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

1. ## 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. 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.

3. 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. A turd by any other name is still a turd.

Heavier is heavier.

5. Beech riding benefits from having gears...fyi.

Grant ruminates on wheel weight and climbing.

7. Originally Posted by autodoctor911
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.

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. 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. Originally Posted by autodoctor911
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. Originally Posted by Shark
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.

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. candidate for triple merge here...

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

14. 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.

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

17. Originally Posted by Scoobytao
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.

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.

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

19. "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.

20. Originally Posted by beachride
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. Originally Posted by smilinsteve
- 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.

22. Nice, another thread that has an inviting topic just to read wally in the first couple of lines.

23. Longer cranks!

24. Originally Posted by Dustin Mustangs
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. Originally Posted by smilinsteve
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.

26. Having had a Walgoose for a while now, I have a feeling you're going to be in for a rude awakening when you hop on this bike and try to ride it in sand deeper that 1/2".

That being said, I've geeked out on mine, dropped a TON of weight and have no problems in deep(ish) sand/gravel etc.

27. I don't know about the flywheel effect of heavier wheels/tires helping much in climbing steep hills that are more than a few bike lengths long, unless you are able to maintain a lot of speed. If you are slowing down to a crawl to make a longer steep grade, the overall weight will be hurting you more than the fairly low amount of energy those wheels have going at those speeds.

For fairly short, not so steep climbs, where you can maintain the speed you had on the flats, then I would say yes, the inertia of the spinning wheels means less effort to keep the same speed up the short grade.

28. Originally Posted by Volsung
OP, do you have a fat bike yet or are you just theorizing before the delivery on your walgoose?
Just theorizing. It should be here any minute now. I expect to require hernia surgery from lifting the box.

29. Originally Posted by Shark
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.
The wild shores of LI.

And yes I can see how gears can help. Especially with the wind thing.

30. This is the worst troll post ever

31. Originally Posted by AC/BC
This is the worst troll post ever
pretty much

32. I dunno. I think that this is an interesting topic. Regardless of the folks who immediately discount any posts pertaining to the walgoose. The idea is applicable to all bikes. Is heavier an immediate detriment to efficiency? Is lighter better all the time? I find myself agreeing with Mikesee in the link he posted. Mind you the weights we're talking about here are all fairly light in the grand scheme of things and when we say heavy we are still talking about pretty light stuff. I can feel a difference with my legs in the weight of the wheels on my light, 26" SS and my big geared Pug with RDs, heavy tubes, and Vee missions. That said I don't think the weight hurts me at all I love the planted feeling when crawling through really rocky, twisty, rooty, up and down techy stuff as well as when barreling downhill. Climbing, I'm rarely thinking "I wish my bike was lighter." I'd rather have the damping effect of the big heavy bike. I think this discussion is cool.

33. Originally Posted by AC/BC
This is the worst troll post ever
How so?

34. Originally Posted by Jim Hannoonen
Having had a Walgoose for a while now, I have a feeling you're going to be in for a rude awakening when you hop on this bike and try to ride it in sand deeper that 1/2".

That being said, I've geeked out on mine, dropped a TON of weight and have no problems in deep(ish) sand/gravel etc.
Do you have a larger cog/lower gearing?

35. Originally Posted by beachride
Do you have a larger cog/lower gearing?
Yes. I changed the rear cog from an 18t to a 20t.

36. Originally Posted by Jim Hannoonen
Yes. I changed the rear cog from an 18t to a 20t.
Great job on the bike! I hope to put at least a 22 on the back. I expect some trial and though error.

37. Originally Posted by Shark
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.
Yeah sorry, I was being a bit sarcastic. For the record, I think my phone is smarter than me - it kind of makes me worry that it is plotting against me late at night. And I prefer gears too - especially when riding up Sitka Spruce.

But even if you have 27 speeds, we only ride in one gear combination at a time. The only question: "Is it the right one." It actually sounds like the op here has limited needs (not a lot of varying terrain -presumably just flat beach, not dunes, since he said no uphills) and low expectations that are commensurate with the low cost. He appears knowledgeable and can easily swap out the rear cog to whatever works in his neck of the woods, (or rather beach).

