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Old 04-06-14, 03:47 PM   #1
Walter S
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Is it possible to predict what gear inches you'll want for a given grade of hill?

For example, you see that a hill is 15% grade. You know that your lowest gear is 19". You weigh 150 lbs. and your loaded bicycle is 100 lbs.

Do you think "piece of cake" or "OMG"?

How do you arrive at that feeling?
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Old 04-06-14, 04:05 PM   #2
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I rarely even know what the % grade that I'm riding. The time of day, my physical condition, wind, and current emotion come into play just as much as the grade. I always feel good when I'm on my next to lowest gear, knowing I can bale to the lowest. My experience has been that I can, at least, grind it up any paved road I've come across so far, back county dirt is another thing. Pushing a bike is always an option.

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Old 04-06-14, 07:18 PM   #3
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Experience helps a lot ..


Drop to the granny gear and shift to one of the smaller cogs in back and as the hill gets steeper
keep shifting down to the bigger cogs as they are needed ..

once you are at the granny and the biggest cog in back and its still too hard a climb, get off and push ..

always tour, IMO, in shoes you can walk in ..

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Old 04-06-14, 08:29 PM   #4
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Quote:
Originally Posted by Walter S View Post
For example, you see that a hill is 15% grade. You know that your lowest gear is 19". You weigh 150 lbs. and your loaded bicycle is 100 lbs.

Do you think "piece of cake" or "OMG"?
If I were riding a 100lb bike, I'd be thinking "OMG" every minute of the day, let alone when I see that I have to pedal it over a 15% grade...

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How do you arrive at that feeling?
You practice riding up hills on your fully-loaded touring bike. At least that's what I did. And it prompted me to change the gearing on my bike before I left on my first tour...
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Old 04-06-14, 09:31 PM   #5
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Quote:
Originally Posted by Walter S View Post
For example, you see that a hill is 15% grade. You know that your lowest gear is 19". You weigh 150 lbs. and your loaded bicycle is 100 lbs.

Do you think "piece of cake" or "OMG"?

How do you arrive at that feeling?
Truthfully I don't know what gear inches I'm using at any point in time unless I'm in bottom or top. Experience is the only teacher, which includes Big Aura's comments and more.

Brad
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Old 04-06-14, 10:00 PM   #6
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All of the above and:

When I start up a hill I usually shift down to my smallest chainring, and go up 2 higher gears on my cassette. This leaves me in about the same gear I was in prior to the double shift. This allows me to use only my rear derailleur as I work my way up the hill, resulting in smoother shifting, and no chance of a dropped chain on the front.
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Old 04-07-14, 08:45 AM   #7
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I suppose it's possible if you want to play with analyticcycling.com. Start by finding a local hill with a known gradient, and figuring out how fast you can sustain climbing it comfortably. Put that into the analyticcycling model, with your weight and your bike's weight, and figure out your power level. Then bump up the bike's weight, put in your desired grade and estimated power, and figure how slow you'll be climbing. Take that and play with a gear inch table to try to keep your cadence at whatever you're comfortable with (for myself, I want to make sure I never drop below a cadence of 60 rpm, or my knees will let me know I did something stupid!).

Not too many people can stay balanced while climbing with a load below about 2.5-3 mph. Just sayin'.
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Old 04-10-14, 07:33 AM   #8
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Walter, as mentioned, there is no chart or online thingee that will replace having to get out there and finding some differently graded hills to see how it works for you. I would however recommend thinking hard and fast about carrying upwards of 70lbs of stuff, assuming your bike is probably 30-35lbs.
Again, you are going to have to get out there and see what it feels like, but if you can reduce your load by 10, 20, 30 lbs the difference in how much work you have to do will be very much noticed, especially if you can reduce it to the 40-45 lb range.

