Adventure Cycling Association Forum

Bicycle Travel => Gear Talk => Topic started by: salabes on April 16, 2014, 11:38:44 pm

 
Title: 11-32 vs 11-34
Post by: salabes on April 16, 2014, 11:38:44 pm
11-32 vs. 11-34
I'm hoping that some of the frequent and knowledgeable contributors will weigh in on their opinion. I'm 69 years old. At 65 I rode self-contained from Chicago to Boulder (1,250 miles) without too much trouble. I have stamina but lack power. In May 2014 I plan to attempt the TransAm east to west self-contained. My bike is a Trek 520. The current configuration which has served me well is:
   Years ago I swapped out the crankset for a 22/32/44.
   The cassette is the original 11-32
   Tires are 700 x 32c
Do I have much to gain by replacing the 11-32 with an 11-34 or will the benefit of a slightly lower gear be negligible. I'm thinking that with the low 22 granny chainring the benefit will be slight. Shifting has been smooth and I've had no problems. What do you think? Do I have much, if anything, to gain by going to an 11-34?
Thanks in advance.
George
Title: Re: 11-32 vs 11-34
Post by: staehpj1 on April 17, 2014, 06:27:59 am
It is a personal preference thing, but...  I wouldn't bother.  Your 22-32 is low enough and two teeth on the rear won't make all that much difference.  If it actually did make the difference between walking and not (unlikely), the steepest climbs on the TA are in the Appalachians and worst case they are short enough to walk in a reasonable amount of time.
Title: Re: 11-32 vs 11-34
Post by: John Nelson on April 17, 2014, 08:04:43 am
Ride your 11-32 until it wears out and then buy an 11-34 to replace it. The difference is small, but every little bit helps.
Title: Re: 11-32 vs 11-34
Post by: Cyclesafe on April 17, 2014, 09:33:42 am
What they said.

But you might want to try an 11-36 (after you wear out your 11-32) if your rear derailleur is a long cage model.  As a practical matter, however, the difference will still be small.....

With your tires, a 170mm crank arm, and a "spin" of 80 rev/min a 22/32 yields 4.4 mph, 22/34 yields 4.2 mph, and 22/36 yields 4.0 mph.  As important is your second to the lowest gear combination of 22/28 (5.0 mph), 22/30 (4.7 mph), and 22/32 (4.4 mph), respectively.
Title: Re: 11-32 vs 11-34
Post by: Pat Lamb on April 17, 2014, 11:44:18 am
As John said, it'll make a little difference.  As Pete said, it probably won't be enough.  Get some Shoe Goo and put it on your shoes in Charlottesville so you don't wear the soles out walking before you get to Missouri.
Title: Re: 11-32 vs 11-34
Post by: dkoloko on April 17, 2014, 01:31:55 pm
You don't say how many cogs your bike has, 8-9-10 or what; that may limit which cassettes are available. If change, I would change to 12-36, not 11-34 or 11-36. Personally, I would use existing cassette, and not change unless I had to; but, since you asked, maybe you'll be more comfortable changing before you begin trip.
Title: Re: 11-32 vs 11-34
Post by: mbattisti on April 17, 2014, 07:27:31 pm
I have stamina but lack power.
You're a spinner.  If you have a long-cage derailleur, give yourself peace of mind and put a 36 tooth on.  You may be able to proudly tell your grandkids you never had to walk a single hill in the steep Appalachians.  We did (walk) with our loaded tandem with our lowest being a 34 x 24 (700 wheels).
Title: Re: 11-32 vs 11-34
Post by: zzzz on April 17, 2014, 10:45:16 pm
Hi George:

You haven't mentioned how much weight you're carrying and that has a significant affect on how low a gear you need.

22 up front and a 32 in back is an 18" gear, that's a really low gear. It's 1/2 the gear (38.4") that led mbattisti to walk his tandem up those hills. Frankly, if I had a low gear of 34/24 I probably would have been walking up that hill from Vesuvius to the Blue Ridge Parkway myself.

69 no longer counts as young but you've ridden a 1200 mile trip in the last 4 years, thats relatively recently so you got a pretty good idea of your abilities. If you're carrying under 40 lbs (a good ides anyway) I would think you'll be fine. Those hills are tough... but they're not that tough.

