bikecommuter13

I have been reading about this from various sources and I think this is pretty conservative chart on what gears I should select on my 3 x 9 speed bike to avoid cross chain:

The left most column is my 9 speed, the lower row is my 3 chainrings. The X's are the ones I should be using. With this, I have only use 11 speeds. Am I being over conservative? Any other combo's are ok? I am thinking 36 X 26 should be fine.

asmac

Here's my take on it and I come up with 11 useful combinations that minimize cross-chaining while using the full range of available gearing with minimal gaps. The colours represent different chainrings and the X-axis is the cassette sprockets from small to big.

shelbyfv

At least one more in the big, maybe a couple in the middle. You can tell if it's rubbing, otherwise you won't hurt anything for the brief periods you would want to avoid a front shift.

nfmisso

One of my commuters is a 1 x 9 (44 x 12-36); no trouble accessing all nine in back, so unless your chain stays are really short, the middle ring should be able to access all nine in back - if the middle ring is centered on the middle of the cassette.

Our tandem is a 3 x 9 (54/44/26 x 11-34); again, no issues access all nine with the middle ring, the big ring will also work okay with the 34T when needed.

tyrion

I think you can use the middle 7 cogs in the middle chainring without issue. Remember, people are using 12 cogs all from the same chainring these days.

FBinNY 

This whole "cross-chain" is greatly overblown.

Nobody thinks anything is wrong with riding in low (small/small) yet riding crossed large to 2nd low is only marginally worse, and large to 3rd low is actually better. The same holds true in the opposite direction, and you can draw your own conclusions about the middle of a triple.

So, rather than obsess about it, understand that a properly set up bicycle allows riding in any combination, except possibly small/small on some 10s road bikes due to chain rub on inner face of outer ring.

So, feel free to shift according to the situation, ie. stay on outer ring, if you need only shift to the inner rears for a short while as you top a short climb. Of course, it's better for the chain, and more efficient to ride in aligned combinations, so try not to make a steady diet of more crossed combinations.

So, shift according to the situation, and don't fret when/if you find a crossed combination is working for you.

bikecommuter13

Nice take! Thanks!

bikecommuter13

Efficiency is the key. I didn't get this straight chain = efficiency idea util after 4 years of bike commuting

FBinNY 

Yes, but it's better to think about as a spectrum than good and bad.

70sSanO

While it is only 3x8, my wife can run all 8 off the middle chainring, without FD rub... barely. Efficiency sounds nice, but what you are saying is that a 1x9 with a properly setup chainline only gets 4 gears? Kids across the street are running 1x11 on their mountain bikes.

Even if in a theoretical, or your commuting experience, it is the best efficiency, I find it hard to imagine how you are not prematurely wearing out your chainrings when you are in a tweeter ratio between 2 chainrings.

John

ThermionicScott 

+1 to FBinNY's (and others') comments. One of the great -- dare I say beautiful -- things about a triple (as opposed to a compact) is all the overlap between the gear ranges. You can be riding along in one chainring, and dip into another chainring's gear range to get through a steep bump or dip in the terrain with quick and easy rear shifts, rather than being obligated to shift the front all the time. Of course, a triple gives you more opportunities for good chainlines than other cranksets, so you get the best of both worlds.

Racing Dan

This!

Racing Dan

My take:

Bicycle Gear Calculator

bud16415

I have weighed in before on the 3x9 question with regard to cross chaining. I tried every variety of 3x9 combos I could think of and finally the reality struck me. I was always looking at my total range of gear inches and then the total usable gears without duplication and keeping the smallest steps possible. Although the start and stop points of the range are important what is most important is the gear inch you are in when on the middle ring and the middle cog.

That should be your happy place IMO. I then wanted my gearing to radiate out in both directions on the cassette off the center ring like I was riding a 1x9. I consider the granny ring a completely different bike and the size of that ring can be whatever you need for the hills where you live. I always looked at that gearing as a 1x6 or a 1x5 range and never plan on using the outer 3 or 4 cogs. Once I set my gearing up like that I pondered long and hard what do I need the big ring for?

I was about to take it off and replace it with a bash ring and be mostly happy with a 2x9 when the old idea of half-step came back to me. I knew 42 was my magic number for a middle ring in the front and 12-36 with a 21t cog in the center of it was my happy place. I played with the calculators and found 45t was to be my new big ring as it gave me 6 new GI’s spaced perfectly in between my center ring GI’s.

I set the bike up like that and gave it a go and was very pleased and surprised by a couple things. The first being how easy the shift was in both directions going 42/45. Every bit as easy as a one cog shift in the back. The second and most impressive thing I didn’t expect was how good the straighter chain line felt off the big ring on the 3 smallest cogs. That and the fact I dropped from a 52t to a 45t made those gear much more likely to be used.

