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Originally Posted by brianappleby
(Post 5751268)
ok, to sum up, because I'm sick and stuck at home.
Air resistance increases as the square of speed. This means that going twice as fast is going to be pushing wind back at you with 4 times the force. BUT Energy is force times distance, and power is force times speed. This means that going twice as fast actually requires 8 times as much power, if your frontal area/aerodynamics situation doesn't change. Your resistance of "6" doesn't change with speed, so on a stationary bike at the gym, going twice as fast will only require twice as much power. Another way of saying it is that speeding up on a stationary bike will be 4 times easier than a similar speed increase on a real bike. Not to say that training indoors isn't a good idea, it just can't be compared to actual riding. If you know your personal HR zones, then you can get a comparable workout inside as you would outside, and the best measure is power (I would argue), but I haven't seen a bikes at the gym that measures power. (cheap gym) Even then, riding indoors presents a different physiological situation than riding outside. For me at least: I sweat like a b*tch when i'm inside, even with fans on me, and I find it harder to maintain the same HR or power that I would be able to maintain outside. (properly calibrated) I would guess that this is a mixture of warmer temps/higher humidity at the gym (or my garage), and lack of motivation to ride indoors. Moral of the story, it doesn't matter how fast you are. If you have to ask, nobody cares. The correct answer is always "not fast enough". Air resistance increases APPROXIMATELY as the square of velocity. Your "force x distance" argument is WRONG. No offense, but you sound like an intro physics student just plugging numbers into random formulas that they don't understand until something that looks right comes out. The power output of force times velocity is not the bike moving twice as fast, but if you were applying the same force and pedaling at twice the cadence (the force is applied at the crank). Everyone shifts to avoid this, so that's not the point. The argument you've made is essentially that wind resistance increases as the cube of speed, which is less right than the square. The main point, and I think you were trying to make it, is that speeding up outdoors is not the same as speeding up in a gym, and whatever creative resistance/flywheel setup they have does not do a good enough job approximating the real thing so as to be able to compare it with the world outside. *edited for content |
Sometimes, when I'm feeling saucy, I put some blocks under the front wheel and turn a fan on for the 'uphill into a headwind' trainer mode.
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Originally Posted by chill123
(Post 5751316)
ok so what time would an avge cat 4 rider expect to do an outdoor 20mile TT in over an average course?
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Originally Posted by chill123
(Post 5751316)
ok so what time would an avge cat 4 rider expect to do an outdoor 20mile TT in over an average course?
At the Fitchburg stage race in MA, the first stage is a short uphill TT. Keep in mind this is a focal point race for the locals so everyone, from Cat 4s to the Cat 1s, are typically in very good form. For the pros it may be less important. The winning Cat 4 (out of about 120 racers) would have placed 10th in the 3s (out of about 120 racers) and about 60th in the Pro race (110 racers, so about mid pack). This is why time trials do not count towards upgrades. Time trialing measures steady state power. Racing mass start races factors in bike handling skills, speed, and tactical thinking. You can say the same for hill climbing ability. A strong Cat 4 (or 5) climber will typically out climb the majority of Cat 3s and will be able to climb with a lot of strong Cat 2s. Since climbing is related to time trialing (i.e. steady power, but now with weight as a factor), it's an indication of overall fitness and perhaps ability, but not of mass start racing skills. I can't TT or climb - I'd be a Cat 6 if that's how they up/down graded racers. On a phenomenal day in a phenomenal year I can hold 25 mph without going anaerobic. A more normal scenario is 22-23 mph. I rarely train over 17 mph avg per hour, sometimes as low as 12-14 mph. a Cat 3, if you can believe that, cdr |
Originally Posted by chill123
(Post 5751316)
ok so what time would an avge cat 4 rider expect to do an outdoor 20mile TT in over an average course?
lets say if you can crank out 20 miles in 46 minutes you are tooling along a cat 4 level 23 mins/10 miles, twice. good pace |
Originally Posted by kudude
(Post 5751350)
Your "force x distance" argument is WRONG.
BUT -- One problem with the argument is that it assumes that the gym bike has a resistance that is constant vs. speed. Who knows if that's right? Also, it's pointless to argue how some random gym bike compares with real world cycling. There's really no reason to introduce physics into the discussion at all. |
Originally Posted by umd
(Post 5751295)
Btw, sorry I didn't reply back to you sooner, I was out riding real miles on a real road.
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Originally Posted by chill123
(Post 5750904)
waterrockets & umd: are you able to explain why the computrainer miles aren't worth their salt?
when marathon training a few years ago i remember reading up on treadmills quite a bit and the general consensus i found was that you need about a 2% incline to get the similar workout to running outdoors. if 'they' can calibrate a treadmill to be fairly accurate, why not a stationary bike? Clicky, clicky. |
cheers lowcel - me just a newb!
