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#46 | |
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dumb blonde
Join Date: Sep 2002
Location: Belper, Derbyshire, UK
Posts: 2,983
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Joe |
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#47 |
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Registered User
Join Date: Apr 2009
Location: Sant Cugat
Posts: 5
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I am having trouble myself with steep hills, of the kind you would climb with the shortest gear of a mountain bike. Being the geeky type, I tried to figure out the theoretical maximum slope you can climb with a unicycle. It turns out there's a very simple relationship between crank length (r), wheel radius (R) and maximum slope (s):
sin(s) = r/R. So, if you know the geometry of your unicycle, you can easily draw a triangle that shows the maximum slope: ![]() This is neat (I think) but unfortunately not quite true: it assumes that you can load all your weight on the pedal when the crank is horizontal. And you typically can't, because the critical point when climbing is the top dead spot of the pedaling cycle. The only thing that will get you out of the dead spot is inertia: the faster you go, the further will the cranks rotate away from the top spot, and the more efficient your effort will become. If you assume that inertia will allow you to move 20 degrees from the top spot (which I suspect is reasonable) you'd have to multiply r by sin(20), like: sin(s) = sin(20) r/R. It's only an approximation, but it's probably enough to compare what should be possible with different wheel/crank configurations. In order to do better than this you'd probably have to do the dynamic analysis. And, btw, there's a way to overcome this limit: grab the saddle and pull up from it as you push down on the pedal. If you can do this you should be able to climb any slope. I don't know if this will be of any interest for anybody, but as I had been thinking about it I thought I'd share. Cheers, Juan Reyero http://unarueda.com |
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#48 |
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dumb blonde
Join Date: Sep 2002
Location: Belper, Derbyshire, UK
Posts: 2,983
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That's a neat bit of maths. Although doesn't it assume that the unicycle is zero mass? Which might be a better approximation for the 20" riders than for a coker!
About the dead spot - you still have quite a lot of traction on the pedal at that point due to shoe grip, so I don't think it is the case that you only have inertia to get you past it, although you clearly can't put down as much power. Also the 20 degrees figure is surely very low - typically when it gets really limiting, you'll be doing a massive push, then pausing with horizontal pedals, and doing another massive push, and it seems like you can get a lot further round than you'd think. And like you say, there's the saddle - most strong riders hold the saddle most of the time. Having said that though, for a 26" (330mm radius) unicycle with 150mm cranks, the big figure gives a 27 degree slope, which would be about 50% gradient, which is unrideably steep, and the smaller (multiplied by sin(20)) figure gives an 8.94 degree slope, which is about a 15% slope, which is dead easy to ride up on a 26", so maybe the right multiplier is a bit more than sin(20) (but less than 1). Or maybe I did my calculations wrong. Joe |
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#49 |
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Is it June yet?
Join Date: Mar 2009
Location: San Jose, CA
Age: 53
Posts: 1,105
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I don't know about all the math/trig stuff, but my biggest issue on a steep climb is foot slippage. One of my feet will move and mess me up on a steep section. I don't run out of strength or lungs first. I am used to bike pedals that are locked in place so when grunting up a hill I lose footing.
I also wonder how you hang on to the seat and pull up while pedaling. Do you stay seated or do you stand up? When I hold the seat I have a harder time balancing. I practice holding the seat on downhills and flat ground but steep up is hard. I hope these problems are because I'm still new. My husband taped me climbing up a dirt trail and I was amazed at the amount of arm flailing that I did. I look like a bat. |
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#50 |
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dumb blonde
Join Date: Sep 2002
Location: Belper, Derbyshire, UK
Posts: 2,983
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I stand up when it gets really steep. Flailing arms are something that diminishes with practice.
Joe |
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#51 | |||
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Mainly XC Muni
Join Date: Aug 2004
Location: Dartmoor, England
Age: 44
Posts: 2,876
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Rob |
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#52 |
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Registered User
Join Date: Jul 2006
Location: Sha'arey Tikva, Israel
Age: 41
Posts: 898
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Snake it up!
There are two useful bits of technique that have not been mentioned here.
