Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Aero trumps weight, until it doesn't

Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Aero trumps weight, until it doesn't

Old 09-19-17, 06:39 PM
  #1  
blazin
Blazer of saddles, trails
Thread Starter
 
Join Date: Dec 2016
Location: Inside the Beltway
Posts: 111
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Aero trumps weight, until it doesn't

BMC time trial coach Marco Pinotti told Cyclingnews that a 2kg difference in bike weight could give a 20-second benefit, with other seconds gained thanks to the familiarity of riding on a road bike.
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?
blazin is offline  
Old 09-19-17, 06:53 PM
  #2  
rpenmanparker 
Senior Member
 
rpenmanparker's Avatar
 
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,408

Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build

Mentioned: 103 Post(s)
Tagged: 1 Thread(s)
Quoted: 6343 Post(s)
Likes: 0
Liked 4 Times in 4 Posts
Is there a descent? If not, and the climb is very significant, the balance could easily shift from zero to weight.
__________________
Robert

Originally Posted by LAJ View Post
No matter where I go, here I am...
rpenmanparker is offline  
Old 09-19-17, 06:55 PM
  #3  
rubiksoval
Senior Member
 
Join Date: Nov 2015
Location: Music City, USA
Posts: 2,901

Bikes: Felt AR

Mentioned: 47 Post(s)
Tagged: 0 Thread(s)
Quoted: 1679 Post(s)
Liked 66 Times in 38 Posts
If BMC's TT bikes really weigh 2kg/4.5 lbs more than their road bikes, I'd start looking as to why they have almost a 20 lb bike.

That's amateur-league.
rubiksoval is offline  
Old 09-19-17, 07:00 PM
  #4  
HTupolev
Senior Member
 
Join Date: Apr 2015
Location: Seattle
Posts: 2,734
Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 1184 Post(s)
Liked 23 Times in 18 Posts
It takes 20 seconds to raise 2kg by 215 meters... if you're pedaling at 200W. And that's for otherwise like-for-like cases.

It seems like you'd really have to introduce very-case-specific biomechanical quirks, perhaps including gearing changes, to give a 2kg-lighter road bike a 20-second advantage on the climb.

Originally Posted by blazin View Post
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?
Yes, easily. For most people, the performance difference between a road bike and a TT bike on the flats is obvious. On a climb, not so much; grades often have to get pretty significant before the TT bike stops winning. And unless the gearing bottoms out no matter how steep the grade, a TT bike should never be that much slower than a road bike a few pounds lighter.

Last edited by HTupolev; 09-19-17 at 07:03 PM.
HTupolev is offline  
Old 09-19-17, 07:06 PM
  #5  
Dean V
Senior Member
 
Join Date: Oct 2009
Posts: 2,368
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 781 Post(s)
Likes: 0
Liked 18 Times in 13 Posts
I think it is more than just weight that handicaps a TT bike on a climb. The forward saddle and layout of the handlebars isn't helping either.
Dean V is offline  
Old 09-19-17, 07:11 PM
  #6  
blazin
Blazer of saddles, trails
Thread Starter
 
Join Date: Dec 2016
Location: Inside the Beltway
Posts: 111
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Course ends at the top of the climb.


Last edited by blazin; 09-19-17 at 08:11 PM.
blazin is offline  
Old 09-19-17, 11:11 PM
  #7  
Maelochs
Banned
 
Join Date: Oct 2015
Posts: 11,525

Bikes: 2015 Workswell 066, 2014 Dawes Sheila, 1983 Cannondale 500, 1984 Raleigh Olympian, 2007 Cannondale Rize 4, 2017 Fuji Sportif 1 LE

Mentioned: 136 Post(s)
Tagged: 0 Thread(s)
Quoted: 5449 Post(s)
Liked 115 Times in 76 Posts
For this year's Worlds Only this might all make sense. No descent, and anyone who misjudges power output could lose Huge time on that hill. The pro women's race was won by a Dutch woman who went marginally slower in the first third and saved extra for the climb---and they had to descend.

