# Climbing Stairs?



## BigLarry (Jul 30, 2004)

I once tried climbing some normal stairs but found I got jammed by the rises and lost traction as well. I keep thinking a good large travel suspension might make climbing normal set of stairs possible. After all, the angle isn't any worse than some tough short climbs I've done. 

Has anyone been able to climb a flight of stairs? Is it possible with a good suspension? 

(Sorry if this isn't the right forum - couldn't find another - and as the exact opposite of downhill it sort of fit.)


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## E30Evolution (Sep 18, 2004)

It's really all about technique. I know there is a "limit" on how many stairs you can climb before your momentum falls on its face.

I'm sure if you had the skills and practice you could climb stairs on a fully rigid bike, but really its all about practice and not 12 inches of travel.

God, one of the 1st MTB boards I was on had a thread on stairclimbing..Search around, youll find the answers somewhere


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## dirtdonk (Jan 31, 2004)

definitely much easier with a longer travel bike. i've been able to climb short stretches of stairs with a standard type of rise to it( like in a house). much steeper than a steep trail i would say. but just my eyeball impression. stairs with less than standard rise can be accended fairly easily. kind of got to push the front end into the stair. i've never been able to do it on a rigid. i'm sure it could be done but i think you're talking trials quality rider. basically pogo up the steps.


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## Skygrounder (Apr 26, 2004)

For some reason I'm blessed with the extraordinary capability to climb lots of stairs. If only I could trade all of this capability to jump worth a s***, I'd be thrilled. But anyway...

Stairs that are very steep, having about a 2/3 rise/run, i.e., stairs inside of a house, can pretty much only be climbed with the "momentum" method, where you carry speed in, select a gear so you can apply some power halfway up, but not enough to sustain the climb.

Stairs that are shallower, like those typically found in parks and leading up to buildings that have a 1/2 rise/run can be ridden up indefinitely (well, until you run out of steam). For such long flights of stairs I ride up to them at the same speed that I'll be maintaining while going up them. Select a nice low gear on the inner ring, i.e, inner 1st or 2nd. Keep your weight over the seat (you should almost be sitting down). And then just ride up the bastards like you're going up a steep hill.

Clipless pedals help A LOT. When you're going slow on undulating terrain like stairs, you need to be able to put even power down around the entire revolution. I haven't yet tried any real stairclimbing with platforms (I only started to convert to trying to use platforms all the time about 2 months back). But I'm somehow guessing it's a bit more difficult.

Another skill that may help with riding up stairs is learning how to bunny hop up stairs, one stair at a time. To do this, ride up them as far as you can in a low gear such that your front wheel is on the highest stair possible where your rear wheel remains on the ground before the stairs. Then start hopping, one stair at a time. One advantage of learning to do this is that it will help you out when you're trying to sustainably ride up a dozen or more stairs with your clipless pedals and you lose traction. If you know how to bunny hop up the stairs, you don't have to worry about trying to get out in time to not "captain crash". That and if you've almost made it to the top anyway, you can just bunny hop up the last few, which I've found results in your friends ridiculing you a bit less than if you walk it up 

Stairs can be climbed on anything. When I first got the hang of stair climbing it was on a rigid with a Mag 21, with 1.8" of ''travel''. That said, I've ridden a Demo9 a few times up stairs and it's frickin' amazing...it's feels like you're riding up a smooth ramp, and requires about as much effort.


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## BigLarry (Jul 30, 2004)

*Normal Rider, Normal Stairs*



E30Evolution said:


> I'm sure if you had the skills and practice you could climb stairs on a fully rigid bike, but really its all about practice and not 12 inches of travel.
> 
> God, one of the 1st MTB boards I was on had a thread on stairclimbing..Search around, youll find the answers somewhere





dirtdonk said:


> definitely much easier with a longer travel bike. i've been able to climb short stretches of stairs with a standard type of rise to it( like in a house). much steeper than a steep trail i would say. but just my eyeball impression. stairs with less than standard rise can be accended fairly easily. kind of got to push the front end into the stair. i've never been able to do it on a rigid. i'm sure it could be done but i think you're talking trials quality rider. basically pogo up the steps.


 I did a search on a couple terms like "stairs" before posting and didn't find anything on this subject in mtbr.

I'm asking about a normally skilled aggressive rider just climing up normal stairs at moving speed, like a (very) steep technical climb. I'm not asking about a trials rider slowly jumping in semi-static position from stair to stair. I know someone like Hans Rey can do this. I've seen that.

