Necro's Bike Repair Help - Ask me how to fix stuff and I'll give it a shot.

Discussion in 'Motorized Bicycle General Discussion' started by TheNecromancer13, Nov 8, 2015.

  1. TheNecromancer13

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    Although I'm not the greatest with repairing engines yet, I do know how to build a normal bike from the frame up and diagnose and fix pretty much anything that might be wrong with any part of your bicycle which was there before you put the motor on it. So I thought I'd let people pick my brain. Gears not shifting, brakes need adjusting, wheels out of alignment, how do I fix this, what could be wrong that would make the bike do that, etc, etc. Ask away!

    I will try to update this thread often.
     
  2. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    What's you tip for balancing wheels?
    Hint, this is a test, haha.
     
  3. TheNecromancer13

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    Deleted due to incorrect information
     
    #3 TheNecromancer13, Nov 10, 2015
    Last edited: Dec 8, 2016
  4. Tony01

    Tony01 Active Member

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    I think your response is inaccurate in many ways.

    A wheel can be out of true side to side and still be balanced. I do vertical trueness first, then do side to side. The vertical trueness is the one you feel to be out of whack at over 25mph. Forget the pencil and tape, or the c-clamp brake, just use a zip tie on the fork or seatstay.

    You also forgot the part on stress relieving new spokes before use. Do your research before pretending to be a pro! The people who read stuff here ride at non trivial speeds and giving advice to build an improperly built or repaired wheel could result in a major catastrophe.

    And yeah, welcome to the forum, a place where anybody can give their opinion on any topic they please.... laff
     
  5. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I made my truing stand out of scrap wood and hardware -0- cost.
    Also, when you (always) remove the tire and tube a screwdriver works waaaay better than buggering up the spokes with plies.

    Or use a proper spoke wrench.

    Anyhow, I missed the part about how to balance the wheel there, I think...
     
  6. leo

    leo Member

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    i usually get another rim if i bang one up bad enough to be concerned about it, it's not like they cost a lot to replace one.

    back in the day, i would have spent as much time as needed, not so much any more...
     
  7. bluegoatwoods

    bluegoatwoods New Member

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    "The people who read stuff here ride at non trivial speeds and giving advice to build an improperly built or repaired wheel could result in a major catastrophe." --beginner01

    Anyone who rides at non-trivial speeds without making absolutely sure for himself, or without knowing what he's doing, is the one and only person who is responsible for what happens. It's definitely not the person who offered some advice in a helpful spirit.

    And I don't even see what's so wrong with necromancers description of how to true a wheel. Don't forget that you'll get a lot of different opinions on just what is the "right" way.

    I say "Thanks!" to the necromancer for volunteering to be helpful to those who might be able to benefit from it.

    It's not a wrong thing to do.
     
  8. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I still missed the part about balancing one, haha.
     
  9. bluegoatwoods

    bluegoatwoods New Member

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    That's true.

    Either he mis-understood the question or he felt that taking the 'oval' out of a wheel was what was meant.
     
  10. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    If the wheels aren't balanced, they can be worse at speed that a wobbler.
     
  11. Tony01

    Tony01 Active Member

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    Above 25 mile an hour is a non trivial speed. Cheap bikes destroy themselves after enough miles at this speed.

    So what, are you saying each person must do hours of research before they get the right answer? Shall I link to my strong wheel build thread? Would you be the first to comment on it?

    The bicycle wheel. By jobst Brandt. How many books did you read on the subject of motorbikes? Or just bikes? This stuff goes deep, and you must educate yourself in many other forms than just the internet.

    The internet is basically garbage in, garbage out.
     
  12. Tony01

    Tony01 Active Member

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    And I say no way. If you don't know the answer for 100% don't post. We talkin bicycle components for use on small motorcycles. This ain't no game!
     
  13. Tony01

    Tony01 Active Member

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    As far as balancing a wheel, we start by considering the design parameters. Our 26" bicycle wheel goes .077 mph per rpm, so at 50mph it is doing 650rpm. At this rotational speed, balance may be an issue if the components are not the same weight all around even if the wheel is perfectly round. Due to relatively precise manufacturing tolerances, we'll assume that the parts of the wheel are the same weight all around. After truing, a wheel may still be slightly out of balance weight wise, and we can either fix this by adding weight in the right places, or just let it go as it will not be noticeable anyway. On cars this is a larger issue, as the wheels are sometimes smaller and must turn much higher rpms, so weight balance is a real issue.

