Technical FAQ: 12-speed chain with 11-speed Derailleur, brake mineral oil compatibility, bike shaking in the wind

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Dear Lennard,

I read somewhere that people use 12s chains on Shimano 11s drivetrains to quiet them down a bit. I was curious about this and Googled around a little to see what the different external widths of chains are. This led me to an old post of yours discussing using an 11s chain on a 10s drivetrain. You mentioned that the space between derailleur cage plates might be a factor. Why would using an 11s chain on a 10s derailleur be an issue, or a 12s chain on an 11s derailleur, for that matter? What are your thoughts on using a 12s chain on an 11s drivetrain to quiet it down a bit? I’m not worried about indexing since I run a fun, manual transmission, but I do have to really dial in the adjustment to keep the noise down.

—Ray

Dear Ray,

Good for you running a “manual transmission!”

I only meant that the narrower chain has enhanced ability relative to a wider chain to jump off of the teeth of one of the lower jockey wheel and sit alongside it and grind away on the inboard side of the derailleur cage plate as the chain continues to be driven forward. Anybody who has experienced this as a recurring phenomenon is aware of the annoyance of it. Each time the chain pops off the jockey wheel and continues to be driven forward alongside the cage plate, it removes material from the plate. A carbon-fiber derailleur cage plate will wear away particularly quickly, and it tends to be pretty quiet while this is happening, so you might ride for some time this way without noticing. The more worn-away the plate is alongside the jockey wheel, the less the cage is able to prevent the chain from jumping off of the jockey wheel, so the more it happens, so the more the plate wears, so the more the chain jumps off against it, and so on.

If you start with a narrower chain than the derailleur was designed for, it’s as if you are starting with this process already underway. You have made it easier for the chain to come off and rub more material off of the cage plate. Due to bouncing of the chain and derailleur, this derailment is more common during gravel riding, and the noise of the tires on the dirt and washboards makes it less likely that you will hear the chain rubbing inside the derailleur cage, so it will merrily grind away on it until you stop and re-center it on the jockey wheel.

― Lennard

Dear Lennard,

I’m building up a Campagnolo Ekar group and I have a huge bottle of Shimano mineral oil. Is there any reason I cannot just use this, or should I really go with Campy or Magura oil?

—Pete

Dear Pete,

You can use Shimano hydraulic-brake mineral oil in your Campy brake. On this bike, I used Magura Royal Blood mineral oil in a Campagnolo caliper connected to a Shimano road lever. It works fine. I can see no reason why it wouldn’t work the other way around.

― Lennard

Dear Lennard,

I have a question regarding geometry.

Currently riding a size Large Chapter2 Rere. I crashed heavily coming down 93 towards Marshall Rd. just outside Boulder a couple years ago when a strong crosswind caused the front of my bike to start oscillating uncontrollably, sending me into the roadside ditch. I was trying to slow down at the time, but the front seemed to bob up and down violently. Was running a pair of late-model Mavic Cosmics at the time (the updated U-shaped profile version).

Since then, I simply don’t feel stable descending on it, with or without any sort of crosswind. Compared to my older bikes that have always felt super planted and stable up to even 60mph, the Rere has a 2.1cm shorter wheelbase. My older Scott Foil was always rock solid in that regard. My fit on the Rere is good and hasn’t changed in decades. Was recently fitted at Retül and they didn’t change much other than lowering saddle a bit (getting older).

Could it be the shorter wheelbase that is causing this or is it just in my head? Was coming down Lee Hill Road this past weekend and basically dragged the rear brake the whole way as I was scared that the wobble would come back.

—Evan

Dear Evan,

The chainstay length contributed to this only in the same sense that everything in the bike’s design contributed to it bucking you off; I have a high degree of confidence that it was by no means a determining factor. Rather, that frame is unable to properly control the out-of-plane twisting of the front and rear wheels relative to each other with you on it. This is high-speed shimmy, and in general, it is caused by insufficient torsional stiffness of the frame for the rider aboard.

It can be caused by a crack in the frame taking away its stiffness, as happened to Chris in this column. Or it can be caused by insufficient stiffness in the design and layup of the frame.

I suppose it’s also possible that the larger side area this aero road frame and wheels present to the sidewind contributed in a way similar to that described here in this discussion of the 1940 collapse of the Tacoma Narrows bridge. The twisting of the vertical girders as the wind blew against them from the side created oscillating vortices behind them that added to the torsional twisting of the girders.

I have written about frame shimmy a lot, and you can follow links back in this column to more theoretical discussions of it. Suffice it to say that either your frame is cracked and needs to be repaired or replaced, or it was built that way and simply won’t work for you. In general, the taller the frame and the heavier the rider, the higher the likelihood of high-speed shimmy, and crosswinds always exacerbate it.

By the way, you are one of many riders to contact me over the years after having crashed on that same descent due to their bike shimmying. For those unfamiliar with it, that descent is the fastest section of the Morgul-Bismarck course (northbound highway 93 into Marshall), made famous by the Coors Classic and featured in staged crashes in American Flyers. I have ridden it innumerable times and raced on it many times as well, even winning on that course once (in 1980). Every bike I have ridden on it over the past 43 years has behaved differently on that wide, multi-lane, high-speed descent with a frequent strong, gusting crosswind from the west made gustier by cars passing at over 65mph. It’s a perfect scenario for a bike prone to shimmy to have those oscillations increase in amplitude to the point that the rider can no longer hang on. While I have never crashed there, I have certainly felt a lot less stability and control on some bikes than on others and slowed down accordingly. I felt super confident on that descent on the bike I won the Morgul-Bismarck on. On the final lap, I held a super-tight tuck the entire way down that hill and got a big gap on my breakaway companion, whose bike didn’t give him that same feeling of confidence. I soloed the remaining miles to the finish.

― Lennard

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Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder and purveyor of non-custom huge bikes, a former U.S. national team rider, co-author of “The Haywire Heart,” and author of many bicycle books including “Zinn and the Art of Road Bike Maintenance,” “DVD, as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”
He holds a bachelor’s in physics from Colorado College.

Follow @lennardzinn