t-cycle

Can anyone please explain what it is about bike mechanics that has us seek lighter bicycles regardless of how much we may weigh? If we weigh over, say 200lbs, we still pursue the lightest bicycle we can afford. Losing thirty pounds would exceed the weight of most bikes, and still not really overly affect the bike. Is there some psysics’ principle that has to do with the weight of our bike and motion or work or something else regardless of how much weight we place on the bike???

Thanks.

Ricardo

No, there is not a valid reason for that. I've always said that weight is the most overrated aspect of cycling. As a matter of fact, it is SO overrated that many component manufacturers sacrifice durability for weight.

My .02

Ricardo

Psimet2001 

I think most on this forum will pretty much agree (they will never all agree) that as long as there is *EDIT:excess* weight that can be removed from the human frame then there isn't much of a point in trying to reduce weight on the bike.

AlanS

Psysics**********????

ed073

lol....

Paniolo

I always felt that way too. It was all about the engine and not the bike. But I just came across a "can't pass up deal" on a 61cm CF Fuji that weighs in under 19#. My old steel bike was in the mid 20's. I've instantly picked up 10% in my average speeds over the same routes. FWIW

BoSoxYacht

The only excess weight I carry is hair .



I'd rather shave weight off my bike.

Pizza Man

At a recent hill climb race I was racing on my 17.5 pound Felt F2C. One of my competitors had a Cervelo R3, with all of the most expensive and lightest components available and he claimed it weighed 12 pounds 10 ounces. (I picked it up and I believe him)

I did end up beating the guy on the R3, but I lost the race by 19 seconds to 2 other riders (who I guessed were on 15 pound rigs)

Putting the bike weight numbers into a calculator, it says that I would have saved about 25 seconds climbing with the 12 pound 10 ounce bike, which may have been the difference in me being able to stay with the 2 leaders and not have to ride solo for the last 3 miles.

In this particular race every 80 grams of weight shaved saves about a second.

So my point is that saving 20 or 30 grams here or there will not make any difference, but if you go to the extreme in making your bike as light as possible (and you're not carrying around any extra body weight), it can make a significant difference in a hill climb race.

urbanknight

Are you putting the numbers into a calculator as the weight of the bike, or the bike plus rider? That would make a huge difference in your outcome.

stea1thviper

honestly now is it that hard to double check spelling of a word at dictionary.com?

lol anyway, i think for 99% of us anything 19 pounds and under is enough to not blame the bike for losing a race. yeah sure maybe you calculated you saved seconds here or there, but you also have to remember racing also has a huge mental aspect (fighting for and knowing when to fight for position, knowing when to save energy, etc). of course you're going to get those ppl who will justify the 3k they spent saying it actually helps them, but I wouldn't worry about it. hey if i spent that much money on a bike id make some justification arguement as well =)

Psimet2001 

Again showing that it is more worthwhile to elimnate your own excess body weight first.

fmw

Weight weenieism is a hobby. I don't think it has much to do with cycling but people enjoy it. I had a fling at it for a short time. Glad it was a short fling.

MrCjolsen

Basically, ten pounds on your bike or on your butt equates to about 1/10 of one mph on the flats. More importantly, your legs do not know if the extra weight is on your bike or on your butt. That's about 30 seconds in a 40 k time trial.

I commute 13 miles each way, every day. Some days I've been loaded to the point that bike+gear equals over 50 pounds. I've noticed a slight difference in the amount of energy I need to maintain my usual speed. And much of that could very well be due aerodynamics rather than weight.

On a climb it's a little different, but not much. Mainly, a lighter bicycle is more nimble when you get out of the seat and saves some energy that you can transfer to power. I believe 10 pounds going up an average hill equates to about 1/2 of one mph.

That's significant if you are racing and really concerned about where you finish.

It's a question of priorities. If finishing 10 seconds faster means the difference between being first and second in a race, then spending $$$$$ on a lighter bike might be worth it as long as I've done every single other thing to make myself faster. But if it means (like my case) the difference between fininshing 93rd or 94th (out of 125) then I'll just ride whatever I have.

BTW, my Surly Crosscheck weighed 23 pounds when I got it used. Now it weights 26 pounds after I "fixed" it.

derath

Based on a majority of the posts I would say it must be that hard.

-D

waterrockets 

Weight on the flats only affects acceleration. It won't change your cruising speed at all.

I agree that lightweight can help in a climbing race, assuming the rider is trim. If you have a rider who is a climbing talent, then it makes a lot of sense to make that extra effort to optimize the rig. Somebody like Robbie McEwen really has no reason to right a featherweight -- he might break something going for points midway through the stage.

For the vast majority of riding --- even racing, bike weight doesn't matter (within reason).

spiderbike

two watterbottles can weigh 3-4#s...just lose the water or other equiptment

gcl8a

Or use the shift key?

boyze

The primary physics is something most folks learn in high school: F=ma and Work=Fv. Add a few other things like rolling resistance, aerodynamic drag and biomechanics and the story becomes more complete. Once you get further into this you will soon find that weight is not weight It depends where it is and how it is used. Do a search. These topics have been discussed and debated extensively

asgelle

Not true. There is a weight component to the rolling resistance term which means that speed decreases with increasing weight even at ateady state on the flats. It may not be large and it may or may not be significant, but it's there and it's not zero.

substructure

What about in terms of power transfer? Or is this even comparable?

For instance, I have a good friend who just purchased some German Lightweights with tubulars. This made his bike super light but he mainly commented about the noticeable power transfer from crank to wheels.

Is this because of the wheels themselves, the weight factor of the bike, or both?
And if you could choose, what choice would you make? Weight or P.T.?

waterrockets 

You should adjust your tire inflation according to your weight. You want the same size contact patch on both tires, and that patch should be the size and shape designed for the tire.

merlinextraligh

I don't understand why people say bike weight only matters if your light. Obviously the heavier the rider , the less significant bike weight is as a percentage of the total weight being lifted. But I can tell you as a guy who's often on the edge of hanging onto the pack on hills, I need all the help I can get, and it may be more siginficant at the back. For me it may be the difference between maintaining contact and regrouping, and being there at the end of the race, or being dropped and limping home.

Obviously you can get carried away with weight weenism, but toward the extremes it does matter. For me doing my saturday morning group ride the difference between riding my 21lb+ Paramount, and my just under 17lb Merlin is the difference between competing to be up front on the biggest climb , and struggling to hang on the back.

SilentShifter

the lighter the bike, the less energy you use to move that bike - IT DOESN'T MATTER if you are going uphill or on a flat.

This is the same concept as two cars with equal horsepower and aerodynamics.......the lighter car will be faster.

Period!

Pizza Man

Here's the calculator I used: https://w3.iac.net/~curta/bp/velocity/velocity.html

It considers both rider weight and bike weight.

While I may never have a sub 13 pound bike, building a 15 pound bike shouldn't be too hard.

I'm pretty skinny, but could probably still lose a couple pounds if I really tried.

asgelle

You should also eat your spinach, Oh wait, not any more. In any case, the issue isn't inflation pressure, it's the monotonic increase in rolling resistance with weight which always slows a rider down as weight increases - all else being equal. If all else is not equal, all bets are off but the we aren't talking about single effects.