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Old 12-23-10, 02:36 PM   #1
TrekmanDan
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Max Speed on Flat Ground

My bro in law and I were doing some bike talk just recently and he claims that he did a top speed of 50mph according to the app on his Motorola Droid phone. I basically told him to get a cyclometer because it'd be more accurate, but he says that it IS pretty accurate. He just got his bike over the summer and it's not like he has crazy leg muscles, so is 50mph even possible on flat ground with no wind!? He has a 2009 Jamis Ventura Comp.
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Old 12-23-10, 02:58 PM   #2
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It is possible if your sister is married to Mark Cavendish, Rob McEwen, Thor Hushovd, Alejandro Pettachi, or perhaps Oscar Freire.
If your sister is married to someone else, I'm afraid the Droid Phone is in error.
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Old 12-23-10, 03:08 PM   #3
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Several options here...

a) reading is in km/h not m/h
b) BIL is compensating for something being rather small by exaggerating to the point of ridiculousness
c) app is wildly inaccurate
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Old 12-23-10, 03:20 PM   #4
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d) 30 kt tailwind.
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Old 12-23-10, 03:23 PM   #5
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Clock him in a car.

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Old 12-23-10, 03:30 PM   #6
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It is possible if your sister is married to Mark Cavendish, Rob McEwen, Thor Hushovd, Alejandro Pettachi, or perhaps Oscar Freire.

If your sister is married to someone else, I'm afraid the Droid Phone is in error.
50 mph is about 80 kph. Even if his sister is married to Mark Cavendish, Rob McEwen, Thor Hushovd, Alejandro Pettachi, Oscar Freire or even Super Mario (in his prime), that Droid phone is still wrong.
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Old 12-23-10, 03:35 PM   #7
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No way, in my opinion. If he gets out of the 30's he's done well.
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Old 12-23-10, 03:36 PM   #8
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He probably has it set to kilometers.

50 kph = 31.0685596 mph
Which is still moving at quite a clip.
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Old 12-23-10, 04:02 PM   #9
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HPV, fully streamlined, one guy, Sam Whittingham, pedaling,
current mark is at 133 km/h (83 mph).

http://en.wikipedia.org/wiki/Sam_Whittingham


http://www.ihpva.org/hpvarec3.htm#nom01

Last edited by fietsbob; 12-23-10 at 04:18 PM.
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Old 12-23-10, 04:06 PM   #10
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He probably has it set to kilometers.

50 kph = 31.0685596 mph
Which is still moving at quite a clip.
Quite a clip but if he's talking about a peak speed rather than a sustained speed it's believable. I can hit 25-26mph on flat ground (tarmac) on my mountain bike, so don't have a problem believing someone could hit 30mph on a road bike without being an Olympic athlete.

Sustaining that speed is another matter, of course.
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Old 12-23-10, 04:30 PM   #11
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I think 45-46 mph would put him in world record territory for a flat-ground, no-assist sprint.
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Old 12-23-10, 05:35 PM   #12
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Just go ride with him and ask him to demonstrate..assuming you're in better shape, that is.

Be careful about the "no wind" assumption. There are times when I feel exceptionally fit and fast, and don't realize I have a tailwind. I doubt he did 50 mph with a tailwind, either, but if you want to be sure, go both directions and average or something like that.
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Old 12-23-10, 06:55 PM   #13
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Quite a clip but if he's talking about a peak speed rather than a sustained speed it's believable. I can hit 25-26mph on flat ground (tarmac) on my mountain bike, so don't have a problem believing someone could hit 30mph on a road bike without being an Olympic athlete.

Sustaining that speed is another matter, of course.
I've hit 35 on flat ground. That was a few years ago, but I was still over 50 when I did it. Of course I did it coming off a wheel going probably 27 or so and got to 35 and held it for all of 3.5 seconds before realizing that if I held it for 10 I'd puke.

But remember you are pretty much overcoming wind resistance, and the drag is a function of the SQUARE of yuor speed. That means going 50 would require twice the power outout that 35 does.

Last edited by Keith99; 12-23-10 at 06:58 PM.
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Old 12-23-10, 07:07 PM   #14
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If an observer is in a vehicle travelling at 35 mph toward your BIL riding his bike, then this is feasible.
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Old 12-23-10, 07:08 PM   #15
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I think 45-46 mph would put him in world record territory for a flat-ground, no-assist sprint.
Looking this up is a real pain, it is easy to find records for HPV, whicj means fully enclosed and recumbent.

I pretty much think your numbers are pretty close, but hard to be sure.
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Old 12-23-10, 07:53 PM   #16
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sounds like bs.

Tell your BIL that you will give him $10 for every MPH over 30 he can do on flat ground, not coming off of a hill. Subsequently, he owes you $10 for every MPH under 50 he goes. I'll bet his story changes real quick.
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Old 12-23-10, 07:53 PM   #17
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Apparently my estimate was a little bit low.