The guys doing these remote expeditions chose the drivetrain they felt was most ideal, and the simplicity of a singlespeed in that particular trek on that 200+ miles of beach won out OVER other options.

So, if the op wants to buy a Walgoose and ride on the beach for as long as it lasts and has fun. I say "Ride On!"

And if he lives in Alaska (where there is more coastline that the rest of the US combined), he can compare the rate of rust decay with the those of us already beach riding their steel Pugsleys, Moonlanders, Evinsons, and Wildfires up here.

38. Originally Posted by autodoctor911
I don't know about the flywheel effect of heavier wheels/tires helping much in climbing steep hills that are more than a few bike lengths long...
IMO it definitely helps. Not from a momentum standpoint, but from a slow speed stability standpoint. Traction aside, I can climb a steeper grade on my FB than my MTB due its slow speed stability from spinning all that weight. Of course, this requires the proper gearing which pretty much makes it a moot point for the walgoose. Put that in your walmart pipe and smoke it silly goosers!

39. Originally Posted by Dustin Mustangs
Put that in your walmart pipe and smoke it silly goosers!

GOOSERS! I love it!

40. I guess I'm goint to have to do some cypherin' and show you guys that mathematically the inertia and stability from heavy wheels is insignificant, while the energy to accelerate them is very significant. (Sh1t I hope I can figure out how to do that).

41. Originally Posted by smilinsteve
I guess I'm goint to have to do some cypherin' and show you guys that mathematically the inertia and stability from heavy wheels is insignificant, while the energy to accelerate them is very significant. (Sh1t I hope I can figure out how to do that).

If the energy to accelerate them is significant then their inertia is significant.

42. Originally Posted by beachride
Do you have a larger cog/lower gearing?
Lower gearing = more torque on the too weak hub carrier axle. See the carnage documented at;
Mongoose Beast modifications

43. Originally Posted by GrayJay
Lower gearing = more torque on the too weak hub carrier axle. See the carnage documented at;
Mongoose Beast modifications

Good point.

Luckily, I'm old and weak.

44. Originally Posted by GrayJay
Lower gearing = more torque on the too weak hub carrier axle. See the carnage documented at;
Mongoose Beast modifications
Can you be more specific?
I want to see the carnage, but I am not going to read through that whole thread.

45. Originally Posted by smilinsteve
I guess I'm goint to have to do some cypherin' and show you guys that mathematically the inertia and stability from heavy wheels is insignificant, while the energy to accelerate them is very significant. (Sh1t I hope I can figure out how to do that).
If you're gonna bother, don't forget to factor *every* variable into that cypherin'.

46. I don't think that anyone would choose heavier wheels over lighter ones no matter what the application, all other things being equal(width, strength, tread/traction, rolling resistance,etc.).
I think some people are theorizing about the possible benefits of extra rotating weight to justify having gotten a heavy combination for other reasons, whether it be cost, flotation, protection or traction.

47. But on a level beach weight should not matter much except in terms of rolling resistance. As that article referenced said...dropping 15 pounds from a bike man combo of 200 is only a 7.5% drop in total weight......Now, does that translate into a drop in RR by 7.5 % ?

48. Originally Posted by mikesee
If you're gonna bother, don't forget to factor *every* variable into that cypherin'.
2

Oh yeah man, I'm going to start working on it.

49. If you want to use my bikes as an example, my mukluk rear wheel complete weighs 3900g and my mtb rear wheel complete weighs 1800. I believe the hubs and skewers are about 200g of that difference. I don't want to end your math fun before it begins, but off the top of my head I am pretty sure that means around twice the gyroscopic force in my FB wheel.

50. Oh boy, now we're talkin gyroscopic force, as well as rotational inertia.
I have read papers and text books on engineering mechanics, which when talking about single track vehicle dynamics(motorcycles and bicycles) they state that gyroscopic forces on a bicycle contribute to self stability by helping to steer the front wheel into a turn when leaned in that direction. They call this Precession, and it is inversely proportional to speed.
They go on to say that the rear wheel is prevented from precession because of friction with the ground, and thus the gyroscopic forces provide no resistance to tipping.