Pete
Title: Re: 11-32 vs 11-34
Post by: mbattisti on April 17, 2014, 11:14:47 pm
It's 1/2 the gear (38.4") that led mbattisti to walk his tandem up those hills. Frankly, if I had a low gear of 34/24 I probably would have been walking up that hill from Vesuvius to the Blue Ridge Parkway myself.


Recalculate. That's a 34 driven by a 24 tooth ring gear (should have typed 24 x 34 I guess)
Title: Re: 11-32 vs 11-34
Post by: Patco on April 18, 2014, 12:38:01 am
My touring bike has the same setup that you are contemplating (except I ride on 700X28's). I have elected to have low end gears I may not use versus high end I use on the downhills only. I haven't experienced the need to walk on the steeper and longer climbs....but that doesn't mean I don't stop for a break.
Title: Re: 11-32 vs 11-34
Post by: mathieu on April 18, 2014, 03:11:09 pm
If you have to ask this question, the best advice is: take 11-34.
As others have said, the difference between 32 and 34 is about half a gear change or -6% in speed at the same cadence. This doesn't sound much, but feels big in the lowest gear.

If you ride at 20 mph, the kinetic energy of your bike and body is about a factor of 20 higher than the energy input from one pedal rotation. If you stop pedalling for a moment the kinetic energy keeps you moving, speed drops slowly and as air resistance drops with the third power of speed, the speed drop is much less than linear with time.
But if you ride uphill with 3 mph, kinetic energy is only about half the energy input from each stroke and gravity weighs linear with speed (at constant gradient). Each pedal stroke has a sense of urgency and speed gets a sawtooth profile because the energy input is only substantial when the crank arms are near horizontal. This 'do-or-die' pounding of the pedals doesn't feel comfortable and doesn't look great.  The more rotations per minute, the smoother and more efficient the pedalling and the less the strain on body (knees) and mind. 

So why doesn't everybody opt for 34t? Well, there is a small weight penalty and the greater efficiency with faster pedalling stops at about 80 rpm. With a 22/32 combination and a 700-32c tires, at 80 rpm you advance about 2.0 m/sec (4.5 mph). At a gradient of 8 degrees, the altitude gain is 0.28 m/sec, which for a weight of 80 kg for rider+bike takes 220W (proportionally more if you are heavier or carrying an additional load). There are not many recreational cyclists around who can produce 220W power in steady-state, say over 20 minutes. Many will reach their limit at 175W steady power output. But those who can produce more power, are lighter or cycle lesser gradients, don't need 34t.

Slopes of  8 degrees is about the maximum you will see on the TransAm. Not in the Appalachians, but in the Ozarks. The Rockies and the Cascades are also less steep.
Title: Re: 11-32 vs 11-34
Post by: John Nelson on April 18, 2014, 04:26:35 pm
Slopes of  8 degrees is about the maximum you will see on the TransAm.
I think you'll find a lot of people who would dispute that.
Title: Re: 11-32 vs 11-34
Post by: mathieu on April 21, 2014, 08:54:36 am
Slopes of  8 degrees is about the maximum you will see on the TransAm.
I think you'll find a lot of people who would dispute that.

John, there are probably few people who are more knowledgeable about the TransAm route than you, so I reverently give way. Still I tried to remember where those wickedly steep slopes occurred. Maybe in Kentucky, where the adrenalin from the many dogs in ambush drove me over the hills?

Did your remark take into account that I mentioned a slope of 8 degrees? More often slopes are expressed as the ratio of rise over run, which for an angle of 8 degrees amounts to a grade of 14%?
Title: Re: 11-32 vs 11-34
Post by: staehpj1 on April 21, 2014, 09:14:56 am
Slopes of  8 degrees is about the maximum you will see on the TransAm.
I think you'll find a lot of people who would dispute that.

Did your remark take into account that I mentioned a slope of 8 degrees? More often slopes are expressed as the ratio of rise over run, which for an angle of 8 degrees amounts to a grade of 14%?
I don't know abut John, but I missed the "degrees" and thought "%" automatically.  Degrees seems like an odd way to express the steepness only because "%" is pretty much universally used.

Oh and based only on my impression of them...  The hills in Missouri climbing up out of the river valleys were pretty tough, but a few in the Appalachians definitely were harder for me so I'd assume they were steeper than the ones in Missouri.  Two that I remember were at Vesuvius and another that I think it was at Big A mountain.  Those were climbs for eastbound riders.  There were a least a couple others that seemed steeper to me than the ones in Missouri.