I am betting more than a few male riders will run out of steam two-thirds of the way up that hill. A five-second bike change could almost pay for itself given the steepness of the first three k of that climb.
Maelochs is offline  
Old 09-20-17, 04:36 AM
  #8  
Campag4life
Voice of the Industry
 
Campag4life's Avatar
 
Join Date: May 2007
Posts: 12,599
Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 1185 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Your subject says it perfectly OP....and why bikes that aren't optimized for aerodynamics however do hit the UCI 15 lb weight limit...most standard race bikes have usual aero cues including slippery wheels...why Tarmac's, TCR's now shaped a bit more aero than before...and similar models still have a place in pro racing...also why almost nobody rides disk brakes. Weight matters if elevation changes.

Last edited by Campag4life; 09-20-17 at 04:42 AM.
Campag4life is offline  
Old 09-20-17, 06:31 AM
  #9  
San Pedro
Senior Member
 
San Pedro's Avatar
 
Join Date: Jan 2015
Location: Kota, Aichi, Japan
Posts: 1,274

Bikes: 2011 Giant Seek R3, 2015 Specialized Allez Elite, 2017 Giant TCR Advanced 2

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 342 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by blazin View Post
Course ends at the top of the climb.

That's a stiff hill at the end of a TT. It would be tough for me on any bike. 9% average over three kilometers.
San Pedro is offline  
Old 09-20-17, 06:53 AM
  #10  
Kevindale
Senior Member
 
Kevindale's Avatar
 
Join Date: Apr 2013
Location: Amsterdam
Posts: 1,689

Bikes: 1980 Koga-Miyata Gentsluxe-S, 1998 Eddy Merckx Corsa 01, 1983 Tommasini Racing, 2012 Gulf Western CAAD10, 1980 Univega Gran Premio

Mentioned: 47 Post(s)
Tagged: 0 Thread(s)
Quoted: 597 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Of the first 20 or so riders through the course, most are opting not to change bikes. The first rider on the course had a poor change and ended up getting a push off the carpet. No word yet if he's disqualified, or what penalty he'll get.

EDIT: I'm following it here.

Last edited by Kevindale; 09-20-17 at 07:12 AM.
Kevindale is offline  
Old 09-20-17, 07:29 AM
  #11  
Grasschopper
He drop me
 
Grasschopper's Avatar
 
Join Date: Jul 2004
Location: Central PA
Posts: 11,647

Bikes: '03 Marin Mill Valley, '02 Eddy Merckx Corsa 0.1, '12 Giant Defy Advance, '13 Salsa Vaya

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 123 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Hey...no spoilers plis...I actually do have this being recorded at home. Man I love this new Olympic channel.

__________________
The views expressed by this poster do not reflect the views of BikeForums.net.
Grasschopper is offline  
Old 09-20-17, 08:03 AM
  #12  
San Pedro
Senior Member
 
San Pedro's Avatar
 
Join Date: Jan 2015
Location: Kota, Aichi, Japan
Posts: 1,274

Bikes: 2011 Giant Seek R3, 2015 Specialized Allez Elite, 2017 Giant TCR Advanced 2

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 342 Post(s)
Likes: 0
Liked 1 Time in 1 Post
It's streaming on YouTube. Looks like official feed, FWIW.
San Pedro is offline  
Old 09-20-17, 08:29 AM
  #13  
Grasschopper
He drop me
 
Grasschopper's Avatar
 
Join Date: Jul 2004
Location: Central PA
Posts: 11,647

Bikes: '03 Marin Mill Valley, '02 Eddy Merckx Corsa 0.1, '12 Giant Defy Advance, '13 Salsa Vaya

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 123 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by San Pedro View Post
It's streaming on YouTube. Looks like official feed, FWIW.
oooh....something to do at work. Wait...I'm not finding it...got a link?
__________________
The views expressed by this poster do not reflect the views of BikeForums.net.
Grasschopper is offline  
Old 09-20-17, 09:56 AM
  #14  
Iride01
Senior Member
 
Iride01's Avatar
 
Join Date: Jul 2017
Location: Mississippi
Posts: 2,305

Bikes: '91 Schwinn Paramount '78 Raleigh Competition GS

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 852 Post(s)
Liked 25 Times in 22 Posts
I think part of the difference might be the wider range and more smoother gear transitions you can put on just one bike nowadays. And with electronic shifting you don't have to suffer cadence hits because you didn't shift the front and back correctly to the next higher or lower ratio.