I know everyone thinks of how a top spinning is kept from tipping over due to the gyroscopic forces that tip it back toward center. It is actually trying to turn, or tip 90 degrees from wherever it starts to lean, and then this tilts it that direction, chasing that gyroscopic force all the way around the circle. the faster it is turning, the slower this happens. You notice as the top slows down you can see the circular motion as it happens faster and faster till it can't keep up and it leans more and more.

Since as a bicycle wheel tips over, it's gyroscopic force is at 90 degrees to the tipping direction, it just tries to turn the wheels, which in the front steers it toward the lean, and in the back just tries to twist it in the frame, and nothing happens.

One other way to prove it is to take a wheel mounted in a fork and spin it up really fast and try to balance it upside down with the top of the steerer tube in your hand. It doesn't stay upright any easier than a non spinning wheel, and when it starts to lean it will try to spin around in your hand.

I have read of where to prove this they constructed a bicycle with counter-rotating weights that would cancel out any gyroscopic effect, and demonstrated that it was easily kept upright while riding. The forces that keep a bike upright are generated by moving the front tires contact patch from one side to the other to counteract the leaning forces with the force of the ground against the inertia of the forward movement of the bike and rider.

Any stability gained with fat tire bikes when climbing at slow speeds is from the wider tire itself, not the rotating weight.

51. Hmmmm, that is news to me! Some good reading on it here. Apparently I can't explain it, but I am certainly able to ride my FB much slower than I can ride my MTB, steep hill or not. I have wandered a little off topic so maybe this is fuel for another thread on another day.

52. Originally Posted by Dustin Mustangs
IMO it definitely helps. Not from a momentum standpoint, but from a slow speed stability standpoint. Traction aside, I can climb a steeper grade on my FB than my MTB due its slow speed stability from spinning all that weight. Of course, this requires the proper gearing which pretty much makes it a moot point for the walgoose. Put that in your walmart pipe and smoke it silly goosers!

I think u should smoke less and think more. Do u think slow speed stability has anything to do with that fat ass platform of a tire between u and the ground? Easy test would be to track stand your fat bike and any other mtnbike and see which is easier. 11 times out of 10 its the fatty.

53. Originally Posted by autodoctor911
Oh boy, now we're talkin gyroscopic force, as well as rotational inertia.
I have read papers and text books on engineering mechanics, which when talking about single track vehicle dynamics(motorcycles and bicycles) they state that gyroscopic forces on a bicycle contribute to self stability by helping to steer the front wheel into a turn when leaned in that direction. They call this Precession, and it is inversely proportional to speed.
They go on to say that the rear wheel is prevented from precession because of friction with the ground, and thus the gyroscopic forces provide no resistance to tipping.

I know everyone thinks of how a top spinning is kept from tipping over due to the gyroscopic forces that tip it back toward center. It is actually trying to turn, or tip 90 degrees from wherever it starts to lean, and then this tilts it that direction, chasing that gyroscopic force all the way around the circle. the faster it is turning, the slower this happens. You notice as the top slows down you can see the circular motion as it happens faster and faster till it can't keep up and it leans more and more.

Since as a bicycle wheel tips over, it's gyroscopic force is at 90 degrees to the tipping direction, it just tries to turn the wheels, which in the front steers it toward the lean, and in the back just tries to twist it in the frame, and nothing happens.

One other way to prove it is to take a wheel mounted in a fork and spin it up really fast and try to balance it upside down with the top of the steerer tube in your hand. It doesn't stay upright any easier than a non spinning wheel, and when it starts to lean it will try to spin around in your hand.

I have read of where to prove this they constructed a bicycle with counter-rotating weights that would cancel out any gyroscopic effect, and demonstrated that it was easily kept upright while riding. The forces that keep a bike upright are generated by moving the front tires contact patch from one side to the other to counteract the leaning forces with the force of the ground against the inertia of the forward movement of the bike and rider.

Any stability gained with fat tire bikes when climbing at slow speeds is from the wider tire itself, not the rotating weight.
Bravo!

54. With the lightest wheelset, the acceleration from my legs, and recovery of those legs late in a ride feels like being an elite roadracer compared to the "leaden/groggy" feel while riding my bike heavy and with a heavy wheelset/tire combo.