In other words, gearing like 19 g.i. for me works well with about 40lb of stuff in hilly areas, but add in another 20 or 30lbs and it would be pretty darn unpleasant---this comes down to the 'ol "been there, done that" thing for me, on my first fully loaded tour I had too much stuff, steep long hills and being a skinny guy meant I learned next time to take a good 10lbs of stuff off, plus lowered my gearing.

the old rough estimate of having your bike weight + load weight = about half your body weight, works for me and fits in with what I figured out on my own before seeing this rough estimate suggestion.

bike 30lbs, stuff 40lbs, = 70, about half of me at 140. I've done a fair number of touring with that load and about 21 g.i., but on reasonable graded roads (probably not much more than 15%)

I've travelled in places with steeper grades, with lots of regular steep stuff, but on a bike with only 25lbs of stuff and about 19 g.i. I knew at the time that if I were to travel in areas like that with a full load of 40-50lbs, I'd have to lower the gear inches to lower than 19 or it would be unpleasant.

question, is your estimate of a bike weighing 100lbs just on paper, or have you actually put all this stuff together and ridden your bike with it like this? Figure I'd ask this before asking specifics about your packing.
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Old 04-10-14, 08:14 AM   #9
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Quote:
Originally Posted by fietsbob View Post
Drop to the granny gear and shift to one of the smaller cogs in back and as the hill gets steeper
keep shifting down to the bigger cogs as they are needed ..

once you are at the granny and the biggest cog in back and its still too hard a climb, get off and push ..

always tour, IMO, in shoes you can walk in ..
This is what I do. When I see a 15% grade I think OMG regardless of load. 15% is steep no matter what.
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Old 04-10-14, 08:25 AM   #10
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there's always the 2 foot gear .. the British do call them 'push-bikes' for a (historical) reason ..
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Old 04-10-14, 09:28 AM   #11
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If you actually want to do the math, and you know your FTP, you can go to a variety of web sites to calculate speed from power, weight, % grade.

BUt really, the answer is 15% is hard no matter how much your bike weighs, and there is no such thing as too-low of a gear on a touring bike.

I use a 22x34 low gear.
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Old 04-10-14, 09:57 AM   #12
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If you actually want to do the math, and you know your FTP, you can go to a variety of web sites to calculate speed from power, weight, % grade.

BUt really, the answer is 15% is hard no matter how much your bike weighs, and there is no such thing as too-low of a gear on a touring bike.

I use a 22x34 low gear.
No. 1. On a touring bike, low gears are a beautiful thing (your knees will thank you) and 15% is a pretty tough climb.
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Old 04-10-14, 10:50 AM   #13
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I rarely even know what the % grade that I'm riding.
I'd suggest that riders almost never accurately know the percentage of the grade. Even when posted on a sign or map it is likely to be wildly inaccurate. Then there is the fact that grades are often extremely variable through out their length. So if the posted grade is correct at all, is it referring to the little 100' piece that is the maximum, the average for the whole climb, or something else. So basically any accurate grade number is unknowable in most touring situations.

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For example, you see that a hill is 15% grade. You know that your lowest gear is 19". You weigh 150 lbs. and your loaded bicycle is 100 lbs.

Do you think "piece of cake" or "OMG"?
As soon as you said "your loaded bicycle is 100 lbs" I said OMG. That much total weight would be unpleasant to me regardless of the pitch of the grade. I have never carried that much even on my first tour, a Trans America where I was carrying more than my share of group gear and was not that sharp about packing decisions. I'd have to have some very special reason that went well beyond normal touring to carry that much on a tour.
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Old 04-11-14, 07:02 AM   #14
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I just went down from a 26 to a 24 chain ring in the front. My biggest cog is a 34.

I'm going to just hope for the best. I'm not too worried about it. If it were a normal tour and an undoable route then I'd just turn around and do something else. But as it stands, I've picked about the easiest route I can find to Vogel and if I turn around that means not going to my mother's 80th birthday party! (but in reality I would just phone somebody to come rescue me - albeit not what I'd prefer).

I think google earth does a pretty good job of reporting the grade of a hill. Both the average and for little sections of it. That's based on anecdotal evidence of what it says when I spot check some known grades that have been manually calculated for certain roads I know. And for some posted grades on major highways, where the grade clearly does not vary much to look at it visually or in what google earth says about it.

