Advertise on Bikeforums.net



User Tag List

Page 4 of 5 FirstFirst ... 2345 LastLast
Results 76 to 100 of 112
  1. #76
    powered by Racer Ex gsteinb's Avatar
    Join Date
    Jun 2005
    Location
    teh Jersey
    Posts
    16,421
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    I'm racing a crit tonight. This has ceased to be relevant.

  2. #77
    Senior Member
    Join Date
    Aug 2013
    Location
    Hoboken, NJ
    My Bikes
    Trek 1.2
    Posts
    618
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(s)
    Where? I know you're not doing FBF

  3. #78
    Ninny globecanvas's Avatar
    Join Date
    Jan 2010
    Location
    The Gunks
    Posts
    1,424
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)
    Rent, most likely

    [edit] no, duh, Exeter.
    Last edited by globecanvas; 06-24-14 at 03:13 PM.

  4. #79
    Senior Member aaronmcd's Avatar
    Join Date
    Aug 2013
    Location
    SF Bay Area, CA
    My Bikes
    Cervelo S2, Ultegra 6700
    Posts
    1,402
    Mentioned
    14 Post(s)
    Tagged
    0 Thread(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?

  5. #80
    ¯\_(ツ)_/¯ Ygduf's Avatar
    Join Date
    Jun 2008
    Location
    Redwood City, CA
    My Bikes
    road bikes
    Posts
    5,945
    Mentioned
    21 Post(s)
    Tagged
    0 Thread(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.

    twitter.com/ygduf
    strava.com/athletes/ygduf

  6. #81
    ¯\_(ツ)_/¯ Ygduf's Avatar
    Join Date
    Jun 2008
    Location
    Redwood City, CA
    My Bikes
    road bikes
    Posts
    5,945
    Mentioned
    21 Post(s)
    Tagged
    0 Thread(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.

    twitter.com/ygduf
    strava.com/athletes/ygduf

  7. #82
    ¯\_(ツ)_/¯ Ygduf's Avatar
    Join Date
    Jun 2008
    Location
    Redwood City, CA
    My Bikes
    road bikes
    Posts
    5,945
    Mentioned
    21 Post(s)
    Tagged
    0 Thread(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

    twitter.com/ygduf
    strava.com/athletes/ygduf

  8. #83
    Ninny globecanvas's Avatar
    Join Date
    Jan 2010
    Location
    The Gunks
    Posts
    1,424
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(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.

  9. #84
    powered by Racer Ex gsteinb's Avatar
    Join Date
    Jun 2005
    Location
    teh Jersey
    Posts
    16,421
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(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.

  10. #85
    Making a kilometer blurry waterrockets's Avatar
    Join Date
    May 2006
    Location
    Austin (near TX)
    My Bikes
    rkwaki's porn collection
    Posts
    26,087
    Mentioned
    19 Post(s)
    Tagged
    0 Thread(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.

  11. #86
    powered by Racer Ex gsteinb's Avatar
    Join Date
    Jun 2005
    Location
    teh Jersey
    Posts
    16,421
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(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.

  12. #87
    Making a kilometer blurry waterrockets's Avatar
    Join Date
    May 2006
    Location
    Austin (near TX)
    My Bikes
    rkwaki's porn collection
    Posts
    26,087
    Mentioned
    19 Post(s)
    Tagged
    0 Thread(s)
    Well, yeah. Heal up fast.

  13. #88
    Killing Rabbits
    Join Date
    Apr 2005
    Posts
    4,688
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(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.

  14. #89
    powered by Racer Ex gsteinb's Avatar
    Join Date
    Jun 2005
    Location
    teh Jersey
    Posts
    16,421
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(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?

  15. #90
    These Guys Eat Oreos Creatre's Avatar
    Join Date
    Jun 2010
    Location
    Atlanta, GA
    My Bikes
    Yes
    Posts
    3,375
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(s)
    It's very very slightly worth more than weight elsewhere. Not sure if it's worth the value without some numbers.
    Category 2 | | Velogames BikeForums Leagues: 1st - 2012 Veulta, 1st - 2011 Vuelta, 2nd - 2013 Vuelta, 3rd - 2012 Giro, 4th - 2012 TdF

  16. #91
    powered by Racer Ex gsteinb's Avatar
    Join Date
    Jun 2005
    Location
    teh Jersey
    Posts
    16,421
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    they're made up. ascribe your value

  17. #92
    Making a kilometer blurry waterrockets's Avatar
    Join Date
    May 2006
    Location
    Austin (near TX)
    My Bikes
    rkwaki's porn collection
    Posts
    26,087
    Mentioned
    19 Post(s)
    Tagged
    0 Thread(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.

  18. #93
    Senior Member
    Join Date
    Aug 2007
    Posts
    1,883
    Mentioned
    13 Post(s)
    Tagged
    0 Thread(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.

  19. #94
    These Guys Eat Oreos Creatre's Avatar
    Join Date
    Jun 2010
    Location
    Atlanta, GA
    My Bikes
    Yes
    Posts
    3,375
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(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.
    Category 2 | | Velogames BikeForums Leagues: 1st - 2012 Veulta, 1st - 2011 Vuelta, 2nd - 2013 Vuelta, 3rd - 2012 Giro, 4th - 2012 TdF

  20. #95
    Senior Member hack's Avatar
    Join Date
    Oct 2006
    Location
    Folsom, CA
    Posts
    1,212
    Mentioned
    8 Post(s)
    Tagged
    0 Thread(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.
    Cat 2 upgrade status: never

  21. #96
    ¯\_(ツ)_/¯ Ygduf's Avatar
    Join Date
    Jun 2008
    Location
    Redwood City, CA
    My Bikes
    road bikes
    Posts
    5,945
    Mentioned
    21 Post(s)
    Tagged
    0 Thread(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)

    twitter.com/ygduf
    strava.com/athletes/ygduf

  22. #97
    In the Pain Cave thechemist's Avatar
    Join Date
    Mar 2008
    Location
    Nashville, TN
    Posts
    1,661
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(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

  23. #98
    powered by Racer Ex gsteinb's Avatar
    Join Date
    Jun 2005
    Location
    teh Jersey
    Posts
    16,421
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(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?

  24. #99
    Senior Member
    Join Date
    Sep 2010
    Posts
    651
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(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.

  25. #100
    Ninny globecanvas's Avatar
    Join Date
    Jan 2010
    Location
    The Gunks
    Posts
    1,424
    Mentioned
    7 Post(s)
    Tagged
    0 Thread(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.

Page 4 of 5 FirstFirst ... 2345 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •