Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

"The 33"-Road Bike Racing We set this forum up for our members to discuss their experiences in either pro or amateur racing, whether they are the big races, or even the small backyard races. Don't forget to update all the members with your own race results.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 06-24-14, 02:51 PM   #76
gsteinb
out walking the earth
Thread Starter
 
gsteinb's Avatar
 
Join Date: Jun 2005
Location: teh Jersey
Bikes:
Posts: 19,851
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
I'm racing a crit tonight. This has ceased to be relevant.
gsteinb is offline   Reply With Quote
Old 06-24-14, 02:58 PM   #77
Gramercy
Senior Member
 
Join Date: Aug 2013
Location: Hoboken, NJ
Bikes: Trek 1.2
Posts: 812
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Where? I know you're not doing FBF
Gramercy is offline   Reply With Quote
Old 06-24-14, 03:03 PM   #78
globecanvas
Ninny
 
globecanvas's Avatar
 
Join Date: Jan 2010
Location: The Gunks
Bikes:
Posts: 4,436
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 126 Post(s)
Rent, most likely

[edit] no, duh, Exeter.

Last edited by globecanvas; 06-24-14 at 03:13 PM.
globecanvas is offline   Reply With Quote
Old 06-24-14, 03:30 PM   #79
aaronmcd
Senior Member
 
aaronmcd's Avatar
 
Join Date: Aug 2013
Location: SF Bay Area, CA
Bikes: Cervelo S5
Posts: 2,460
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 55 Post(s)
Quote:
Originally Posted by globecanvas View Post
Popularly known as "watts."



Ignoring everything but gravity and keeping power constant, time is linear with mass. So your method is fine. Cutting weight in half cuts climbing time in half. Cutting weight to zero places you at both the top and bottom of the hill at the same time.
What will happen if you ride at ~2.998*10^8 m/s?
aaronmcd is offline   Reply With Quote
Old 06-24-14, 04:08 PM   #80
Ygduf 
¯\_(ツ)_/¯
 
Ygduf's Avatar
 
Join Date: Jun 2008
Location: Redwood City, CA
Bikes: aggressive agreement is what I ride.
Posts: 9,393
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 78 Post(s)
Quote:
Originally Posted by globecanvas View Post
Popularly known as "watts."



Ignoring everything but gravity and keeping power constant, time is linear with mass. So your method is fine. Cutting weight in half cuts climbing time in half. Cutting weight to zero places you at both the top and bottom of the hill at the same time.
that's what I'm saying. There's a lot of effort being expended where you can get a really good guess just using a the ratio of time/weight with consistent power. I round down to account for additional wind and crr at higher speed.
__________________

strava.com/athletes/ygduf
Ygduf is offline   Reply With Quote
Old 06-24-14, 04:09 PM   #81
Ygduf 
¯\_(ツ)_/¯
 
Ygduf's Avatar
 
Join Date: Jun 2008
Location: Redwood City, CA
Bikes: aggressive agreement is what I ride.
Posts: 9,393
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 78 Post(s)
Quote:
Originally Posted by aaronmcd View Post
What will happen if you ride at ~2.998*10^8 m/s?
you'd burn up from the heat generated by the wind well before you reached the top.
__________________

strava.com/athletes/ygduf
Ygduf is offline   Reply With Quote
Old 06-24-14, 04:09 PM   #82
Ygduf 
¯\_(ツ)_/¯
 
Ygduf's Avatar
 
Join Date: Jun 2008
Location: Redwood City, CA
Bikes: aggressive agreement is what I ride.
Posts: 9,393
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 78 Post(s)
Quote:
Originally Posted by gsteinb View Post
I'm racing a crit tonight. This has ceased to be relevant.
that has never stopped us before
__________________

strava.com/athletes/ygduf
Ygduf is offline   Reply With Quote
Old 06-24-14, 04:21 PM   #83
globecanvas
Ninny
 
globecanvas's Avatar
 
Join Date: Jan 2010
Location: The Gunks
Bikes:
Posts: 4,436
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 126 Post(s)
Quote:
Originally Posted by Ygduf View Post
you'd burn up from the heat generated by the wind well before you reached the top.
At that point I think the wind is less of a factor than other issues like tunneling through the multiverse and accidentally becoming your own grandfather.
globecanvas is offline   Reply With Quote
Old 06-25-14, 03:27 AM   #84
gsteinb
out walking the earth
Thread Starter
 