Has anyone relatively normal ever cleared a full 1-story (10 foot) flight of stairs on a bike? I can run up a set of stairs real fast and easy without a bike. So why can't a bike go up? I suspect the biggest problem is traction. But as long as the bike's got good traction, say from a good low pressure tire, and doesn't get jammed on one of the risers, say from a good new suspension that allows the front to keep moving and rear to stay planted with good pedal efficiency, why can't it be done by most people?


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## BigLarry (Jul 30, 2004)

*Thanks Skygrounder*



Skygrounder said:


> Stairs that are very steep, having about a 2/3 rise/run, i.e., stairs inside of a house, can pretty much only be climbed with the "momentum" method, where you carry speed in, select a gear so you can apply some power halfway up, but not enough to sustain the climb.


 Thnx for the info. You seem to say normal stairs can't be done except with momentum to help go half way up one story. (I never get even that far.) Have you ever been able to clean a full one-story flight?

But I'm still puzzled that a good MTB rider can probably run fast up several flights of stairs before bonking. Why can't this be done on a bike?


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## binary visions (Jan 18, 2004)

I don't understand why you're comparing riding a bike up stairs to running up stairs? Where's the similarity?


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## oneoldman (Aug 22, 2004)

I have just recently learned to climb stairs on my new bike. I have 6" travel in back and 4" up front- I find that its easiest to climb if you come in at a good clip, in a medium-low gear adn pull a wheely right before you hit the stairs so that your front wheel goes straight to the 4th or 5th step w/o having to climb over all of them. After wards lean forward and realy crank the pedals. I can completely clear up to 10 steps using this technique. Watch out for snakebiting tubes though.


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## acme5432one (Sep 14, 2004)

Make sure your tires are hard as can be. I've had a few pinch flats from stairs in my day.

That said, the most stairs I have ever been able to make it up or even attempt was a flight of 5 with a small landing and then a flight of 7 to finish it off on the top. With steep stairs you pretty much just have to come at them with speed and just pull up and give it a few cranks half way through. I ride a Kona Kikapu with a Fox Vanilla up front at 130mm and something like 85mm in the back, so I wouldn't call my bike long travel.

Just start small and work your way up.


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## dirtdonk (Jan 31, 2004)

BigLarry said:


> I I suspect the biggest problem is traction. But as long as the bike's got good traction, say from a good low pressure tire, and doesn't get jammed on one of the risers, say from a good new suspension that allows the front to keep moving and rear to stay planted with good pedal efficiency, why can't it be done by most people?


but you don't have good traction. you have a very small point of contact as compared to going up a trail. as with all riding tire pressure is a fine line between getting a pinch flat (too low) and having less tire contact (too high). again i think you're talking a much steeper pitch than you think with standard stairs.


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## Primus (Oct 4, 2004)

I was able to regularly climb sets of 14-20 steps on an i-drive (i-breakwaytooeasy) while seated. The suspension helped quite a bit, however, more important was the rise/run of the staircase. 
But getting to the answer of your question:
The reasons for the difficulties in climbing stairs on a bike are not so complicated as you may think. The first reason, is that you are _not_ climbing a semi-constant incline; you are climbing a _vertical _section followed by a horizontal section, and so forth. Now, we all know that there are not very many bikes that climb a standing tree, so why would we expect one to be able to climb a (albeit short) vertical stair? The second reason boils down to basic physics. I'll spare all of the mathematical rigmarole behind it because pictures are a bitcch to draw in a text editor. If I end up getting *really* bored today, I might make a drawing and post it, but don't hold your breath. Basically, it boils down to the fact that while climbing a stair there are few forces that are acting on your bike to propel it up the stair; you have the *downward* force of your weight and the extra push on your pedals; you have a *backward* force of the step acting on your tire; and you have an *upward* force of the step also acting (at the same point) on your tire. Given the geometry of the situation, you are at a severe disadvantage in terms of propelling yourself *up* the stair. The vertical force acting to turn your tire backwards (i.e. you roll back down the stairs) applies a larger amount of torque than you could ever apply using your legs (you'll have to trust me on this). Not to say that climbing stairs will always be impossible to do on a bike, it's just that for the most part, the rider is at a severe disadvantage. This same problem is further compounded by the fact that your front tire is undergoing the same thing. This effect is often worsened when the rise-run of the stairs happens to match your bike and your front and rear wheels begin to try to climb a stair at the same time (eeeerrrrrrcccchhhhhh). The reason that suspension helps is that it allows your wheels to get up the stair before your body is lifted. This, in turn, reduces the necessary forces required to ride up. Hopefully this explaination has been helpful.


