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Gear ratios for Hills

Old 06-21-20, 12:53 PM
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Roadgraveller
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Gear ratios for Hills

Hi all,

I hope you can help.

I'm new to cycling and live in a very hilly place (Lake District) which has 25% - 30% hills, I have SRAM Force Etap AXS gears - 10/33 and 33/46 gears which gives a 1:1 ratio which I hear is quite low for road cycling.

However, I was wondering how much easier it would be going up hills if moving to 10/36 and 30/43? The cost of change I think is quite high so don't want to make the change only to find the difference is tiny. I'm planning a 112m 13k feet of elevation ride and need all assistance possible.

Any advice would be appreciated.

Cheers.
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Old 06-21-20, 12:59 PM
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There are no gears that will make a 30% grade "easier." If you're built like a world tour rider, 30% would require +500W to manage 5mph. The rest of us would more than likely have to get off and walk.

I don't know where people live where these insane, virtually impassable grades exist in number. I have one paved road in a 20 mile radius that exceeds 20%, and it's an access road to a reservoir, closed to traffic, reached only by lifting a bike over a fence. It's that steep for about 60 yards.

If you have any questions about more realistic conditions, we may be able to offer some suggestions.
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Old 06-21-20, 01:20 PM
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Originally Posted by DrIsotope View Post
There are no gears that will make a 30% grade "easier." If you're built like a world tour rider, 30% would require +500W to manage 5mph. The rest of us would more than likely have to get off and walk.

I don't know where people live where these insane, virtually impassable grades exist in number. I have one paved road in a 20 mile radius that exceeds 20%, and it's an access road to a reservoir, closed to traffic, reached only by lifting a bike over a fence. It's that steep for about 60 yards.

If you have any questions about more realistic conditions, we may be able to offer some suggestions.
Thanks for the note back - yes I know the hills are surprisingly steep aren't they, they are all paved and used by cars. I live in the hilliest part of England, if you search 'top hill climbs lake district' you'll see the top 8 hills all of which are within 1-15 miles from where I live. I even got it wrong, the steepest is actually 33% not 30. These are the stats for Hardknott pass:Distance: 2.2km
Height gain 298m
Average gradient: 13%
Max gradient: 33%
I hope you can now see the reason behind the question, the hills are monsters around here.

Cheers
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Old 06-21-20, 01:28 PM
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If that is indeed the case, then get to work on getting stronger. There are no free passes-- I'd need like a 20T front ring to make those kinds of hills repeatable. Hopefully you're under 150lbs, or it's gonna be tough going forever.

As I'm about 97kg rider weight, I would ride 25 miles out of my way to avoid those hills-- and I climb (on average) 400,000ft (122,000m) a year.
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Old 06-21-20, 01:41 PM
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Have you tried using the gearing you already have to see if it works for you?
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Old 06-21-20, 02:24 PM
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The change gives up too much on the high end for the extra low gear IMO-

it can't be all uphill where you live.
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Old 06-21-20, 02:25 PM
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Start on medium gear then shift to lower gears as ascend the hill
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Old 06-21-20, 02:35 PM
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Changes to the front or rear will definitely be worthwhile, those are some tough climbs for most recreational cyclists. Will your crank support smaller chainrings? If so, reducing the size of the small ring would probably be the most economical. After that, the larger cassette if your rear derailleur can handle it.
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Old 06-21-20, 02:36 PM
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Blimey mate, you need a mountain bike with 27 speeds. That'll get you down to around .65 ratio on the low end without sacrificing on the high end, which it appears will be mostly down hill anyway.
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Old 06-21-20, 02:46 PM
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Originally Posted by Roadgraveller View Post
Hi all,

I hope you can help.

I'm new to cycling and live in a very hilly place (Lake District) which has 25% - 30% hills, I have SRAM Force Etap AXS gears - 10/33 and 33/46 gears which gives a 1:1 ratio which I hear is quite low for road cycling.

However, I was wondering how much easier it would be going up hills if moving to 10/36 and 30/43? The cost of change I think is quite high so don't want to make the change only to find the difference is tiny. I'm planning a 112m 13k feet of elevation ride and need all assistance possible.

Any advice would be appreciated.

Cheers.
When it comes to touring bikes, 18 gear inches is considered a good granny gear. Gear inches is how many inches you travel forward for one complete pedal revolution. Even with a 10/36 and 30/43 setup, your lowest gear would afford you 22 gear inches given a 700c/32 wheel/tire combo. You should go lower. Aim for that 18 gear-inch number with your lowest ratio.

Frankly, I think you'd be better served by a rigid MTB on slick road tires or a touring bike with a triple crankset, given those ludicrous grades.
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Old 06-21-20, 03:07 PM
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Wow thanks all for the comments and advice.

Thankfully I'm just 140 pounds (63.5kg) and reasonable fit from years of rock climbing and mountaineer.

I have 'just' made it up all the hills a few at a time in a day but man-a-live it nearly killed me I thought I was going to blackout! Hardest effort I've put into anything for a long time.

