By Jim Langley

Before we get into this week’s main subject – paceline safety responsibility – I want to share a couple of helpful comments that came in about last week’s column on diagnosing chains that fall of the chainrings. Readers Chuck and Frank added that front derailleur adjustment issues can cause chains to fall off, including a bent derailleur cage and improper limit screw adjustment that lets the derailleur throw the chain one way or the other. Let’s look at these issues:

Bent front derailleur cages

It’s relatively easy to bend a derailleur cage if you get something like your pants or a shoelace snagged on it while pedaling. Try to avoid this and if something snags, check if the cage is now crooked. If it is, first make sure that the derailleur is tightly attached to the frame. If it was even a little loose, it might have only moved out of position, not gotten bent. If so, simply move it back and tighten it. If it turns out that it was bent, gently bend the cage back where it belongs (an imaginary line bisecting the cage should run parallel with the chainrings).

Tip: Whether it clamps on the frame tube, is bolted onto a mount brazed to the frame or to a mount that’s screwed onto the frame, if the front derailleur loosens, it can throw the chain and/or move and possibly get damaged when it’s shifted. For these reasons, I recommend checking the bolt(s) that hold the front derailleur in position at least twice a year. Some carbon and aluminum frames have bolt-on front derailleur mounts with small hidden allen bolts. Don’t forget to also check them if you have them.

Limit screws another possible culprit

While derailleur limit screws don’t normally change adjustment, if they were adjusted even slightly off, as the drivetrain breaks in, that slight maladjustment can lead to issues. If the chain is thrown to the inside, you need to turn the inside screw clockwise. And for chains thrown to the outside, do the same with the outside screw.

Checking chainline on triple drivetrains

Another reader, Gregory, also asked how to check your chainline when you have a triple crankset.

Oops, that was an oversight on my part. I meant to explain that last week and forgot.

To check chainline on a triple, you ballpark it by putting the straightedge between the small/medium chainrings, followed by between the medium/large chainrings. In each straightedge position, you note where the straightedge rests on the cassette and find the middle point.

That middle point should be on the middle point of the cassette if you have a perfect chainline. Checking this way is not as easy as with a double since you have to eyeball it, but it’s still pretty easy to see if your chainline is off, and by how much.

Maybe a better way to check chainline?

Final thought on chainline checking: I haven’t tried this, but there might be a way to check bicycle chainlines by first marking the bike’s centerline with a laser level. If that was possible, you would only need to measure from the center of the chainring and the center of the cassette to the laser-marked chainline and compare the measurements to check your chainline very precisely. Maybe someone who knows laser tools can tell us? (Comment below the Newsletter version of this article, if so.)

Post paceline-crash thoughts and questions for you

While it may not seem like a technical topic, riding in pacelines is highly technical and not understood well by most riders – regardless of how experienced, fit or skilled they are otherwise. We’ve provided lots of expert guidance over the years. Here are 3 good pieces we've done on paceline rules:

Paceline are on my mind because of a crash I was in last Saturday. Don’t worry, apart from bruises and very minor road rash, no one was hurt. But I and my friend in front of me hit the deck at about 25mph. The fall taco’d both of his wheels, so we landed hard.

The primary cause of the crash was a squirrel that caused my friend to brake and slow suddenly and rapidly. As you know there are no brake lights on bicycles (at least none that work instantly in a situation like this). Also, no one yelled or pointed out the hazard. And I never saw the critter. So I had no warning at all.

I realized I was about to rear-end my buddy just in time to throw my weight left to try not to hit him straight-on. And, though, I ended up flat on my back on the pavement, I think I smashed into him first, which knocked him down, and may have been what destroyed his wheels.

Whose fault, or whose responsibility, is it?

My first adrenaline-fueled angry thought just moments after crashing was, “Who the heck hits the brakes in a paceline?!” Learning pacelining with the Putney Bicycle Club back in Vermont in the '70s, we were coached to never, ever hit the brakes in a paceline unless you were at the very back of the line. The reason is that everyone behind you is relying on you, and you can cause a big pile-up through your actions.

If a dog darts out from a yard (or a furry-tailed rodent) you don’t want to hit the dog and crash, but you know that even more important is letting the riders behind know about the dog. So you shout or point out Fido and take whatever evasive action you can, but without endangering the folks behind.

I didn’t bring all this up to the other crashee because as I started calming down from the jolt of the crash, it dawned on me that he had actually seen the squirrel while I hadn’t seen anything. It turned out that two other guys had seen it, too. So, obviously, I was not paying as close attention as they were. So, I feel like it was my fault that I crashed, too.

However, I still believe that as a rider in a paceline, you should never brake hard enough to risk crashing those behind. And I would also say that it’s everybody’s responsibility when riding in a paceline to shout and/or point out hazards. And to never assume the others see them and don’t need a warning.

Hopefully, these simple safety tips will keep the shiny side up for you on your group rides.

It would be interesting to get your take on whose responsibility it is to keep everyone safe in a paceline? Maybe we can all learn something? Please Comment below the Newsletter version of this article. We'll report back on your feedback.


Jim Langley is RBR's Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He's the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his "cycling aficionado" website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim's streak of consecutive cycling days has reached more than 8,000. Click to read Jim's full bio.

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