Reason i ask is when i load my bike properly with groceries it dont feel any diffrent and ill have around 30 pounds of stuff

Hi,

Total weight (you + your bike + your groceries) matters for acceleration, braking, and climbing hills. Adding 30 lbs is a much bigger (correction: smaller) deal if you + your bike are already 300 lbs compared to 150 lbs.

If you don't have hills and don't race, then, no, as long as your bike isn't so heavily loaded that it's dangerous, it doesn't matter too much either.

Cheers, Charles

Good info i do live at the bottom of a huge hill its brutal

actually, isn't the total opposite true?

300# bike/person + 30# groceries = 10% extra

150# bike/person + 30# groceries = 20% extra

i am also into kayaing and i always wonder if weights mater in the water i mean wouldnt the water be suprting the kayak?

Sure, but the more weight you put in the kayak the lower it'll sit in the water and the more surface area of kayak will be touching water (wetted surface area). That'll increase the drag force you need to overcome with your paddling. Extra weight will also make it harder to turn and maneuver the kayak so it'll act more sluggish.

But a little extra weight won't be as noticeable when kayaking as when bicycling since you won't be climbing any mountains while paddling.

+1 ^ This, plus extra mass also becomes a negative factor when facing headwinds...

I don't understand... can you explain further?

Yes, weight matters.

https://en.wikipedia.org/wiki/Archimedes'_principle

Just ride. Don't worry about it.

If all other things are equal, mass has little effect on flat ground speed and only comes into play when you are climbing as you have to do more work to lift more weight.

For climbing and acceleration, I think it's pretty clear that the 150lbs person will have a tougher time adding 30lbs of weight because of the proportional increase in power output required.

Braking is actually an interesting question. I can see two plausible approaches: (1) what acidfast7 wrote, and (2) that getting the total bike weight to 330lbs will exceed the machine's braking power, particularly if going downhill. Seems like both are potentially valid points, depending on the limitations of the equipment.

+1.

Yes.

Weigh to go. You just made him a pound heavier.

To expound upon my point, I have commuted with a 40lb steel MTB, a race-level MTB in the low 20s, and my current CX bikes which are somewhere in between. The only reasons I am faster now than I was in 2006 are route optimization and fitness level. Bike weight has little-to-nothing to do with it.

I've heard that before, but pulling a loaded pedicab on flat ground takes a lot more effort than pulling an empty one. Maybe it's just the friction from tires deforming, but you really notice the difference between a 200lb and 1000lb load

also, the ground is never perfectly flat...

But an odd thing in boats, longer boat has less hydrodynamic drag than a short one.



Anyhow a light framed Bike with a heavy load will feel Noodly with that Load.

that is why Touring Bike Frames are not of the Lightest weight materials.

I think we're all feeling a little heavier today.

It's more difficult to accelerate a heavier mass than a lighter mass.

Inertia always resists any change in motion and is mass-dependent. If the headwind is opposing your motion and slowing you down, it becomes necessary for you to oppose the force of the wind. This requires you to "speed up" or accelerate, as you attempt to make forward progress against the wind. This would require a greater expenditure of energy, for a larger mass.

Besides...

It takes more energy and greater force, to move more massive objects through distances anyway.

Back to the OP, when I load my bike down it definitely feels different, but not in the area of speed and acceleration - it handles differently. It loses it's "crispness" I guess you'd call it, but it seems more stable. (I'm not saying it is more stable, I'm saying it feels more stable). Also it's a little more comfortable loaded. I don't know why, but I suspect the extra weight is compressing the tyres a bit for a softer ride (just a theory). But average road speed (about 14 to 15 mph) is not different, and acceleration from a stop doesn't seem any different. After all, slow is slow! lol

I feel much faster on my 17 pound single speed vs my unloaded MTB commuter. Acceleration is much slower on the heavier bike. If the MTB is loaded with both panniers it becomes even slower.

For commuting, the most practical difference of bike weight is how much easier it is to carry the bike by hand.

When you start talking about rider weight, you gotta admit that heavier riders are carrying the equivalent of several complete bikes as body fat. Any rider will be slower and work harder carrying useless mass like that; after all, your typical 300-lb person is not armed with twice the muscle mass of a 150-lb person.

Um... Yeah... What he said...



(I corrected the original post)

It does take significantly more energy to get a 200lb load and 1000 lb load moving rest to moving at say 8 mph. This isn't just rolling resistance.

To keep it moving at 8 mph, the difference between the two loads is basically rolling resistance.

Oh, and yes, small inclines can make a big difference with loads of that type.