That said I don't have accurate numbers for any of them.  Furthermore I have decided that we seldom know the actual grades because the signs posted are often way off and even the maps can be pretty misleading.  Also the grades on smaller roads are generally extremely variable along their length.  So do you call the grade by a 100' section that is steepest, by the average from bottom to top, or something else?  In any case the numbers can be misleading wrt to the difficulty in riding them.
Title: Re: 11-32 vs 11-34
Post by: John Nelson on April 21, 2014, 10:32:10 am
I don't know abut John, but I missed the "degrees" and thought "%" automatically.  Degrees seems like an odd way to express the steepness only because "%" is pretty much universally used.
When I see someone give a road pitch in "degrees," I always assume they misspoke and mean "percent." Nobody, nobody, cites road pitch in degrees. So yes, I responded as if it said 8%.

With the exception of Kansas and eastern Colorado, the entire TransAm is hilly. There is no escape. Some of the hills in eastern Kentucky seemed insanely steep, perhaps only for 50 to 100 yards, but definitely made your legs work to maximum effort.

I don't place much stock in numbers to describe hills. On many 8% hills, there is at least one five-foot section that is 25%. Some people like to call that a 25% hill. The difficultly of a hill cannot be expressed by one number. In Colorado, you might climb at 6% for 30 straight miles. That's one kind of difficult. In eastern Kentucky, you might climb much, much steeper hills, each of which is fairly short, but there might be a hundred of them in a row. That kind of wears on you. That's another kind of difficult.

Clinch Mountain, near Hayters Gap Virginia, is regarded by many as the hardest west-bound climb of the TransAm. It's not that it's all that steep, but it the combination of steepness and length. Since I went east-to-west, I got to descend to Vesuvius, the hill where most west-bounders complain of having to stop frequently and let their brakes cool down. The psychological problem with both these hills is that they are very twisty and hemmed in with heavy trees, making it impossible to guess how far away the top is.

And yes, I remember well those Missouri river valleys, especially the valley formed by the Current River between Ellington and Houston. The Ellington park manager told me, "You got some hellacious mountains ahead of you!" Well, being from Colorado, I don't call them "mountains" but they were certainly difficult.
Title: Re: 11-32 vs 11-34
Post by: Pat Lamb on April 21, 2014, 10:56:09 am
It's always helpful when people use a common language to discuss things.  For road steepness, that's grade in percent.  Sure, it's technically possible to use centiradians from vertical, but it's not reasonable to expect other people to participate in a discussion when you use that kind of odd terminology.

The best I can figure, the Vesuvius grade averages 10% for 3 miles.  That's based on GPS, bike computer, and topographic maps.  It's built like most old mountain roads, so I wouldn't be surprised if there's stretches of 15% or more embedded in that 3 miles.

Lookout, KY was perhaps the worst grade going west.  I don't remember the numbers off the top of my head, but it was rough.  And we just had to laugh at the series of U-shaped dips southeast of Irvine, KY.

Back to the gearing question, pack light, gear low, and get a good running start on the flatter 8% sections to tackle the next 100 yards at 12%.  And there's no shame in walking.
Title: Re: 11-32 vs 11-34
Post by: staehpj1 on April 21, 2014, 11:49:11 am
And yes, I remember well those Missouri river valleys, especially the valley formed by the Current River between Ellington and Houston. The Ellington park manager told me, "You got some hellacious mountains ahead of you!" Well, being from Colorado, I don't call them "mountains" but they were certainly difficult.
The Ozarks were kind of weird to me.  I kept wondering when we would be in the mountains and never really saw anything that seemed like a mountain on the TA in the Ozarks even by Appalachian standards.  Hills into and out of river valleys, yes and very steep ones at that.  It got to where I dreaded seeing the Ozark Scenic Riverways signs.  Those signs always meant a steep descent and then a steep ascent back up the other side.  It was especially rough since it was crazy hot when we were there. and dealing with rafting company buses on the shoulder-less roads was "interesting".  Still, as I said, I don't think they were as hard or as steep as some in the Appalachians.