    So the logical way to balance a wheel is to make sure each part is the same distance from the center. Start by loosening all spokes and then hand tightening them to the same amount. Give the wheel a spin watching for radial trueness. Adjust as necessary until the spokes are the correct tension (see my thread link; spokes can be tensioned roughly to a pitch that depends on their length). From there true horizontally and dish the wheel if needed. But not too much! Properly dished wheels use different length spokes for right/left, but for our purposes running single speed we don't really care.

    To make adjustments: radial: tighten groups of spokes both sides a quarter turn, then loosen spokes on the 180deg around side side the same amount. Very tedious ; usually better to start with a rim that is true.
    Horizontal: tighten spokes on one side the same amount that spokes on the other side are loosened.
    A rim that is out of true as stock should be replaced, but sometimes you can get away with truing it to shape. You can always reuse your old spokes. Easy way to do this is to zip tie crossing spokes, then remove nipples and replace the rim.

    When loosening spokes, turn it farther back than you want to loosen, then tighten back up to the new setting.


    The important next step is to stress relieve the spokes. This is done by squeezing together crossing spokes, going around the wheel. This step subjects pairs of spokes to a much higher tension than they would undergo in use, and they settle back to their tensioned state with miles to go before reaching their yield strength.

    Ride the wheel maybe 20-40 miles, then true and stress relieve again. DONE!

    I balance radially to within .010". Once I trued a rim with the zip-tie guide, then threw the dial indicator on there just for kicks. I was within about .005" side to side! The indicator has not seen another wheel.

    Link to my 48 spoke rear wheel riding on a 36h drum hub. Link to spoke tension pitches is in there.
    http://motorbicycling.com/showthread.php?t=59790
     
    #13 Tony01, Nov 11, 2015
    Last edited: Nov 11, 2015
  14. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Removing those giant reflectors that screw on to the spokes makes a HUGE difference in balance.
     
    #14 Bikeguy Joe, Nov 12, 2015
    Last edited: Nov 12, 2015
  15. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Despite all he math and ect ., you can have a wheel that is out of balance enough to feel it, especially at 20-30 mph.
     
  16. maniac57

    maniac57 Old, Fat, and still faster than you

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    I've been riding bikes my entire life, including several years racing professionally.
    Never ONCE balanced a wheel.
    Truing is all you need. Anyone claiming to be able to feel an imbalanced wheel under 50mph is delusional or has lead attached to the rim.
    It's a chinadoll on a bicycle. Why overthink it?
     
  17. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    You would have to be delusional NOT to be able to tell if you have an out of balance wheel @ 25 mph.
    Ever heard of reflectors?
    How about fat tires?
    Guess not.
     
    #17 Bikeguy Joe, Nov 13, 2015
    Last edited: Nov 13, 2015
  18. bairdco

    bairdco a guy who makes cool bikes

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    There's been a few discussions about balancing wheels. It has nothing to do with truing a wheel. An out of round wheel isn't out of balance, it's just not round.

    Tires and tubes will affect balance the most. Valve stems are usually the heavy spot.

    The only way to balance a wheel is to static balance it. Spin the wheel, the heavy spot ends up at the bottom, you put some kind of weight on the top. Simple in theory.

    But, pointless, in my opinion, and in my experience.

    I spent years busting tires. I used to balance tires for race cars, using the latest hi tech equipment, like shavers that skimmed off the high spots of rubber on a tire. Works great, unless the tire slips on the rim.

    Car tires attain a certain resonance at certain speeds. Usually at 33 and 66mph. (Check that on your car, if your front wheels are out, you feel it in the steering wheel, rears, the whole car.)

    Our bikes are too light to feel an unbalanced wheel, and at speeds, there's usually a whole lotta other things vibrating and shaking to notice. An out of round wheel, yeah, you'll feel it, but no amount of "balancing" will get rid of that.

    As to the rest of this thread, anything you need to know about bikes is available on reputable sites, like Sheldon Brown's or Park tools, so you can save time and look up your problems there.

    The OP has good intentions, but after I read "...pliers..." in how to true a wheel, I stopped reading.

    Most spoke nipples are chrome plated brass. You will never get your spokes tightened properly with pliers. And if you try to loosen tight spokes with them, you might as well throw your wheel away.

    Pliers, channel locks, and vice grips are tools for holding stuff, or to remove an already butchered nut or bolt.
     

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