This is empirically, seat of the pants-derived data. No math involved except that I know my light rims weigh half what the other ones do.

also, HANDLING of the bicycle is important to holding or correcting a line on a climb and keeping a snow/sand bike on line in squirrely/soft and/or narrow trail conditions. Wouldn't you agree? The front end needs to steer quickly and with light force?!

QUICK handling comes from light wheels. Slow handling comes from heavy wheels.

I've tried to state this in a simple way.

55. Originally Posted by autodoctor911
Can you be more specific?
I want to see the carnage, but I am not going to read through that whole thread.
Scroll down page 7 and you'll see my busted driver.

Mongoose Beast modifications

56. Originally Posted by jonshonda
I think u should smoke less and think more. Do u think slow speed stability has anything to do with that fat ass platform of a tire between u and the ground? Easy test would be to track stand your fat bike and any other mtnbike and see which is easier. 11 times out of 10 its the fatty.
So you think a pneumatic tire with a round casing can transmit a moment to the rim? I would like to see a free body diagram or technical document outlining how that works! And for S&G's, I was just out in my garage track standing my bikes (1.75" rubber vs 4.7" rubber) and there was no discernible difference. This was quickly followed by some inflatable ball sitting, no difference in stability relating to size there either.

BTW, it would be fantastic if we could have big boy conversation either without personal attacks or at least with some smilies thrown in to help relay sarcasm. Okgreatthx.

57. An article:

How do we manage to stay up on a bike? Gyroscopic forces are not important for the stability of a bicycle - as you can see if you read on below...

Hugh Hunt - Cambridge University - Are Gyroscopic Effects Significant When Riding A Bicycle ?

58. Originally Posted by autodoctor911
I don't know about the flywheel effect of heavier wheels/tires helping much in climbing steep hills that are more than a few bike lengths long, unless you are able to maintain a lot of speed. If you are slowing down to a crawl to make a longer steep grade, the overall weight will be hurting you more than the fairly low amount of energy those wheels have going at those speeds.

For fairly short, not so steep climbs, where you can maintain the speed you had on the flats, then I would say yes, the inertia of the spinning wheels means less effort to keep the same speed up the short grade.
+1. I noticed a difference changing from a Nate27tpi 1800g rear to On-One's Floater 1400g. The Nate carries a lotta speed-You can feel it, but You gotta pedal harder to create that speed, unless it's coming from a previous downhill. I've only had it on one ride, but the Floater was invisible to me-I forgot it was even there.I'm currently checking the Strava & other sites for the best elevation profiles for me & my BEAST! Anything but steep uphill is a BLAST! ROWRF!

59. Originally Posted by beachride
But on a level beach weight should not matter much except in terms of rolling resistance. As that article referenced said...dropping 15 pounds from a bike man combo of 200 is only a 7.5% drop in total weight......Now, does that translate into a drop in RR by 7.5 % ?
So quoting myself to continue the analysis. From what I've seen it looks like rolling resistance should be about 1/2 of the power output required to peddle the bike at slower speeds. So if rolling resistance is half of the equation, a drop of rr of 7.5% means a drop in power output required of 3.75%

To sum up. On a level beach with firm sand and no wind, the power output required for the beast vs a 15 pound lighter bike to maintain the same speed should be about 4% more.

60. Originally Posted by beachride
So quoting myself to continue the analysis. From what I've seen it looks like rolling resistance should be about 1/2 of the power output required to peddle the bike at slower speeds. So if rolling resistance is half of the equation, a drop of rr of 7.5% means a drop in power output required of 3.75%

To sum up. On a level beach with firm sand and no wind, the power output required for the beast vs a 15 pound lighter bike to maintain the same speed should be about 4% more.
I think well over half, depending on sand conditions, up to 99% could be rolling resistance, but I don't see any reason to believe rolling resistance is directly proportional to weight. It does increase with weight, but not at a linear rate, and the rate depends on the type of surfaces.

That would be true for calculating friction forces on something sliding across a firm(elastic) surface, or to calculate how much force to start sliding an object on a firm surface since the Force of friction equals the Coefficient of friction times the Normal force(weight) and the coefficient of friction for this type of friction will generally stay the same for a large range of load(weight) and speed[except for the large difference between 0(static) and anything above that(sliding)]. The coefficient of friction for rolling resistance varies too much with speed, and load, so you can't calculate changes in the rolling resistance as easily by changing only one variable.