I think one of my Trans America companions found that type of hill harder though and I think she would tell you the Ozarks were the hardest part of the trip for her.  I definitely don't feel that way myself.
Title: Re: 11-32 vs 11-34
Post by: staehpj1 on April 21, 2014, 11:55:39 am
Lookout, KY was perhaps the worst grade going west.
If that is the grade I am remembering that doesn't surprise me.  It was a pretty crazy descent for us.

And there's no shame in walking.
Many folks will go to extreme lengths to avoid a bit of walking and I used to myself.  I have in more recent years found that it is nice to walk a bit sometimes just for a change of pace even where it is definitely not necessary.
Title: Re: 11-32 vs 11-34
Post by: mathieu on April 21, 2014, 12:05:30 pm
Sorry for the odd grade measure (yet Wikipedia puts Angle first in Nomenclature http://en.wikipedia.org/wiki/Grade_(slope) ).
Anyhow, it sparked off several interesting topical memories.
Title: Re: 11-32 vs 11-34
Post by: DanE on April 21, 2014, 12:20:18 pm
I had a friend who kept an old bicycle racing magazine around which had an interview with Greg Lemond published in it. In the article Greg was asked what the most difficult mountain climb he had done. His answer was Reed Gap in Virginia, used in the Tour DuPont. Now Reed Gap is not on the Trans-Am, but it is right next to Vesuvius just off the Blue Ridge Parkway south of Afton.  That is just a little story to confirm that is a world class climb coming up that ridge to the BRP.
Title: Re: 11-32 vs 11-34
Post by: zzzz on April 21, 2014, 08:20:40 pm
This has wondered pretty far off the original post but we've gotten into the territory of something I've wondered about for some time.

I went back and looked at the trace (I have a Garmin) from my ride from Vesuvious up to the Blue Ridge Parkway. The exact points are hard to grab and I never corrected the altimeter function but I picked a point at the bottom but where it was already showing as steep and it read elevation 1500' and milage 22.08 and then I picked a point near the top but it had not leveled off yet and it was elevation 2865' and milage 25.00.

So you've gained 1365' in 2.92 miles. You plug that into your handy/dandy incline calculator:

http://www.csgnetwork.com/inclinedeclinegradecalc.html

and you get a incline of 8.8%,(which seems awfully low for that hill)

It was 2 years ago now so I don't remember exactly but the Garmin was reading 10 - 13% the whole way up that hill. And this is not an isolated incident, whenever I'm on something steep and I check to see what the read out is on the Garmin and then cross check it against the incline calculator, the Garmin readout is 2-3-4% high.

Now, the math is the math. I'm sure the incline calculator is giving you the right % for the numbers you put in. But the Garmin is doing it's own math.

Any theories?

Pete
Title: Re: 11-32 vs 11-34
Post by: John Nelson on April 21, 2014, 11:36:01 pm
This has wondered pretty far off the original post but we've gotten into the territory of something I've wondered about for some time.

I went back and looked at the trace (I have a Garmin) from my ride from Vesuvious up to the Blue Ridge Parkway. The exact points are hard to grab and I never corrected the altimeter function but I picked a point at the bottom but where it was already showing as steep and it read elevation 1500' and milage 22.08 and then I picked a point near the top but it had not leveled off yet and it was elevation 2865' and milage 25.00.

So you've gained 1365' in 2.92 miles. You plug that into your handy/dandy incline calculator:

http://www.csgnetwork.com/inclinedeclinegradecalc.html

and you get a incline of 8.8%,(which seems awfully low for that hill)

It was 2 years ago now so I don't remember exactly but the Garmin was reading 10 - 13% the whole way up that hill. And this is not an isolated incident, whenever I'm on something steep and I check to see what the read out is on the Garmin and then cross check it against the incline calculator, the Garmin readout is 2-3-4% high.

Now, the math is the math. I'm sure the incline calculator is giving you the right % for the numbers you put in. But the Garmin is doing it's own math.

Any theories?
It's human nature. When you say that it was reading 10-13% all the way up the hill, that means that it was reading 10-13% every time you looked at it. But when did you look at it? When you were curious, of course. When were you curious? When the hill was the steepest.

This is why we think hills are steeper than they are, why we think headwinds are worse than they are, why we think we ride faster than we do, etc.
Title: Re: 11-32 vs 11-34
Post by: RussSeaton on April 22, 2014, 12:59:22 am
So you've gained 1365' in 2.92 miles. You plug that into your handy/dandy incline calculator:
http://www.csgnetwork.com/inclinedeclinegradecalc.html
and you get a incline of 8.8%,(which seems awfully low for that hill)
Now, the math is the math. I'm sure the incline calculator is giving you the right % for the numbers you put in.

