Sand And Weighting ?s

Discussion in 'Motorized Bicycle General Discussion' started by Kayper, Aug 26, 2010.

  1. Kayper

    Kayper New Member

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    Hey, not new to two strokes know 'em inside and out. However I have not installed a kit on a bicycle, I am however getting prepared. I have a Giant Iguana (older 90s?) regular sozed tubes 26" should fit fine, added front shock forks. My question is I know people fill their handlebars with sand or what have you, has anyone tried the same with your frames? I know it would make your bike heavier by a decent few lbs but would this help vibrations as I understand solid mounting is best not rubber. I realise you can't completely fill the frame but from the seatpost atleast as its a mounting point. One more question anyone tried wrapping a Dynamat (soundproofing for cars many forms just a brand name) product around their frame for vibraion it's not neccessarily that heavy or bad looking if done properly.
     
  2. skyl4rk

    skyl4rk New Member

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    I don't think vibration is all that bad. Lighter weight is better with these relatively low powered motors.

    You could try some inner tube rubber on the mounts but honestly I don't think you need it.

    A comfortable seat is more important than anything else, one you can sit on for a few hours.

    A front fork with shocks is a very good move.
     
  3. Goat Herder

    Goat Herder Gutter Rider

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    Welcome to the forum Kayper!(^) Got any picts of the bike? I am kinda thinking towards what Sky14rk is saying.
     
  4. Kayper

    Kayper New Member

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    Hey thanks goat your setups are sick. Ya i've been lurking the forums for a while just haven't signed up. I don't think an extra 5lb of sand in the seat post tube will hurt, the frame is all aluminum. I would like to run no tentioner if possible but if it wont clear the frame I'll fab one up since it seems to be a huge safety hazard. The bike looks pretty horrible at the moment no paint and all the good stuff, different coloured shocks haha. I don't think I'll even put anything between the motor mounts and frame, not worried about paint, just a cheap project. Something to rip around on until I get my car back, but man I love tinkering on these little two strokes. Plan to add the grubee pipe out of the shop the one it has no header pipe basically. I can buy a kit locally 150$ and the pipe for 50$. Got a fire extinguisher for gas can should hold plenty fo long rides. It's a small one ill drill out add a bung for a fuel line Haven't decided where to mount it will wait for my kit. In the mean time i'm putting a pocketbike engine on another frankenbike the engine is all modded flipped the jug over so the exhaust goes in the right direction and turned the piston around. I plan to keep the kit simple just a pipe, port and polish just match exhaust and intake ports maby bigger motor mount bolts. I hope the stock mounts are sufficient, I'll let everyone know the difference between the sand in the frame vs none since I have never heard of doing this. Just figured if it works on the handle bars might help a little on the scource of the vibrations, can always dump it out if it's just added weight, i'll keep you informed, any others tried anything along these lines? I definately will be adding a nice fat saddle with seat post shock. Thanks guys! brnot
     
  5. Goat Herder

    Goat Herder Gutter Rider

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    Thanks. Looking forward to your projects! Lets us know how the sand does? Its not like you are adding much weight with sand. I think density is the best aprouch like black sand. [Think ankle weights] Although its much heavier. Lead shot like for shot guns will have more density too.

    These bike creations should come with a warning! Extremely addictive! I got Ideas crawling though my head all the time.They are fun.lol
     
  6. xen

    xen New Member

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    Just a word of caution on the sand in the seatpost - most tubes in a bicycle frame are not sealed off from one another. Bike manufacturers purposefully drill holes in the head tube, seat tube, and bottom bracket shell where they meet the other tubes (I have no idea why, but they do). If you dump sand into the seatpost, it could potentially fill up the bottom bracket area that houses the bearings for the cranks. If you have a cartridge bottom bracket then you wont have much of a problem, but if you have an older style bottom bracket, which is very likely on a bike from the 90's, then you will be dumping sand directly into your bearings. You may want to check it out before you fill it up.
     
  7. Goat Herder

    Goat Herder Gutter Rider

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    There is a high end latex silicone that may seal that up. Can't tell of a brand. Did an A/C job on a minivan years back. We had to rebuild the hoses to the rear evaporator. There at the floor board was the most brutal glob of white colored what looked like a latex caulk. We had an air chisel after it. What ever it was it looked quit invincible! Getting those hoses out was an act of denial for a few. [The cursing]
     
  8. Chalo

    Chalo New Member

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    I was thinking the same thing, but with another potential complication. If abrasive sand plus vibration causes the sand to work its way into the bottom bracket threads, it could make the BB darned near impossible to remove. Sand and machinery are just a bad combination all the way around. It works with handlebars because their openings communicate only to the outside world, and not to the bike's internal workings.

    If the OP wants to ballast the frame or any other part to damp vibration, it would be a good idea to add ballast in the form of relatively large lead shot-- I'm thinking #4 buckshot-- to make the ballast easy to remove later and unlikely to leave lingering abrasive debris. Stay away from hard abrasive sand and materials that could absorb and retain water (because this is a recipe for truly horrible corrosion).

    Vibration damping is one of those places where a little might be a good thing, but that does not mean a lot of it will be better. A normal bike frame is a pretty stiff truss, as opposed to normal handlebars which are cantilevers. The poorly supported cantilever is much more susceptible to resonant vibration than the truss.

