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Aero trumps weight, until it doesn't

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Aero trumps weight, until it doesn't

Old 09-20-17, 09:51 PM
  #26  
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Originally Posted by Dean V View Post
Your numbers would be closer if you used 400w instead of 200w.
Sure, if you're Romain Bardet. In that case, K is at 15 seconds. Even given that K is a relatively simple model, that parameter change actually reinforces my position that the numbers the teams were thinking (10-20s gained) are not orders of magnitude different than what you'd likely hear 'round these parts.

I would comment on how bike changes worked out, but I'd rather not be accused of spoiling anything. I could've sworn there was a tag for that....
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Old 09-20-17, 10:29 PM
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Originally Posted by Bacciagalupe View Post
Sure, if you're Romain Bardet. In that case, K is at 15 seconds. Even given that K is a relatively simple model, that parameter change actually reinforces my position that the numbers the teams were thinking (10-20s gained) are not orders of magnitude different than what you'd likely hear 'round these parts.

I would comment on how bike changes worked out, but I'd rather not be accused of spoiling anything. I could've sworn there was a tag for that....
Calculations based on weight are fairly insignificant. Again, as both bikes are likely near the same mass.

The wheels are different with climbing wheels being near 50% of the TT wheels.

This goes to that conversation that mass is mass. Statically - yes, moving, certainly some don't think so (nor do I).
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Old 09-21-17, 06:38 AM
  #28  
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if the rules apply to everyone then why bother allow change bike ? if you can't climb that mean you are weak and let better rider wins.
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Old 09-21-17, 07:26 AM
  #29  
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Originally Posted by San Pedro View Post
Sorry, fell asleep.

https://www.youtube.com/watch?v=vtbejVR1Y9I

UCI channel.

It just popped up on my homepage last night.
Uploader has not made video available in my country. WTF UCI?
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Old 09-21-17, 08:12 AM
  #30  
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Originally Posted by Grasschopper View Post
Uploader has not made video available in my country. WTF UCI?
I'm usually the one who gets that message. Bummer, but I bet there is something on YouTube.
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Old 09-21-17, 08:28 AM
  #31  
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Originally Posted by San Pedro View Post
I'm usually the one who gets that message. Bummer, but I bet there is something on YouTube.
Eh...I've got it on my DVR at home...I watched the Elite Women's TT last night but was falling asleep toward the end so I went to bed. I'll watch the men tonight.
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Old 09-22-17, 04:39 PM
  #32  
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Originally Posted by Grasschopper View Post
Uploader has not made video available in my country.
The UCI broadcast is for countries who don't have an official broadcaster. Steephill has a list in progress for Live Video Streaming and TV Coverage. US online options include NBC Sports Gold and FuboTV.
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Old 09-22-17, 09:15 PM
  #33  
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I've got the Olympic channel so I had it DVRed. Great race IMO.
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Old 09-24-17, 04:41 AM
  #34  
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I watched some of the highlights of this, especially interested in the bike change bits and thought the majority of the riders that did the bike change were clumsy and amateurish looking. And the helper pushed them off too hard almost causing some of them to crash. A lot of the riders were having trouble clipping in and wobbling around like Freds. Surely they would of practised doing bike changes? Didn't look like many of them had.
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Old 09-24-17, 05:46 AM
  #35  
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Originally Posted by Falchoon View Post
I watched some of the highlights of this, especially interested in the bike change bits and thought the majority of the riders that did the bike change were clumsy and amateurish looking. And the helper pushed them off too hard almost causing some of them to crash. A lot of the riders were having trouble clipping in and wobbling around like Freds. Surely they would of practised doing bike changes? Didn't look like many of them had.
Was the change being carried out already into the upslope. That could be a problem even for a pro.
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Old 09-24-17, 11:17 AM
  #36  
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The change area was on a very slight uphill ... but mostly form what I saw, it seemed the pressure got to people. Timing things properly takes practice, and apparently no one had.

More than pushing too hard, it seemed a lot of mechanics didn't get to push the rider before the end of the transitions zone, so the rider had to clip in and pedal off, uphill, from a dead stop, which cost more time than any bike change could have saved.

The fastest I saw was ten seconds ... but I'd still call it fifteen counting braking and acceleration to competitive speed. The worst were painful ... a Lot of riders on a three-or-five-percent slope trying to clip in and take off without assistance.
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Old 09-24-17, 11:27 AM
  #37  
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Old 09-24-17, 11:36 AM
  #38  
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Excellent graph ... as in, simple enough that I can understand it (I think.) Looks like four guys pulled off a bike swap:y Roglic, Oliveira, Keldermann, and Gougeard. (Didn't Gougeard crash?) Thing is it is impossible to tell how well the others would have climbed on their TT bikes.Looks like six of the top ten didn't switch.

Now we need a graph showing the time it took each one to swap bikes.
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Old 09-25-17, 04:59 AM
  #39  
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How about the Engineering Notes by Cervelo?

https://www.cervelo.com/en/engineeri...weight-vs-aero
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Old 09-25-17, 07:01 AM
  #40  
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"But where is the tipping point? How steep does a climb have to be before the weight savings trump the aero gains? The answer depends on the rider’s weight and speed, as a faster rider would encounter higher aerodynamic forces while the gravitational forces stay the same. For an average 250 Watt rider, the tipping point is around a 5-per-cent slope. For a good pro who puts out 400 Watts, it’s 8 per cent."