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## BigLarry (Jul 30, 2004)

binary visions said:


> I don't understand why you're comparing riding a bike up stairs to running up stairs? Where's the similarity?


 Great question and goes to my point. Because one can run up stairs at even a faster rate than biking, it indicates the problem with biking up is not one of individual power output on the steep climb, which is way, way more than needed.

Rather, the problem must be that the bike is simply not able to transfer one's power output to the climb, and/or is having lots of power sapped by the very bumpy stairs. This is why I keep thinking a modern high performance suspension might help as they've greatly improved performance on both of these problems over the last few years. Some here say that suspension doesn't necessarially help, but others say it may. But it's apparantly not a big win to have a suspension. It could be a suspension, when it smoothes out the bumps, still robs lots of power in the damping (compression and rebound). So the problem may be energy inefficiency of the suspension doesn't help the climb much.

Anyway, I'm still trying to puzzle out the technical issue in stair climbing, as it should be possible from a power stand point. The issue is something technical in the way the bike works on the stairs.


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## binary visions (Jan 18, 2004)

That was actually a really excellent explanation. I had an idea in my head about why it was so difficult, but that was far better explained than I had the inclination to do  (and definitly more detailed than mine would have been anyway).


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## Primus (Oct 4, 2004)

binary visions said:


> That was actually a really excellent explanation. I had an idea in my head about why it was so difficult, but that was far better explained than I had the inclination to do  (and definitly more detailed than mine would have been anyway).


Glad you liked it. I must have really wanted to reply, because halfway through writing it I accidentally pushed the microsoft shortcut key called, "Push this button if you want to remove everything you've written and never be able to get it back," so I started over...
Ride On!

_______________
"Nihilists...f*ck me. I mean, say what you want about the tenets of National Socialism...at least it's an ethos..."


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## mtbman4 (Jan 28, 2004)

Think about how much energy you lose if you plow right into a curb. Well, ten of them in a row isn't going to be easy.

About comparing walking up stairs to riding up them: When you are walking, you are only standing on the run, and also, you don't have wheels.  

I used to live on the 5th floor of a dorm building, and it was great fun riding all of the way down the stairs, but riding up was way cooler. I could get up the first set (10 or so) by riding straight up them. But the remaining 7 sets, I had to hop up them sideways (front wheel 1 stair above the rear). By the way, the sideways method is MUCH easier than trying to hop up them with your bike pointed directly up the staircase!


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## binary visions (Jan 18, 2004)

Primus said:


> I accidentally pushed the microsoft shortcut key called, "Push this button if you want to remove everything you've written and never be able to get it back,"


Yes, and did the little obnoxious paperclip pop up and say: "Hi! It looks like you have deleted everything you've written! Ha ha!"


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## BigLarry (Jul 30, 2004)

*Counter examples*

In terms of torque applied to the wheel winning over leg force, this is the standard gearing problem. Another way of saying it is that the gearing isn't low enough. But standing in the lowest gear should be able to work on even the steep incline of stairs.

The vertical slope of a given stair shouldn't be an impenetrable barrier either. After all, one can easily hop over logs or up over ledges of 1-2 feet. And people here say they can get over several steps. It's just the combination of them acting repeatedly on both wheels that seems to be an issue in simply disipating energy.



Primus said:


> I was able to regularly climb sets of 14-20 steps on an i-drive (i-breakwaytooeasy) while seated. The suspension helped quite a bit, however, more important was the rise/run of the staircase.
> But getting to the answer of your question:
> The reasons for the difficulties in climbing stairs on a bike are not so complicated as you may think. The first reason, is that you are _not_ climbing a semi-constant incline; you are climbing a _vertical _section followed by a horizontal section, and so forth. Now, we all know that there are not very many bikes that climb a standing tree, so why would we expect one to be able to climb a (albeit short) vertical stair? The second reason boils down to basic physics. I'll spare all of the mathematical rigmarole behind it because pictures are a bitcch to draw in a text editor. If I end up getting *really* bored today, I might make a drawing and post it, but don't hold your breath. Basically, it boils down to the fact that while climbing a stair there are few forces that are acting on your bike to propel it up the stair; you have the *downward* force of your weight and the extra push on your pedals; you have a *backward* force of the step acting on your tire; and you have an *upward* force of the step also acting (at the same point) on your tire. Given the geometry of the situation, you are at a severe disadvantage in terms of propelling yourself *up* the stair. The vertical force acting to turn your tire backwards (i.e. you roll back down the stairs) applies a larger amount of torque than you could ever apply using your legs (you'll have to trust me on this). Not to say that climbing stairs will always be impossible to do on a bike, it's just that for the most part, the rider is at a severe disadvantage. This same problem is further compounded by the fact that your front tire is undergoing the same thing. This effect is often worsened when the rise-run of the stairs happens to match your bike and your front and rear wheels begin to try to climb a stair at the same time (eeeerrrrrrcccchhhhhh). The reason that suspension helps is that it allows your wheels to get up the stair before your body is lifted. This, in turn, reduces the necessary forces required to ride up. Hopefully this explaination has been helpful.