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Originally Posted by edzo
(Post 5751092)
the point I think we are trying to argue, is "how fast am I ?" cannot be estimated unless you
get on a bike and go find out how fast you are for real. trainers do in fact work great, but they will not answer "how fast am I ?" |
Originally Posted by chill123
(Post 5751758)
cheers lowcel - me just a newb!
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I see your Pirates and raise it by Lord of the Rings 1 - 3 all special Edtions over 12 hours. Now that was a challenge and a half. Had never been saddle sore before that!!
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Originally Posted by LowCel
(Post 5751826)
No problem. Just about all of us have done the "am I fast" or "how fast am I" at one point or another. We all get the same answers. :o
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despite the differences in road riding and trainer riding, you still get something out of trainer riding, and it is not necessarily a joke workout
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Originally Posted by LowCel
(Post 5750690)
How about Pirates 1 - 3? Would that be an accomplishment?
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Originally Posted by redirekib
(Post 5750675)
If you can watch Ocean's 11 and Ocean's 12 back to back while staying on a trainer then you have accomplished something.
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Originally Posted by chill123
(Post 5751628)
ever heard of humility?
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Originally Posted by Phantoj
(Post 5751592)
No, it's not. Maybe you should retake your intro physics. :)
BUT -- One problem with the argument is that it assumes that the gym bike has a resistance that is constant vs. speed. Who knows if that's right? Also, it's pointless to argue how some random gym bike compares with real world cycling. There's really no reason to introduce physics into the discussion at all. |
Originally Posted by umd
(Post 5751295)
Look up pro/1/2 times for 40K TTs (close to 20 miles) and you will find your time doesn't stack up very well even if it were real.
Actually the 40k TT is closer to the old 25 mile standard time trial. 40k = 24.8 miles. |
Originally Posted by LowCel
(Post 5750690)
How about Pirates 1 - 3? Would that be an accomplishment?
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Originally Posted by Spartan112
(Post 5755222)
It would be an accomplishment if you could do it without throwing up.
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Originally Posted by kudude
(Post 5751350)
you said some correct things, but overall I'm not sure you made sense.
Air resistance increases APPROXIMATELY as the square of velocity. Your "force x distance" argument is WRONG. No offense, but you sound like an intro physics student just plugging numbers into random formulas that they don't understand until something that looks right comes out. The power output of force times velocity is not the bike moving twice as fast, but if you were applying the same force and pedaling at twice the cadence (the force is applied at the crank). Everyone shifts to avoid this, so that's not the point. The argument you've made is essentially that wind resistance increases as the cube of speed, which is less right than the square. |
Originally Posted by umd
(Post 5752491)
I think its pretty much agreed upon that you can't count that as "miles"
ok so there is no wind resistence and the distance calibration may (or may not) be off slightly. both of these factors can be offset by increasing the level/resistence. it is well accepted that treadmill running can be counted as "miles".....don't forget that the Norwegian runner Ingrid Kristiansen broke the world marathon record after training solely on a treadmill during a Scandinavian winter. |
Originally Posted by chill123
(Post 5755400)
but why?!
For my training I count my trainer miles from using the cycleops 2 trainer together with my powertap. I also count the miles from my computrainer. I do this because by using the powermeter I can compare this training to actual training rides that I have done outside on the bike. I am actually able to get more focused training time inside than I am outside because of fewer variables. I do not count any of the miles from using a stationary bike at the gym, I just count that as cardio time. In my opinion, and this is just my opinion the gym equipment is calibrated to make people feel good about themselves so they will continue to come back. They can say (or think) that they rode 20 miles an hour average even though the same person would do well to average 16 mph out on a real bike in real conditions. |
Originally Posted by kudude
(Post 5752857)
ok, when i said "force x distance" argument it wrong it was. what exactly is right about it? yes work = f x d, and power = f x velocity, but 20 mph at the same force and cadence as 10mph is the same work. Period.
"Force" where? If you're talking about the velocity of the bike (i.e. "the force increases with the square of velocity"), you need to be considering the force applied by the bike tire to the ground to maintain a certain speed. If you're talking about the force at the pedals, and cadence, then you're incorrect to say that the force increases with the square of velocity. Cadence is really irrelevant to the discussion. Climbing a hill is an example of a force (gravity) that is constant with speed. So the power output required varies linearly with speed. Wind drag varies roughly with the square of speed. So the power required varies with the speed cubed. Can you think of a force on the bike that varies linearly with speed? The power required to overcome that force would vary with the speed squared. :) |
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