For grand tours it lets the same bike be used for both flats and mountains. You don't see bike changes for mountains like we did in the past. I don't do TT, so I can't say if that's part of it.

New gearing technology is probably causing a lot of rethinking.
Iride01 is offline  
Old 09-20-17, 10:16 AM
  #15  
FlashBazbo
Chases Dogs for Sport
 
FlashBazbo's Avatar
 
Join Date: Feb 2007
Location: Middle Tennessee
Posts: 4,019

Bikes: BMC SLR01 TeamMachine Disk Di2; OPEN new U.P. Di2

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 797 Post(s)
Liked 17 Times in 13 Posts
Originally Posted by rubiksoval View Post
If BMC's TT bikes really weigh 2kg/4.5 lbs more than their road bikes, I'd start looking as to why they have almost a 20 lb bike.

That's amateur-league.
That's actually pretty normal -- because of the wheels, seatpost, and frameset. The PRO rear disc wheel ALONE weighs more than their road bikes' complete wheelset. It's a very heavy wheel. The wheels account for more than 1kg extra. The TM01 frameset probably has at least .5kg on the SLR01 frameset. Pro triathlon and TT bikes routinely weigh 20.5 to 22 pounds, ready to race. On a flat course, it doesn't matter.
FlashBazbo is offline  
Old 09-20-17, 12:28 PM
  #16  
joejack951
Senior Member
 
joejack951's Avatar
 
Join Date: May 2004
Location: Wilmington, DE
Posts: 11,857

Bikes: 2016 Hong Fu FM-079-F, 1984 Trek 660, 2003 Specialized Hardrock, 2004 LOOK KG386i (RIP), 2005 Iron Horse Warrior Expert, 2009 Pedal Force CX1, 2016 Islabikes Beinn 20 (son's)

Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1120 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Dean V View Post
I think it is more than just weight that handicaps a TT bike on a climb. The forward saddle and layout of the handlebars isn't helping either.
Climbing on a TT bike is like climbing on a road bike one size too small. Nothing is in the right place in my albeit brief experience.
joejack951 is offline  
Old 09-20-17, 05:52 PM
  #17  
San Pedro
Senior Member
 
San Pedro's Avatar
 
Join Date: Jan 2015
Location: Kota, Aichi, Japan
Posts: 1,274

Bikes: 2011 Giant Seek R3, 2015 Specialized Allez Elite, 2017 Giant TCR Advanced 2

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 342 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by Grasschopper View Post
oooh....something to do at work. Wait...I'm not finding it...got a link?
Sorry, fell asleep.


UCI channel.

It just popped up on my homepage last night.
San Pedro is offline  
Old 09-20-17, 06:13 PM
  #18  
Athens80
Senior Member
 
Join Date: Aug 2007
Posts: 1,156
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 115 Post(s)
Liked 3 Times in 3 Posts
So how did Primoz Roglič, Wilco Kelderman and Nelson Oliveira do after changing bikes for the final ascent?
Athens80 is offline  
Old 09-20-17, 07:40 PM
  #19  
Bacciagalupe
Professional Fuss-Budget
 
Bacciagalupe's Avatar
 
Join Date: Aug 2005
Posts: 6,472
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
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.
Oh? I'm not so sure about that.

Using the good ol' Kreuzotter: 140lb rider, 200 watts, 20lb bike, 9% grade, 3.4km = 19m 46s. Chop the bike down to 15 lbs, and it's 19m 11s. Assume you lose 15s to the bike change, and that's still a 20s gain.

