. Perfect for your
    pedal spindles. If you can obtain it, machine it, and heat treat it,
    that is.

    Ken
     
  19. I'd love to have that stuff for more than just the pedal spindles. I
    somehow get the feeling that it'll be insane to machine, though, since
    it'll be stronger than my cutters on the lathe. Not to mention, if it's
    that exotic of an alloy, who's going to know how to heat treat it?


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