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Your average speed is time averaged. You spend much more time going up then coming down. Hills will always lower your average speed.
How much? Depends on the size and number of hills. I have two routes one with hills and one that is relatively flat of roughly the same length. My average speed on the hill route is consistently 3 mph less then flat. And the hill course is more taxing then the flat course. Someday I hope to be able to maintain my speed up those hills but not right now.... |
Originally Posted by Paul01
(Post 12692831)
Potential energy is the last food you ate? No?
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Originally Posted by Runner 1
(Post 12692905)
Okay, this brings me to the next logical question then...
On flat, wind-less ground, what sort of 40 km time trials (or whatever the most popular distance is) correspond to what categories? I know Pro1/2 is like 27+ mph, but what about Cat 3, 4, and 5? Like maybe 25, 23, 21? Then go out and do the same route and compare away. You could get even more detailed by going to wunderground.com and looking up the historical weather data for that day and the time and compare that to the day and time you ride the route. Here is one I found in less than a minute for a Cat 4/5 time trial. http://connect.garmin.com/activity/86999466 |
Originally Posted by bikerjp
(Post 12692193)
Care to share the secret? I don't see anything on the Garmin connect site settings for stopped/moving min or similar setting.
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Originally Posted by AdelaaR
(Post 12692315)
I said you gain "potential energy" and then afterwards you release it to go faster on the descent.
This is not some sort of magic but physics :) |
Originally Posted by pallen
(Post 12693518)
On the 705, when you log into Garmin Connect and upload, you will see Average Speed and Moving Average in the report. I think you can also add this as a data field on the screen if you want. You have to customize the layout.
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BTW the physics is correct, you could theoretically get all the energy back you put into climbing the hill. Unfortunately, it just doesnt work that way. The human body is not a perfect adiabatic engine. You end up wasting all kinds of energy generating heat, friction in your muscles, chemical inefficiencies, etc. You are not operating at your highest efficiency when you are climbing a hill and your body is not requiring 0 energy while you are going down. Throw in wind, braking, rolling friction, etc and your average is definitely taking a hit when you ride through hills.
Of course, we all know that looking at averages is pointless anyway... |
Originally Posted by bikerjp
(Post 12693560)
I see the data, I'm wondering how to tell the Garmin to not stop recording data at low speeds.
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Originally Posted by Runner 1
(Post 12692837)
I like to consider the laws of physics to be suggestions.
Anyway, a lot more replies than I expected! In case you're wondering, the reason I'm trying to "compare" my average speed is because I'm a college kid without a job who has all summer to train as much as I want each day (nice, right?) and it's really the only method of comparison I have to see how well I'm doing. Racing's not too popular where I live and I won't be able to get into that until I go back to school in the fall, so I can't compare myself against cat-whatever racers. And there's no way I can afford a power meter. So that pretty much leaves average speed. Although... I just realized there is a perfectly flat 1 mile loop around a local high school. Once the school is empty for summer, I can go and time trial around it and I think that would give me the best basis for comparison. Anyway, thanks for your all's help! It does seem like the hills can indeed make a good bit of difference. In regards to the climbing, I'll take 10-15 minutes going up a hill on the way out, and it takes me like 5 minutes on the way back in, so I do spend a lot more time at a slower speed. So practise and watch your average speed over a known loop. Be aware that some days you'll have a headwind and some days you'll have a tailwind. Some days you're the pigeon and some days you're the statue. Hopefully over time your average speed will trend upwards. If you find yourself being the guy who always overtakes everyone else then your speed is above average. If you're always being overtaken then you're below average. If you get your average speed up to X mph and come on here to find people claiming X+5 mph then either they are fitter than you, or they are measuring it a different way, or they are lying. |
Originally Posted by pallen
(Post 12693609)
If I understand what mine is doing properly, its always recording everything, and reports both averages - including the stops and excluding.
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They make your average speed decrease when you go up, and increase when you go down. Kinda like how going slowly over flat land makes your average decrease, and it increases when you speed up. Math doesn't care if there are hills in the way.
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Originally Posted by Runner 1
(Post 12690327)
I wouldn't think hills would make more than a 1-2 mph speed difference (avg) but I don't know... has anyone done a comparison between their average on hilly terrain (eg North Georgia) vs flat (Florida)?