I have a 24t granny on now but I hung on to the 30t and the 26t. My bike is a tour bike that mainly gets used around town. I could see a person putting the 24t on to tour and normally use a 30t for commuting as the shift is a bit easier.

I love having the in between gears. I don’t shift up the half-step pattern like the old days. I just run across the cassette like it was a 1x9 but if the wind changes a little or the grade changes a half shift let me keep my cadence and effort constant and in effect gives me gearing like I had a 1x15 with granny without cross chaining.

Here are my numbers. 45-42-24 X 12,14,16,18,21,24,28,32,36
My Granny without cross chain will give me this GI range. (6 gears)
17.7
20.0
22.8
26.6
30.4
35.5

And my main rings with half step will give me these without cross chaining. (15 gears)The ones shown with the minus sign are the new half steps off the 45t.
31.4
35.3
40.4
47.1
- 50.5
53.9
- 57.7
62.8
- 67.3
70.7
- 75.7
80.8
- 86.6
94.3
- 101.0

bud16415

Hi Nigel
I agree with you and for myself if I was living in a fairly normal area with minimal steep hills. I would do exactly what you did with a 1x9 (44t front & 12-36t in the back) those look like really nice commuting gears on a light bike. And there is something to be said for the simplicity of a single chain ring.

I think almost all people do most of their riding in a somewhat flat area. The rest of the gearing is about the exception to the rule and if you need it or not. I know people live in mountains and climb hard half the time they ride, but most casual riders that live in areas like that I find load their bike on the car and drive it to a flatter place to go for a ride. I would also say most casual riders wouldn’t find the spacing on the 12-36 to be excessively large. Serious riders would want a finer spacing.

I like your gearing a lot and if I ever move from these hills I will give it a try.

bradtx

bikecommuter13, Everybody, with few exceptions, tries not to cross chain their drive trains, but I don't feel it should be taken too far, as in your example.

With a bum knee I have many triples and all are set up so that the middle chain ring can access all cogs, the inner chain ring is used primarily with the inner cogs, where that combination is needed and the outer chain ring is used primarily with the outer cogs. I often use the large chain ring with a cog somewhere in the middle, no problems.

With a derailleur system there is only one combination of cog and chain ring that might result in a correct chain line. Occasional cross chaining, even at the maximum, has little effect on component life.

Brad

asmac

Not at all. I'm saying is that, if you use all three chainrings, the ideal shift points are where my graph shows them to be.
Starting in the lowest gear:
Small chainring, use three sprockets starting with largest
Shift to middle chainring, then go three more sprockets
Shift to large chainring, then go the last three sprockets to the smallest


This yields 11 unique gear ratios.


Of course you can use other combinations if that pleases you but the chainline will not be as straight and you'll probably get some overlap. Around the city, I settle mostly in the middle chainring and do most shifting at the rear. Whether or not that actually matters I have no idea and I'm not too concerned about a 'perfect' chainline or maximum efficiency.

GAJett

Hey Bud,
I feel like a kindred spirit finding another with a passion for the half-step+granny! We've independently arrived at the same rear cluster and the same front middle and outer chain wheel difference, mine a 44 / 41. My first half-stepper was n the mid-70's, so some might think I drank the kool-aid early🤣. I describe the setup to others as a wide range compact with an option to "fine-tune" the upper range.

As to cross-chaining, if so many now run 1x10 / 1x11 / 1x12 it seems that the industry is now saying it's really not much of a problem. Only remaining problem would be the chain rubbing the next outer rings when on an inner or middle. Not the classic definition of cross-chaining!

One problem with half-stepping now-a-days is sourcing odd-toothed chain wheels. Other than TA Carmina/Zephyr do you know any others?

Another issue is the availability of front mechs. Mountain triples don't work. Any modern racing doubles work? The old ones often did (SunTour Cyclone & Superb, Campy Record & NR, even the delicate Heuret Jubalee!, among many)

70sSanO

This was my point. People don't ride on an efficiency graph. Even you won't adhere to it. In the real world people shift to their ability and terrain. Some people like half step but most people, IMO, with a triple will ride in the middle for rollers & city, big for wide ops flats, and small for climbing.

I run a 2x on my mountain bikes. 24 is for climbing or if I'm not sure of the terrain, 34 for descents and flats. Since I'm only running 7 speeds, spaced closer together at 8, I can easily hit all cogs with either chainring. It is imperative for me at my age to make sure I'm not caught in the 34 with a sudden terrain change. While not as critical on my road bike I try to select a chainring for a ride section and I don't constantly toggle between chainrings, unless I suddenly have to dump to the granny unexpectedly.

