How much of a difference would one notice in 1.9 gear inches, climbing wise? I am looking at two different cranks, one of which gives me a low of 20.2, and the other a low of 22.1. I can't go higher on the cassette without changing out the derailleur, and if it isn't such a big deal, I find the middle gearing on the crank that gives me 22.1 at the lowest to be more useful (plus the all important it looks better).

Also, what differences would I notice in going from a 170 to a 175 crank arm, if any? I have no specific reason to make the change, other than price difference, at the same time this bike is the only one of mine with a 170, everything else being 175.

Not much difference. I recently rode part of the Blue Ridge Parkway and was concerned my gearing might not be low enough with 26 x 32 and 21.1 gear inches. On previous touring bike I had 24 x 32 for 19.5 gear inches. I found the 26 x 32 worked well enough for 15%+ grades with camping gear, etc. On the steepest sections I was riding about 5 to 6 mph; any lower gearing I would probably have to walk the bike.

10% is normally noticeable, though those are both very low gears, and 22 inches is low enough for just about anyone. It can be hard to balance when you go that slowly.

Yeah, that is what it currently has, I can barely ride the bike in that gear on level ground. It doesn't get used much where I ride now. Never thought of the balancing with bags angle.

Given how low 22" is to start with, I wouldn't make another 2" drive your decision on the crank. As others have mentioned, there is a lower limit on gearing below which the issues of balance make walking more practical than riding precariously. That being said, you really need to get on some 10%+ slopes with the load you plan on carrying to know whether you need lower and to assess your own sense of balance and the ride vs. walk decision.

Some like especially long or short crank arms as they prefer spinning vs. torquing up hills and there is the issue of cornering clearance, but if you don't have a decided preference, I'd let your height and frame size dictate - go with the 175 if you're taller than 5'-10" and/or ride a bigger than 56cm frame.

- Mark

While 10% is about one full gear step, I'd prefer better closeness in the mid range where I ride 90% of the time, to that extra step at the bottom end, that I might need now and then. Of course, it will cause some regret on that steepest climb, but I'm sure you can tough it out.

Your leg will be 10 mm higher at the top of a pedal stroke. (The saddle height is based on the distance when the crank is at the bottom, and there's 5mm more at the bottom and the top.)

The longer crank is 175/170 = about 3% easier when climbing.

I replaced my chainring with Deore XT that had a 35% discount. (In anticipation of riding in some mountains, before breaking some ribs last spring.) I certainly could tell the difference in going from a low of 20 to 17.5 g.i. on steep hills with a heavy steel bike and camping load. The steep discount was only on a model with 170 mm crank arms. I never noticed any difference in going from 175 to 170.

22.1 gear inches is 9.4 percent higher. I would notice the difference.

You already know that you can pedal with a 175mm with no knee problems, so that is not an issue.

A 175 will give you a bit more torque, a bit under 3 percent difference so probably not noticeable for most people. And 175mm will drop your cadence slightly. One of my bikes has 170, other bikes are 175mm. I do not really notice the difference, but for hill climbing if I had a choice I would pick the 175 for that little bit more torque.

My Rohloff touring bike, I had to decide what chainring to put on it when I built it up. I concluded that for touring where I might have tall steep hills I wanted to have a cadence of 72 at 3.5 mph. That cadence is the slowest where I feel that it is a smooth stroke and that speed is the slowest that I can easily maintain vertical and directional stability. I calculated that I wanted a lowest gear of 16.5 gear inches to accomplish that.

That said, my derailleur touring bike has a low gear of 19.2 gear inches. If my heart rate goes too high when climbing hills on that bike, I get off the bike and walk it up the hill at a slower speed.

Both my derailleur touring bike and Rohloff touring bike have 175mm cranks.

[MENTION=406915]jefnvk[/MENTION], You will be able to tell the difference between the two grannies, but there may be no real consequence choosing one over the other. My touring bikes are 3 GI different in the granny.

I don't spin my 175 mm crank arms as fast as my 170 mm crank arms and even though I know there is a leverage advantage with the 175 mm crank arms, I can't really feel it.

Brad

My low gears are at or near 20 gear inches. I appreciate that one last gear when loaded; unloaded, it doesn't make much difference (usually). Starting on a steep hill in the low gear is sometimes difficult, but I've been able to balance once I'm clipped in. I don't know how much lower I could balance, but with experience I can easily balance even with bags.


Of course, YMMV!

Take this as a compliment; I would not take gearing advice from someone who rides roads with 40% grades.

I have toured fully loaded in various terrain over the years, and my drive train has evolved based on that experience. Today, we run 44/32/22 cranks with an 11-34 cassette for 17.2 GI. In the Swiss Alps, even with this low gearing, it still required pushing at times.

My wife, an excellent bike handler, can ride up steep hills fully loaded at 3.5 mph at about 60-70 RPM without a wobble. If you ever hit really long steep climbs, you will appreciate the low gearing. It is much more efficient to ride up a hill at 3.5 MPH than to push it up at 2 MPH ( I'll post the reference if it is wanted, but I really don't want to look for it now).

I also believe it is much easier to ride smoothly when there is some resistance from the pedals. Ridding a low gear on flat ground is not the same as riding low gearing on a hill.

I've never felt the need for a higher gear on a tour, but I often wished I had one more shift

jefnvk,

What rear cassette are you running now? I believe that you will notice a 10% difference.

At those grades I walked and pushed my bike. When grades got over 20% to 25% for a distance more than 100 yards, I tend to walk. Too exhausting to ride on very steep grades. I recall in Lake Jocassee area there was a stretch about 1 mile where the grade was about 11%, and after facing those steeper grades, the 11% felt so refreshingly easy.

