RLinNH

I gotta ask. Stopped by my LBS yesterday evening while riding by and had my mechanic check my shifting out. It's a new bike that barely has 300 miles on it. Anywho, he propeed it up in the bike stand and asked me to look at what gear I was in. I then told him "A very bad one. I'm cross chained." He nodded his head and told me that was very bad. Now, I have known for many years that cross chaining is bad. I just have never had anyone explain to me why it is bad. Does it place unnecessary stress on the chain? That's all I can come up with.

lostarchitect 

It causes a lot of wear to the drivetrain, which shortens the life. Plus it's usually noisy.

Al Criner

Stress on chain, chain rubs on front derailleur or large chain ring, adds unnecessary friction which is inefficient and accelerates wear, more likely to drop a chain, noisy.

Bill Kapaun

It increases wear on the chain and teeth.
I typically run my 3X9 as a 1X9 using the middle ring.
I don't worry about it. In the whole scheme of things, I'm not worried about spending a couple $ more per year on my drive train. It's worth the convenience.

I use a slightly long BB spindle that moves my chain line about a cog further out than it should be and spend little time in the 2 largest cogs.

FBinNY 

Yes, the issue is a higher wear rate, and nothing else (except that many 10s and 11s bikes cannot be ridden in the small/small combination because the chain snag's on the inside of the outer chainring).

You get added wear two ways.

1- the chain rubs the sides of the teeth as it engages and disengages at an angle, causing added friction and wear on the affected surfaces.

2- it causes more concentrated bearing loads on the pins, as the force is concentrated on one end or the other. This can bring the pressure above the film strength of the oil and accelerate wear.

To visualize this imagine sawing a thick limb or chunk or wood. To get through it faster, you rock the saw so you're sawing on a narrower face and the saw can take deeper bites. As the area you're cutting gets broader, you rock the saw again and attack a narrower front. Flexing to one side as it bends onto a sprocket works the same way to increase the bite and saw through the pin faster (but not that much faster).

BTW- while there who consider cross-chaining a no-no, I'm not nearly that down on it. I'd characterize it as not so god, rather than bad. It's like ice cream, OK from time to time, but not as the mainstay of a diet.

joeyduck

I run a 3*9 with a 48 big ring and a 11-32 cassette. I ride nearly exclusively in the big ring.

I cross-ring. To me I prefer to cross ring a little than need to switch the middle ring. As mentioned above a bit of wear on my commuter is not a concern. The wet gritty winters make a bigger impact on my chain and cassette.

I tend to start in the 48-28 combo. On hills I will occasionally pop up to the 48-32, but not long less than 500 m. So I do not do it much.

But I just got a bike with a double (53-39) and 12-23 9-speed cassette and I need to figure out my ratios since I need to shift between front rings without question.

chasm54

Actually, on 10-speed and 11-speed drivetrains, cross-chaining is a trivial issue. The chains are engineered to be more flexible than their thicker cousins, and the additional wear on both chain and cassette is quite small. If you're running a standard or compact double crankset, it's perfectly normal to run up and down most of the cassette in each chainring. The horror expressed at crosschaining on modern equipment is an anachronistic hangover from the past.

ThermionicScott 

Like you, I tend to hang out in the big ring most of the time, only shifting to the small ring to climb hills. One thing to consider is reducing the size of the big ring -- removing any unused gears at the top -- so that it becomes more useful for all-around riding. I like a 48T or 50T on my bikes, which have 130 BCD "standard" cranks.

zacster

I never worry about it anymore. It may wear out your parts faster but I replace mine every now and then anyway. It isn't like you are going to ruin the whole bike, just a chain and cassette/.

prathmann

Never found it to be all that bad in the past either. But on some drivetrains certain cross-chained gears do cause problems. As someone mentioned above, there are cases where the small/small combination has the chain nicking the teeth on the large chain ring and others where large/large results in very noisy operation which is probably associated with extra wear.

On my first derailer bike ('70 Varsity) the gears felt nice and smooth in all cogs on the small ring and I used small/small quite frequently without any issues. But on that bike the largest two cogs in combination with the large chain ring were noisy and added noticeable vibration when pedaling so I tended to avoid them. Conversely on my current Cannondale all the cogs work equally well in combination with the large chain ring and I frequently climb using the large/large combination instead of shifting in front. But the small/small combination feels rough and I avoid staying in it for any length of time.

etw

Other cyclists will look down on you with scorn. Most won't wave.

gregjones

Gear Calculator

Plug in your numbers. Then go down to the "Speed over RPM Range" chart and check the "Sort" box. It will lay out how the cassette cogs fall into place in relation to each other on the chainrings. You can see at a glance where your ratios overlap.

FBinNY 

Don't over think this, you're not a machine which depends on gauges and telemetry to know what's going on. Your legs will tell you through the same biofeedback system that we all use all the time.

If you're working too hard on a hill, and need a lower gear, shift to one. If you're spinning and feel you could produce more speed, shift up. At some point along the line, you may have to shift the front over. Do so wherever it makes sense, but if downshifting on hills, before the RPMs drop, so it shifts smoothly. After a short while you'll be reading hills, and making a judgement about the gear changes you'll need and plan the FD shift within the sequence accordingly, is, not at all, or 1/3rd of the way up he hill, or whatever.

There are no rules, only what works for you ---- today, because things can change daily depending on how you feel at the time.

LastKraftWagen

I didn't see it herein, and it's probably more of a tandem bike issue, but even from the factory you may get a bike/model where the derailers won't handle the cross chain, not with wear but with capacity. You may get a chain a bit too short for the big/big combination, or more likely, your RD won't have the capacity to handle the small/small without the chain resting on the chainstay while coasting.

Like I said, probably more likely on tandems and the mixed groups we often get on new bikes.

crazyjons

It's not always bad. What IS bad is a rider that can't tell when it IS bad!






Other than that, keeps us selling new drivetrains.



Jon

RR3

Friction. Slows you down and costs you money.

"Bad" depends how much you ride, components, and your budget.

Rings can run $350 or $50 a set, cassettes $400 or $40, and chains can be $60 or $15. Some riders do 1,500 miles per year and others do 15,000. I very rarely use the two biggest cogs with the large chain ring and never use the two small cogs with the smalll chain ring. If I need to jam a hill to remain in contact, I will keep it in the big ring and use the 25T

bradtx

RLinNH, Cross chaining isn't the end of the world. My older daughter does it on a regular basis (big-big) and there's no breaking her of it. A friend of mine cross chains big-big commuting and turned her chain ring into a ninja weapon; it cut her husband's fingers when he serviced her bike. I don't remember the mileage that it took, but it was well over 5K miles, possibly closer to 10K miles.

I don't like cross chaining because it induces needless friction and accelerates wear, primarily on the chain.

Brad

joeyduck

@FBinNY. This is what I meant. I just need to ride it more to get a feel. It is tough to commute on it when I need to take my son to day care. I am limited to one weekday ride and one on the weekend if the legs hold out