bobbyl1966

When one road bike old steel is weight 28 pounds and one new bike one colnago master weight 18 pounds what is make that weight difference. I mean lighter frames is more fragile than heavy frames because used less material in the frame for take off the weight? Where is affect in ride lighweight bike and ride heavy weight bike. What is the difference there wxample in max speed

Homebrew01

A 10 pound difference in bike weight is from the frame and all the components combined.
There will not be a huge difference in "speed" on flat ground. Weight differences are most noticeable when climbing hills.

unterhausen

a high-end steel bike back in the '70s weighed about 23 pounds, so that's probably the comparison you should make. The tubes are definitely lighter nowadays, but the biggest difference is in the components

cb400bill

Moved from Framebuilders forum to General Cycling.

MichaelW

Lighter steel frames use less steel, but usually better quality steel with a higher tensile strength. Some high-end steel is heat-treated for extra strength.
A heavy budget frame may use hi-tensile steel, manufactured very crudely, eg tube ends cut straight, not mitred to fit. It won't be stronger than a good quality, mid-weight chromoly-steel touring frame.

Phil_gretz

That's simply not true. High-end and pro level bikes weighed in the 21-pound to slightly sub-21 pound range, across the board. This is in the early-to-mid 1970s during the boom.

fietsbob

If it Matters.. get data directly .. strip bikes down to bare frames , then weigh the frame separately.



Speed is still more about overcoming Air resistance with your Muscles or energy from a motor .

cale

To measure the "effect" of weight on bike performance, you need to appreciate some of the laws of physics. Namely, that a object (w/mass) in motion wants to stay in motion. That answers the question, "Why isn't it easier to "ride" (maintain a constant speed) a light bike than a heavier bike?"

Unfortunately for us earthlings, the laws of physics also say that in order to accelerate a bike (acceleration in physics is a bit different than its usual use because it means both changing speed up AND down) you need to take into account its mass (weight). Heavier bikes take more energy to accelerate than lighter bikes.

It is the second point, that acceleration qualities are different, that make a light bike such a pleasure to ride. You can ride faster, in the sense of making better overall time, on the light bike with less effort (energy).

70sSanO

You can't just look at the frame. In my experience lighter wheels make a bigger difference. And the wheels don't have to be feather weight either. Just going from 2500 grams to 1800 grams is a massive difference. Same goes for tires. And if you go from steel rims with heavy wire bead tires to good aluminum rims and kevlar bead, the bike will seem like rocket.

John

IcySmooth52

Exactly. The centripetal inertia is the only mass that's constantly working against you. Rim/tire weight, not the hub weight on the wheels.

This is why the industry isn't putting their focus on weight anymore. Aerodynamics are the thing now, but that's because it's 99% aerodynamic aesthetics. And this has more effect on sales than true performance factors. Their aero frames are the wrong place for aerodynamic development though. Teardrop downtubes might help one millionth of a %, but as soon as you put a bottle cage where they've placed bolts for one...

Clothing is where people should look to save energy from aerodynamics. And those that go for deep rims, put the deeper rim or disc wheel on the front! NOT just the back! (Matters far more in front)

andr0id

You should be a politician, while you're not lying it's not really the truth.

let's take an "average" rider that's not a pro and not overweight. a guy that's 170 lbs in his tighty-whities. he's going to be wearing about 5 lbs of gear to cycle including shoes, helmet and clothing. So you got a 175 lb rider.

Now you got your 15 lb bike and your 20 lb bike, but not really because you go riding with 2 bottle of water unless you're an idiot. So we're talking about 48 oz in 2 x 24 oz bottles which is pretty much the norm. That's 3 lbs.

Let's assume our rider never get flats, but if you do, that's another 2 lbs in your saddle bag.

So we've turned our 15 lb bike into an 18 lb bike and our 20 lb bike into a 23 lb bike.

Now we add it up 175 + 18 = 193 lbs for the 15 lb bike and 198 lbs for the 20 lb bike. That's total mass on the hoof which is what counts. The bike doesn't ride by itself.

So the truth is that you looking at 193 vs. 198. So in fact there is only a 2.5% difference.