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## BigLarry (Jul 30, 2004)

*My Current Summary*

I getting from others that riding up stairs is indeed really VERY hard. It wasn't just me. It's not clear anything (like suspension) helps much. The only thing that seems to help is lots of momentum in a running start, as one can't apply enough power in the climb.

Here's my summary of comments heard:
1. Stairs are really steep. They'd be a tough climb even on a smooth ramp.
2. There's not much grip on a tire at the edge of a stair. Eg. some get pinch flats. A foot on a step provides much greater traction.
3. Most importantly, the repeated pounding of front and rear tires running against the vertical steps dissipates a LOT of energy no matter what the bike technology does. Eg. Even a running start slows down quickly. 
All put together, _sustained _ riding up of normal slope stairs is impossible - only one story is possible with a running start.


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## Primus (Oct 4, 2004)

BigLarry said:


> In terms of torque applied to the wheel winning over leg force, this is the standard gearing problem. Another way of saying it is that the gearing isn't low enough. But standing in the lowest gear should be able to work on even the steep incline of stairs.
> 
> The vertical slope of a given stair shouldn't be an impenetrable barrier either. After all, one can easily hop over logs or up over ledges of 1-2 feet. And people here say they can get over several steps. It's just the combination of them acting repeatedly on both wheels that seems to be an issue in simply disipating energy.


As for your first comment, "...standing in the lowest gear should be able to work...". Well, you're only 2/4 right, and here's what I mean. When people refere to gearing of their bike, they're talking about how many revolutions of your feet produce one revolution of your wheel. But the problem lies herein; there are actually 4 "gears" that one must consider when calculating the torque output at the rear wheel given torque input at the cranks: your cranks, your front chainring, your rear chainring, and the radius of your rear wheel . Let's illustrate this with an easy example. Let's say that you're in granny-gear and you're running a 17-tooth chainring up front and 34 in back. That's a ratio of 2:1 meaning that it will take 2 revolutions of your feet to get one revolution of the rear wheel. Now let's say that you can apply (by body weight and leg strength) a torque of 86 ft-lbf (175mm cranks with 150 lbf force), that would translate to 172 ft-lbf (86*2) of torque at your rear wheel. However, there's a catch. You see, when you are standing on your bike, some of your weight is attempting to rotate your rear wheel backwards, and the wheel has _alot_ more leverage (26"/2=*13"* vs 175 mm (*6.9"*)). So now say that your weight is also trying to rotate your tire backwards, the torque it can apply is 150 lbf*13 inches=163 ft-lbf. So, looking at the numbers, you have 86-ft-lbf of positive torque and 163 ft-lbf of negative torque, for a net of 77 ft-lbf of torque acting to roll your a$$ back down the stairs.

So why then, is it easier to climb over stuff like logs and stairs with a 26" wheel than it is with a 20" wheel? Don't you have a better torque output at the rear wheel (assuming the chainrings and cranks are the same) with the 20" wheel? The reason for this "discrepancy" is not a difference in torque output, it's a matter of where the stair or log or whatever contacts the tire - with a larger diameter wheel, more of the resultant force is going to propel you forward rather than upward (hence the Gary Fishers of the world riding 29" wheels). Take it on a very large scale, imagine you are riding a bike with 500 foot diameter wheels. Those little stairs wouldn't seem quite so significant, would they? (Taken in the reverse, imagine a set of stairs where each step had a rise of only 1/4-inches. Kinda starts to resemble a dirt trail, doesn't it?)

As for your second comment, "The vertical slope of a given stair shouldn't be an impenetrable barrier either." Well, yes, a vertical slope _is_ an impenetrable barrier. Why? Because there is no amount of force that one could apply in a (truly) vertical direction that would ever produce a resultant action in a (truly) horizontal direction. But that's somewhat off a moot point because in the case of riding a bike up a stair, you already have components of motion in the horizontal direction (e.g. momentum, etc.).