1365 feet elevation gain
5280 feet per mile
2.92 miles
2.92 x 5280 = 15,417 feet
1365 / 15417 = 8.85%

As you said, the math is the math.  It works out exactly right.  As for 8.8% seeming low for the hill, well, that is the right percentage.

Whether you have a 32 or 34 big cog on the cassette, it won't make any difference climbing, you won't notice any difference pedaling.
Title: Re: 11-32 vs 11-34
Post by: staehpj1 on April 22, 2014, 05:34:11 am
As you said, the math is the math.  It works out exactly right.  As for 8.8% seeming low for the hill, well, that is the right percentage.
Yes that is probably the correct average percentage for the climb, but I can't think of two reasons why it seems low.  First, the climb is not really steady so if it certainly has sections that are steeper than the average and probably some short sections are substantially steeper.

The second reason is that many of the grades we are mentally it to comparing have signage with a percentage that is much higher than the actual grade.
Title: Re: 11-32 vs 11-34
Post by: salabes on April 22, 2014, 09:54:29 am
George here, original poster. Now that you guys have put a fear in me, and wandered off my original querry about the 11-32 vs 11-34 question, my take away is - spirits undampened but there's no shame in walking. If I'm not too proud to walk, then perhaps the switch to a 34 becomes irrelevant.  Fascinating discussion you guys are the best. Plan to leave Yorktown 5/31.
Thanks
George
Title: Re: 11-32 vs 11-34
Post by: John Nelson on April 22, 2014, 11:31:57 am
Different people here have posted different opinions as to whether or not you'd notice the difference between 32 and 34, but if somebody offers to give you either an 11-32 or an 11-34, take the 11-34, just in case.
Title: Re: 11-32 vs 11-34
Post by: RussSeaton on April 22, 2014, 04:24:22 pm
Different people here have posted different opinions as to whether or not you'd notice the difference between 32 and 34, but if somebody offers to give you either an 11-32 or an 11-34, take the 11-34, just in case.

Yes.  No one who posted about there being no real difference between the 32 or 34 cassette claimed the 34 was not easier.  It is.  A little bit easier.  But the difference in ease is negligible.  Probably never notice the difference if you rode both cassettes back to back.  Not worth spending money to change the cassette unless you just want to spend money.  If you have a free choice, then take the 34 cassette.  Assuming your rear derailleur will fit underneath the 34 cog.  Some derailleur hangers are sized so the derailleur cannot get under a 34 cog.  Just fits under a 32 cog.

The person who posted the question has a 44-32-22 crankset and 11-32 cassette.  Assume 9 speed on his Trek 520.  The 22x32 low gear is 18.2 gear inches.  At 90 rpm he is going 4.9 mph.  With a 22x34 low gear the gear inches are 17.1.  At 90 rpm he is going 4.6 mph.  At 80 rpm he is going 4.3 mph with the 32 cog and 4.1 mph with the 34 cog.  0.2 to 0.3 mph difference.  Can you tell the difference?
Title: Re: 11-32 vs 11-34
Post by: zzzz on April 22, 2014, 04:52:15 pm
To George (the original poster):

Good luck w/ your trip, I'm sure you're going to have a great time.

As far as your gearing/ equipment concerns, remember that nothing is set in stone. About 20 miles west of Charlottesville you're going to hit the climb up to the Blue Ridge Parkway. I was heading the other way but I presume that climb is going to be as tough as anything else your going to hit. The Parkway itself is pretty hilly but then you will drop down off the ridge line about 20 miles down the road.

Then you got about 200 miles of rolling hillside to decide if you want to change something with your bike. There's a beautiful little town called Damascus Va. right on your route before you hit the steep stuff again. Your map list's several bike shops in town but all except one are bike rental places that are of no use to you. There is one real bike shop, it's called Adventure Damascus. It's easy to spot, the facade looks like it's a replica of a 60's rock album cover.

If that first big climb shook you up, here's your chance to change your gearing. After Damascus starts about 250 miles of the hilliest part of the trip unit it flattens out around Berea, Ky. Also, there are post offices all along the way. If your not using something, get rid of it. You will notice every couple of lbs you can shuck off.

Pete