genejockey 

It's like some folks think riders in the peloton are riding in a literal vacuum with NO aerodynamic drag, rather than a slipstream with REDUCED drag. I'd name the other one, but he tends to appear if you speak his name, so....

PeteHski

Show us the physics equations to prove this nonsense or go home. You seem happy to critique mathematical models (which actually model wheel inertia) simply because they don’t agree with your “feelings”. Modern data science has made the performance comparisons objective and taken away all the previous guesswork. The same thing happened in my own field of motorsport over the last 25 years. Many long standing beliefs were laid bare by cold hard data and facts. It was all a bit much for some of the older engineers, who often didn’t have formal engineering qualifications anyway.

However I have massive respect for those old NASA engineers and scientists. They knew their maths and physics and would have laughed at this old saying because there is no real physics supporting the claim.

rydabent

If I agreed with you, then we would both be wrong.

Without the brake area, the rims can be lighter. With out the brake area, the rims can be more aero. With out the brake area, the profile can be more triangular, and everyone knows a triangle is exceptionally strong.

All most always making a machine dual purpose ends up with it not doing either thing job very well.

You should not fly into the face of common sense and logic.

terrymorse 

Theoretically, I'd give up a few extra watts when tucked into the peloton, where I'm not working very hard any way, for a few extra watts on a climb, where the suffering has no limit.

Make the choices that reduce the worst suffering.

tomato coupe

But, they're not.
Again, they're not.
And, for the hat trick, they're not.
Sorry, but reality wins.

PeteHski

I take it you didn't read the SwissSide article then. Based on SwissSide's computer model, Ineos used aero wheels on almost every tour stage. Watching the tour these last few years, it's clear that most riders are climbing the big cols on aero bikes and wheels. Those on dedicated climbing wheels are now the exception. That's not to say a recreational rider is not better off climbing big mountains on ultra-light climbing wheels. The break-even gradient for a recreational rider is just over 5%, rising to over 8.3% for a pro (and that was for a 700g difference in total bike weight i.e. 6.8 kg lightweight climbing bike/wheels vs a 7.5 kg aero race bike/wheels ).

https://www.velonews.com/gear/road-g...els/#_reg-wall

PeteHski

That SwissSide article also has a neat representation of the micro speed variations during the pedal stroke. Note the swings are actually higher with lower rotational weight.



Quote: "Although the total kinetic energy of a bicycle is the sum of translational and rotational kinetic energy, rotational energy is only a tiny part of the total. Reducing rotational weight of rims, tires, and tubes saves energy only when the wheel is accelerating, and, as long as the rider doesn’t hit the brakes, he or she gets that energy back when the wheel is decelerating."

terrymorse 

Yes, I read it.

I am disagreeing with the "pick equipment that makes riding in the peloton easier" notion. That doesn't matter.

I say pick equipment, whatever it may be, that makes the climb easier. That equipment choice is dependent on the grade, and how fast you expect to go on that grade. Obviously.

Obviously. Which scenario will produce the higher muscle fatigue? The answer to that is not so obvious.

Trakhak

I can confirm that, as you say above, "the swings are actually higher with lower rotational weight." I once had a pair of Hi-E's lightest tubular wheels, which made them almost certainly the lightest wheels on the market at that time, and the requirement to get them back up to speed with every pedal stroke was disconcertingly obvious. They also made the bike feel top-heavy. I used them only for a few time trials and then sold them.

genejockey 

Wot, AGAIN? Reality's on a tear!

Fredo76

Thank you for offering plausible alternative explanations for my perceptions. It is helping.

Fredo76

I am home, and I'll post as I please, thank you.

elcruxio

No no, he might actually do the occasional local cycling association fun ride every now and then.

But judging by his views on aero and always writing about how keeping the wheel is the most important thing in the world, it's clear he never does any pulls. We all know that type from group rides...

Eric F 

IMO, wheel choice for racing is best served by what improves your strengths, more so than what compensates for your weaknesses.

