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  1. #1
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    The weight of the bike and rotating mass does not matter.....

    within reason, if one is not going up hills or braking. There I said it. In a troll-y way.

    I'm going to be getting my Wallbeast in a couple of days. It's heavy, with heavy wheels. But here's the thing. I will be riding it on the beach at steady speeds. To my way of thinking the problem with the weight is if one is accelerating or going uphill. Since I will be doing neither the weight shouldn't matter. The only way it will matter for me is that with heavier weight the bike will push down on the sand a little more causing more rolling resistance since a little more sand will be pushed aside.

    However, I can see how higher rotating weight might actually help! Here's how it would work.....Every time we turn the cranks the power is not applied evenly. It is actually a series of pulsating power strokes, particularly if one is not using clipless pedals. So every time this pulse is applied, the rear tire on the sand will tend to "peel out" or slip a little resulting in it digging a little deeper and adding friction. By having a larger rotating mass the power strokes will be more evened-out. The mass will absorbed the power strokes and the higher inertia will cause a smoother, more even speed, thus causing less slippage at the rear tire and more efficient power distribution.


    Yes? No? I know I am crazy so don't bother reminding me.

  2. #2
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    Rolling resistance of the tires is far more important than bike weight [within some reasonable limits] at MTB speeds. Energy suck tires slow you down every pedal stroke - even on the flats.
    Safe riding,

    Vik
    www.vikapproved.com

  3. #3
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    I tend to agree with all of you're statements.
    You may need a lower gear to ride in loose sand on the Beast though.
    Weight will make some difference in rolling resistance on any surface. You can generally overcome this with more pressure on hard surfaces, and it all balances out.
    On soft surfaces though, more pressure will likely make you sink more, and you may want to run lower pressure with more weight.

    Oh, you could get some iron disc wheel covers, if you want to increase the flywheel effect you are talking about, just don't mount them on bearings like the spinner hub caps. it won't help at all then.

  4. #4
    Laramie, Wyoming
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    A turd by any other name is still a turd.

    Heavier is heavier.

  5. #5
    ouch....
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    Beech riding benefits from having gears...fyi.
    Riding.....

  6. #6
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    Read this. Rivendell Reader: Pugsley!

    Grant ruminates on wheel weight and climbing.

  7. #7
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    Quote Originally Posted by autodoctor911 View Post
    I tend to agree with all of you're statements.
    You may need a lower gear to ride in loose sand on the Beast though.
    Weight will make some difference in rolling resistance on any surface. You can generally overcome this with more pressure on hard surfaces, and it all balances out.
    On soft surfaces though, more pressure will likely make you sink more, and you may want to run lower pressure with more weight.

    Oh, you could get some iron disc wheel covers, if you want to increase the flywheel effect you are talking about, just don't mount them on bearings like the spinner hub caps. it won't help at all then.
    I plan on putting on a larger cog.

    and adding lead weights to the rim. I'm going to use motorcycle wheel balancing weights and maybe add twenty pounds or so for the ultimate flywheel effect. Once they're moving nothing will slow them down.

  8. #8
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    Quote Originally Posted by vaultbrad View Post
    Read this. Rivendell Reader: Pugsley!

    Grant ruminates on wheel weight and climbing.
    Hmmm interesting. One would think heavy wheels would have to slow one down on uphill climbs. Perhaps the larger tires and contact patch and steadier speed from the inertia leads to less slippage at the rear tire during the heavy pedal pumping of an steep uphill.

  9. #9
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    I was kidding about the iron discs. I hope you are kidding about the wheel weights. Those Beast tires, rims and tubes should give you more than enough flywheel effect,

  10. #10
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    Quote Originally Posted by autodoctor911 View Post
    I was kidding about the iron discs. I hope you are kidding about the wheel weights. Those Beast tires, rims and tubes should give you more than enough flywheel effect,

    Ummm yeah, I was kidding....of course......yeah kidding.

  11. #11
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    Quote Originally Posted by Shark View Post
    Beech riding benefits from having gears...fyi.
    Someone forgot to tell that to these bunch-o-morons and slackers. They don't appear to know anything about beach riding and fat biking.

    Bikerafting Alaska's Lost Coast: Yakutat to Glacier Bay. on Vimeo


    Or, given the spelling you chose, you might be meaning they need gears if you want to climb beech trees with their fatbike? If so, I'd concur.

  12. #12
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    candidate for triple merge here...

  13. #13
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    The power required to drive a heavy rider is going to be the same as a lightweight rider. Does not compute

  14. #14
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    In Baja my GF ride essentially the same Pugsleys [hers being a 16" vs my 18"]. In any loose sand she cruises more easily than I do due to the 60lbs differential in our weights. I'm stronger so I can keep up no problem, but she is clearly working less.

    Turning leg power into speed on a bicycle is a surprisingly complex topic.

    One variable I rarely see discussed on MTBR is frame stiffness. Bicycle Quarterly has done quite a few tests on various frames and come up with the surprising result that frame that flex in certain ways are faster for the same power input than uber stiff frames.

    I tested that hypothesis by ordering a custom randonneur bike in the skinniest thinnest walled tubing the builder and I figured I could ride. The bike is a noodle by todays carbon road bike standards. It also happens to be a rocketship making the most out of my puny leg's ability to turn the cranks - particularly on the climbs. This is no light bike as I run 42mm 650B tires, dynohub, front rack/bag and some supplies, leather saddle, etc...