gsteinb's Avatar
 
Join Date: Jun 2005
Location: teh Jersey
Bikes:
Posts: 19,851
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
crashed on the bell lap, sitting in the four hole and certain I'd win the field sprint. going to become a hill climb specialist, so carry on.
gsteinb is offline   Reply With Quote
Old 06-25-14, 05:57 AM   #85
waterrockets 
Making a kilometer blurry
 
waterrockets's Avatar
 
Join Date: May 2006
Location: Austin (near TX)
Bikes: rkwaki's porn collection
Posts: 26,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Quote:
Originally Posted by gsteinb View Post
crashed on the bell lap, sitting in the four hole and certain I'd win the field sprint. going to become a hill climb specialist, so carry on.
That really blows. You and shovel doing alright? Sucks when guys like you go down, because I know you weren't just overreacting to something in front of you like 99% of the crash videos posted around here. Well, and it sucks for anyone to crash.
waterrockets is offline   Reply With Quote
Old 06-25-14, 07:56 AM   #86
gsteinb
out walking the earth
Thread Starter
 
gsteinb's Avatar
 
Join Date: Jun 2005
Location: teh Jersey
Bikes:
Posts: 19,851
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
In tge the interest of fairness some times things just happen I crashed on tge bell lap at the pointy end of the field (2 away). A bunch of us were going aggressive for the same small space. The rider I collided with cdt's teammate was up against tge barrier and had no where to go. He saw it as my fault. Of course I didn't think he belonged where he was.
gsteinb is offline   Reply With Quote
Old 06-25-14, 08:35 AM   #87
waterrockets 
Making a kilometer blurry
 
waterrockets's Avatar
 
Join Date: May 2006
Location: Austin (near TX)
Bikes: rkwaki's porn collection
Posts: 26,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Well, yeah. Heal up fast.
waterrockets is offline   Reply With Quote
Old 06-25-14, 10:29 AM   #88
Enthalpic
Killing Rabbits
 
Join Date: Apr 2005
Bikes:
Posts: 5,142
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Quote:
Originally Posted by Gnosis View Post
The following is intended respectfully.

It’s unnecessary to compute the additional element of “force”, as there’s a more direct method being that you already know the three key factors, those being, the object’s mass, the gain in vertical elevation (height), and gravity’s accelerative influence, 9.8 m/s/s.

In such cases, we more simply apply the straightforward longstanding equation associated with “gravitational potential energy” as provided below:

E = mgh

Whereby,

E = gravitational potential energy “in Joules”
m = mass of object “in kg”
g = acceleration via gravity, a constant 9.8 m/s/s
h = height to which object must be raised “in meters”

.25 pounds * .45359237 = .113398093 kg mass
3,000 feet * .3048 = 914.4 meters height

Once the conversion to SI (Standard International) units has been made, we apply these factors to the gravitational potential energy equation, E = mgh, to yield the product, Joules of energy:

.113398093 kg * 9.8 m/s/s * 914.4 meters = 1016.173915 Joules of energy

If we wish to derive the average power required per second during the ascent, we merely divide the Joules of energy by the total seconds required to achieve the desired gain in vertical elevation (height). For instance, if it requires 1 hour, we divide by 3,600 seconds:

1016.173915 Joules / 3,600 seconds = 0.282270532 Joules of energy (per second)

Thus, the element of “force” need not be computed. Naturally, it’s anyone’s prerogative to compute the desired outcome it in any manner that yields the correct answer however, this is the most direct method in physics concerning this matter.
-10% due to sig figs.
Enthalpic is offline   Reply With Quote
Old 08-08-14, 07:04 AM   #89
gsteinb
out walking the earth
Thread Starter
 
gsteinb's Avatar
 
Join Date: Jun 2005
Location: teh Jersey
Bikes:
Posts: 19,851
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
so 1.25-1.5 pounds in the wheels...is that more significant than similar weight somewhere else, and and in real world terms of time and dollars and sense what's it worth?
gsteinb is offline   Reply With Quote
Old 08-08-14, 07:22 AM   #90
Creatre
These Guys Eat Oreos
 
