On Wednesday, June 19, 2019 at 5:32:05 PM UTC-7, Frank Krygowski wrote:
On 6/19/2019 7:45 PM, jbeattie wrote:
On Wednesday, June 19, 2019 at 11:18:52 AM UTC-7, Frank Krygowski wrote:
On 6/19/2019 10:25 AM, jbeattie wrote:
On Tuesday, June 18, 2019 at 8:06:37 PM UTC-7, Frank Krygowski wrote:
On 6/18/2019 1:24 PM, jbeattie wrote:
On Tuesday, June 18, 2019 at 9:49:50 AM UTC-7, Frank Krygowski wrote:

For ordinary riding? No, most tiny improvements make no noticeable
difference. Even though we all know the near-magic power of red paint.


What is a "tiny improvement"? The frame on my Emonda probably weighs less than the Columbus steel forks off my last custom racing bike. Those things were suitable for clubbing baby harp seals or home defense. Weight and stiffness do matter when climbing. If we're talking about aero bits, that's harder call -- except that dopes on aero bars riding in packs can result in a massive worsening of your riding experience. Wearing aero shoe covers may keep your feet warmer on chilly mornings, which might make you faster. It all adds up.

Stiffness probably does not make a detectable difference, unless the
frame is so flexible that things are scraping. Remember the discussion
we had about the bike magazine's test of modern stiff CF frames vs.
older, heavier steel frames? The test riders gushed about how the
stiffness improved their climbing, but the math showed the speed
difference was precisely what would be predicted by the weight difference.

Weight matters when climbing. If getting to the top of the hill before
your buddy is really, really important, a lighter bike will help by
whatever the percent difference in total bike+rider weight. If a 160
pound rider changes his 20 pound bike for an 18 pound bike, he should be
about 1% faster up a steep hill. Whoopee!

Make that a 5lb weight difference. You need to borrow a well-fitting modern 15lb racing bike with an appropriate gear range and then do a long ride with lots of hills. It's not a subtle or imagined difference compared to a T1000 or old-school steel sport touring bike, particularly if you're trying to keep up with others.

Again, I'm not saying the weight doesn't make a difference! The
difference it makes on an uphill is the percentage difference in
bike+rider weight.

Does nobody remember the discussion a couple years ago where the
magazine article's data proved that? They put young racers on modern CF
bikes, then on 1980s steel racing bikes and timed them up long hills.
The speed difference was exactly what the weight difference predicted.

Think about changing to a bike that was five pounds lighter, but then
strapped a five pound weight around your waist. Hopefully people here
wouldn't think you'd still be way faster up the hills, right?

And again, the stiffness, the snappiness, the magical handling of a CF
bike made no difference at all in that comparison test. There were other
details the youngsters liked on the new bikes - as in "I was afraid to
take my hands off the hoods to shift" - but the speed difference was
apparently due to the weight.

If others think there's some other energy savings or power increase,
please explain it in engineering or scientific terms. Explain how it's
not magic.

Well, go to all the reviews of retro bikes on GCN. E.g. https://www.youtube.com/watch?v=V4JAvQCp8ww Again, go borrow a 15lb modern racing bike that fits, then do hill repeats. Now do that on a Biketown bike. Really, there is no difference! It's all placebo effect! Now do it on a Surly Moonlander. No difference!

At what point would you agree there is a difference -- and why that point? Even without almighty "data" (presumably something created by a machine and not anecdotal reports), most of us would agree that some bikes are dogs and others aren't.

Geez, guys, you're very diligent about confusing yourselves!

As I told Sir, I'm _not_ saying weight doesn't make a difference! I'm
quantifying that difference.

Didn't we all meet guys in the 1970s who thought "My new bike has six
cogs instead of five, so it's going to be 20% faster"? Don't we still
meet guys who think 11 cogs will be 10% faster than ten cogs? But that's
silly and very unscientific. It shows a poor grasp of basic physics

In the same way, there seem to be people who think "My old bike weighed
20 pounds but my new bike is 18 pounds. It's going to be 10% faster up a
hill."

Sorry! What matters is total weight, bike+rider. a 160 pound guy who
goes from a 20 pound bike to an 18 pound bike has lost 2 out of 180
pounds. He's improved the total weight by about 1%.

Will it make a difference? Yes, a difference of about 1%. So weight
_does_ matter - that much.

"Oh, but try a bike that's FIVE pounds lighter!!" OK, that one will be
2.8% better. It won't be 25% better.

If 1% or 2.8% is worth it to you, fine. It is to some people. Other
people may have a different view.

BTW, the first national bike convention we ever attended was 1978 in
Michigan. Since we lived in an area where we knew only one other avid
cyclist, I was fascinated by all the beautiful high-end bikes.

But one weird one was a guy on a super light custom frame, with the
highest end and lightest SunTour components, many of which he had
drilled holes in. Super light rims with tubular tires, too. He was just
in awe of his own bike, telling people over and over how little it
weighed (somewhere under 20 pounds).

Then the big mass start parade into town started. I watched carefully as
he started out, because I wanted proof it would support him. I guessed
he weighted somewhere around 300 pounds, and very little of it was muscle..

Applying a formula and coming up with a "percentage better" based on total bicycle and rider weight is deceptive. A better paradigm is lifting weights -- moving 15 pounds uphill rather than 20. You have to determine the additional energy needed to move that weight and how the additional energy affects the rider over time. Energy needed may depend on frame flex, tires and a number of other factors that are bicycle dependent.

The effect on the rider depends on many things. We are not constant speed motors. Assuming a rider is attempting to maintain the same speed on a heavier and less efficient bike, the additional effort may be enough to exhaust him or her before the top of a climb -- which turns the last miles into a creep-along. Time is not off by 2% based on some formula but is off by more -- depending on how badly he or she blows. When you run the tank out, you could end up walking the last miles or sitting under a tree and resting.

-- Jay Beattie.