Weight distribution of bike

Saus

I know that "rolling weight" - such as wheels, crank, etc - is more important than static weight (frame, etc). However, when considering things like weight of saddle or weight of handlebars - is static weight more important toward the upper part of the bike or the lower part of the bike?

Camilo

You'll probably get some educated answers, but I think we're getting into the realm of "how many angels can dance on the head of a pin" type of tiny, tiny differences, even in theoretical terms. We've all heard the arguement that rolling weight is more important to static weight, but the real-life situation is that if there is a difference, it is hardly meaningful. In other words, 3 ounces saved in wheels vs. 3 ounces saved on the bike is theoretically different, but doesn't have a lot of practical effect.

Then we get to the question of how much static weight change is meaningful, and the differences are even less. My guess is that upper vs. lower is even less meaningful.

It will be interesting to hear the theoretical analysis though (I'm serious - this stuff is interesting even if it isn't meaningful).

mikesbytes

If you were asking the question about motorcyles, then where the weight is distributed does count.

On a bike the bulk of the weight is your own body. What makes a bike handle is the geometry, optimised rigidity, the tyres & their inflation and how the rider positions their body and controls the bike. Weight distribution would make virtually no difference at all.

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TheDarkLord

I haven't thought about it in great depth, but at the top of my head, I would say that it doesn't matter how the static weight is distributed. The only part of the bike that is rotating are the wheels (other than the pedaling of course), and so the rotational constants that count are the moments of intertia of the wheels. So, purely from a weight perspective, the distribution of static weight shouldn't matter. Now, aerodynamics is a different matter, but it is not a simple function of the weight distribution. If any of above is incorrect, someone please do correct...

Saus

It may be "theoretical", but on a long ride, it makes a difference. In fact on a SHORT ride, there's a difference in pure pleasure.

Weight affect depends upon the circumstances - for example, a ski pole 48" long and weighing 7 oz. feels discernably different from one weighing an ounce more. In flyrods, an ounce is huge, and the difference in performance and feel of a 6 foot graphite rod of 3.5 oz. is different from the feel of an 8 foot graphite rod of 3.5 oz. And the difference between casting a fishing lure of 1/4 oz. and one of 1/2 oz also is huge.

As for bicycles, the pleasure (never even mind the performance) of riding a 15 lb. bike as compared to an 18 lb. bike is huge - at least, it has been for me, and I can't imagine anyone wouldn't feel the difference. The feeling of acceleration on a 15 lb carbon bike with really light wheels is a joy.

So far, the repsonses are minimizing the affect of weight and weight distribution and are from riders who think it makes not any significant difference. I'd like to hear from someone who really cares about it.

Camilo

I don't doubt wyat you're saying, but in my example, I was talking about the relative difference between the same amount of weight taken from wheels vs. the frame, etc. Plus, I wasn't talking about the difference between an 18 and 15 lb bike. I have no doubt that it is a significant and very fun difference. I doubt if there's much to be noticed between a 16 and 16.5 lb bike, and I doubt if there's much difference between a few ounces (e.g. 100-150 grams) lost in wheels vs. other parts... in feel or in measurable performance. JMHO of course.

alienator

The difference in "accelerating a 15lb carbon bike" isn't very much at all. Positive thinking, though, makes all sorts of new stuff feel fast. With the same force applied a 15lb bike and 170lb rider will accelerate 1.6% faster than an 18lb bike and 170lb rider. I didn't consider wheels, but if you want to add the differences of acceleration with different wheels, feel free. It'll only make a fart's worth of difference.

Last time I checked, 1.6% is anything but huge in this context.

gemship

I really hate to admit this because I paid quite a bit for my 16 pound road bike but since I ride so much on my Trek 4300sl for commuting purpose I have gotten very adept to it particularly whislt climbing. In certain instances the Trek is actually faster due to my gearing and standing postion on the pedals as well as my control using a more flat mountainbike style handlebar vs. a dropstyle. To add more insult to injury I suspect the Trek to way around 34 pounds with its mechanical disc brakes and Topeak luggage carrier/bungeed milk crate.