Creatre's Avatar
 
Join Date: Jun 2010
Location: Atlanta, GA
Bikes: Yes
Posts: 3,422
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It's very very slightly worth more than weight elsewhere. Not sure if it's worth the value without some numbers.
Creatre is offline   Reply With Quote
Old 08-08-14, 07:23 AM   #91
gsteinb
out walking the earth
Thread Starter
 
gsteinb's Avatar
 
Join Date: Jun 2005
Location: teh Jersey
Bikes:
Posts: 19,851
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
they're made up. ascribe your value
gsteinb is offline   Reply With Quote
Old 08-08-14, 08:06 AM   #92
waterrockets 
Making a kilometer blurry
 
waterrockets's Avatar
 
Join Date: May 2006
Location: Austin (near TX)
Bikes: rkwaki's porn collection
Posts: 26,130
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I ran numbers based on actual 4-corner crit accelerations. If you completely removed the weight of decent tires and tubes from the wheels, it was something like 1/5 of a Watt average for the race, just from rotational accelerations -- which is the only difference from carrying the weight elsewhere. Since some of this rotating weight might be in the hub too, where it has much less torsional influence, 1/5 of a Watt is an unlikely-to-be-met maximum.

If you're on a course with little or no braking, then it's probably a wash, as the rotational inertia will help you carry speed into a hill.
waterrockets is offline   Reply With Quote
Old 08-08-14, 09:10 AM   #93
tetonrider
Senior Member
 
Join Date: Aug 2007
Bikes:
Posts: 3,526
Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 105 Post(s)
yep, what WR says is correct. there's a difference but it is so small as to not be worth considering.

in most cases, aero trumps weight. most = when grades are below 6% and when one rides down whatever was ridden up. for special cases (finishing climbs are pure HCs with grades 6% or steeper) weight starts to get a small advantage.

the amount varies with rider weight and power, but at "normal" racer weights and power the above is true. the lighter/faster you are, the greater the benefit of aero gear. i.e., chris froome can benefit from aero equipment up steeper grades than i can.
tetonrider is offline   Reply With Quote
Old 08-08-14, 09:22 AM   #94
Creatre
These Guys Eat Oreos
 
Creatre's Avatar
 
Join Date: Jun 2010
Location: Atlanta, GA
Bikes: Yes
Posts: 3,422
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by tetonrider View Post
yep, what WR says is correct. there's a difference but it is so small as to not be worth considering.

in most cases, aero trumps weight. most = when grades are below 6% and when one rides down whatever was ridden up. for special cases (finishing climbs are pure HCs with grades 6% or steeper) weight starts to get a small advantage.

the amount varies with rider weight and power, but at "normal" racer weights and power the above is true. the lighter/faster you are, the greater the benefit of aero gear. i.e., chris froome can benefit from aero equipment up steeper grades than i can.
^ That's why I went aero vs light on my new build. Could have gotten a frame for about the same price that would have built to about 1lb lighter if focused on weight. But already being 1.9 lbs/in, I went the aero route. Because of my low weight I don't generate the raw watts of bigger guys, and need that wind savings as much as possible on flats/rollers.
Creatre is offline   Reply With Quote
Old 08-08-14, 10:00 AM   #95
hack
Senior Member
 
hack's Avatar
 
Join Date: Oct 2006
Location: Folsom, CA
Bikes:
Posts: 3,134
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 80 Post(s)
So...in general, for the average cyclist/racer, it's better (in terms of performace, $$, and watts saved) to lose 5 pounds from the body than 0.5-1 pound from the bike? I'm starting to feel like this bike industry has duped me.
hack is offline   Reply With Quote
Old 08-08-14, 10:19 AM   #96
Ygduf 
¯\_(ツ)_/¯
 
Ygduf's Avatar
 
Join Date: Jun 2008
Location: Redwood City, CA
Bikes: aggressive agreement is what I ride.
Posts: 9,393
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 78 Post(s)
Quote:
Originally Posted by tetonrider View Post
in most cases, aero trumps weight. most = when grades are below 6% and when one rides down whatever was ridden up. for special cases (finishing climbs are pure HCs with grades 6% or steeper) weight starts to get a small advantage.

the amount varies with rider weight and power, but at "normal" racer weights and power the above is true. the lighter/faster you are, the greater the benefit of aero gear. i.e., chris froome can benefit from aero equipment up steeper grades than i can.
this is the prevailing logic now among the people I trust to give good advice.