1) If you are riding up dirt road hills or singles it is important to try and find the BEST LINE to make it up. Even small rocks and areas with steeper dirt will break your flow and cause you to use more energy. It is better to snake around obstacles or unsmooth areas rather than to power over them. Off course if you are on smooth asphalt this piece of advise is worthless. 2) Zig Zaging in order to hit the hill and attack it at a less deadly angle also helps. However you will have to pedal farther and it takes longer. Think of it like mounting perpindicular to the hill. When pulling up on the handle you do have more power but less ability to balance and this is important on non smooth uphills. I try to avoid pulling up on the handle until it is nessesary. Unicorn
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Keep your eyes on the stars and your feet on the pedals, and you will accomplish great feats! The Unicycling Commune |
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#53 |
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Is it June yet?
Join Date: Mar 2009
Location: San Jose, CA
Age: 53
Posts: 1,105
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Thanks for the replies. I am on a 24" with 150 cranks. If I were on a 29" with 150 cranks, I would imagine that riding uphill would be harder.? I would also assume downhill would be easier.?? I'm saving for a new unicycle and am thinking about a 29". I wonder if I'm setting myself up for failure (on hills). It will be a while before I can buy one though and I should have a lot more practice in.
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#54 |
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Stupidity gets you 2 of these:
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Yes and no.
You would have a taller efective gear, but if you have a lighter rim/tire than your 24 it would be creating less drag. Also the larger wheel will have more inertia, so provided you can maintain a moderate pace you could end up getting up the hill w/ less total effort. Also some of it is whichever you are used to, so when you get that bigger wheel, give yourself a few weeks to adjust to it.
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Ride everywhere and never just ride anywhere. If you can ride where you are going within a hour, do it, and if you can do a trick 50-75% of the time do it along the way.- Bob Burnquist What's next? Learn2Ride&doTricks TrialsClasses&Building Last edited by skilewis74; 2009-04-29 at 07:58 PM. |
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#55 | |
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GranPa goes-a-wobblin'
Join Date: Mar 2003
Location: European Union (S-W)
Age: 64
Posts: 2,109
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Quote:
on Youtube there is a video of me and Cocal riding down that one
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One Wheel : bear necessity |
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#56 | ||
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Registered User
Join Date: Apr 2009
Location: Sant Cugat
Posts: 5
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Yes, or that the acceleration is zero. It's the static solution of the problem, which is valid for one particular point of the pedaling cycle. Only an approximation anyway; I haven't been able to solve the full movement equation, and haven't had time to look at it numerically.
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Thanks, Juan Reyero Monociclos en español |
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#57 | |
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is what it is
Join Date: Sep 2004
Location: hella Nor Cal
Age: 35
Posts: 6,557
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Quote:
When you pull on the handle you tense a lot more muscles in your body: your arm, your shoulder, your back. This burns calories much quicker than if you relax your upper body while climbing. Your goal, when possible, is to only use the muscles you need to climb. Focus on relaxing your hands, arms, shoulders, even your face and jaw. Every little bit helps in the long run.
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"The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt." - Bertrand Russell |
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#58 |
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Hartman Rocks, Uncompahgre beyond..
Join Date: Sep 2006
Location: Huntsville, Alabama
Age: 38
Posts: 995
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I've already mentioned this earlier in this thread, but for me at least, developing some basic "trials" skills have really helped improve my climbing ability. By basic trials skills I mean being able to ride slow and in control and be able to balance in place (still stand) with either foot forward with the cranks level to the ground. Getting good at those two skills has made just about all hill climbing much easier for me. For normal grades where you don't have to stand up out of the saddle just take it easy and concentrate on one half crank revolution at a time. When the going gets steep and I'm standing up out of the saddle, to me it seems more like I've got my hand on top of the saddle sort of pushing down rather than pulling up. It least that's what it seems like to me, like the palm of my hand is on top of the handle with my fingers curled down and around the handle. And when the going is steep I just concentrate on one crank half revolution at a time, often, especially if it's hot out and I feel like I'm about to red-line or go anaerobic I'll sort of take a short pause every full revolution. These little "micro breaks" really seem to help me out. I'll even pause into a still stand for a bit longer if I need more of a breather; then continue on. Sometimes however you can't help but to redline, especially if you hit a more technical bit of ground to climb up, no problem just make sure to use the next easier bit to recover; i.e. ride slower, take a micro break or two. I've never really ridden with others before so I don't know how you all climb, but that is pretty much how I do it with some fair success.
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