21.5 MPH on flat ground 20.5 MPH up a .3% false flat 22.5 MPH down a .3% false flat 21.5 MPH average 25.0 MPH down a 1% hill 18.2 MPH up a 1% hill 21.1 MPH average 12.5 MPH up a 3% hill 31.6 MPH down a 3% hill 17.9 MPH average 7.6 MPH up a 6% grade 40.3 MPH down a 6% grade 12.8 MPH average 4.1 MPH up a 12% grade 52.4 MPH down a 12% grade 7.6 MPH average (this was originally a typo at 11.4) Traffic lights can also make a big difference even when your bike computer stops when you're not moving - I spend as much time not pedaling approaching them as I do actually stopped and you also need to accelerate back to full speed. |
Originally Posted by Drew Eckhardt
(Post 12693769)
Neglecting traffic lights 200W might net
4.1 MPH up a 12% grade 52.4 MPH down a 12% grade 11.4 MPH average |
He did say "200W" ... so what I think he means is that with a consistent power output of 200 Watts you will get those numbers.
This is completely irrelevant in the real world because people are able to use anaerobic power to get much higher wattages while going up and then recover while coasting down. |
Originally Posted by bikerjp
(Post 12693698)
Someone mentioned earlier that if you are going too slow, the Garmin may stop recording. Apparently the speed at which it decides you are not moving can be adjusted and that's what I'm trying to figure out.
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Someone please check my math.
4.1 mph up a 12% grade that is 4.1 miles long would take 1 hour. Descending that same 4.1 mile long 12% grade at 52.4 mph would take about 4 minutes 40 seconds. Total time to travel 8.2 miles is 64:40 and an average speed of about 7.6 mph. |
Uphill, 1 hour.
Downhill, near enough (4:41.7 to be pedantic) So total time of 64:40 to do 8.2 miles = 7.605mph Of course that assumes the speeds you've quoted are actually achieved... |
Now there's something I am not familiar with, having no hills on a ride. Is that possible? Do people actually have places to ride without hills? :-)
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Originally Posted by ladyraestewart
(Post 12694097)
Now there's something I am not familiar with, having no hills on a ride. Is that possible? Do people actually have places to ride without hills? :-)
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Originally Posted by AdelaaR
(Post 12693842)
He did say "200W" ... so what I think he means is that with a consistent power output of 200 Watts you will get those numbers.
This is completely irrelevant in the real world because people are able to use anaerobic power to get much higher wattages while going up and then recover while coasting down. Head up-hill 5500' over 20 miles (like once Grand Mesa gets steep on the Colorado Western slope) and you won't even manage threshold power. A hypothetical 180 pound rider averaging 200W will be spending 2.25 hours before he gets to the downhill leg. The first 45 minutes of the last short hilly California ride I went on had 5-10 minute up-hill chunks separated by a minute or two down-hill and might have allowed for 5% over threshold power on the long chunks which isn't significant and perhaps 10% on the short ones. OTOH, for a highway overpass I might just work 70-100% harder and spin up. |
For long climbs this is correct indeed.
I don't have any of those available though. |
Originally Posted by bikerjp
(Post 12693806)
How did you calculate the average speed? Miles per hour is a distance divided by time function and there isn't any time or distance in your numbers.
200 Watts is a reasonable power output most male cyclists should be able to manage. I assumed it for up-hill and down-hill until I got to the 12% grade at which point I figured the cyclist would be spun-out and no longer pedaling. Distance/speed = time Distance/time = speed (1 mile up + 1 mile down) / ( (1 mile up) / (miles/hour up) + (1 mile down) / (miles/hour down)) You could use any other distance and it would work out the same. |
Originally Posted by bikerjp
(Post 12693861)
Someone please check my math.
4.1 mph up a 12% grade that is 4.1 miles long would take 1 hour. Descending that same 4.1 mile long 12% grade at 52.4 mph would take about 4 minutes 40 seconds. Total time to travel 8.2 miles is 64:40 and an average speed of about 7.6 mph. 2/(1/4.1 + 1/52.4) 7.604955766 |
Originally Posted by Drew Eckhardt
(Post 12694206)
Right - there was a typo in that one
2/(1/4.1 + 1/52.4) 7.604955766 |
Originally Posted by bikerjp
(Post 12694374)
Perfect. Then this would seem to settle the debate about whether or not hills impact your average speed. Clearly we can all do better than 7.6 mph average on flat roads - many people claim over 20 mph. Up and down 12% grades would seriously impact our average and your other examples also show similar, although less severe, impacts on average speed.
/Thread. |
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