    Chalo
     
  9. Kayper

    Kayper New Member

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    Thanks for he concern boys, I believe the crank and so on are not open inside the frame having taken them off already. Busckshot in that amount could be quite costly i'm not limited to sand but i'd like to remove it down the road if it does me no good. A good hard pack should help, any materials youd sudggest besids buckshot but similar for cheap would be great i's most likely compact it with the vibration and intentionally to give the frame more rigidityjust at the bottom end where the motor mount(rear) is places it is not connected to the down tube until much higher up. If anything even a couple bottles of caulking could help and be lighter while dampening the vibrations. I have no guage of vibrations as of yet but I have a genral idea and id like something atleast in the seatpost for dampening. Sand just seemed good because of the removal factor I'm open to suddgestions, if anything it will also lower the center of gravity making it more stable, deffinately not planning to fill the frame just the seat post down tube. As the rear mount seems the most problematic. If the sand works I could always seal it with silicone or w.e. material I come up with cement? basically sand but wont leak into bearings, even if their not exposed also wont shift around while im riding. Starting the bike up would also rid the air bubbles hehe. Let me know if anyone has ideas thanks!
     
  10. camlifter

    camlifter Active Member

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    i've had good luck spraying the expanding foam insulation from lowes into the bars and frames, absorbs most of the vibration, works well on aluminium frams too, they seem to make more noise than steel frames and the foam helps, weighs next to nothing too.
     
  11. Chalo

    Chalo New Member

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    Seatposts get stuck too; I have to extract one by extreme means every so often at work. You don't want sand in that interface if you can help it.

    Zinc or copper plated BBs are cheap in quantity and would have many of the advantages of buckshot. I notice that most of the dead blow mallets I've seen recently have switched to steel shot from lead.

    Chalo
     
  12. KCvale

    KCvale Active Member

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    Just a tip Kayper, throw some line breaks in your posts.
    You can hit enter all you want while typing for them, it does not save the post doing that, and it sure makes it easier to read.

    That said your concern is potential vibration...

    In my experience it is only 4 things that make the most difference in what you feel.
    The first of course is a solid mount and good drive train.
    If your motor can vibrate with a poor mount or buck because of a misaligned chain or poor sprocket, you will feel it. Pay attention to this if you do ;-}

    Second is road vibration which you with licked with front shocks.

    Third is as mentioned a really good saddle with a seat post shock.

    Last but far from least is the hand grips.
    The stock hand grips are hard plastic junk that will make your hands ache no matter how good everything else is after an hour.

    I just cut the one off the throttle and throw it away along with the matching one they include for the clutch side.

    The throttle barrel that fits over the handlebars is obviously wider so few regular grips will fit over it, but those $8 foam BMX Racing grips will with a little dish soap, hot water, and some coaxing.
    Check for the Handgrip topic here for more, but their nice foam padding will impact what you feel as much as most anything.

    On the sand...

    Unless your frame is like beer can gauge aluminum you shouldn't need to worry about it.
    With your nice long seat with a shocks pipe will reinforce it pretty well on the business side, though I do like camshifter's expanding foam idea for the seat post if you are worried.

    Even with front shocks I can't see anything in the handlebars doing anything but off-setting the center of gravity higher.
    Comfortable grips will do more than anything else for your hands.
     
  13. Chalo

    Chalo New Member

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    Long distance motorcyclists often use bar end weights or shot inside the handlebar to change or damp the bar's resonant frequency, when that coincides with a common engine RPM. In the case of plain bar end weights, there isn't even any damping applied-- just changing the "note" the bar will ring into one that corresponds to an unused or less-used engine rpm range.

    As you say, grips are more important overall. But when you have the unfortunate circumstance of 65mph in top gear on the highway being a frequency that gets your motorcycle's bars really buzzing, grips alone won't make it stop. That's the sort of situation where ballasting your bars can help a lot.

    I think doing the same thing with the frame, which is orders of magnitude stiffer and therefore has a much, much higher resonant frequency-- is misguided at best.

    Chalo
     
  14. KCvale

    KCvale Active Member

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    Ahhh, OK, I think get it now. So a vibration at a give rpm may not be the motor or drive train at all, but just the handlebars (or frame) resonating?
     
  15. Chalo

    Chalo New Member

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    Right. Or more specifically, it's the handlebars' natural tendency to buzz at a certain frequency being stoked when the motor vibrates at that same frequency. (I don't have any reason to believe one way or the other whether that's the nature of the OP's complaint.)

    Handlebars are basically prongs that can twang if you pluck them hard enough. Compliant parts like grips and tires will quickly damp out that vibration as long as a motor isn't feeding it back in at the same time.

    Chalo
     
  16. Goat Herder

    Goat Herder Gutter Rider

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  17. Chalo

    Chalo New Member

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    [​IMG]

    If it convinces a compliant young lady to perch on the handlebars or the rear rack, then that would do a great job of damping vibration!

    Chalo
     
  18. 2door

    2door Moderator
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    I'm surprised, or maybe I missed it, but no one has mentioned tires to the OP. Knobby mountain bike tires might look cool but they'll give you a rougher ride than smooth tread road tires. Look for the smoothest tread design you can find for the smoothest ride.
    Tom
     
  19. Kayper

    Kayper New Member

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    Thanks I got that taken care of. As for the expanding foam that could dampen any resonant freaquencies but might now be dence enough. I realised some tubes are open to tohe tubes but as long as my filler material is on the bottom of the bike any extra weight will just lower its center of gra ity.

    I am liking the idea of silicone only a few tubes just for the dampening factor. I ride my seat post all the way down so i chopped off most of the post it shouldn't Have a problem sticking, i'd never raise it anyways, thankks for the advice bruhs.
     
  20. Goat Herder

    Goat Herder Gutter Rider

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    Hard to tell about tire vibration when you run 26x2.7 or larger tires. Those26x1.75 are a absolute joke to me regardless of tread.
     

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