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Originally Posted by fietsbob
(Post 16355967)
the choice is: take it, or leave it at home. bring it, then mail it home, works too..
When I arrived in Australia at the beginning of a 3-month tour, I was under the mistaken impression that I needed 4 panniers, my Carradice, and my handlebar bag. After a few days of struggling around the Sydney area (hilly), I stopped at the house of an acquaintance, and spent the evening going through everything I brought. I left 2 panniers filled with stuff (about 10 lbs in total) behind ... and didn't need any of it for the remainder of the 3 months. Then at about the 1.5 month point, I mailed home several pounds of stuff. |
Originally Posted by Walter S
(Post 16357619)
How do you support a claim that efficiency goes down with load? I would think that factor, if true, is already accounted for in calculators/math on this topic. Since calculators such as bikecalculator.com are translating energy output into actual speed, losses due to inefficiency are built into those calculations by necessity. Otherwise the calculated speed value will be wrong and I would think experts raise that as an issue.
Do you think there are efficiency losses that the math does not account for? 2) Yes, of course there are efficiency losses that the math does not account for. That's the trouble with simple mathematical formulas calculated in isolation of reality. Fatigue is one such factor.
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Originally Posted by Machka
(Post 16359169)
1) We can support the claim that efficiency goes down with load through extensive experience and experimentation. We've ridden with lighter loads, heavier loads, and everything in between ... in all sorts of conditions. You can do all the mathematical calculations you want, but until you're struggling your way up yet another 7 km 15% hill and regretting every single thing you brought, you don't really know.
2) Yes, of course there are efficiency losses that the math does not account for. That's the trouble with simple mathematical formulas calculated in isolation of reality. Fatigue is one such factor.
We've just seen a couple struggling up a hill on their bikes fitted with four panniers, a handlebar bag and backpacks. From what I could judge, their gearing wasn't at all matched to the conditions -- really low cadence and speed up only an 8 to 10% grade. I thought about this thread, and surmised that their day might have been a bit better if they had reduced their weight to increase their speed or least reduced their effort to get over the first of a number of hills ahead of them. |
Originally Posted by Rowan
(Post 16359181)
And not forgetting that rehydration can play such a vital role in how a rider feels the next day.
We've just seen a couple struggling up a hill on their bikes fitted with four panniers, a handlebar bag and backpacks. From what I could judge, their gearing wasn't at all matched to the conditions -- really low cadence and speed up only an 8 to 10% grade. I thought about this thread, and surmised that their day might have been a bit better if they had reduced their weight to increase their speed or least reduced their effort to get over the first of a number of hills ahead of them. Getting a good night's sleep, rehydrating, fatigue, are all factors that are important of course. But I don't think those things are specifically related to the impact of weight on speed and whether or not you can even out the energy output of competing trip profiles by simply slowing down to compensate for the varying loads. |
Originally Posted by Walter S
(Post 16359283)
I appreciate the reality of the factors you and Machka mention above. But I don't think these things are related to efficiency. Personally I think this is best summed up as issues related to fully appreciating the impact of weight/wind drag on speed along with difficulty absorbing that impact and still making what feels like acceptable progress on the tour. It's not that the bicycle was slowed down by factors that can't be mathematically analyzed in terms of energy output and resultant speed.
Getting a good night's sleep, rehydrating, fatigue, are all factors that are important of course. But I don't think those things are specifically related to the impact of weight on speed and whether or not you can even out the energy output of competing trip profiles by simply slowing down to compensate for the varying loads. 2) Are you suggesting that the situation is simply this ... If the bicycle weighs 20 lbs ... and you can cycle 20 km/h ... Then if the bicycle weighs 120 lbs ... you should be able to slow down to compensate for that weight? And if the bicycle weighs 20 lbs ... and you can cycle up a 6% grade hill at 8 km/h ... Then if the bicycle weighs 120 lbs ... you should be able to slow down to compensate for that weight? If that is what you're suggesting, I'd question how slow you're prepared to go. For example, the overloaded couple we saw today could hardly hold their bicycles upright as they climbed the hill (and it wasn't overly steep). And I can sympathise with them. When my speed drops to 4.5 km/h, I can't hold the bicycle upright anymore ... especially if it is loaded with panniers. I have to get off and walk. And if I have to get off and walk ... I have to push the bicycle. I have to walk and push a heavy bicycle up a long hill, and that is tough! I've climbed hills where I've walked and pushed 25 steps (I count them), and then I stop to puff and wheeze, then 25 more steps, then more puffing and wheezing ... for several hours. This is what I'm talking about when I say that when the weight of the bicycle + gear goes over about half my body weight, I struggle. I struggle holding the bicycle upright at the slow speeds I have to ride. I feel like I'm fighting with the bicycle to keep it moving in a relatively straight line. And I really struggle when I've got to walk and push all that up a hill. But I don't climb hills well at the best of times, and I'm a slow cyclist at the best of times, so how do the mathematical calculations take those factors into consideration? |
Originally Posted by Machka
(Post 16359290)
2) Are you suggesting that the situation is simply this ...