As for your third comment, "After all, one can easily hop over logs or up over ledges of 1-2 feet. And people here say they can get over several steps." Well, that's hopping, not pedaling. (I'm not trying to be a smart-a$$)

And finally, your fourth comment, "...seems to be an issue in simply disipating energy." I couldn't _partially_ agree with you more. While energy dissipation (rebound/compression of your shocks, compression of your tires, the list goes on) is a big factor in the sustainment of a good stair-climb, it isn't the primary factor in the prohibitive nature of climbing stairs on a bike - it's the physics that gets you!

Quote from the band *Clutch* (if you haven't heard of them, check 'em out):
I'd be a richer man today, if it weren't for physics;
if I could levitate, I would sell lots of tickets, 
and maybe do an interview with Larry King while floating...


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## prerogative (Jan 15, 2004)

Wouldn't another factor be wheelbase to stair tread . . . not sure how to describe this. I've never done a regular flight of stairs - only park/city ones, but did notice: If the front tire hit stair tread off sequence from rear, it seemed easier to peddle up. One could hit the stairs at an angle to change this a little bit, but most of it is up to wheelbase vs. tread hits being dead opposite for front/rear.

Did I make any sense?


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## Primus (Oct 4, 2004)

prerogative said:


> Wouldn't another factor be wheelbase to stair tread . . . not sure how to describe this. I've never done a regular flight of stairs - only park/city ones, but did notice: If the front tire hit stair tread off sequence from rear, it seemed easier to peddle up. One could hit the stairs at an angle to change this a little bit, but most of it is up to wheelbase vs. tread hits being dead opposite for front/rear.
> 
> Did I make any sense?


Makes perfect sense; in fact, I mentioned this in my first thread, "This effect is often worsened when the rise-run of the stairs happens to match your bike and your front and rear wheels begin to try to climb a stair at the same time."


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## binary visions (Jan 18, 2004)

Primus!

Please post here more often. Your posts are coherent, well informed, well punctuated, and educational 

Thanks for my physics lesson for the day...


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## ezweave (Jul 9, 2004)

Why are you climbing stairs? This is the DH/Freeride forum... we don't pedal up sh!t. Jump them stairs.


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## eman (May 2, 2004)

I can get up 6 or 7 on my trek 820 with like 1.5inchs of travel in the front.
I go at the stairs at walking speed, wheelie into em so the front tire hits a few steps up and at the same time as the back tire, and pedal up. It just depends on the steepness of hte steps like a lot of people said. On some steep ass concrete steps I could only get up 5, anymore and i had no traction.


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## BigLarry (Jul 30, 2004)

*Got it*



ezweave said:


> Why are you climbing stairs? This is the DH/Freeride forum... we don't pedal up sh!t. Jump them stairs.


Ok, so it's

Carry the bike up.

Jump the stairs down.

Now I got it.


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## Skygrounder (Apr 26, 2004)

ezweave said:


> Why are you climbing stairs? This is the DH/Freeride forum... we don't pedal up sh!t. Jump them stairs.


Because until you learn to climb stairs you can never be a true moon master.


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## penguinofdoom (Sep 10, 2004)

comeon, when you're doing some totally sweet jibing/urban freeriding at your local community college, and those damn security guards come and try to chase you off, it's helpfull to know how to get up some stairs to get away from 'the man'...

i hear root beer bullits are particularly good at climbing stair cases. 

p.s. the technique that i learned is to ride into the stairs pretty quick, as you need a decent ammount of momentum to get up 'em.. and then when you get to the first steps, do a sorta bunny-hop into the stairs, so that you're basically pulling your bike up the stairs.


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## Felpur (Jan 22, 2004)

When I was learning "real" mt biking I use to like biking up stairs..It made me pop alot of tubes and $3-5 bucks a tube I coudnt afford this much fun....this was on my old xc rig with 4" of travel front n rear... I found that you could bike up most any set of stairs ( maybe not the humungo ones) it's all about momentum getting going fast enough and should be able to go up any flight assuming it's not too large or you dont pop or bust your bike.... on my fr bike I can go up the same set of stairs much slower...suspension I bet makes all the differece there.. on the xc rig5-7 stairs... on my Banshee maybe close to double that.. I admit it is fun fooling around on stairs up/down/over etc... just that the challenge no longer exists for the up part... each there own...... On the Kranked 5 video there is a clip that I think is really cool... it shows a guy flying up a double set of stairs, and respectable amount of stairs at that. The cool part comes into play because he is on a hardtail and going so fast that he flies up set one, and bunny hops at the top and actually jumps the entire second set....