Looks like keeping what I have and just putting more training in will be the major winner. I've seen that many road bikes run 36 front and 28 back - with that ratio I'd need to be a Tour rider.

Sadly most of the good rides do involve one or more of the steep hills, the Lake District is quite small and I live in the middle (big mistake 😂🤣&#128514.

Cheers.
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Old 06-21-20, 03:33 PM
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Also, depending on how wide the roads are, you can try tacking or zig-zagging up, which has the same effect as gearing down, as it spreads your elevation gain across a longer traversed distance.
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Old 06-21-20, 03:38 PM
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Originally Posted by General Geoff View Post
Also, depending on how wide the roads are, you can try tacking or zig-zagging up, which has the same effect as gearing down, as it spreads your elevation gain across a longer traversed distance.
That's great advice, thanks. The roads are fairly narrow but definitely wide enough to zig-zag.
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Old 06-21-20, 03:40 PM
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Originally Posted by General Geoff View Post
Gear inches is how many inches you travel forward for one complete pedal revolution.
Someone take this myth out back and kill it. "Gear inches" refers to the gear ratio x wheel diameter, traditionally calculated off a 27" wheel. It's a throwback that has been around long enough that it makes a useful universal reference for gearing (apparently from the era of penny-farthings, when all gear ratios were "1:1", but multiplying this by the wheel diameter made no more sense then than it does now). The number of inches you move forward for a single pedal revolution is the gear ratio x the wheel circumference - or 3.14 x the "gear inches" value.
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Old 06-21-20, 03:55 PM
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Originally Posted by Litespud View Post
Someone take this myth out back and kill it. "Gear inches" refers to the gear ratio x wheel diameter, traditionally calculated off a 27" wheel. It's a throwback that has been around long enough that it makes a useful universal reference for gearing (apparently from the era of penny-farthings, when all gear ratios were "1:1", but multiplying this by the wheel diameter made no more sense then than it does now). The number of inches you move forward for a single pedal revolution is the gear ratio x the wheel circumference - or 3.14 x the "gear inches" value.
Thanks for the correction, the name of this measurement is misleading. The more correct measurement appears to be "development" or "rollout" which measures distance traveled with one revolution of the cranks, typically measured in meters.
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Old 06-21-20, 04:03 PM
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Walk. 33% grade is heavy work even when walking. For most of us (your case does sound unusual) having to walk once in a while makes more sense than rigging an ultra low gear that is only rarely used but must be carried along all the time. At 33% it also gets difficult to keep front wheel on ground. If you decide you have to have sub 1:1 gears it is easier than it used to be, can be done, but trouble, expense, not encouraging that path until you are sure.
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Old 06-21-20, 04:16 PM
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It's okay to have a bit of a stroll in the middle of your ride. You don't have to do things the absolutely hardest way you can find.

(Litespud, it's actually pi x wheel radius.)
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Old 06-21-20, 04:37 PM
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I spend a lot of time riding in the forth hilliest city in the US. We have over 40 climbs that I call thigh burners with grades of 15% - 33%. I run a 50/34 - 11/32 and have never not made it up a climb. I weigh 225 lbs. so not the lightest rider on the block. I don't use the zig zag method, because for me the quickest way up is a straight line. Besides I kind of like the suffering, but that's just me, have fun.
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Old 06-21-20, 05:09 PM
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The Basics: little in the front Big in the back .. a 56 or 54 BCD Granny on a triple can have a 20t..


[Brompton 16" wheel 2 speed geared crank ,in low range, the pedals turn 2.5X faster than the chainring,
+ 3 speed hub .75 reduction gear stage..
low is 17" .. almost 1:1 x 16" wheel..




..

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Old 06-21-20, 05:20 PM
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Originally Posted by Roadgraveller View Post
I even got it wrong, the steepest is actually 33% not 30. These are the stats for Hardknott pass:Distance: 2.2km
Height gain 298m
Average gradient: 13%
Max gradient: 33%
I hope you can now see the reason behind the question, the hills are monsters around here.
At least around here, any hill that hits 33% only does so for a couple of blocks at most. As you say, your hill is average at 13%.

Sometimes I even wonder if the "max gradient" is so short that it is difficult for an accurate measurement by normal GPS and mapping. A car length or two?

Still, we have some wicked hill climb rides up in Portland, some of which I struggle with.

RondePDX

It doesn't look too bad from the maps, but at every corner, one turns the corner and back up a hill at 10% to 20%, or more.

As @Tacoenthusiast suggests, just go and try out your bike like you have it. None of us can tell what it will be like for you do do the climbing. You may have to stand up from time to time. Having pedal retention (toe clips, clipless, etc) will help with short-term power to pull over some of the steep stretches, but can be a pain with starting when stopped on a hill.

One thing about the super low gearing, at least for me, it just means I go slower, and ultimately spend more time on the slopes.