There's Wikipedia, here, which shows the UCI record just short of 50 mph, and the 'UCI best human effort' obviously not recumbent, at 56 mph. The recumbent mark is 56 mph, too -- for the hour.

That doesn't make it any more likely that brother-in-law could come anywhere near 50 mph.
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Old 12-23-10, 09:14 PM   #18
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Just go ride with him and ask him to demonstrate..assuming you're in better shape, that is.

Be careful about the "no wind" assumption. There are times when I feel exceptionally fit and fast, and don't realize I have a tailwind. I doubt he did 50 mph with a tailwind, either, but if you want to be sure, go both directions and average or something like that.
I would definitely ride with him, but he's in Michigan and we're down in Texas...
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Old 12-23-10, 09:17 PM   #19
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... But remember you are pretty much overcoming wind resistance, and the drag is a function of the SQUARE of yuor speed. That means going 50 would require twice the power outout that 35 does.
Not to put too fine a point on this discussion, but power increases as the cube of velocity (no wind, level course). Wind resistance, as stated, does increase as the square. 50 mph versus 35 mph requires that power increase by a factor of 2.9.
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Old 12-23-10, 09:22 PM   #20
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I've hit 35 on flat ground. That was a few years ago, but I was still over 50 when I did it. Of course I did it coming off a wheel going probably 27 or so and got to 35 and held it for all of 3.5 seconds before realizing that if I held it for 10 I'd puke.

But remember you are pretty much overcoming wind resistance, and the drag is a function of the SQUARE of yuor speed. That means going 50 would require twice the power outout that 35 does.
I've done 30mph on my mountain bike a couple months ago on flat ground and no wind by pedaling my legs off. Once I hit 30, i knew i couldn't go any faster, so i didn't bother trying. I probably held it for a second or two and that was it. So, if he said mid 30's, I'd definitely say it's realistic, but 50 is another story... Although he didn't claim to have sustained it for more than a few seconds, I definitely think him doing 50mph is impossible.
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Old 12-23-10, 09:32 PM   #21
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Edit: Here's the video of Theo Bos's world record Flying 200 meter: 9.772 seconds for 200 meters. Per Google Calculator, that's (200 meters) / (9.77200 seconds) = 45.78 mph



Lets see... using Bike Calculator:

I'll change bike position to aerobars (yeah, full power on the aerobars, sure.)
bike weight or rider weight doesn't affect the results,
keep grade=0, headwind=0, temperature=75
elevation=1000 feet,
transmission efficiency: increase to 98% from the 95% default.

1700 watts = 50.7 mph.

Changing to drops instead of aerobars:
1700 watts= 46.7 mph.
2100 watts= 50.2 mph. That's kinda difficult.

OK. More realistically, at 1000 watts: a -6% grade (!) would get you 50 mph. That's not bad, since coasting down a -6% grade is about 35 mph.

Last edited by rm -rf; 12-23-10 at 09:48 PM.
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Old 12-23-10, 09:38 PM   #22
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Originally Posted by calamarichris View Post
It is possible if your sister is married to Mark Cavendish, Rob McEwen, Thor Hushovd, Alejandro Pettachi, or perhaps Oscar Freire.
If your sister is married to someone else, I'm afraid the Droid Phone is in error.
HAHA... Mark Cavendish...he's fast, but his big head creates too much drag!
And just an FYI, I'm married to his sister... Brother in law that is.
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Old 12-23-10, 11:48 PM   #23
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Apparently my estimate was a little bit low.

There's Wikipedia, here, which shows the UCI record just short of 50 mph, and the 'UCI best human effort' obviously not recumbent, at 56 mph. The recumbent mark is 56 mph, too -- for the hour.

That doesn't make it any more likely that brother-in-law could come anywhere near 50 mph.
You need to watch your units. The hour record is in kph, not mph.
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Old 12-24-10, 12:22 AM   #24
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My bro in law and I were doing some bike talk just recently and he claims that he did a top speed of 50mph according to the app on his Motorola Droid phone. I basically told him to get a cyclometer because it'd be more accurate, but he says that it IS pretty accurate. He just got his bike over the summer and it's not like he has crazy leg muscles, so is 50mph even possible on flat ground with no wind!? He has a 2009 Jamis Ventura Comp.
Flat ground with no wind means the rider must be pedaling. Bikepedia says that bike has a 50/11 top gear and 700x23mm tires. Sheldons gear calculator puts him at 42.6 mph IF he can spin that gear at 120 RPM. (haha)

Decide for yourself if your brother in law is stronger and can spin the cranks faster than this.
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Old 12-24-10, 10:41 AM   #25
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You need to watch your units. The hour record is in kph, not mph.
I recall a certain group of Rocket Scientists that got miles and kilometers confused,
in the communications , and a soft landing on Mars, came out a little hard.
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