Unless you are instrumented with a PowerTap or other types of scientific meters, you will not be able to tell a 2.5% difference and even then only on a longer ride where you are comparing data over several runs with 2 types of bikes.

Spending a lot of money makes a lighter bike a pleasure to ride.
Any decent road bike at 20 lbs or under is going to be more than sufficient unless you're a pro.

spdracr39

But the financial placebo effect is so strong you will get many arguments on this one.

AlmostTrick

If it's a truly lightweight frame you are wanting, CF is the way to go. When it cracks in two it will weigh half as much, plus you'll have two!

IcySmooth52

Lol. This will be a good show!

Let's see what profiles are phony & counterfeit avatars used by the manufacturers...

cale

Where that mass is located also makes a difference. You can put heavy wheels on a light frame to make it perform like the heavier bike does.

With all due respect, I'm pretty experienced in why light bikes are more fun (completely subjective) than heavier bikes. We don't need a math equation to understand that when you put ME on a heavier bike it is "slower" than a lighter bike. I've ridden both, not once or twice, over five decades.

andr0id

The question asked was about frames (Note the title of the thread) so our hypothetical bicycles have exactly the same components and wheels. The only difference is the frame and fork are 5 lbs heavier.

cale

Okay, you still can't cheat physics. Mass is a factor in acceleration.

Blue Belly

Weight will usually follow geometry. Geometry is designed into purpose. A fast frame is designed to go fast. However, it takes a fast rider to go fast & the proper components arguably are more important than the frame, in many ways. But, geometry determines handling & a certain degree of ride quality. Then you have wheels, gearing & setup. Everything that goes into building up a bike is important in function.

cale

Weight may have a relationship to geometry but mass is simply a number. You could build two bikes, one in the traditional fashion and the other out of ultralight tubing but a lead bottom bracket and they could have the same mass. (It doesn't matter how much energy the rider has available, that rider will need to apply MORE energy to accelerate the heavier bike. It's simple physics. Force=mass X acceleration, Newton's Second Law of Motion.)

Talking about different riders, what they carry, and so forth just muddies the waters.

If you want to explore aerodynamics, friction, and types of tubing, the question has to include those concerns as well. In this case, as was pointed out to me, we're just concerned with mass.

andr0id

You have two wheels touching the ground with a total contact patch of about 2 sq inches.

Other than marginal aerodynamic differences that have to be detected with wind tunnel test by bicycle manufacturers trying to sell you stuff, there is no such thing as a "fast frame." A few lbs difference between bikes made by any of the quality manufactures does not matter to the average rider and telling them that a bike that is 3 or 4 lbs lighter will make them "faster" is using physics to lie to make a sale.

There are fast HANDLING frames (due to steeper geometry), and there are frames that can be stiffer with regards to the rear triangle and flexing. But once you put a decent pair of wheels into the dropouts and a rider in the correct position on the saddle, they all go exactly as fast as the rider makes them go.

Crappy heavy bikes ride crappy because they have crappy heavy components. But heavy components don't even ride crappy because they are heavy, they ride crappy because the bearing quality prevents them from even being adjusted correctly in the first place.

Additionally crappy heavy bikes come with crappy inflexible tires on them which have a very "dead" feel to them and have terrible rolling resistance.

You will note that all the big manufacturers equip stock bikes with tires that make the bikes feel the way they want them to feel to differentiate the price difference.

Ask to ride a Domane with the wheels from a Madone 9 on it, and all of the sudden that "super fast feel" that cost $3K more shrivels away.



No, it doesn't. Bikes frames don't ride themselves in a lab or wind tunnel. You have to take the rider into account to know the true situation. Without knowing about the rider, you know almost nothing.

cale

Strange comment from one who just moments ago reminded me that we are solely concerned with weight. Make up your mind.

Blue Belly

i think you missed my point completely

Blue Belly

Again, missed the point completely,

andr0id

YES, TOTAL RIDER + BIKE WEIGHT OUT THE DOOR is the single most important factor when fit, components, wheels and tires are equal.

The weight of the FRAME is a tiny contributor to that TOTAL WEIGHT.

cale

If you say so but you'll disagree when /if you get old and fat. Haha