What incline can B ridden with ultra low 22 chwhl & 36 cog?

Noticed that Shimano makes a 29er cassette with a 36 teeth cog. Got to thinking (DANGER!, DANGER VBG ;))that the cassette with a 22 teeth chainring would give a really low low gear. Used with 26.125 MTB tires it'd be 15.9 gear inches, 3.0 Km/Hr at 40 rpm. I guess that if the tire was grippy enough you could ride up a pretty steep slop providing you could keep the front whell down on the surface. What sort of incline do you think such a low gear could climb if the rider could balance the bike? I'm not concerned with how fast the bike wouldbe going or that it might be faster to walk it. Just wondering like some people wonder how fast you could go with a certain big gear.

Cheers

Sir Ridesalot wrote:
Noticed that Shimano makes a 29er cassette with a 36 teeth cog. Got to thinking (DANGER!, DANGER VBG ;))that the cassette with a 22 teeth chainring would give a really low low gear. Used with 26.125 MTB tires it'd be 15.9 gear inches, 3.0 Km/Hr at 40 rpm. I guess that if the tire was grippy enough you could ride up a pretty steep slop providing you could keep the front whell down on the surface. What sort of incline do you think such a low gear could climb if the rider could balance the bike? I'm not concerned with how fast the bike wouldbe going or that it might be faster to walk it. Just wondering like some people wonder how fast you could go with a certain big gear.

Cheers

Hmm. Well, to simplify things a bit: If the crank arm's horizontal and
the rider's weight (Wr) is on the forward pedal, the thrust at the
ground (i.e. the pavement's up-the-hill push on the bottom of the rear
tire) would be crank radius / tire radius * 35 / 22, or about 0.8 * Wr

Let's assume a bike weight about 15% of the rider weight, so total
weight is 1.15 * Wr.

Drawing a free body diagram with X axis aligned to the road surface, and
that surface tilted up at an angle theta, and assuming equilibrium in
the X direction, i.e. X components totaling zero, it looks like
0.8 * Wr - 1.15 * Wr * sin(theta) = 0

I get theta to be roughly 45 degrees. IOW, a 100% grade. But yes,
pitching over rearward would be a real problem, if it's anything like a
standard bike.

Complications are, if the crank arm's non-horizontal, which it usually
is, that maximum possible angle would be less. OTOH, a rider can pull
upward on the bars, generating more pedal force than his weight, and
allowing for acceleration during the power phase, to counter
deceleration when cranks are near vertical.

And of course, he can pull up on his rear foot, if he's got the right
equipment!! ;-)

--
- Frank Krygowski

On Sep 17, 6:23*pm, Sir Ridesalot wrote:
Noticed that Shimano makes a 29er cassette with a 36 teeth cog. Got to thinking (DANGER!, DANGER VBG ;))that the cassette with a 22 teeth chainring would give a really low low gear. Used with 26.125 MTB tires it'd be 15.9 gear inches, 3.0 Km/Hr at 40 rpm. I guess that if the tire was grippy enough you could ride up a pretty steep slop providing you could keep the front whell down on the surface. What sort of incline do you think such a low gear could climb if the rider could balance the bike? I'm not concerned with how fast the bike wouldbe going or that it might be faster to walk it. Just wondering like some people wonder how fast you could go with a certain big gear.

Cheers

I don't know the precise grades of inclines, but I have climbed up
pitches on the Slickrock Trail in Utah that were difficult to walk on.
That's steady state climbing by pedaling, not by charging into it with
momentum. The gearing I used most commonly for such episodes there was
24/34 although obviously lower is possible. One does not (and cannot)
remained seated for such exploits so balance is still over the pedals
and the front/rear balance is easily adjusted with body English.

As for speed/cadence here's a short chart for that gearing ( view in
a fixed font)
Velocity (MPH) from Cadence (RPM), Chainring= 22t , Wheel
CIRC.=2040.0mm
Cadence- 40 45 50 55 60 65 70 75
80
----------------------------------------------------------------------------
36t | 1.9 | 2.1 | 2.3 | 2.6 | 2.8 | 3.0 | 3.3 | 3.5 |
3.7 |


DR

On Sep 17, 6:59*pm, Frank Krygowski
wrote:
Sir Ridesalot wrote:
Noticed that Shimano makes a 29er cassette with a 36 teeth cog. Got to thinking (DANGER!, DANGER VBG ;))that the cassette with a 22 teeth chainring would give a really low low gear. Used with 26.125 MTB tires it'd be 15.9 gear inches, 3.0 Km/Hr at 40 rpm. I guess that if the tire was grippy enough you could ride up a pretty steep slop providing you could keep the front whell down on the surface. What sort of incline do you think such a low gear could climb if the rider could balance the bike? I'm not concerned with how fast the bike wouldbe going or that it might be faster to walk it. Just wondering like some people wonder how fast you could go with a certain big gear.

Cheers

Hmm. *Well, to simplify things a bit: *If the crank arm's horizontal and
the rider's weight (Wr) is on the forward pedal, the thrust at the
ground (i.e. the pavement's up-the-hill push on the bottom of the rear
tire) would be crank radius / tire radius * 35 / 22, or about 0.8 * Wr

Let's assume a bike weight about 15% of the rider weight, so total
weight is 1.15 * Wr.

