RChung

Yeah. You could plot crank torque on the y-axis and cadence on the x-axis; then power will be a series of hyperbolas or contours. My guess is that along the same contour (and thus the same power) you'll perceive a difference in how that power was generated.



In this plot, look at where the "center of mass" is for 200 watts, then move up to 300 watts, then 400. I think you'll see that there's an overall pattern.

PeteHski

Does it feel harder simply because you are effectively over-geared at 15% and your cadence has dropped very low. Therefore you are relying on muscle strength more than cardio?

terrymorse 

Maybe it's the lower cadence that makes it feel harder. But I just looked at a steep segment from today, and my cadence was 65 -- not "that low". On a 7% segment, my cadence was 75.

RCMoeur 

Do you remember which website this was? Back when I worked for Arizona DOT I could go down to Engineering Records and pull the plan set for a state highway segment to see the profile grade, but roads like Gates Pass owned by other agencies weren't typically available. Below is a sample plan and profile from back in the ink and blueprint days, from AZ 177 at "End of the World" between Winkelman and Superior on the classic Mining Country loop:


I can attest to that 10% grade being a bit of a challenge.

This is the hill leading into my neighborhood, as seen from the Google Street View camera:


I rode this twice yesterday on my fixie (both up & down). I surveyed it with a level and rod a while back, and the maximum grade is 17%, but fortunately only for less than 100 leg-straining feet.

Another steep hill in north Phoenix was 9th Street coming into the Pointe Tapatio Cliffs resort. This private road is now closed and double-gated due to slope instability, but was a 20% grade my friends and I used to have grudge sprints up when we were in the mood. Had a few people run out of momentum before they got to the top and pull a "full Arte" as gravity won out over balance and down they went. Again we turn to (annotated and corrected) Google Street View - it's the upper street in this picture.

andrewclaus

[QUOTE=RCMoeur;23044416]Do you remember which website this was?...[QUOTE]

No, and you're right, it wouldn't have been ADOT. It may have been Pima County, but I can't find it now. All I see are biking sites and I wouldn't trust those.

Gates Pass Road doesn't strike me as particularly steep--I was surprised to see the 13% number, somewhere. I lived in Phoenix for a couple of years and never rode those slopes you mention. There were a few steep local roads in Prescott, where I lived for four years. Local lore was that they were 15%, but I never saw any engineering data to back that up.

RChung

A bit more than a decade ago I corresponded with a guy who was trying my approach to measuring CdA and Crr. He had laid out the roads in a nearby subdivision but during the 2008-9 crash the developer had gone bankrupt so the place was empty and there was no traffic so he was using one of the hills he'd laid out for aero testing. He couldn't get the virtual slope and virtual elevation to line up: my calculations showed the hill must be about a meter taller than he'd designed. So he pulled out his Topcon GPT-3000 laser surveying instrument and went out there to measure the hill. The hill was about 1.2 m higher than he'd laid it out to be -- before the developer had gone bankrupt, he'd tried to save money on grading and moving dirt.

big john

Was he an Englishman?

big john

You can't even appreciate the science and how a brilliant man took a different approach to measuring gain. It's just another chance for you to ridicule people who you don't understand.

PeteHski

In that case, was your power output actually the same for both gradients?

terrymorse 

Power was pretty close, about 15% higher on the steeper grade. Both "high zone 3" efforts.

PeteHski

10 rpm lower cadence and 15% more power would feel quite a bit harder on my legs. Depending on your base power, that could be easily 30-40 Watts difference.

John E

Cited in "The Dancing Chain":

Take the inverse of the grade, multiply by 7, and that's the ratio in gear-inches that one needs when standing on the pedals.

Example given: 10% grade = 1/10; 10*7 = 70 inch gear (I think I can handle that seated, with a bit of effort, although I would normally prefer to use something closer to 60 gear inches)

Extending this: 20% grade 1/5; 5*7 = 35 inch gear (I think I believe that one as a conservative estimate

Low gear on my mountain bike = 24 gear-inches; low gear on most of my road bikes is 39.5 gear-inches

t2p

indyfabz

I rode up this the day before in 90+ degree heat and high humidity. During an unsupported overnight camping/cooking trip. It was one of two 14% sections.

indyfabz

Check out this route profile:

COOPER PASS - A bike ride in Wallace, ID (ridewithgps.com)

I have camped in Wallace twice before heading back into MT. The above roads were not available on Street View at the time. As such, I always went over Dobson Pass to Delta, Kings Pass to Murray and then over Thompson Pass (the last 4 miles of which average something like 7.4%, with the final two averaging 7.8%) to get to Thompson Falls, MT. The above route is noticeably shorte, but has some intense grades, especially on the descent, the first three miles of which are almost all in double digits. And look at that unpaved section on Street View.

Leisesturm

Found this earlier this evening. Wrote a post about it but don't see it. Since you guys are still at this I figure why not.

rsbob 

As you will most likely agree,, the constant need to put down others is usually a testament to a lack of positive self-esteem. The unfortunate thing about this method is, the feeling of superiority is only transitory, unlike volunteering for a cause/helping others, and thus has to be repeated often to get the same ‘high’. Even though my first reaction is usually disgust, it usually turns to sympathy since they lack the tools. I would encourage this person to find a positive outlet to gain satisfaction and meaning rather than continue this Sysphusian effort.

It will be interesting to see if there is a negative reply.

spelger

wonder how accurate it is. and will it only disappoint me as if i had a power meter telling me what i was really doing instead of my imagination.

RChung

It probably isn't bad if you're standing still. It probably jumps around if you're pedaling along.

Leisesturm

If they've done it right the fluid will have just enough 'damping' to steady the ball. Still, my guess is that thing is quicker responding than a phone based app or standalone computer, at least as accurate, and just as free from 'jitter' (jumping around). Not too shabby at the price.

terrymorse 

But it won't connect via BlueTooth to Strava app, and that's a deal breaker.

PeteHski

You are probably right, but it doesn't tell you what grade is coming up ahead or how far to the top of the climb. Knowing the grade I'm currently on is only of academic interest. It has no influence on my riding. But knowing exactly what lies ahead I find invaluable for pacing.

terrymorse 

Yes. When using hills as intervals, it's great to know how much farther it is to the top of a climb, and Garmin's ClimbPro feature will tell you that.

But now that I've been using a power meter for several years, that's my preferred pacing tool. I just keep the power in my target range, and just keep on pedaling.

PeteHski

I also use a power meter, but I will ride at different power targets depending on the profile of the climb ahead. Knowing the profile of a climb is key for my pacing strategy and that's what ClimbPro provides in real time. For example I may decide to ride above my FTP on a steep section if I know it flattens out further ahead. I might also take it easy at the start of a climb that I know is going to get dramatically steeper further up the road.

When I ride events in a group it's usually pretty obvious which riders know the profile of a climb and those that don't. I use ClimbPro to set my strategy and my power meter for implementing it.