I'm not saying that google earth is consistently correct. But it's at least close for some climbs I've known about for years. For example, for my trip next week to Vogel State Park, it's part of a ride that me and other bicyclists have known as "tripple gap" that's a circuit running from Dahlonega, to Vogel, to Suches, and back to Dahlonega. Some of the more serious riders had hand-calculated the grade of some of those climbs and when I look at those with google it comes within about a percent of the figures I've heard for years.

If you want to know the difference between a 12% or a 13% grade, I agree its unknowable. But if you know that 10% has been a challenge for you, and you see a predicted 18%, you're well advised to be concerned.

I was looking for some math to help me predict what's doable because the last time I rode up there I was on a lightweight road bike - before my evolution to a car-free lifestyle where that kind of riding is now rare. Now if I want to ride in the mountains, I'll spend a day getting there first instead of throwing my bicycle in the car and going in a couple hours.

I think once you have some experience with similar loads and grades you can forget the math and just go on the basis of that experience. I'll learn a lot just from this trip next week.
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Old 04-11-14, 08:05 AM   #15
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I think once you have some experience with similar loads and grades you can forget the math and just go on the basis of that experience. I'll learn a lot just from this trip next week.
That is the real answer IMO. Also remember if you run out of lower gears walking is always an option and if you find a 24-34 not low enough, it is steep enough that walking won't be that bad of an option.
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Old 04-11-14, 09:25 AM   #16
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I think once you have some experience with similar loads and grades you can forget the math and just go on the basis of that experience. I'll learn a lot just from this trip next week.
all the best with your trial run.
Growing up doing stuff like some backpacking, or canoe camping where we had to carry our canoe packs on portages, I got used to keeping stuff to a minimum simply because it was so hard to carry a heavy pack. Like I said, on my first big bike trip I still took too much stuff, and so was really careful in later trips with weight just because the extra 15lbs or whatever I reduced my load to made all the difference in my enjoyment.

Along the lines with weight, your question about gearing and gradient really does come down to how much your bike weighs, it would be neat to have a graph or something to give you an idea of what an average rider (whatever that is???) would want for gearing for a 15% hill + a bike that weights "X" weight, but there isnt one.

Certainly in my experience every extra 5 or 10 lbs or whatever more on your bike means you'll need lower gearing, so to repeat myself, your 65lbs of stuff is going to be damn hard to get up hills.
Another consideration is without lower gearing, this is going to hard on your knees--going from your mentioning of your mother's 80th, we could be of similar age, so 40 or 50 yr old knees might not like your 100lb bike and steep hills, and to be frank, if you love bicycling, why risk a knee injury because you have too much stuff.

*what about mailing some of your "party clothes" there or whatever extra stuff is, so you dont have to schlep the stuff you wont be using on the actual journey?

anyway, good luck with seeing how it goes next week.
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Old 04-11-14, 09:51 AM   #17
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As another poster said earlier, but without the links, get your power from this calculator by noting your speed on a known gradient and weighing everything:
Bicycle Speed And Power Calculator
Then plug your power back in to get your speed on any gradient.

Then plug that speed into either of these calculators:
Bicycle Bike Gear Ratio Speed and Cadence Calculator
http://www.gear-calculator.com/#
and you'll find what gearing you need to produce a particular cadence at that speed. This works very well and is accurate, though you may be a little surprised at the result.
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Old 04-11-14, 10:11 AM   #18
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CFfeller, interesting thing, but to be honest, I have absolutely no idea what watts I put out, and I suspect for most people this is an unknown thing as well. I wonder how accurate this is in terms of giving us a watt output number?
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Old 04-11-14, 10:52 AM   #19
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It has not been mentioned yet but the length of the climb is also critical. For example, if you know that a mountain pass is on your chosen route with no easy way around, the length of the climb, even if not extraordinarily steep, might be a show stopper.
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Old 04-11-14, 11:00 AM   #20
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CFfeller, interesting thing, but to be honest, I have absolutely no idea what watts I put out, and I suspect for most people this is an unknown thing as well. I wonder how accurate this is in terms of giving us a watt output number?
The Kreuzotter calculator is quite accurate. It uses the well-known and tested equations of bicycle motion. If you upload your ride information to your computer or a website, it's pretty easy to get speed at grade information, though that depends on the software or website. Strava is good if you use a Garmin. The Polar software is good if you use a Polar.