    Boulder Bicycle Allroad - a set on Flickr

    Now that I am attuned to the beneficial flex from this bike I really don't enjoy riding overbuilt frames anymore as they feel dead and don't respond as well to my chicken legs.
    Safe riding,

    Vik
    www.vikapproved.com

  15. #15
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    All sand is not equal. Lots of beaches could be ridden on a single speed road bike, lots will be a struggle with a Bud and Lou or BFL and twenty gears. The beach I ride can change significantly depending on the temp, the last storm or strong wind that shifts the sand around, if you ride near the water or dunes, or how many people/cars/horses have been out. Unlike the middle of the woods, the wind can also make one direction a walk in the park and the other direction a suffer-fest even with a light bike and gears.

  16. #16
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    OP, do you have a fat bike yet or are you just theorizing before the delivery on your walgoose?

  17. #17
    ouch....
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    Quote Originally Posted by Scoobytao View Post
    Someone forgot to tell that to these bunch-o-morons and slackers. They don't appear to know anything about beach riding and fat biking.

    Bikerafting Alaska's Lost Coast: Yakutat to Glacier Bay. on Vimeo


    Or, given the spelling you chose, you might be meaning they need gears if you want to climb beech trees with their fatbike? If so, I'd concur.
    I'm sure the op was planning on taking his walmart fatty to Alaska...i ride beaches for fun, and from what I've found, gears help.

    You can blame the typo from my not so smart phone.
    Riding.....

  18. #18
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    Probably worth delving (back?) into THIS.

  19. #19
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    "Every time we turn the cranks the power is not applied evenly. It is actually a series of pulsating power strokes..."
    This is an important point missing in most arguments about wheel weight on a bike. We put out power a lot more like an old two cylinder john deere tractor than an electric motor that would apply constant power to the drive train. Like on a tractor with a big flywheel the big wheels on a fat bike act as a flywheel and are a benefit to me. Maybe if I weighed less and rode faster than an old two cylinder john deere I would have a different opinion.
    laotzucycles.blogspot.com

  20. #20
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    Quote Originally Posted by beachride View Post
    However, I can see how higher rotating weight might actually help! Here's how it would work.....Every time we turn the cranks the power is not applied evenly. It is actually a series of pulsating power strokes, particularly if one is not using clipless pedals. So every time this pulse is applied, the rear tire on the sand will tend to "peel out" or slip a little resulting in it digging a little deeper and adding friction. By having a larger rotating mass the power strokes will be more evened-out. The mass will absorbed the power strokes and the higher inertia will cause a smoother, more even speed, thus causing less slippage at the rear tire and more efficient power distribution.

    I disagree with the logic above.

    What you said here is true:

    the problem with the weight is if one is accelerating or going uphill.
    But what you describe as pulsating power strokes means in fact, a small acceleration and and then deceleration with each stroke. Therefore, a heavier bike takes more energy. On a smooth bike path along the beach, the pulsing effect is negligible, and it is easy to have a smooth pedal stroke that maintains constant velocity. But in the sand, the sand slows you down a bit after each stroke. Depending on how soft the sand is, which effects the amount of deceleration, it could be a significant disadvantage to have a heavier bike.

    Other problems with the paragraph above:

    -Pulsing force does not necessarily to tire slippage. In fact, it shouldn't.
    - Inertia of the entire system (mass of rider plus bike) is most important so heavy wheels don't really do much to help you keep your speed.

    After you get it, compare it with someone's nice lightweight weight beach bike, and let us know.

  21. #21
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    Quote Originally Posted by smilinsteve View Post
    - Inertia of the entire system (mass of rider plus bike) is most important so heavy wheels don't really do much to help you keep your speed.
    While I don't disagree completely, I will say the extra rotational weight going from my 26" MTB to my fatbike is very apparent to me in real world conditions. For example, the way I approach and my ability to climb the steepest of climbable accents is completely different between the two... distinct advantage to the heavier fatbike.
    Whatever floats your bike, dude

  22. #22
    Fat & Single
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    Nice, another thread that has an inviting topic just to read wally in the first couple of lines.
    Ti O'Beast
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  23. #23
    Ride da mOOn Moderator
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    Longer cranks!

  24. #24
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    Quote Originally Posted by Dustin Mustangs View Post
    While I don't disagree completely, I will say the extra rotational weight going from my 26" MTB to my fatbike is very apparent to me in real world conditions. For example, the way I approach and my ability to climb the steepest of climbable accents is completely different between the two... distinct advantage to the heavier fatbike.
    How would you suppose the heavy wheels help you with steep climbs? I would guess it has more to do with traction from the bigger footprint.

  25. #25
    Dr Gadget is IN
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    Quote Originally Posted by smilinsteve View Post
    How would you suppose the heavy wheels help you with steep climbs? I would guess it has more to do with traction from the bigger footprint.
    The traction from the bigger footprint is a part of it, as is the rolling diameter - similar to a 29er, less likely to be slowed down by roughness. But the flywheel effect does come into play. I recall rebuilding a very heavy bike for a friend many years ago. This thing was solid steel everywhere, frame/hubs/rims - thought it would be a horrible flog to ride it back over to it's home, but it was actually very smooth and required less effort to climb the short grades over railroad tracks and irrigation ditches. This bike had 26"/schwinn 571mm wheels and road tires, and I was comparing it to my HT 26"/559mm mtb with knobbies. I guess this may call in the "tire rolling resistance" as well.
    This isn't a "you're doing it wrong" topic.

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