I still went with reynolds rims over zipp for the 200g weight advantage because I'm a sucker (and 1/3 the cost and relatively minor aero delta to boot)
__________________

strava.com/athletes/ygduf
Ygduf is offline   Reply With Quote
Old 08-08-14, 12:41 PM   #97
thechemist
In the Pain Cave
 
thechemist's Avatar
 
Join Date: Mar 2008
Location: Nashville, TN
Bikes:
Posts: 1,669
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Ygduf View Post
this is the prevailing logic now among the people I trust to give good advice.

I still went with reynolds rims over zipp for the 200g weight advantage because I'm a sucker (and 1/3 the cost and relatively minor aero delta to boot)

I really agree with the above logic. I just wish I saw what I believe in practice more often. Granted, it is good if competition doesn't catch on but...

1) why don't I see more skinsuits in crits?
2) shoe covers?
3) deeper wheels? Our main local crit is not technical at all. One wide 180 is about the only real braking needed and to that degree I would rock stinger 90/70 combo or similar if I had the funds.

What gets interesting @Ygduf is not only the weight savings of a wheel like reynolds but how each company decides on what yaw angle to focus on. I think over the course of a crit you won't see much past 10 degrees in a typical paceline and often wonder why more companies don't focus on low yaw angles. HED for example is VERY good at low yaw angles
thechemist is offline   Reply With Quote
Old 08-08-14, 12:45 PM   #98
gsteinb
out walking the earth
Thread Starter
 
gsteinb's Avatar
 
Join Date: Jun 2005
Location: teh Jersey
Bikes:
Posts: 19,851
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 32 Post(s)
Let's tip the hill above 6%. Make it 8, for an hour. What's a pound save, and what $ amount would you be willing to spend under what circumstances?
gsteinb is offline   Reply With Quote
Old 08-08-14, 01:24 PM   #99
misterwaterfall
Senior Member
 
Join Date: Sep 2010
Bikes:
Posts: 1,241
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by thechemist View Post
I really agree with the above logic. I just wish I saw what I believe in practice more often. Granted, it is good if competition doesn't catch on but...

1) why don't I see more skinsuits in crits?
2) shoe covers?
3) deeper wheels? Our main local crit is not technical at all. One wide 180 is about the only real braking needed and to that degree I would rock stinger 90/70 combo or similar if I had the funds.
In our local crits, skinsuits, covers, and deep wheels are the norm. Usually 404s/808s or similar on about half the bikes, other half are regular depth for people who know they aren't sprinting for the win.
misterwaterfall is offline   Reply With Quote
Old 08-08-14, 02:09 PM   #100
globecanvas
Ninny
 
globecanvas's Avatar
 
Join Date: Jan 2010
Location: The Gunks
Bikes:
Posts: 4,436
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 126 Post(s)
Quote:
Originally Posted by gsteinb View Post
Let's tip the hill above 6%. Make it 8, for an hour. What's a pound save, and what $ amount would you be willing to spend under what circumstances?
8% for an hour and some reasonable other assumptions, I think a pound off the bike works out to 20-30 seconds saved on the climb.

I don't have a specific enough scenario in mind to opine about the dollar value of saving that time.


Quote:
Originally Posted by tetonrider View Post
in most cases, aero trumps weight. most = when grades are below 6% and when one rides down whatever was ridden up.
This is true in the absence of other race dynamics (consider a spherical cow...), but personally I opt for weight over aero if there are any hills over about 7 minutes. Losing the lead group by a few seconds can be the whole race, and chasing back on the descent is a lot more exhausting than holding the wheel over the top.

Most of my opinion on this matter is informed by a single race with a 10 minute, 4% varied hill, where I chose heavier aero wheels, fell off the breakaway by just a few seconds on the climb, and couldn't get back on. A pound off the wheels might have kept me in the break.

Last edited by globecanvas; 08-08-14 at 02:13 PM.
globecanvas is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 11:51 AM.