Or you can accurately time when you begin and end a climb and look the climb up on Google Earth. That'll give you vertical ascent in meters (VAM) or in feet. You can then assume any gradient, calculate what your speed would have been at that gradient and plug that into Kreutzotter to get power. Doesn't even need to be a steady grade, just a steady effort. Or better, get the distance from your computer or plot it on RidewithGPS. Then you can calculate the gradient in percent. That's actually what I do because it's the most accurate if you use a long climb, say a few hundred feet or more. Free power meter.
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Old 04-11-14, 11:11 AM   #21
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It has not been mentioned yet but the length of the climb is also critical. For example, if you know that a mountain pass is on your chosen route with no easy way around, the length of the climb, even if not extraordinarily steep, might be a show stopper.
Which is the reason I go against the grain on this forum and recommend training for a tour. Mountain pass shouldn't be a problem if you have the gearing for it. And maybe have figured out you need to carry less than 70 lbs. of gear on your bike. It's just time spent pedaling in beautiful country.
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Old 04-11-14, 11:26 AM   #22
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...
Along the lines with weight, your question about gearing and gradient really does come down to how much your bike weighs, it would be neat to have a graph or something to give you an idea of what an average rider (whatever that is???) would want for gearing for a 15% hill + a bike that weights "X" weight, but there isnt one.
...
Just an aside ... Google Maps does a pretty good job at estimating the time for "an average rider" for a given route. Google doesn't know our weight, riding position or bike (but don't put it past them eventually), so it's necessarily a really broad estimate. Broad estimate is all OP is needing however.

Math works. Plug the hill part in to Maps, see how long Google says it will take, figure the speed from that, plug the speed, weight and grade into the calculator for a reality check on the power required.

Time, distance, grade and weight gives you everything you need for "what-ifs" using one of the online calculators. Just say "I'm going to put out 160 watts on the climb" and see what that speed is. Figure cadence from the speed and gear inches. If the cadence is way low, there's a problem.

Ps, I just did a spot check using 250 pounds & 15% grade, and 170 watts. You're climbing at 2.2 mph. With 19 gear inches that's a cadence of 40. That looks to me to be pretty difficult to sustain, very low speed very low cadence.

Last edited by wphamilton; 04-11-14 at 11:34 AM.
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Old 04-11-14, 12:55 PM   #23
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CF and WP, interesting. Might take a proper look at these when I have more time or inclination (about 15% max I hope ;-)
I'm more of a seat-of-the-pants sort of fellow, but shouldnt be too ludditish about a new thing, and it might be neat to see how this sort of stuff translates to real world.
I would add that all this math and stuff doesnt always reflect how one feels from day to day, ie at the end of the day and you havent slept well, havent eaten well, have a cold, or whatever. I still feel that getting ones arse out there and figuring out what works for you is more important--although again, I guess I shouldnt be too quick to dismiss a tool that could work to help folks-although it seems to me it involves a lot of computer time. With a gps unit it makes sense that with having the data of a ride already, it would be easy to plug the numbers in and compare a given climb for instance with a given weight on the bike.

For me especially, it would be neat to get an idea of power output, like I said, I havent a clue except knowing it is probably pretty low to average.....
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Old 04-11-14, 01:47 PM   #24
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Make sure you have good walking shoes. With a 100 pound load I'm pretty sure you'll be walking up the steep hills any way. No sense in cycling up a steep gradient with that kind of load.
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Old 04-12-14, 12:10 PM   #25
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Math works. Plug the hill part in to Maps, see how long Google says it will take, figure the speed from that, plug the speed, weight and grade into the calculator for a reality check...
Interesting commom sense approach.
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