Hermes

For cyclists, one kjoule measured by a power meter on the bike approximately equals one calorie (food calorie).

Here is a write up from Trainerroad. https://www.trainerroad.com/blog/calories-and-power/

For years, I have used a rule of thumb that one mile of running or three miles of cycling burned 100 calories. Today, with power measurement on the bike, the ratio for cycling is approximately correct. I ride the same routes all the time and 30 miles of riding requires approximately 900 kjoules or 900 calories. If I ride harder i.e. generate more power per mile then the time is shorter to complete 30 miles but the kjoules required stay about the same. Of course wind and hills can bias that rule of thumb. Today, I use my power meter kjoule measurement if I want an accurate measurement of calories burned during a ride due to the distance traveled over time.

40Km or 26 miles will require approximately 780 kj using my rule of thumb and will have to be biased due to the climbing.

I have done intermittent fasting and bonk style training on the bike. It is okay but hard to measure if there is a performance improvement other than body weight fluctuations where in general, less weight is better for endurance sports. I will add that if I ride fasted, many times I SEEM to perform better with less food in my digestive track. Feeling hungry does not slow me down.

Bearhawker

I don't care if it is not accurate - I only hope it is consistent.

I do know that riding a 50+ pound bike with possibly the worst aerodynamics with a 28T front ring is a lot of work. I don't bother trying to pedal above 30 km/h as the effort is more than the return. I try to never get below 10 km/h on hills but the hills on Thursday had me down to 5 or possibly less at times.



The fact that I do that - and ALL rides - fasted is because of my diet and the fact that IF is my default. Sometimes 23 hours a day, often less. Effectively NEVER less than 12 hours.

I wouldn't have considered a 2-hour hard effort without fueling before. I once bonked on a 5 hour effort due to a lack of snacks... before my current situation. Now a 5-7 hour hard (for me hard is pushing my fatbike at 20 km/h non-stop) without ever eating *anything* is not only possible but my preferred method. As long as I have water and salt I'm good to go all day, day after day. Food freedom

Seattle Forrest

I'm so glad to hear you agree that calories are real things sense not just magic. We're making progress! 🙂

MinnMan

Here I am vying for the title of resident pedant, making comments about which nobody will care, but so it goes....

Calorie is not an imperial measurement. If it were, it would be the energy to raise (an ounce, a pound) of water by 1 degree F*. It's calculated from metric units (grams, degrees celsius). So it is based on the metric system. It is not, however, recognized as part of the official (SI) metric system. That slot is taken by "Joules".

*BTU is an imperial energy unit. It is the heat required to raise one pound of water by 1 degree Fahrenheit.

When I first encountered simple physics in junior high school, all of the units were in foot-pounds. If I recall from those days, 1 horse power is 550 foot-pounds/second

MinnMan

This not only reflects that I am old, but also that my Jr. HS science teacher was very old. I don't think she had revised her curriculum from its inception in the first half of the 20th century.
I suspect that other people in Jr. High in the 1970s were doing their pulley ratio calculations in metric units.

Seattle Forrest

As a climber I prefer newtons.

MinnMan

fify

MinnMan

Scratching my head about this one. Is this possible?

Iride01 

Mods can't remove all the evidence of the stuff they sometimes do. Maybe they touched something minor up for you hoping you wouldn't notice!

Did you have a cuss word or something in there?

MinnMan

Hadn't noticed that Hermes is a mod now. I think he removed the quote of his post, which had an inaccuracy. It's OK, I knew (and said) that I was being a pedantic jerk

No hard feelings.

holytrousers

bikeforums' website is a real mess and they should consider hiring some bike mechanics to fix it .

Hermes

Moderation note: Below is the sub forum for suggestions. Please return to topic.

https://www.bikeforums.net/forum-sug...er-assistance/

GhostRider62

You must have went to one helleva junior high school. We did not do those types of conversion until AP Physics in 12th grade at my public HS. We sent two kids to MIT, two to Harvard, one to Princeton, many to the lessor Ivys, six to Tufts, five to BC, etc.

Pulley conversions and contraptions were freshman engineering......college

MinnMan

I did indeed. Public high school, but from a very high achieving NY suburb. In my year there were 12 who went to Harvard, though in more typical years it was "merely" 5 or 6. And I couldn't count how many to the other Ivys and equivalents.

In the 8th grade "Honors" science class , we did a whole bunch of stuff with pulleys. I loved it.