Drawing a free body diagram with X axis aligned to the road surface, and
that surface tilted up at an angle theta, and assuming equilibrium in
the X direction, i.e. X components totaling zero, it looks like
0.8 * Wr - 1.15 * Wr * sin(theta) = 0

I get theta to be roughly 45 degrees. *IOW, a 100% grade. *But yes,
pitching over rearward would be a real problem, if it's anything like a
standard bike.

Complications are, if the crank arm's non-horizontal, which it usually
is, that maximum possible angle would be less. *OTOH, a rider can pull
upward on the bars, generating more pedal force than his weight, and
allowing for acceleration during the power phase, to counter
deceleration when cranks are near vertical.

And of course, he can pull up on his rear foot, if he's got the right
equipment!! ;-)

--
- Frank Krygowski

So what's the ;-) for?
Indeed, I can confirm that there is a particular climb just off Moab's
Slick Rock Trail that I was never able to clean until getting the
secure pedal connection provided by SPD's.
That pitch is a short, VERY steep climb by which one accesses the
"Mountain View Cave."
In my circle of cyclists, the climb was called the "spillway." I
don't know whether that was a term used by others.
But in any case I can guarantee you that NOBODY has ever climbed that
using crap like Lyotard Model 23's.
Oh, sorry. Does that word still offend you?

DR

trying to find an image of Yuma Proving Ground's or GM there, inlcine test hill visible from thr public road....no find

but UTUBE HAS A plethora of bicycle hill video, adding 'test' and muktiple electrics show up

http://www.youtube.com/results?searc.... 8z7eqXt9lA4

I came upon an official Cal Road sign at Gold Bluff beach on way to mouth of the Klamath read:

CAUTION STEEP GRADE

a dune right ? I used caution n almost did an endo..a flyer...


try: 2 wheel drive motorcycle

for max without pedaling forces and with fatty tires

eg: http://www.rokon.com/

there's a Rokon dealer in West Palm Beach, kinda flat, for oil exploration

On Tuesday, September 18, 2012 8:49:58 AM UTC-4, datakoll wrote:
I came upon an official Cal Road sign at Gold Bluff beach on way to mouth of the Klamath read:



CAUTION STEEP GRADE



a dune right ? I used caution n almost did an endo..a flyer...





try: 2 wheel drive motorcycle



for max without pedaling forces and with fatty tires



eg: http://www.rokon.com/



there's a Rokon dealer in West Palm Beach, kinda flat, for oil exploration

Isn't there any way to discuss bicycles on a BICYCLE group without morphing the thread into a motorcycle or other powered vehicle one? ;)

Cheers

On Monday, September 17, 2012 5:23:52 PM UTC-7, Sir Ridesalot wrote:
Noticed that Shimano makes a 29er cassette with a 36 teeth cog. Got to thinking (DANGER!, DANGER VBG ;))that the cassette with a 22 teeth chainring would give a really low low gear. Used with 26.125 MTB tires it'd be 15.9 gear inches, 3.0 Km/Hr at 40 rpm. I guess that if the tire was grippy enough you could ride up a pretty steep slop providing you could keep the front whell down on the surface.

That's really it - weight distribution and traction. Seems like you'd have plenty of torque to go straight up a cliff.

What sort of incline do you think such a low gear could climb if the rider could balance the bike? I'm not concerned with how fast the bike wouldbe going or that it might be faster to walk it. Just wondering like some people wonder how fast you could go with a certain big gear.


I'm not sure I could turn it around fast enough to keep from tipping over, myself.

On Sep 17, 6:23*pm, Sir Ridesalot wrote:
Noticed that Shimano makes a 29er cassette with a 36 teeth cog. Got to thinking (DANGER!, DANGER VBG ;))that the cassette with a 22 teeth chainring would give a really low low gear. Used with 26.125 MTB tires it'd be 15.9 gear inches, 3.0 Km/Hr at 40 rpm. I guess that if the tire was grippy enough you could ride up a pretty steep slop providing you could keep the front whell down on the surface. What sort of incline do you think such a low gear could climb if the rider could balance the bike? I'm not concerned with how fast the bike wouldbe going or that it might be faster to walk it. Just wondering like some people wonder how fast you could go with a certain big gear.

Cheers

http://www.adventuredad.com/images/070210moabsteep.jpg
I'm surprised I can't find more such images, but that's just an
example of a grade that appears to be ~36°/73%.
And while that shows a rider descending, that is not particularly
difficult to climb.
DR

On 09/18/2012 12:49 PM, DirtRoadie wrote:
On Sep 17, 6:23 pm, Sir Ridesalot wrote:
Noticed that Shimano makes a 29er cassette with a 36 teeth cog. Got to thinking (DANGER!, DANGER VBG ;))that the cassette with a 22 teeth chainring would give a really low low gear. Used with 26.125 MTB tires it'd be 15.9 gear inches, 3.0 Km/Hr at 40 rpm. I guess that if the tire was grippy enough you could ride up a pretty steep slop providing you could keep the front whell down on the surface. What sort of incline do you think such a low gear could climb if the rider could balance the bike? I'm not concerned with how fast the bike wouldbe going or that it might be faster to walk it. Just wondering like some people wonder how fast you could go with a certain big gear.

Cheers

http://www.adventuredad.com/images/070210moabsteep.jpg
I'm surprised I can't find more such images, but that's just an
example of a grade that appears to be ~36°/73%.
And while that shows a rider descending, that is not particularly
difficult to climb.


Maybe not on a mountain bike but if I encountered that on my road bike,
I would scream.