Not all riding in a peloton is easy cruising. More times than I can remember, I’ve been at the limit of my suffering ability for quite a while with my front tire within inches of the rear tire in front of me, while flying on flat ground. An extra few watts of aero savings is going to be valuable to me in that situation. If it was a race where climbing was the deciding factor, it wasn’t likely I was going to be around to compete for the win, regardless of how light my wheels were. My best opportunity to win was a sprint finish at the end of a crit or punchy road race, and I’d take the high-speed advantage of aero wheels at the cost of a bit more weight because it sharpens my best weapon.

For you, I expect that light wheels sharpen your best weapon, but (maybe) aero wheels aren’t going to make much difference for you in a bunch sprint.

PeteHski

The article was actually discussing what makes riding easier both in the peloton AND on the climbs. I'm not disagreeing about your own personal choice as a recreational rider focusing on long climbs steeper than 5%, where lighter wheels do trump aero (very marginally). I thought you were talking "theoretically" about what you would do as a competitive rider in a pro peloton. If that's not what you meant and you are not riding in the peloton then I don't understand why you even mentioned it "theoretically". The real pros nearly always choose the aero option, even on alpine stages, with few exceptions. Especially teams like Ineos who have access to advanced modelling and can run detailed calculations for every stage.

PeteHski

I don't think the observation that higher inertia makes pedalling smoother was obvious to some people in this thread actually. As for muscle fatigue in this scenario, isn't it obvious that it would be less for the same overall weight? So if you saved 1 kg on the frame vs 1 kg on the wheels, you would be smoother pedalling up hills with no penalty in overall power. Totally counter-intuitive to the old saying "An ounce off the wheels is worth a pound off the frame" nonsense.

The only obvious thing is that if you saved 1 kg on the wheels and saved nothing on the frame, then you would be faster up steep hills. But not because of the reduction in rotational inertia. Simply because you saved 1 kg in total weight

RChung

This is the General Forum, not the racing forum, but racing isn't steady state: it's a series of punctuated equilibria, where the punctuations are crises that you either survive or you get dropped. After you get dropped, you're left behind facing a new drag regime. Mostly we analyze these things as if we were in steady state and riding by ourselves so we come up with comparisons like, "doing this saves you 20 seconds over 40 km" and most riders rightly say, "that's not important." But to a racer, we're not facing a steady state, we're facing a gauntlet of crises. A small advantage either lets you drop a competitor (so he or she faces a more perilous drag regime) or lets you hang on and sometimes rest and recover until the next crisis arises. If you get dropped, the gap can end up being way way more than 20 seconds. I'd regularly be in a different zip code when the winner crossed the line.

Typically, crank inertial load is higher on the flat than during climbs. Some hypothesize this is one of the reasons why cadence is different on flats than on climbs.

Eric F 

Valid point that this isn't the racing forum. The same scenarios play out in fast group rides, as well. City limit sign sprints are serious business - LOL.

terrymorse 

Yes, that's what I was thinking. Light wheels to help where I have the best chance of being competitive, which is on grades of 8% or more.

There's almost no chance of me ever seeing the front end of a bunch sprint, I'm afraid.

I get the part about high inertia wheels make pedaling smoother (less change in crank rotation speed), but I'm not convinced that it's clearly less fatiguing to leg muscles.

A roughly analogous situation:

Is it easier to throw a heavy ball a short distance, or is it easier to throw a light ball a long distance? The answer is not obvious (not to me, at least).

Eric F 

Right. This is exactly my point. We are at our best when our tools compliment our strengths.

In the real world of today's wheel technology, we aren't stuck with extremes of just aero or light. We have a range choices of aero wheels that are pretty light, light wheels that are pretty aero, and varieties in between. Choose wisely.

HTupolev

No, not obvious. That's getting into the physiological side of things, which is weirder and less well-understood.

genejockey 

To the OP - I've seen the Eastern Shore, and it's flat as all hell. Makes me think "crosswinds". So, I'd really take that into account when thinking about aero wheels.

rydabent

So you are a know it all about ALL rims produced now. Sorry I dont believe that. If you are an engineering expert, tell us why wouldnt all 3 things I mentioned be true?

himespau 

Triangular shaped rims are not the most aero as has been shown with many tests.

smd4

Which is why I prefer circular ones.