GhostRider62

We cut up dead stuff in 8th grade honors biology or as much as I can remember. Maybe just a different sequence putting the physical sciences after the life sciences.

Sad that curricula have been dumbed down, especially the maths.

Pertoni

Hey guys!
Sone thoughts on starting fasted and then eat every a certain amount of time/kj burned? It would be a decent compromise to perform, especially for hard days and/or long days

MinnMan

IIMHO, Hard and long days require a good store of glycogen in advance. Trying to catch up on the bike is a losing proposition.

There are others here who seem to believe in the magic of "fat burning" and doing extended efforts on the bike fasted.

Bearhawker

My magic is on Strava so it must be real.

if:
Day 1 - 92 km ridden, 835 meters climbed
Day 2 - 100km with 1951 meters climbed
Day 3 - 102km with 1300 meters climbed (crazy headwind most of the day)
on a fatbike with zero food consumed before or during the rides is magic then so be it. Imma wizzard.

Supper (the only food I ate on the trip) Day 1 & Day 2 was a can of spam, 1 low-carb flat bread and a couple hard boiled duck eggs. I had a few cups of tea each night with heavy whipping cream.

The only other possible source of calories was the Nuun tablets - left home with a part tube for that ride in 2019 and still haven't finished them off. A full tube is claimed 150 calories - I didn't consume anywhere near a full tube over 3 days and ~18 hours of non-stop, grueling (for me) riding.

Everyone else on the ride ate all the carbs they could stuff down for breakfast & stuffed every pocket and pouch with energy gels etc just to make it to the 1st rest stop where they did the same thing to make it to the lunch stop. They did this all three days. I stopped only for water refills - except the 1st day where I stopped at the lunch spot and had a tea... and decided that stopping to chat about the ride instead of actually doing the ride wasn't why I signed up for the ride.

I wasn't fast (happy with my results considering I'm on a 43 pound fatbike!) but curiously I was never the last person into camp each day.

MinnMan

1. The only specs I could find on the Norco Bigfoot 6.1 say that it weighs 33 pounds, not 43. Did you do something extra to add weight?
https://canadiancyclist.com/reviews....cessful-return

2. I don't consider those distances and climbing totals to be difficult rides, particularly if you're doing them at 12 mph, as you've previously indicated. I did something similar today (on a road bike) where I was attacking the hills in friendly competition with my ride partners. I didn't consume any calories during the ride - there was no need. Also, I was somewhat tired from yesterday's century, which WAS a tougher ride and both ate a good breakfast and fueled repeatedly during the second half.

The you're on.a fat bike adds difficulty, to be sure, but that's where your much slower average speeds factor in.

3. If this is al working so well for you, I don't know why you found those rides to be "grueling" (your word). There's no reason why such rides should be hard if you are properly trained and fueled.

4. Maybe you weren't the last one into camp because the others took a leisurely lunch.

Bearhawker

I'm running el-cheapo Kenda tires which seem to be a lot heavier than the stock Jumbo Jims despite being 4" vs 4.8". I have a rear Topeak rack that weighs a lot & the off-brand panniers I use don't properly attach to the rack so I fabbed-up some brackets out of aluminum plate and Adel-style clamps. I have two cargo cages on the fork... Norco for whatever reason put the fork brazeons at a stupid angle so that if you attach any type of cage to them directly, you can't put anything on them as they angle right into the spokes so I made brackets out of angle so that's a bunch of extra weight. Crank Bros candy 1 pedals, air horn, a few lights, garmin speed/cadence sensor, wahoo mount, handle bar end mirror. When I weighed it the other day it also had a Newboler handlebar bag and harness (empty)

The world's smallest triangle bag is also attached with a tube of Nuun in it.

I'm at least 10km/h slower on the fatty than I am on a road bike - there is no way for me to get any aero advantage when pedaling. I'm my own speed brake. Going downhill I can get 5-8 km/h by tucking, and if I take the rear rack off and use the dropper post I can hit 70 km/h on long steep descents. 70 is the aero limit as I have never been able to go faster no matter what position I try. Probably just as well as the amount of tread squirm at 70 is amazing, in a scary sort of way

Also - having a 28T chainring is another limiting factor for me. There is no advantage for me to pedal at any speed over about 30km/h downhill and it's a pretty rare event from me to even approach 30 km/h on a flat section without a serious tailwind. I may go to a larger one for summer riding at some point.

"Grueling" rides for me are often laughable for many other cyclists, especially the more serious ones.

But most of them don't walk with a cane like I do