What I found is that on normal steep roads (15% and less grade) I can ride with the 21 gear inches for a few hours, then when exhaustion hits, it does not matter what gear inch I have, I am walking the bike so my heart rate doesn't get elevated.

yes, you will notice the difference.
and no, it's still not low enough for heavy loaded touring
in big hills. 16-18" mucho gooder.

so you can barely ride it in that 22" gear on flat ground?
course not! those gears are not meant for flat ground.
is the same as saying 108" gears are useless cause
you can barely ride up a 22% incline.

the point of super low gears is you can ride up really
steep hills for a really long time WITHOUT getting
exhausted. don't know about others, but i can ride
up a 10-12% for 6 hours straight at 6 km/h without
getting winded. (32-40 km long hills) okay, maybe
a couple pee breaks, and some stops to take photos....

you're not "spinning" up at 120 rpm wearing yourself
out. that's fine on a short stretch, but for long hills
pretty much continue at the same cadence as the flats,
just moving forward slower.....much slower.

Rear tops out at 28t, I can't go any taller than that without replacing the derailleur. I'm between a 24t and 22t front.

1.You will notice the difference
2.There is no such thing a too low, go for the lowest gearing you can, your knees will thank you.

You would see a real jump going from 28 to a 34. What speed cassette is on your bike? That era was usually a 7 or 8 speed. For about $65 you can replace the RD, chain and cassette. If you are getting this bike ready for your Iceland tour, it might be a good investment. A 24 tooth chainring and a 34 rear cog will give you a 17.3 GI setup with 26" wheels. The bike tourists I talked to there said the wind was the biggest challenge. I was not bike touring when we were there, so I don't have any first hand experience. But it was windy! A few more low gear options are also nice to have on the middle chainring.

Another person who can feel the difference between 22 and 20.
Sure, depends on total bike weight and terrain, but I'd clearly to for the smaller granny.
There will be times as Doug says that you'll be searching for more downshifts.
Take care of these knees.

Very well written, but unfortunately I find a lot of folks just don't believe this.
I certainly get wanting to have closer ratio shifts, I love riding a tighter cassette, but there clearly a are riding environments and total bike weight times that it's advantageous having the lower gears.
I'll be heading off soon to an area where I know there will be stupid steep roads at times, and I'll be carrying more weight than usual due to various factors, so it was a no brainer from my past experience in similar riding terrain with less weight and 19.5g.i to go to a bit under 17.

I think you'll notice a difference. I went from 32 to 34_ on the rear and it makes some climbs easier. I also agree that 20" gears are not too low. Loaded touring up steep climbs will almost always make you want lower gears. Plus I think a 175 crank gives me better climbing ability but I have a 170 on my commuter and its OK too.

Don't bother looking it up, when I get off the bike and push it is not for efficiency.

If my heart rate goes too high at my minimum speed, I get off and push. And when I do that I push at a speed that gives me a better heart rate. In those situations I do not care about efficiency. To maintain vertical and directional stability, I need about 3.5 mph. Some people claim they can stay upright at 2 mph, and if they can I am impressed, but I need about 3.5 mph. But 3.5mph on too steep a hill is more wattage than my body can produce at a sustained rate.

I have also gotten off and pushed on shallower hills, but that was because I spun out. With a gear of 16.5 gear inches on my expedition bike, that results in a lot of torque on the wheel when I am working hard and I have had the rear wheel spin on loose gravel or cobbles which caused me to come to a very rapid halt. I now go up really steep gravel hills using the platform side of my pedals so I can get my feet on the ground faster if I have to. And when I am on a hill like that, it is just too steep to get started up the hill after I have stopped.

I have never had any heart problems yet, but three of my cycling friends in the past five years have ended up in the emergency room with heart issues. So, I do not overexert.

It is a 7 speed. I know it is cheap enough to do, I just like making old things work if I can, plus the whole question of tossing shiny new things on something that was budget to begin with.

My other option, as it seems like after digging around last night, Shimano maybe didn't quite give you the real specs on what the derailleur COULD do, just what the particular group was built with. As a GS length, everything I've read is I should have more capacity than 28t, what I might do is to go with the 14-32 and just see if it works. From looking at what combos I'm in on my other bikes, I think the 14t gearing would keep me in more useful gears than the 13t or 12t that the 34t 7-speeds are available with anyhow. If it doesn't work, I've got the justification to go to a new derailleur. 32t should get me under 20" with either crank.

Tourist, as with most things, what works best for you is what works best for you.

For me, and as Saddlesores wrote, its just plain harder for me physically to push a loaded bike up a hill. Hard on the arms especially, so I'll take an easy low gear spin at 5, 6, 7kph anytime over working waaaaay harder pushing a bike up this steep bit.

ultimately, each person has to figure out what works best for them for a given bike weight/terrain steepness/terrain surface and all of the various factors that vary from rider to rider.
There is certainly no right answer, just suggestions coming from lots of personal experience.

I agree completely with that, I'm just trying to find a suitable starting point for myself. My last (first) tour was credit cards in a land of bars and flat land on a road bike, what I learned there is not really transferable to wilderness with camping gear and hills on gravel roads in the middle of nowhere, other than how not to overpack panniers and not to buy another adjustable rack.

I may be over analyzing it way too much, but hey, I've got long periods of downtime at work I've gotta do something with!

If the 22 GI has the 175 crank, then it's a no brainer. I went from 165 to 180 with a SA 5w and it was night and day difference going up slope. It also stretched the range of each gear. Now going back to my 165 crank derailler, it feels like the BB is behind me somewhere. My Rohloff had 48T at 23 GI, not great. Now I will try 21.8 with 46T smaller front. High gears are useful to preserve momentum, no doubt.

My experience with walking is that I was doing 3.2 mph, only 1 mph diff. Sometimes I get behind someone and can ride that slow alright.