61. Originally Posted by autodoctor911
I think well over half, depending on sand conditions, up to 99% could be rolling resistance, but I don't see any reason to believe rolling resistance is directly proportional to weight. It does increase with weight, but not at a linear rate, and the rate depends on the type of surfaces.

That would be true for calculating friction forces on something sliding across a firm(elastic) surface, or to calculate how much force to start sliding an object on a firm surface since the Force of friction equals the Coefficient of friction times the Normal force(weight) and the coefficient of friction for this type of friction will generally stay the same for a large range of load(weight) and speed[except for the large difference between 0(static) and anything above that(sliding)]. The coefficient of friction for rolling resistance varies too much with speed, and load, so you can't calculate changes in the rolling resistance as easily by changing only one variable.
OK, but even assuming rr is all of the resistance, dropping 15 pounds of bike from a combined bike/rider weight of two hundred means a 7.5% increase in speed. Assuming a linear relationship between rr and weight.

And that will cost 452% more than the cost of the bike.

See, I'm trying to convince myself that I don't need an expensive lightwieght bike.

62. beachride, don't let anyone tell you that you are NOT having fun!

But believe them when they say that they are having fun.....

63. Right. Don't worry about how much slower you might be, just get out and ride and enjoy whatever you can afford for now. I wouldn't spend a whole lot of time or money modifying it though. If you upgrade anything with expensive stuff, make sure it is something you can take off to use on a nicer fatbike if you get one.

64. ## Re: The weight of the bike and rotating mass does not matter.....

Originally Posted by autodoctor911
Right. Don't worry about how much slower you might be, just get out and ride and enjoy whatever you can afford for now. I wouldn't spend a whole lot of time or money modifying it though. If you upgrade anything with expensive stuff, make sure it is something you can take off to use on a nicer fatbike if you get one.
I sort of agree with this and I sort of don't. You have to ask yourself if you really want to get into fat biking or if you just want something to putz around on. If you do really want to get into it, then why not wait and save a little longer, and KEEP that \$200 towards a quality fat bike that you will really love? Just my 2.

65. Originally Posted by Dustin Mustangs
Hmmmm, that is news to me! Some good reading on it here. Apparently I can't explain it, but I am certainly able to ride my FB much slower than I can ride my MTB, steep hill or not. I have wandered a little off topic so maybe this is fuel for another thread on another day.

Is it perhaps because the bottom bracket is further below the axles?

I noticed the same thing on my beast riding in tight circles on my patio. It felt more stable than my MB. I was surprised.

66. Originally Posted by E6roller
beachride, don't let anyone tell you that you are NOT having fun!

But believe them when they say that they are having fun.....

Yeah. Thanks. It's all good. I don't care if I go 7.5% slower or whatever.

I'll have even more fun when my legs get back into riding shape. I also might try a 27 cog for the beach riding.

Seeing as how I will be riding near and in saltwater, I sealed everywhere I could with Goop. Goop is amazing, very adhesive, flexible sealant, thick contact cement type stuff. I sealed where the spoke nipples go into the rim and everywhere else water could seep into something like at the headset, bottom bracket etc.
To make a seal at a moving part..clean off all oils but coat one side of the moving part with grease. Apply Goop. Let dry overnight. The Goop with not adhere where the grease is but will on the other part creating a good seal for rotating parts.

67. Originally Posted by beachride
To make a seal at a moving part..clean off all oils but coat one side of the moving part with grease. Apply Goop. Let dry overnight. The Goop with not adhere where the grease is but will on the other part creating a good seal for rotating parts.
That's so crazy it just might work... I think Goop is the same as Shoe Goo, right?

68. Originally Posted by Bill in Houston
That's so crazy it just might work... I think Goop is the same as Shoe Goo, right?
Yes. I'm pretty sure. The stuff should be in every backyard mechanics and homeowners tool box. Many of the things I put on my boat like the stereo are attached with it. No drilling holes in bulkheads. Goop a piece of wood on and you're good to go.

69. mmm hmm, if you can't glue it with Shoe Goo, it probably can't be glued with anything.

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