John

bud16415

I knew there had to be a couple other smart people in the whole world. Haha

Your set up might even be a smidgen better than mine as every tooth makes a difference shifting up from the granny gear. The 24 to 42 shift requires a little anticipation and a soft shift. With no load on the chain it climbs right up there. Like I said I don’t use my granny like asmac does as a continuation of the total range. When I shift to the granny it is a whole new mountain bike to me. there is even a 2 or 3 gear overlap between the granny and the middle and those gears are what you need so you have opportunity to pick when you want to do the shift back to the middle. The middle and large rings comprise another bike that is close to a double only totally overlapped in half steps. What I never liked about setup like a double or a road triple was that my sweet spot was centered on the cross over of two rings and like my old gearing 42,52 that shift wasn’t that hard to do but it was hard enough I didn’t like making anymore than I had to. The worst was when I had a mountain crank on it. The total range was about the same but then you are really shifting between middle and large all the time.

My front I set as low as I could to just clear the middle and it does look a little odd. I had planned on doing a little machining on it and making it down closer to the large ring. But it shifted great nothing drags or rubs so why mess with it. I did shorten the chain and that helped a lot with the rear not going slack with the smaller granny

The only odd tooth gear on my bike is the 45t big ring. I found some nice ones that were really expensive and I didn’t know how it would work so I bought a cheap chop-saw ring with no ramps. The jump 42-45 is so slight there is no need for pins and ramps and such. I was going to file some in if needed but never did. I also was going to drill some holes or do some fancy cutouts in the big blank chop-saw but I get enough comments on it and opportunities to explain half-step I never got around to making it look like a road ring. I still might chop off the 5 inner tabs for the smaller BC.

As you know a half step with a 9 speed is so slight at first I found myself looking down to see if it shifted. It is really like having a 15 speed cassette.
Here are some pics of the ring I used if you are interested. https://www.bikeforums.net/touring/85...8-32-36-o.html

79pmooney

I've been using the middle ring and the entire cassette (FW) for more than 40 years. The cross-train gods haven't struck me down yet. I try to stay out of the bottom two cogs on the big ring and small ring is limited to whatever cross-over I can achieve without too much chain rub on the larger rings. (Pinned middle and large rings are a curse here.)

One thing I do is try to always use middle chainrings big enough that I am not using very small cogs on normal flat ground riding or the big ring on big cogs. 42 tooth middle ring means I am riding 15 and 17 tooth cogs a lot; nicely located near the middle of my cassettes. (I spent one year a dozen years ago on a 53-39 racing crankset. Hated it. The 39 was too low to be a good flat ground ring and not low enough to be a good climbing ring. Spent a lot
of time in cross-overs and did a lot of double shifts. Compact gearing strikes me as a step worse except that you can go uphill.)

Ben

corrado33

Seriously, you're blowing this out of proportion.

On my 3x9 commuter (overkill, I know) I stick in the middle chainring most of the time, and do the majority of shifting in the back. If I'm flying down a hill I'll kick it up a chainring.

I rarely use the small chainring.

You can definitely use more than 4 gears when you're in the middle chainring. At LEAST 7.

If you shift like you have above, you're going to get annoyed with front shifting quickly.

bikecommuter13

So it happened like this. I bought a brand new fuji touring. Rode it for about 100 miles and brought it to the shop to find out why the shifting isn't 100%, not even close to 60%. After some adjustment, the mechanic pointed out some teeth in my smallest cog are bent. He said it must from cross chaining. I have never use the big ring and the biggest cog or small ring with the smallest cog. But I have use the middle ring with the smallest cog a lot. He said it must be from that. I am not sure if he is right. It's brand new bike...

Anyways, instead of using the middle ring with the two smallest cogs, I think I can do better by using the big ring with the 4th and 3rd small cogs

And regarding to the shifting, it turned out the rear derailleur was not aligned properly. They did some adjustment again, it's better, but still not 100%...

Slash5

Way over thinking this.
Ride in the middle ring. If you hit a hill and run out of large cogs, shift to the granny. Once you are done with the hill, shift back to the middle ring.
If you need to go faster than possible on the middle ring, change to the big ring.
Try not to use more than a couple of large cogs with the granny - but sometimes **** happens.
Try not to use the smallest cog when in the middle ring - but sometimes **** happens.
Try not to use the largest cogs when in the large ring - but sometimes **** happens.

You will find you'll break these guidelines - rolling terrain, a steep hill with a bit of relief in the middle, etc. You can trust a rear shift more than a front shift so when conditions are poor like steep hills or when you need to pre-shift you might need to break the guidelines.

I very much doubt you bent teeth from cross chaining.

HTupolev

I've spent a lot of time doing small-small on doubles, and riding in the small cog while in the middle ring on triples. I've never seen nor heard of that bending teeth.