Cycling efficiency and watts

[NHAero]

The thread about gearing has made me think more about this question. As I wrote, in 1975 I rode the Mt Washington Hillclimb on my MIT bike, and I picked the 1:1 gearing based on how many watts I thought I could generate for the duration. But of course I have no idea how I did that math back then to estimate the watts I could do.

The bike and I weighed about 150 pounds. The net elevation is 4,725 ft. So the lifting energy required is 708,750 ft-lbs. I did the ride in 73:30, so 9,643 ft-lbs/minute. That's 218 watts.

My question is, what is a good estimate of actual total watts, given rolling resistance, drivetrain efficiency, etc.? I don't recall it being super windy (I would remember, if you've ever been in the Presidential Range when it really was windy and my speed works out to 6.2 mph, so I don't know how to assess wind resistance on this ride.

[merckx]

Seventy three thirty is a good time!

[NHAero]

Originally Posted by merckx

Seventy three thirty is a good time!

Yeah, well, I was 21, not 71

[Mark McM]

Plugging the values given, plus a distance of 7.6 miles (and therefore an average grade of 11.88% and an average speed of 6.2 mph), and using the default values for other parameters, this online calculator says it would require about 234 Watts total:

https://www.gribble.org/cycling/power_v_speed.html


This online calculator says 241 Watts:

https://www.omnicalculator.com/sports/cycling-wattage


And this one says 238 Watts:

https://wattscalculator.com/


All of these calculators use different default values, which are required to caculate drag losses (air resistance, rolling resistance, drivetrain friction). The first and third links above report the calculated drag losses used. Air resistance is the smallest smallest of the drag forces, and the first calculator shows that rolling resistance is larger than drivetrain losses, while the third calculator shows that drivetrain losses are larger than rolling resistance.

[martl]

Originally Posted by NHAero

The thread about gearing has made me think more about this question. As I wrote, in 1975 I rode the Mt Washington Hillclimb on my MIT bike, and I picked the 1:1 gearing based on how many watts I thought I could generate for the duration. But of course I have no idea how I did that math back then to estimate the watts I could do.

The bike and I weighed about 150 pounds. The net elevation is 4,725 ft. So the lifting energy required is 708,750 ft-lbs. I did the ride in 73:30, so 9,643 ft-lbs/minute. That's 218 watts.

My question is, what is a good estimate of actual total watts, given rolling resistance, drivetrain efficiency, etc.? I don't recall it being super windy (I would remember, if you've ever been in the Presidential Range when it really was windy and my speed works out to 6.2 mph, so I don't know how to assess wind resistance on this ride.

i used the same formula back when i was more interested in such matters and did a lot of long hillclimb races. When i started to use a powermeter crank, it confirmed the calculated wattage, usually + ~30W for resistances not included in the basic formula.
At arund or less than 10-12 km/h average, the wind resistance is pretty much negligible. Little did i know back then how much faster i could have been with thigh high socks, a waxed chain and an idler pulley the size of a dinner plate! i'd have given Pantani something to think about!!!!!11!

[zap]

Originally Posted by NHAero

The thread about gearing has made me think more about this question. As I wrote, in 1975 I rode the Mt Washington Hillclimb on my MIT bike, and I picked the 1:1 gearing based on how many watts I thought I could generate for the duration. But of course I have no idea how I did that math back then to estimate the watts I could do.

The bike and I weighed about 150 pounds. The net elevation is 4,725 ft. So the lifting energy required is 708,750 ft-lbs. I did the ride in 73:30, so 9,643 ft-lbs/minute. That's 218 watts.

Were you and Gary classmates?

That is a most excellent time for that climb.

[NHAero]

Thanks very much - cool calculators!

Originally Posted by Mark McM

Plugging the values given, plus a distance of 7.6 miles (and therefore an average grade of 11.88% and an average speed of 6.2 mph), and using the default values for other parameters, this online calculator says it would require about 234 Watts total:

https://www.gribble.org/cycling/power_v_speed.html


This online calculator says 241 Watts:

https://www.omnicalculator.com/sports/cycling-wattage


And this one says 238 Watts:

https://wattscalculator.com/


All of these calculators use different default values, which are required to caculate drag losses (air resistance, rolling resistance, drivetrain friction). The first and third links above report the calculated drag losses used. Air resistance is the smallest smallest of the drag forces, and the first calculator shows that rolling resistance is larger than drivetrain losses, while the third calculator shows that drivetrain losses are larger than rolling resistance.

[NHAero]

Originally Posted by zap

Were you and Gary classmates?

That is a most excellent time for that climb.

More than you wanted to know here

[benb]

Originally Posted by zap

That is a most excellent time for that climb.