But in the defence of the 16#er, I don't ride it enough,it's still new to me and really is the lightest, stiffest, most precise bicycle I've had the pleasure of.

Saus

I'm hearing about how little difference weight really makes - and that's not what I asked about. I would appreciate an answer about distribution of static weight - higher or lower on the bike - from someone who can just answer that question: What is the relative importance of the placement of static weight placed higher on the bike versus lower?

Well, there's nothing wrong with differing concerns - but whether it's skis or bikes, I tend to be sensitive to differences. There's no question that, without knowing anything at all about bike or wheel weight, the first time I demo rode a 15 pound bike, the feeling was fantastic - unlike any bike I ever had ridden before.

As to the importance of "rolling weight" I have no doubt. Try taking some lead tape and putting an ounce extra on to each wheel. If your wheels are already far from light weight, you'll notice no difference. If your wheels are very light weight, and you don't notice a difference, then your sensitivity and mine are vastly different. I'm not a large guy - my fat weight is 16o pounds and my fighting trim is 145 pounds. Perhaps if I weighed in at 175 or if I were a Clydesdale, I'd care less about bike weight.

The time trial riders use wheels that have a more aerodynamic design but tend to weigh more than their non-time trial wheels because they basically are more interested in all-out speed over a (relatively) shorter distance. However, over a century ride, those wheels would not be optimum due to weight.

Again, I'm hearing about how little difference weight really makes - and that's not what I asked about. I would appreciate an answer about distribution of static weight - higher or lower on the bike - from someone who can just answer that question: What is the relative importance of the placement of stative weight placed higher on the bike versus lower?

mikesbytes

Saus, re handling: despite you being so light, 90% of the overall weight is your body, so the weight distribution is about your body, there is virtually no difference in where the weight is distributed on the bike.

Weight vs Aerodynamics. At 40kph 80% of the effort is pushing air out of the way and most of that is on your body, after that the front wheel is the next point of aerodynamic focus.

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Saus

This something like telling a javalin thrower that the weight of the javalin doesn't matter because the thrower weighs 200 pounds. Tell me that a pound difference in skis doesn't matter because the skier is 200 pounds. Tell me that the distribution of weight - more toward the food or more toward the tip and tail - makes no difference.

Try taking a five pound weight disc and attaching under the saddle of your bike. Ride it.

Then move the placement of the weight disc to the down tube as close as you can get to the peddles. If you don't notice a difference, then you and I can't communicate on this subject.

Where are my fellow tech weenies when I need them?!

Peter@vecchios

It certainly may but the energy it takes to accelerate a bike is the mass of the bike and rider so....3 pounds of a package(bike and rider) that 'may' be 175 pounds of rider and 15 pounds of bike is 1.5%. It may be there, it may be huge to you but I think there are many other factors involved as to why you think a lighter bike(carbon and stiffness comes to mind, not the weight) accelerates hugely better than a 18 pound bike.

If a light bike and the joy it brings means you ride lots-that's the idea.

Saus

Obviously, stiffness and geometry - and wheel inertia - account for a huge part of acceleration. No argument. But I'm still looking for an answer to my tech weenie question, and no one has even ventured a theory.

Think of taking five pounds of theoritical weight. First, add it to the saddle. Try to imagine what it feels like. Now, remove it from the saddle and put it in the bottom five inches of the down tube. Now try to imagine what THAT feels like. Now imagine each situation over a ten mile sprint. Now try to imagine each situation over a century ride in the Vermont hills, or over AIA in Palm Beach to Miami.

If you just don't give a damn about this or believe it makes no difference, then please don't hesitate for a minute to go to another thread and leave this one alone. I want to hear from those who truly are interested in this theoretical question.

Peter@vecchios

http://www.weightweenies.com