So for me ... basically forget aero ... a .001 % slope and I am tipping over.
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Old 09-25-17, 07:19 AM
  #41  
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Right it would bve really interesting to see how each guy would have done under the same circumstances. I'm sure that this was Tony Martin's argument against this course and against the allowance of bike type swaps for the final climb. There's so many factors for this one:

How well was the swap executed? I saw a couple completely botched swaps, bad clip-in jobs. But then there were a couple toward the end around 7-8 seconds at the end count. But again to Froome's comments before the race: how much momentum was lost? What about rhythm?
How comfortable is each particular rider on the TT bike? That climb was pretty nuts....all those tight switchbacks at the bottom. If a rider isn't comfortable on the TT bike then making those turns on one would be very hard and would mean slowing down even more than normal...regardless of the gradient.

So the question is WAY bigger than just aero vs weight. The guys that put time into perfecting their TT riding are going to be more comfortable on the TT bike than a rider that just TTs because they have to. IMO the bike swap was costing people a minimum of 10 seconds...and the question was could they make that up on the climb. And making that time up was not just aero vs weight...handling (cornering) and pure acceleration had a lot to do with it too.

Honestly when I first heard about it I thought it was a bad course because it hurt the pure TT guys...but having watched it I must say it was hugely entertaining and in the end that's what this is all about. The Tony Martin's can be pissed that the course was a disadvantage for them...but last year a pan flat course was the exact opposite, it favored the pure TT guys. They aren't going to have a course like this every year and personally I think it was ok to have as a one off odd ball course.
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Old 09-25-17, 07:22 AM
  #42  
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Originally Posted by Maelochs View Post
Excellent graph ... as in, simple enough that I can understand it (I think.) Looks like four guys pulled off a bike swap:y Roglic, Oliveira, Keldermann, and Gougeard. (Didn't Gougeard crash?) Thing is it is impossible to tell how well the others would have climbed on their TT bikes.Looks like six of the top ten didn't switch.

Now we need a graph showing the time it took each one to swap bikes.
Makes you wonder, how many seconds could they potentially save if they perfected a bike swap at speed. Cowboy dismount/mount (spinning) while moving, or swing a leg over the top tube, clip in cross-legged and mount up.
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Old 09-25-17, 07:44 AM
  #43  
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Originally Posted by wphamilton View Post
Makes you wonder, how many seconds could they potentially save if they perfected a bike swap at speed. Cowboy dismount/mount (spinning) while moving, or swing a leg over the top tube, clip in cross-legged and mount up.
Jump off the top tube of a moving bike to another bike. I'm sure it would make it into all kinds of action movies... if there weren't cars.
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Old 09-25-17, 08:35 AM
  #44  
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Originally Posted by wphamilton View Post
Makes you wonder, how many seconds could they potentially save if they perfected a bike swap at speed. Cowboy dismount/mount (spinning) while moving, or swing a leg over the top tube, clip in cross-legged and mount up.
I'd bet Zdeněk Štybar could have done it in five seconds.

I bet all of them could have done it in ten and gotten good launches if they had bothered to practice.

Not sure about standing on the saddle one-legged and hopping onto the saddle of the second bike, which the mechanic is pushing uphill .... Peter Sagan could do that, maybe no one else.
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Old 09-25-17, 08:50 AM
  #45  
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Looking at the thread title, I thought this was a political post about Donald Trump's weight. Glad it wasn't. Carry on . . .
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Old 09-25-17, 08:56 AM
  #46  
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Originally Posted by Maelochs View Post
I bet all of them could have done it in ten and gotten good launches if they had bothered to practice.
It's quite possible that on fresh legs and with an uncluttered mind that all of those stumbling pros performed a super clean bike exchange on flat ground. Now pump out hundreds of watts for however many minutes straight in the world TT championship starting on a decent uphill grade and that same bike exchange is a little more difficult.
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Old 09-25-17, 09:00 AM
  #47  
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Originally Posted by Maelochs View Post
I'd bet Zdeněk Štybar could have done it in five seconds.

I bet all of them could have done it in ten and gotten good launches if they had bothered to practice.
Five seconds is slow.
.
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Old 09-25-17, 09:05 AM
  #48  
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IHPVA Battle Mountain Nevada , have been timing flying 200M speeds of over 80 MPH , for 16 years , now..
current record 89.59 MPH/ 144.17 kM ph .. 200 Meters, covered in 5 seconds (4.994")

UCI Bikes are an appendage under a big ball of turbulence trying to push itself thru the air.



...

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Old 09-25-17, 10:42 AM
  #49  
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Originally Posted by fietsbob View Post
IHPVA Battle Mountain Nevada , have been timing flying 200M speeds of over 80 MPH , for 16 years , now..
current record 89.59 MPH/ 144.17 kM ph .. 200 Meters, covered in 5 seconds (4.994")
That's a downhill course. They don't take an average of speeds in both directions.
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Old 09-26-17, 11:54 PM
  #50  
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Originally Posted by blazin View Post
Bike change could be key to Worlds TT success | Cyclingnews.com

Apparently, racers in the world championship time trial plan to change from a TT bike to a road bike due to the benefit the lighter bike will produce over just a 3 km climb. The estimate of that benefit quoted above strikes as much more significant than the small numbers people seem to cite here frequently. I'd be interested, since most of us don't have the luxury of mid-life bike swaps, to know what the difference would be riding the whole course on just a TT or just a road bike. I imagine TT would still come out on top?
The climb is about 300m. Assuming a weight penalty of 2kg that is a 2*9.82*300=5892J penalty. At 400w the it takes 5892/400=14.73s to deliver that energy, meaning the time penalty for riding the heavier bike is 14.73 seconds.
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