A Top Notch time!

Excellent indeed.

I am curious what the race (was it a race then?) was like. Was Tin Mountain already in charge? How expensive was it? Did they let your ride down back then?

I did it in 2001 and 2005. It's always on my list of things I want to do again. I did a 1:23:something and really wanted to get under 1:20. Both times I did it I did it on 23c tires and was getting blown all over the place and had to "dab" at least once in the race cause I was going off the road. It would be interesting to see if I could do it again on a bike more resistant to that and/or with better body position/handlebars and get up it without that problem.

But it is also 100% paved now IIRC, so it would certainly be different.

[bigbill]

Back in the 90s, I used a computrainer and when a time trial was coming up, I would ride in erg mode at 380 Watts and try to hold 90 rpm for an hour. I was a decent TT rider and any race I won was in a break. I recall calculating that I'd need 400 Watts to ride a mid 50s for a 40K. I also assumed that on race day, a little adrenaline would give me the extra wattage. I time trialed with a HRM, only recently have I added a powermeter at 59. Power was always my strength, but not power to weight. If the course was flat to rolling, I could do well. If the course had long climbs, I had a good view of the climbers as they dropped me.

[NHAero]

It was definitely a race. I am unable to find the results anywhere on the web for 1975. In 1976 John Howard won, in a smidge over 1 hour, and the top 6 included both Stetinas and George Mount. John Allis was 18th in 1:13:01 - conditions must have been worse than the previous year. I put brakes and a single speed freewheel on so I'd be legal, and bumped the gearing to 20/18 from 20/20. Was definitely riding tubulars, probably two of the Pirellis we'd bought in a bulk order direct from Italy. I had a bad case of mono a few weeks before the race, and that and tougher conditions (the finish photo I have shows me wearing my venerable 60/40 parka and what look like pants!) I rode almost 11 minutes slower than in 1975. I got second in Novice (unlicensed riders); Olympic XC skier Tim Caldwell somehow rode almost 14 minutes faster than me Esther Salmi, who was National TT champion two years later in 1978, beat me by 1:41.

I think the current record is held by Phil Gaimon at 50:38. Yikes. Would be fun to see Pogacar enter!

I have no recollection of entry cost, and no, they didn't want us to ride down!

Originally Posted by benb

A Top Notch time!

Excellent indeed.

I am curious what the race (was it a race then?) was like. Was Tin Mountain already in charge? How expensive was it? Did they let your ride down back then?

I did it in 2001 and 2005. It's always on my list of things I want to do again. I did a 1:23:something and really wanted to get under 1:20. Both times I did it I did it on 23c tires and was getting blown all over the place and had to "dab" at least once in the race cause I was going off the road. It would be interesting to see if I could do it again on a bike more resistant to that and/or with better body position/handlebars and get up it without that problem.

But it is also 100% paved now IIRC, so it would certainly be different.

[Mark McM]

Originally Posted by NHAero

It was definitely a race. I am unable to find the results anywhere on the web for 1975. In 1976 John Howard won, in a smidge over 1 hour, and the top 6 included both Stetinas and George Mount. John Allis was 18th in 1:13:01 - conditions must have been worse than the previous year. I put brakes and a single speed freewheel on so I'd be legal, and bumped the gearing to 20/18 from 20/20. Was definitely riding tubulars, probably two of the Pirellis we'd bought in a bulk order direct from Italy. I had a bad case of mono a few weeks before the race, and that and tougher conditions (the finish photo I have shows me wearing my venerable 60/40 parka and what look like pants!) I rode almost 11 minutes slower than in 1975. I got second in Novice (unlicensed riders); Olympic XC skier Tim Caldwell somehow rode almost 14 minutes faster than me Esther Salmi, who was National TT champion two years later in 1978, beat me by 1:41.

It should also be remembered that the road was only partially paved back then. For the first hundred years of its existance, the road was just hard-packed dirt and gravel. Paving only started in the 1970's, and it wasn't fully paved until 2022.

Originally Posted by NHAero

I think the current record is held by Phil Gaimon at 50:38. Yikes. Would be fun to see Pogacar enter!

Gaimon is the current record holder, at 50:38, but it has been climbed faster by two other people - Tyler Hamilton climbed it in a time of 50:21 in 1999, and Tom Danielson climbed it in 49:24 in 2011. Both records have since been invalidated due to their doping sanctions. Genevieve Jeanson's women's time of 54:02 set in 2002 was also invalidated due to doping sactions. The current women's record is 58:14 set by Jeannie Longo in 2000, but that record should also be suspect, after she too was implicated in doping (but not sanctioned).