If the bicycle weighs 20 lbs ... and you can cycle 20 km/h ... Then if the bicycle weighs 120 lbs ... you should be able to slow down to compensate for that weight? And if the bicycle weighs 20 lbs ... and you can cycle up a 6% grade hill at 8 km/h ... Then if the bicycle weighs 120 lbs ... you should be able to slow down to compensate for that weight? If that is what you're suggesting, I'd question how slow you're prepared to go. But as I also mentioned on the original post, my weight vs. speed questions that started this thread are not meant to address the boundary conditions. There's a lot of room to go when increasing a load beyond 20 pounds, before you reach the 120 pound mark (as an example of a load that pushes practical limits on certain terrain). It is this domain that has been my focus. I recently took a three week trip loaded with 80 lbs. of gear. I had a few long 7% grade climbs where I found first gear and I hugged the lower limit of my speed (3.5 mph). There were some steeper but shorter climbs where I walked. I got by with about 300 yards of walking during 1200 miles of touring. I probably could have avoided walking at all if my load had been half as much. But the trip was very practical to me - I don't mind walking that short distance to have the benefit I received from covering contingencies and/or personally enjoyable items. |
Originally Posted by Walter S
(Post 16359340)
I recently took a three week trip loaded with 80 lbs. of gear. I had a few long 7% grade climbs where I found first gear and I hugged the lower limit of my speed (3.5 mph). There were some steeper but shorter climbs where I walked. I got by with about 300 yards of walking during 1200 miles of touring. I probably could have avoided walking at all if my load had been half as much. But the trip was very practical to me - I don't mind walking that short distance to have the benefit I received from covering contingencies and/or personally enjoyable items.
But for me, if I rode with 120 lbs (bicycle + gear), I could hardly move the bicycle on any surface more than about 0.5% grade. A few other things ... What about gears? How do they factor into the formulas? I've finally got a gear setup that allows me to get what little I bring up small hills. But with some of my earlier gearing combinations, I've been off and walking while others are happily spinning away? Also, what about fitness? When I was at the peak of my fitness, I could tackle some fairly decent hills. But now, I can barely tackle a gradual incline with my lightest bicycles. And on the topic of fitness and strength ... Rowan is a much better hill climber than I am. If you were to load the two of us up with the same load, he would arrive at the top of a hill long before I would. Do the mathematical calculations take all that into consideration? Incidentally, one of the "formulas" I've read in the past is that a cycletourist should be able to lift their bicycle, complete with gear, and walk 20 or 30 metres carrying it. I believe the idea was that if a cycletourist could carry their bicycle (and gear) a short distance, they could handle pushing it up hills, lifting it over things if necessary, and also hauling it through airports and train stations. That piece of advice helped me settle on the half my body weight limitation. I can lift and carry half my body weight over a short distance ... more than that is difficult for me. But for me, there's a whole lot more that goes into my packing decisions than just a mathematical calculation indicating whether or not I should be able to ride with a load of a particular weight. |
Originally Posted by Machka
(Post 16359379)
What about gears? How do they factor into the formulas? I've finally got a gear setup that allows me to get what little I bring up small hills. But with some of my earlier gearing combinations, I've been off and walking while others are happily spinning away?
Originally Posted by Machka
(Post 16359379)
Also, what about fitness? When I was at the peak of my fitness, I could tackle some fairly decent hills. But now, I can barely tackle a gradual incline with my lightest bicycles.