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## dirtdonk (Jan 31, 2004)

*good in theory bad in application*



Primus said:


> The first reason, is that you are _not_ climbing a semi-constant incline; you are climbing a _vertical _section followed by a horizontal section, and so forth. Now, we all know that there are not very many bikes that climb a standing tree, so why would we expect one to be able to climb a (albeit short) vertical stair? The second reason boils down to basic physics. Basically, it boils down to the fact that while climbing a stair there are few forces that are acting on your bike to propel it up the stair; you have the *downward* force of your weight and the extra push on your pedals; you have a *backward* force of the step acting on your tire; and you have an *upward* force of the step also acting (at the same point) on your tire. Given the geometry of the situation, you are at a severe disadvantage in terms of propelling yourself *up* the stair. The vertical force acting to turn your tire backwards (i.e. you roll back down the stairs) applies a larger amount of torque than you could ever apply using your legs (you'll have to trust me on this).


for your theory to be close the steps rise would have to be the same as the wheels radius. then the tire would be going vertical, but only for a very short distance. the tire would actually be going further horizontally due to the longer run of the standard step. allowing extra time for momentum building. i'll not dispute your math below. i can't say right or wrong on the numbers you've come up with but i will say i'll bet you didn't consider pulling up on the pedals adding substantial foot/lbs in there in regards to being able to climb vertically. i therefore bring it back to a traction issue. stairs are at about 33 degrees. i wonder what those steep sections on slickrock are that we can get up by standing further forward on the bike than we ever imagined possible?


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## Yoshimura (Jan 16, 2004)

last week i was out riding at my skool adn i found this flight of stairs..about 15-16 steps, i was on my turner dhr and i decided to climb it and got up to the top with ease..i guess its all about the technique but i couldnt explain to u how to do it becasue i guess i just do it simultanenously, but another key factor is also getting some good speed and get ur tyres pumped up!! coz wen i did it the 2nd time i got a pinch and had to walk home!!

by the way? y do u want to climb staris?


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## wyrm (Jan 19, 2004)

Not Kranked 5 but I have seen that footage. At first I thought it was cool for someone to go up stairs and land on top of the second set, but apon closer inspection you will see that he had a ramp or some plywood down. So he really wasn't hitting the stairs themselves but just used it to make a ramp. But it was cool.

Wyrm


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## Primus (Oct 4, 2004)

*Well allow me to retort... *



dirtdonk said:


> for your theory to be close the steps rise would have to be the same as the wheels radius. then the tire would be going vertical, but only for a very short distance. the tire would actually be going further horizontally due to the longer run of the standard step. allowing extra time for momentum building. i'll not dispute your math below. i can't say right or wrong on the numbers you've come up with but i will say i'll bet you didn't consider pulling up on the pedals adding substantial foot/lbs in there in regards to being able to climb vertically. i therefore bring it back to a traction issue. stairs are at about 33 degrees. i wonder what those steep sections on slickrock are that we can get up by standing further forward on the bike than we ever imagined possible?


Good point on the pulling *up* on your pedals, but yes, I did consider that. I figured I was already being loquacious with my previous threads, so I decided to cut it off. However, getting to the point of pulling on the pedals, here's my logic on that: by pulling on the pedals you may be able to add, perhaps 30% more torque? If that is the case, 86+30%=112 ft-lbf of torque vs 163 ft-lbf of negative torque, so you'd still be at a loss. Another issue with pulling on the pedals is that some people pull on the pedals by leaning forward and essentially yanking their foot; this would, in turn, tend to give you _less_ traction on the rear wheel while jamming your front wheel harder into the next step. Finally, I was considering the typical freerider/downhiller, the majority of whom rides with platforms and not clipless pedals.

More importantly than pulling on the pedals is your point on the radius of the wheel being equal to the rise of the step. You are absolutely right, for a 26" wheel to roll up an 8'' step, the tire would have to initially climb at an angle of 32 degrees (the angle would decrease after that). So no, you are not climbing vertically, but the amount of torque required to roll you up a 32 degree incline vs. on a flat surface is approx. 48% more. This is a rough estimate, simply using a little bit of trig.

As for the slickrock, well, your guess is as good as mine. I'd be surprised if anyone coudl sustain a climb on anything more than about 45 degrees - but that's not a traction issue, that's an endurance and balance point of your bike (before your a$s topples over) issue.


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