As far as the rides above... I'm no beast by any sense of the word. But, the first time I attempted the rides, I had 39/23 (1.7:1) low end gearing. That really beat me up. I changed to 34/23 (1.48:1) and it was still hard, but mostly doable. I've also done them with 41/26 (1.58:1) gearing. Not fast, a few stops, but I power through the rides. Personally I don't intend to hit 1:1 gearing until I hit age 70 (or I am carrying/pulling a bunch of extra weight).
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Old 06-21-20, 05:24 PM
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Originally Posted by theDirtyLemon View Post
(Litespud, it's actually pi x wheel radius.)
No, it's Pi (or 3.14, as I stated) x the diameter.
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Old 06-21-20, 05:28 PM
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E-bike??
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Addiction is all about class.
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Old 06-21-20, 05:40 PM
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Originally Posted by Litespud View Post
No, it's Pi (or 3.14, as I stated) x the diameter.
If one has a basic 700c wheel, then I typically ignore the wheel size, and just consider gear ratio (front divided by rear).

If you are experimenting with different wheel sizes (20" mini velo or folder, 650c, 700c, etc), then one might go ahead and add in some kind of gear inches calculation. Although, one could also simply multiply by a ratio of wheel sizes (diameter or radius). pi drops out. And one gets an adjusted ratio.

Of course, Junior Racing goes by their own set of rules and rollout is ever so important which one can calculate, but at the race one will need to measure.
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Old 06-21-20, 05:56 PM
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Originally Posted by Roadgraveller View Post
Thanks for the note back - yes I know the hills are surprisingly steep aren't they, they are all paved and used by cars. I live in the hilliest part of England, if you search 'top hill climbs lake district' you'll see the top 8 hills all of which are within 1-15 miles from where I live. I even got it wrong, the steepest is actually 33% not 30. These are the stats for Hardknott pass:Distance: 2.2km
Height gain 298m
Average gradient: 13%
Max gradient: 33%
I hope you can now see the reason behind the question, the hills are monsters around here.

Cheers
The steepest parts are probably at switchbacks, just a brief extra steep part on the inside of the turn.
This video of Hardknott shows two strong riders going all out to keep moving. They say it's a long stretch of 25%.

Even if it's actually closer to 20%, that's very hard for many or most riders to maintain. There's a limit to how slow a rider can climb, without losing steering control or balance. For me, it's near 3 mph. So that limits the max grade I can climb. Even with extremely low gearing like touring bikes have (24 front, 36 rear for example) I don't know if I'd have enough power to keep moving all the way to the top.

An online bike speed power calculator says I'd need to be at 300 watts to climb a 25% grade at 3 mph. I can do that for maybe 2 minutes. I just climbed an 11% grade for 4 minutes at 260 watts, going all out. Two minutes at 3 mph is only 530 feet along the road, which means, at a 25% grade, it's 130 feet high. (Last year, I barely made a 18-21% grade that's 140 feet high, and stopped at the top, where the grade starts leveling off.)

~~~~~
Low gearing
If you go extreme on the low gears, then you may find it has large gaps between shifts at more typical road grades and speeds. One gear may feel a little to hard, but shifting one easier is to high a cadence. Some riders don't care as much, though.

Smaller chainrings can shift the whole range downward, helping to keep reasonable shifts. This actually would work for many cyclists, except for pedaling on downhills. Coasting sooner on a downhill is a reasonable tradeoff.

I like my 34 front 32 rear. It lets me stay seated at 10-12%, where I used to stand up at those grades. I can do much longer hills at this grade by staying seated. Standing is great for very short, very steep climbs, or for using different muscles in the middle of a very long climb.

I might consider an 11-36, like one of the other local riders uses. But I don't think I'd like the big shift gaps at normal speeds.

Last edited by rm -rf; 06-21-20 at 06:00 PM.
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Old 06-21-20, 06:18 PM
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Originally Posted by Roadgraveller View Post
Hi all,

I hope you can help.

I'm new to cycling and live in a very hilly place (Lake District) which has 25% - 30% hills, I have SRAM Force Etap AXS gears - 10/33 and 33/46 gears which gives a 1:1 ratio which I hear is quite low for road cycling.

However, I was wondering how much easier it would be going up hills if moving to 10/36 and 30/43? The cost of change I think is quite high so don't want to make the change only to find the difference is tiny. I'm planning a 112m 13k feet of elevation ride and need all assistance possible.

Any advice would be appreciated.

Cheers.
Oh, your setup looks good.
10-33 in 12 speed: 10 11 12 13 14 15 17 19 21 24 28 33

Mike Sherman's Gear Calculator only goes to 11 speed! So I left out the 13 cog. Just picture it in between the 12 and 14.
Here's your setup (link) with 33 / 46 front and 10-33 rear, at typical flat road cadences. It's works well, with reasonable shifts in the small chainring out past 20 mph.
Plug in different cadence ranges to see how it looks at for different conditions. Or switch the cogs and chainrings. It updates the charts on the fly.




Scrolling down the calculator screen, the 33F, 33R low is 38 rpm at 3 mph. That's pretty low, but I can use very low cadences while seated if the pedal pressure is fairly light.
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