September 15, 2014 Login  


Bike weight and the myth of ‘fast’ bikes
Last Post 08/09/2014 09:52 PM by Orange Crush. 22 Replies.
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Keith Richards

Posts:731

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08/06/2014 01:16 PM
Let’s clear something up. There is no such thing as a “fast bike.” Bikes are neither fast nor slow. Bikes are shiny or expensive. Bikes have a lot of mass or a little. Without a rider, they are stationary. Physics holds a bike in place until you get on it and start pedaling. Even then the bike may not necessarily be fast. Of all the equipment on your bike, your legs are the most critical component. There are plenty of nice bikes on the road that are being ridden slowly. But more insidious than inaccurate vocabulary is a simple overestimation of how much bike weight matters for most riding.


Excerpt from the book FASTER: Demystifying the Science of Triathlon Speed by Jim Gourley 9
----- It is his word versus ours. We like our word. We like where we stand and we like our credibility."--Lance Armstrong.
ChinookPass

Posts:442

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08/06/2014 01:54 PM
and yet if I have two bikes and I can go faster on one than the other, it must be the bike!

but yeah, certain bike characteristics get you in the game, but it's your legs and head that win or lose the race.
Dale

Posts:482

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08/06/2014 02:44 PM
Let the "aero v light" discussion commence
vtguy

Posts:241

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08/06/2014 03:06 PM
We should include geometry (bike fit) in that discussion, too.
79pmooney

Posts:1104

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08/06/2014 03:21 PM
vtguy, my race bike was a true breakthrough. 2-3 lbs lighter than the bike it replaced. With the same wheels it was minutes faster around my 45-50 mile training loop. Like equaling my best time ever going easy my first ride, 2 minutes off that 3 days later and they kept falling all summer. That loop had one significant 1/2 mile hill, not enough for the weight difference to make more that a few seconds of difference.

But fit, yeah! A VERY real difference!

Ben
Oldfart

Posts:469

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08/06/2014 03:46 PM
I ride off road hills that are in excess of 15% often. So I am justified in owning a light hardtail. Or so I say to my wife. But she rides the same bike so it is not a tough argument in my house. I rode trails on the Flank trail in Whistler yesterday that probably approach 25 - 30 %. I walked some of them. Too steep and too loose to stand.

But there is something about light wheels that helps climbing. But I think it was Nelson Vails that said it best. It's the legs man.
Dale

Posts:482

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08/06/2014 03:48 PM
What wasn't discussed was rotational weight vs. static weight.

Take that 15 pound bike with a set of lightweight tubular wheels and compare that to a 15 pound bike with a set of heavy wheels. Total weight might be the same but you'll darn sure tell the difference between the two.
79pmooney

Posts:1104

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08/06/2014 03:51 PM
Andy, it's the legs, yes, but poor fit can keep those legs from getting the oxygen they need. My super long stems are all about deep breathing and not compressing my torso. My old race bike did that for me too.

Ben
longslowdistance

Posts:655

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08/06/2014 05:03 PM
"Laterally stiff but vertically compliant" is the magic formula. That's what Bicycling Magazine sez about every bike they review, so it must be really great.
Cosmic Kid

Posts:1091

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08/06/2014 05:52 PM
Posted By Dale Dale on 08/06/2014 03:48 PM
What wasn't discussed was rotational weight vs. static weight.

Take that 15 pound bike with a set of lightweight tubular wheels and compare that to a 15 pound bike with a set of heavy wheels. Total weight might be the same but you'll darn sure tell the difference between the two.


If the heavy wheels are the same construction as the light wheels (I.e. Rim shape, # of spokes! lacing pattern) then yes, the light wheels will be fractionally faster. If the heavy wheels are more aerodynamic, the heavy wheels are faster. This is not opinion, it is science. Light wheels certainly *feel* faster! but perception is a funny thing. It does not necessarily reflect the realities if the world.
Just say "NO!" to WCP!!!!
Dale

Posts:482

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08/06/2014 11:41 PM
CK, do those studies take into account acceleration and the lower inertia of the lighter wheel? Unless you're doing a flat TT the race is full of accelerations and one would think there are some energy benefits to lower mass.

