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 Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling Do you enjoy centuries, double centuries, brevets, randonnees, and 24-hour time trials? Share ride reports, and exchange training, equipment, and nutrition information specific to long distance cycling. This isn't for tours, this is for endurance events cycling

06-16-14, 07:18 PM   #51
Jim Kukula
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 Originally Posted by Jim Kukula the big hill today was about 14%.
Here is a fun way to look at the climbing on a route. I download the data from mapmyride and then in excel I compute the distance and grade for each little segment and then sort those pairs of values and make a scatter plot. Anyway you can see from this that about 1 km of this ride was above 9% grade - and half of that was above 12%.

Here was a brutal ride from a couple years ago, 70 miles with maybe 5 miles above 10%:

Last edited by Jim Kukula; 06-16-14 at 07:25 PM. Reason: add another ride for comparison

06-28-14, 07:26 AM   #53
Steamer
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 Originally Posted by hamster It's not hard to demonstrate that it isn't. Let's use a calculator at Bicycle Speed (Velocity) And Power Calculator and plug in some numbers. For simplicity, assume that we have a trip that consists of 1 mile uphill at 4%, 1 mile downhill at 4% and 1 mile flat. Pick "racing bicycle - hands on the tops", plug in bike weight 20 lbs, rider weight 160 lbs, power 145 W (2 W/kg - very conservative for a male rider getting back into shape), leave all else at default values.
Hmmm.

My own personal power data from a couple 200Ks, a 12 hr race, and a bazzillion training rides suggests that my ultramarathon limit is at around 60% of FTP. And that's if I am highly motivated. More realistically, it's closer to 50%. That ultramarathon limit is reached somewhere around 6 to 8 hours, or longer.

For a 160 lb rider, who is essentially new to the sport, to have an FTP of 280W is pretty unrealistic.

06-28-14, 11:09 AM   #54
hamster
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 Originally Posted by Steamer Hmmm. My own personal power data from a couple 200Ks, a 12 hr race, and a bazzillion training rides suggests that my ultramarathon limit is at around 60% of FTP. And that's if I am highly motivated. More realistically, it's closer to 50%. That ultramarathon limit is reached somewhere around 6 to 8 hours, or longer. For a 160 lb rider, who is essentially new to the sport, to have an FTP of 280W is pretty unrealistic.
Re-read the starting post in the thread. The person is complaining about being unable to go faster than 10.1 mph even during 2-3 hour rides. My power data has me at 87% FTP for 1h50 and 71% FTP for 3 hours (and I can probably do better than the second number).

Further, the calculation assumes that he's pedaling all the way downhill at constant power. Let's make the model more realistic. Suppose that he goes up hills at 145 W, on flats at 100 W, and coasts downhills after getting up to terminal velocity. That only drops his average speed to 12.7 while dropping his average power to 104 W.

Finally note that my route profile has 70 ft/mile of climbing, which would be pretty hilly even by upstate NY standards.

06-28-14, 12:27 PM   #55
Steamer
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 Originally Posted by hamster Re-read the starting post in the thread. The person is complaining about being unable to go faster than 10.1 mph even during 2-3 hour rides. My power data has me at 87% FTP for 1h50 and 71% FTP for 3 hours (and I can probably do better than the second number). Further, the calculation assumes that he's pedaling all the way downhill at constant power. Let's make the model more realistic. Suppose that he goes up hills at 145 W, on flats at 100 W, and coasts downhills after getting up to terminal velocity. That only drops his average speed to 12.7 while dropping his average power to 104 W. Finally note that my route profile has 70 ft/mile of climbing, which would be pretty hilly even by upstate NY standards.
Consider how flat the CP curve is in the region beyond hours. That only distorts things by a small amount, perhaps 10%. At least that's what my data shows, anyways. It's possible your FTP could be underestimated. That's not a rare problem.

I mentioned the ultramarathon limit mostly because that's the number I have been most interested in, and have the best handle on, and would be the limit of interest to a person completing a 200K, as was referenced by the OP as being his goal.

Aside from that, do you know the CdA and Crr used in that calculator? As you alluded to, therein may lie at least part of the OP's speed problem.

The rest of the discrepancy between your calculation and the OP's report speeds probably lies in his weight (bike plus rider plus crapola/baggage).

Last edited by Steamer; 06-28-14 at 12:31 PM.

06-28-14, 01:17 PM   #56
hamster
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 Originally Posted by Steamer Consider how flat the CP curve is in the region beyond hours. That only distorts things by a small amount, perhaps 10%. At least that's what my data shows, anyways. It's possible your FTP could be underestimated. That's not a rare problem. I mentioned the ultramarathon limit mostly because that's the number I have been most interested in, and have the best handle on, and would be the limit of interest to a person completing a 200K, as was referenced by the OP as being his goal. Aside from that, do you know the CdA and Crr used in that calculator? As you alluded to, therein may lie at least part of the OP's speed problem. The rest of the discrepancy between your calculation and the OP's report speeds probably lies in his weight (bike plus rider plus crapola/baggage).

If anything, my FTP is overestimated. Here are the numbers from 2013: 216 W @ 0:30, 201 W @ 1:00, 193 W @ 1:50 (4300' hill climb), 158 W @ 3:00, 154 W @ 4:00 (6000' hill climb), estimated FTP 220 W.

My last two ultras were a double century with 52'/mile of climbing at average speed 14.4 mph, average moving speed 15.5 mph and average power 115 W, and ... let's call it a 200k (unsupported) with 69'/mile of climbing, with average speed 12.7 mph, average moving speed 14.2 mph and average power 110 W.

CdA and Crr used by the calculator are displayed at the bottom. At our settings, it was using CdA 5.26 ft2 and Crr 0.0033. And yes, that's precisely my point.