That's a big advantage in a pro TT. Amateur TT, less so. Club ride, nah.


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?
Uhhhhh.... yeah.

On the flat part of the course, a TT bike will smoke a standard road bike, even an aero road bike.... that is, by the standards of pro racing. That's why riders tend to use TT bikes on flat TT courses.
Bacciagalupe is offline  
Old 09-20-17, 09:21 PM
  #20  
Dean V
Senior Member
 
Join Date: Oct 2009
Posts: 2,368
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 781 Post(s)
Likes: 0
Liked 18 Times in 13 Posts
Your numbers would be closer if you used 400w instead of 200w.
Dean V is offline  
Old 09-20-17, 09:40 PM
  #21  
San Pedro
Senior Member
 
San Pedro's Avatar
 
Join Date: Jan 2015
Location: Kota, Aichi, Japan
Posts: 1,274

Bikes: 2011 Giant Seek R3, 2015 Specialized Allez Elite, 2017 Giant TCR Advanced 2

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 342 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by Athens80 View Post
So how did Primoz Roglič, Wilco Kelderman and Nelson Oliveira do after changing bikes for the final ascent?
Primoz Roglič gained time on the climb after switching bikes according to Velonews. There were cobbles on the climb as well.
San Pedro is offline  
Old 09-20-17, 09:42 PM
  #22  
Doge 
Senior Member
 
Doge's Avatar
 
Join Date: Jan 2014
Location: Southern California, USA
Posts: 9,485

Bikes: 1979 Raleigh Team 753

Mentioned: 141 Post(s)
Tagged: 0 Thread(s)
Quoted: 2930 Post(s)
Liked 36 Times in 28 Posts
Originally Posted by rpenmanparker View Post
Is there a descent? If not, and the climb is very significant, the balance could easily shift from zero to weight.
No.
Doge is offline  
Old 09-20-17, 09:43 PM
  #23  
Doge 
Senior Member
 
Doge's Avatar
 
Join Date: Jan 2014
Location: Southern California, USA
Posts: 9,485

Bikes: 1979 Raleigh Team 753

Mentioned: 141 Post(s)
Tagged: 0 Thread(s)
Quoted: 2930 Post(s)
Liked 36 Times in 28 Posts
Originally Posted by San Pedro View Post
Primoz Roglič gained time on the climb after switching bikes according to Velonews. There were cobbles on the climb as well.
Look him up. Became a pro at 25. Was in a big ski crash @ 21.
Doge is offline  
Old 09-20-17, 09:47 PM
  #24  
Doge 
Senior Member
 
Doge's Avatar
 
Join Date: Jan 2014
Location: Southern California, USA
Posts: 9,485

Bikes: 1979 Raleigh Team 753

Mentioned: 141 Post(s)
Tagged: 0 Thread(s)
Quoted: 2930 Post(s)
Liked 36 Times in 28 Posts
Thing is all bike should be darn close to 6.8kg and measured. Unless I missed the press, that requirement should be there for both bikes. So if the TT bike was 16 lbs, and climbing bike was 15lbs, I expect it is wheels that is making the difference.
Doge is offline  
Old 09-20-17, 09:49 PM
  #25  
Doge 
Senior Member
 
Doge's Avatar
 
Join Date: Jan 2014
Location: Southern California, USA
Posts: 9,485

Bikes: 1979 Raleigh Team 753

Mentioned: 141 Post(s)
Tagged: 0 Thread(s)
Quoted: 2930 Post(s)
Liked 36 Times in 28 Posts
Originally Posted by rubiksoval View Post
If BMC's TT bikes really weigh 2kg/4.5 lbs more than their road bikes, I'd start looking as to why they have almost a 20 lb bike.

That's amateur-league.
Our (kids TT bike is under 16). But wheels are the primary factor. His TT bike with his climbing wheels means add weight.

I would not change bikes.
Doge is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.