I read somewhere that guys doing the hour liked heavier wheels since once you got them up to speed they carried that momentum nicely.

Another factor in lighter bikes is cyclocross-- I can tell when I have my heavy wheel set on when I go over the barriers
79pmooney

Posts:1104

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08/07/2014 01:04 AM
CK and Dale, what those studies don't address is the fact that road races are often decided by accelerations that determine, for example, who makes the break and who doesn't. Light wheels could mean you make the break. Non-aero means you finished last in the break, but minutes up the road from the guy with aero wheels who didn't make it.

Edit:  I rode 290 gram Fiamme Ergal rims, 250 or 220 gram silks and 15-17 ga. spokes in my racing days  Pretty light for New England roadsjh.  Race accelerations were my biggest challenge and I needed all the help I could get.

Ben
jookey

Posts:138

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08/07/2014 07:24 AM
Light vs Areo... Always an interesting debate. Much depends on your terrain. Where I live it is hilly. Not long climbs, but very little flat. Light wheels rule. You can tell the difference especially when accelerating on a climb. I work 40 miles away. It is pan flat right on the coast. No hills whatsoever. Areo wheels rule here.

I also think that tire selection is an important factor in "fast".
Dale

Posts:482

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08/07/2014 07:35 AM
Posted By Cosmic Kid on 08/06/2014 05:52 PM
Posted By Dale on 08/06/2014 03:48 PM
What wasn't discussed was rotational weight vs. static weight.

Take that 15 pound bike with a set of lightweight tubular wheels and compare that to a 15 pound bike with a set of heavy wheels. Total weight might be the same but you'll darn sure tell the difference between the two.


If the heavy wheels are the same construction as the light wheels (I.e. Rim shape, # of spokes! lacing pattern) then yes, the light wheels will be fractionally faster. If the heavy wheels are more aerodynamic, the heavy wheels are faster. This is not opinion, it is science. Light wheels certainly *feel* faster! but perception is a funny thing. It does not necessarily reflect the realities if the world.


My question/ comments are based on the wheel construction being the same other than weight. I've run enough aero wheels to be convinced of their merit,
Cosmic Kid

Posts:1091

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08/07/2014 08:24 AM
Posted By Michael Carbajal on 08/07/2014 07:24 AM
Light vs Areo... Always an interesting debate. Much depends on your terrain. Where I live it is hilly. Not long climbs, but very little flat. Light wheels rule. You can tell the difference especially when accelerating on a climb. I work 40 miles away. It is pan flat right on the coast. No hills whatsoever. Areo wheels rule here.

I also think that tire selection is an important factor in "fast".


jookey, this is the perfect example of what I was talking about with perception. Lighter wheels "feel" faster, but they aren't vs. aero wheels, even on hilly rides.

In addition, you are focusing on only one aspect of hedge ride - the hills. Aero wheels benefit you the WHOLE ride...up, down and on the flats. Even if light wheels were truly faster on the hills, they still lose out on a net sum basis.

And yes, those realities include accelerations. Again, this is a perception issue. Light weight wheels feel lighter, so they *fee* like they accelerate faster. They really don't.

Go to www.analyticcycling.com and run the numbers for yourself.

Let me give you another example of perception.....saddles. Back when the Flite was first introduced, people went nuts for lightweight saddles. Why? Because it was weight at the end of a "lever" (the seat tube / seat post extension) and as a result, it made bikes feel substantially lighter. But they were still only lighter by about 50 -100 grams. But everyone swore by light saddles because of how they felt. In actuality, the performance gain was nothing, but they sure felt light.
Just say "NO!" to WCP!!!!
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