Originally Posted by Machka
(Post 16359379)
And on the topic of fitness and strength ... Rowan is a much better hill climber than I am. If you were to load the two of us up with the same load, he would arrive at the top of a hill long before I would.
Do the mathematical calculations take all that into consideration? Any sensible plan will not include predicting a speed that's slower than you're actually willing to go. My focus with this thread has been to evaluate how much one needs to slow down based on a given weight, with the assumption that my intuition about that might be wrong. For example, when accelerating I can very much feel the impact of adding weight. That can send a signal from my legs to my brain that makes me feel like "man, this thing is a beast! how will I go 1000 miles like this!". But by realizing that acceleration is impacted more than the resistance at speed, I can put that at bay some and give the real impact a chance to surface by knowing that acceleration is a small part of the journey.
Originally Posted by Machka
(Post 16359379)
Incidentally, one of the "formulas" I've read in the past is that a cycletourist should be able to lift their bicycle, complete with gear, and walk 20 or 30 metres carrying it. I believe the idea was that if a cycletourist could carry their bicycle (and gear) a short distance, they could handle pushing it up hills, and also hauling it through airports and train stations.
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Originally Posted by Machka
(Post 16359379)
Rowan is a much better hill climber than I am. If you were to load the two of us up with the same load, he would arrive at the top of a hill long before I would.
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Originally Posted by Walter S
(Post 16359574)
Tell him he's a slacker and should help more. Or sneak some of your stuff into his pack!:)
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I don't go "ultralight", but I have certainly tried to go lighter. On my first cross country ride in 1986 my bike probably weighed close to 100 pounds (I wish I weighed it before I left). On my 2012 Alaska Highway ride my total weight, including the bike, all the camping gear, all my clothes, (everything from the ground up) was 48 pounds. Food and water added to this total.
It might be psychological, but I definitely notice the difference on climbs. Flats not so much and downhills are the same. One big difference is that I can lift the loaded bike over a fence or easily carry it on my shoulder when I have to hoof it into the woods at night. After every tour I analyze my stuff and see if I can use something lighter or get rid of an item completely. On the Alaska trip there really wasn't anything that I didn't bring that I wished I had. |
One other thought on cost... if going lighter means you can increase your speed from 12 to 15 mph (as in your example) that theoretically means you could do a 1500 mile tour in the same time it would take you to do a 1200 mile tour. What cool things might you see in those extra 300 miles? What's the cost of missing those extra 300 miles with no increase in effort?
I know that's only theoretical and probably wouldn't work out exactly that way in the real world, but if cutting your gear means you can ride easier, faster, smoother, etc., it's worth considering. |
Originally Posted by pataspen
(Post 16360928)
One other thought on cost... if going lighter means you can increase your speed from 12 to 15 mph (as in your example) that theoretically means you could do a 1500 mile tour in the same time it would take you to do a 1200 mile tour. What cool things might you see in those extra 300 miles? What's the cost of missing those extra 300 miles with no increase in effort?
I know that's only theoretical and probably wouldn't work out exactly that way in the real world, but if cutting your gear means you can ride easier, faster, smoother, etc., it's worth considering. I had a similar trajectory in weight loss as you described in your earlier post, and my load weighed nearly the same as yours on my last tour, a 4500 mile coast-to-coaster. I had tried that ride in my younger days with a much heavier load and couldn't make it in one season, and it hurt. Over the decades I dropped the pack weight, made the ride and had fun every day, including the difficult North Cascades Hwy in WA state. You can't put a price on those pounds. Also that ride lasted several weeks less than I had estimated based on my earlier touring mileage. That saved quite a bit of money--the tour came in way under budget. Yet another cost to consider for a heavier and slower ride, if it hasn't been already in this long thread. Good one, though. |
Originally Posted by pataspen
(Post 16360928)
One other thought on cost... if going lighter means you can increase your speed from 12 to 15 mph (as in your example) that theoretically means you could do a 1500 mile tour in the same time it would take you to do a 1200 mile tour. What cool things might you see in those extra 300 miles? What's the cost of missing those extra 300 miles with no increase in effort?
I know that's only theoretical and probably wouldn't work out exactly that way in the real world, but if cutting your gear means you can ride easier, faster, smoother, etc., it's worth considering. Yes, it does depend on what you are touring for... the journey, the destination, or what's in between. |
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